Rozprawy doktorskie: „Gold ores”

1

Leeming, Prudence Mary. "Turbidite-hosted gold deposits". Thesis, Rhodes University, 1985. http://hdl.handle.net/10962/d1005939.

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Turbidite-hosted gold deposits contribute a significant proportion to world lode gold production and have also provided substantial gold to alluvial resources. Turbidity current deposits occur throughout geological time within Archaean greenstone belts, Proterozoic orogenic belts and rifted passive continental margins, and Palaeozoic geosynclines. Representing the end member of the sedimentary cycle, turbidites have the attribute of preservation not only on an individual bed basis but also due to below wave base accumulation in submarine deeps. Cyclic deposition according to the Bouma sequence punctuates turbidite deposition by a series of diastems. Accumulation of organic, pelagic and chemical sediments may concentrate gold to protore enrichment levels i n a primary sedimentary environment. Dewatering during diagenesis and low-grade metamorphism under reducing conditions may redistribute gold with transport as low energy organo- and thio-complexes. Gold may precipitate with diagenetic pyrite and silica near black shale and/or partially replace fine carbonate detritus. Gold solubility increases with high grade amphibolite facies metamorphism (T 400ºC) when efficient leaching of gold and transport by simple chloro- and hydroxychloro - complexes to lower greenschist regions takes place. Reduced permeability of turbidite strata induces hydrofracturing which focuses dewatering solutions. Gold is deposited due to pressure and temperature decrease or local changes in physico - chemico conditions caused by the reaction of fluids with wall rocks (reactive beds in turbidites are predominantly carbonaceous strata). The largest of turbidite - hosted goldfields are confined to back -arc or marginal sea basins with restricted oceanic circulation. The richest concentrations of gold occur proximal to the original source within the greenschist facies formations lowermost in a thick turbidite sequence and exhibit strong combined structural and lithological association. Turbidites represent important strata for the concentration and preservation of gold not only during sedimentation and diagenesis but also during later deformation and metamorphism.

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Slabbert, W. L. "Ore distribution controls of the Navachab Gold Mine, Damara Belt, Karibib District, Namibia". Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1016364.

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The Navachab Gold mine, an orogenic lode gold deposit, is located in the Karibib region of the Pan-African (ca. 550-500) Damara belt of central Namibia. Gold mineralisation is developed within the steeply NW dipping limb of the Karibib dome. Here, ore envelopes trend along three main orientations: a) trends shallowly towards the NE (the down plunge extent), b) trends sub-vertically in and along the down plunge extent and c) trends sub-horizontally across the down plunge extent. The down plunge extent represents the bulk of the gold mineralisation, hosting the only high grade ores mined at Navachab. As such, past work primarily focused on establishing the controls to the mineralisation observed here. The sub-vertical and sub–horizontal ore trends are seen as secondary, lower grade, being hosted in the footwall. By cutting pushbacks into the footwall, in an effort to regain access to high grade pit bottom, future gold production almost exclusively relies upon optimally mining these ores. This underlines the importance to investigate and outline the mineralising controls to the secondary ore trends. This study identified the following prevailing quartz vein sets developed within the footwall, set (1) dips shallowly towards the NE (conjugate vein set), (2) steeply towards the NW (bedding parallel veins) and (3) steeply towards the SE (S2 foliation parallel). The NW and SE dipping sets contain high average gold grades, occurring at an infrequent vein density. The NE dipping veins, as a result of occurrence density alone, was highlighted as the dominant gold hosting set. Veining occurred during the late stages of the NW-SE directed, sub-horizontal shortening (D2) event and is associated with top-to-the-NW thrusting and NW-verging folds. Re-Os molybdenite dating from auriferous quartz veins indicates mineralisation occurred at 525-520 Ma. As crustal shortening amplified the Karibib dome, flexural flow developed fractures along bedding planes, providing the control to bedding parallel veins (NW dipping). With continued crustal compression the dome later experienced fold lock up associated with reduced mean rock stress and sub-horizontal extension occurred along the steeply NW dipping limb. Horizontal extensional gashes sucked in fluids to form the shallowly NE dipping conjugate vein set. These features suggest the regional D2 strain as the first-order control to quartz vein development, down plunge and within the footwall ores. To further define the secondary ores, lithological and structural controls were evaluated on a more detailed local scale. With equal amounts of biotite schist and calc-silicate host rock (bulk of the footwall lithology) material analysed, the biotite schist units were found to contain a larger volume amount of quartz veins. The mineralisation incurred is also developed at higher average gold grades compared to that of the calc-silicates, demonstrating biotite schist having the optimal rheology for quartz vein emplacement. Normal faulting and thrusting occurs widespread, at all scale levels, across the footwall. These were primarily observed along bedding foliations and secondly at higher angles cutting across foliation. The study did not constrain the extent of these, but can conclude faulting plays a very prominent role in re-distributing the secondary ores parallel to bedding along sub-vertical trend planes. Great care should be placed in properly modelling these with 3D software such as Leapfrog. The Navachab gold mineralisation came about as a result of convergent and collisional tectonics activating metamorphic dehydration of the crustal metapelites. As these fluids ascended they absorbed gold from the crust, emplaced by either a magmatic or paleo-placer source. The gold enriched hydrothermal fluids amalgamated in large scale 1ste order structures (shearing of the steep NW limb of the Karibib Dome, the Mon Repos Thrust Zone) that acted as primary active fluid path ways. In the case of Navachab the gold enriched fluid fluxed along these pathways while interacting with fluid sinks related to a physical throttle (brittle schist, folding, bedding parallel shears) and/or a chemical trap (marbles). By summarising and detailing the fluid sinks and active fluid pathways identified by this and previous works, it is strongly recommended that a mineral approach system be designed and implemented as targeting model to lead future exploration endeavours.

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3

Van, den Berg Rudolf. "Inhibition of the pregrobbing phenomenon in gold ores". Thesis, Cape Technikon, 2000. http://hdl.handle.net/20.500.11838/907.

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Thesis (MTech (Chemical Engineering))--Cape Technikon, Cape Town, 2000
In a typical gold-recovery plant, it is estimated that a substantial amount of the gold in residues may be in the form that is recoverable by cyanidation. The gold in residues can be ascribed broadly to (l) the presence of cyanicides, which consume the cyanide radical and thus inhibit dissolution of gold, (2) refractory gold resulting from coatings on some gold particles, (3) large gold particles incompletely dissolved due to inadequate contact time, (4) unliberated gold as a result of too coarse a milled product, and (5) gold dissolved during leaching, then adsorbed by other minerals or by carbonaceous matter in the pulp. This study focuses on the latter, where dissolved gold is pregrobbed during leaching by adsorbent materials in the ore. The term pregrobbing refers to the active adsorption ofgold from cyanide pregnant solutions by components ofthe ore. It has been suggested that gold already dissolved by cyanide may be adsorbed by other minerals and by carbonaceous matter in the pulp. The presence ofcarbonaceous matter in gold ores presents a two-fold problem namely, the poor release of gold from the carbonaceous matrix and the uptake of dissolved gold by the carbonaceous leach residues. Studies by several other investigators using ores from various parts of the world have similarly shown that the natural carbonaceous matter associated with refractory gold ores often behaves like activated carbon when in contact with aurocyanide solutions. Some debate also exists over the extent to which gold may be adsorbed onto the surfaces of minerals. Different authors have identified that minerals such as' pyrite, copper sulphides, quartz and layered silicates, such as kaolin, phlogopite and ilIite exhibit gold adsorbing properties. Activated carbon was first used as a model pregrobber in batch kinetic adsorption experiments in the presence of a gold selective strong base anion-exchange resin.

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Whitfield, Derek. "The genesis and controls of gold mineralization south of Rehoboth, Namibia". Thesis, Rhodes University, 1991. http://hdl.handle.net/10962/d1005560.

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Gold mineralization is hosted within gossanous quartz-haematite veins in volcano-sedimentary lithologies of the Klein Aub - Rehoboth basin of the Irumide Belt, Namibia. Mineralization and hydrothermal alteration are restricted to deformed lithologies particularly the metasediments. Lithological relationships, geochemistry and metallogenic characteristics of the Irumide Belt suggest an intra-continental rift setting. Copper mineralization is well known along the length of the belt, from Klein Aub in the southwest to Ghanzi in the northeast, whereas gold mineralization appears restricted to the Klein Aub Rehoboth basin. The gold is envisaged as having being leached initially from graben fill sequences during rift closure and basin dewatering. Location of the mineralization is strongly controlled by structure and lithological contact zones. Such zones are percieved as having acted as conduit zones for escaping mineralized fluids during basin closure and deformation. Apart from the lack of an effective mineralizing trap, all features consistent with the development of an ore deposit are present. The largest mineralization traps within the area studied are shear zones followed by lithological contact zones. The Mebi and Blanks gold mines are developed over large shear zones while the Swartmodder and Neuras gold mines are situated over mineralized lithological contacts. The Swartmodder copper mine yielded ore from a mineralized schist enclave within granite. Copper and gold occurrences are attributed to two contrasting styles of mineralization. Copper mineralization is suggested to have developed during initial rifting of the belt (ie. stratabound sedimentary exhalative type), while the gold and minor copper resulted from rift closure and basin dewatering. Although no economical orebody was realized during the course of this study a model is proposed for the development of mineralization within the Irumide basement lithologies as a working hypothesis for future exploration.

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Gendall, Ian Richard. "The porphyry copper system and the precious metal-gold potential". Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1005604.

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It has been established that porphyry copper/copper-gold deposits have formed from I Ma to 2 Ga ago. Generally, they are related to the Mesozoic-Cenozoic interval with few reported occurrences from the Palaeozoic or Precambrian. A reason cited is the erosion of these deposits which are often related to convergent plate margins and orogenic belts. Observations of the alteration and mineralisation within and around porphyry copper/copper-gold systems have been included in numerous idealised models. These alteration and mineralisation patterns are dependent on the phases of intrusion, the tectonic setting and rock type, depth of emplacement and relationship to coeval volcanics, physiochemical conditions operative within and surrounding the intrusive and many other mechanical and geochemical conditions. Island arc and cratonic arc/margin deposits are generally considered to be richer in gold than their molybdenum-rich, intra-cratonic counterparts. Metal zonation may occur around these copper/copper-gold deposits, e.g. copper in the core moving out to silver, lead, zinc and gold. This zonation is not always present and gold may occur in the core, intermediate or distal zones. Examples of gold-rich porphyry deposits from British Columbia, Chile and the SW Pacific Island regions suggest gold is closely associated with the potassic-rich zones. Generally these gold-rich zones have greater than 2% magnetite and a high oxygen fugacity is considered to be an important control for gold deposition. High Cl contents within the magma are necessary for gold mobility within the host intrusive centres. Beyond this zone HS₂ becomes an important transporting ligand. Exploration for porphyry copper-gold deposits includes an integrated geological, geophysical and geochemical approach. Petrographic work through to Landsat imagery may be used to determine the chemical conditions of the system, ore association, favourable structural zones and alteration patterns, in order to focus exploration activities.

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Polito, Paul A. "Exploration implications predicted by the distribution of carbon-oxygen-hydrogen gases above and within the Junction gold deposit, Kambalda, Western Australia /". Title page, table of contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09php769.pdf.

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Morasse, Suzanne. "Geology, structure and timing of gold mineralization at the Kiena deposit, Val d'Or, Québec". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0005/NQ31942.pdf.

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Lack, Barbara Anne. "Electrochemical studies of gold bioaccumulation by yeast cell wall components". Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1004969.

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Gold, amongst other group 11 metals, was almost certainly one of the first three metals known to man. In addition to the economic importance of the metal, gold has a wide variety of applications in the medical, electrocatalytical and micro-electronics fields. However, the determination of gold ions in solution, with accuracy, precision, sensitivity and selectivity is still an interesting and much debated topic in analytical chemistry. A system whereby gold ions have been successfully detected employing an electrochemical technique, known as stripping voltammetry, has been developed. The electrochemical method was chosen over other available techniques for the sensitivity, particularly at low concentrations, and selectivity properties; notably in the presence of other metal ions. Under acidic conditions, the electrochemical technique was applied and the presence of gold(III), at a concentration of 2.53 x 10⁻⁵ mol dm⁻³ in a mine waste water sample, was detected. Biomass, in particular yeast and algal types, have been successfully employed in extracting low concentrations of gold ions from industrial effluents. The manipulation of the biological facility for mineral interaction, biohydrometallurgy, may yield numerous potential new technologies. South Africa in particular would benefit from this area of research, since the country is a major ore and metal refining country and if the output and the efficiency of the mines could be improved, even by a small percentage, the financial rewards would be vast. In this study, the application of adsorptive cathodic stripping voltammetry (AdCSV) of gold(III) in the presence of various Saccharomyces cerevisiae cell wall components, was investigated to determine which, if any, were involved specifically in the chemical binding of the gold ions. The chitin and mannan extracts showed the most promise with detection limits of 1.10 x 10⁻⁶ mol dm⁻³ and 9 x 10⁻⁹ mol dm⁻³, respectively; employing the AdCSV technique. A modification of the stripping voltammetry technique, Osteryoung square wave stripping voltammetry (OSWSV), provided the lowest detection limit, for gold(IIl) in the presence of mannan, of 1.70 x 10⁻¹¹ mol dm⁻³ ; utilising a modified carbon paste electrode. The detection of gold(III) has been shown to be dependent on the type of electrode employed, the electrolyte solution and the presence of interfering agents. The effect of copper(II) and silver(I) on the detection of the gold(III) in solution was investigated; whilst the silver(I) has shown no detrimental effects on gold (III) detection systems, copper(II) has indicated the possibility of forming an inter-metallic compound with the gold(III). However, mannan has shown to selectively and preferentially bind the gold(III) in the presence of a ten-fold excess of copper(II). Nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy, as well as computer modelling techniques were employed to further investIgate the mannan-gold(III) interaction and proposed complex formed. The NMR, IR and computer modelling data are in agreement with the electrochemical data on proposing a mannan-gold(III) complex. The co-ordination site was established to be in the vicinity of the H-I and H-2 protons and the gold(III) adopts a square-planar geometry upon co-ordination. The benefits of the research are useful from a biological perspective (i. e. as more is known about the binding sites, microbiologists/biochemists may work on the optimisation of parameters for these sites or work could be furthered into the enhanced expression of the sites) and an industrial one. In addition to the' two major benefits, an improved understanding of gold and its chemistry would be achieved, which is advantageous for other fields of research as well.

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BRAVO, SARA VIRGINIA CHUMPITAZ. "STUDY OF THE PROCESSING OF SULPHIDE ORES OF GOLD WITH THE LOWEST GRADE OF GOLD". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2002. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3947@1.

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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
No presente trabalho são avaliados os fatores físicos e químicos que influenciam o processamento do minério sulfetado de mais baixo teor de ouro conhecido no mundo. A amostra de minério estudada é proveniente da Rio Paracatu Mineração S.A - RPM e é identificada como minério Calha Brava Cl-4, pertencente ao Banco 716, Bloco 508-B da mina. Alguns circuitos de beneficiamento de minérios auríferos incluem processos de concentração gravítica e flotação visando atingir máximas recuperações de ouro e, conseqüentemente, elevada produção a baixo custo. A seleção das técnicas de processamento do minério depende, basicamente, da mineralogia e distribuição das partículas minerais no minério, do tamanho da partícula de ouro ou dos minerais e outros metais associados ao minério. A distribuição do teor de ouro nas diferentes frações granulométricas do minério Calha Brava Cl-4 revelam que 80,4 por cento do ouro encontra-se na fração acima de 104 um e 25 por cento encontram-se na fração fina (< 28 um). A recuperação total de ouro, enxofre e arsênio obtida nos ensaios de concentração gravítica por meio do concentrador centrífugo Knelson e flotação foram 80,44 por cento, 64,9 por cento e 58,22 por cento, respectivamente. A recuperação em massa dessa etapa foi 10,14 por cento. A recuperação total de ouro, enxofre e arsênio obtidos na concentração de jigagem e flotação foi 88,91 por cento, 86,82 por cento e 49,07 por cento, respectivamente. A recuperação em massa do concentrado recuperado foi de 19,5 por cento. Nos ensaios de flotação direta, a maior recuperação de ouro (87 por cento) foi obtida para o minério cominuído a uma granulometria com P80 = 86 um e recuperado por flotação na presença de 30 g/t do coletor amil xantato de potássio (AXP), 20 g/t de metil isobutil carbinol (MIBC), pH 6,3 e potencial de polpa 0,209 V vs Eh, em relação ao eletrodo de hidrogênio. A recuperação em massa do concentrado obtida foi 4 por cento. No caso das partículas grossas do minério (P80 = 130 um), constatou-se a necessidade de maiores concentrações do coletor. A maior recuperação de ouro (85,33 por cento) foi obtida com a concentração de 60 g/t para o AXP, pH 6,3 e potencial de polpa de 0,218 V vs Eh. A recuperação em massa do concentrado foi de 9 por cento.
The work involves the evaluation of physical and chemical factors that influence the processing of sulphide ores, with the lowest grade of gold known in the world. The studied sample is from Rio Paracatu Mining S.A. and is described as Calha Brava Cl-4, belonging to the 716 bench, block 508-B in the mine. Some industrial processing of gold include gravity concentration and flotation processes in order to reach the maximum gold recovery, aiming at raising production levels with lower costs. The selection of the mineral processing depends on several factors as mineralogy, particle size distribution and other minerals associated with the ore. The distribution of gold grades to the different size fractions in the studied ore, reveals that 80.48 percent of gold occur in the particle size fraction above 104 um, and 25 percent of gold occur in the fine fraction (< 28 um). The global gold, sulphur and arsenic recoveries, obtained by centrifuge gravity concentration (Knelson)and flotation tests, were 80.44 percent, 64.90 percent and 58.22 percent, respectively. To these processes, the mass recovery was 10.14 percent. The total gold, sulphur and arsenic recoveries obtained in concentration processes by jig and flotation techniques were 88.91 percent, 86.82 percent and 49.07 percent, respectively. The mass recovery was 19.5 percent. In the flotation tests, the maximum gold recovery (87 percent) was obtained with the grounded ore (P80 = 86 um), using 30 g/t collector potassium amyl xanthate (PAX), 20 g/t methyl isobuthyl carbinol (MIBC), pH = 6.3 and potential of pulp 0.209 V vs Eh. The mass recovery was approximately 4 percent. When coarse particles (P80 = 130 um) were floated, the need of am increase in the collector concentration was observed. The maximum ore recovery (85.33 percent) was obtained at concentration of 60 g/t PAX, pH = 6.3 and potential of pulp 0.218 V vs Eh. The mass recovery was 9 percent.

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Feldmann, Robert Max Werner. "Use of low concentrations of hydrogen peroxide in extracting gold from metallurgically complex gold ores". Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/1826.

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The study was to understand the fundamentals of benefits hydrogen peroxide has shown in cyanide leaching of complex, gold bearing ores. The understanding was gathered by a comprehensive literature review followed by laboratory experiments including leach experiments, electrochemical studies, several analytical methodologies and statistical data analysis.

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Khalesi, Mohammad Reza. "Integrated modeling of grinding, liberation and leaching of gold ores". Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27466/27466.pdf.

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Mann, P. L. "Surficial placer gold deposits". Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1018245.

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This review summarises the factors which control the formation and distribution of surficial gold placer deposits. Regional tectonic and climatic conditions as well as gold source are considered. The characteristics of eluvial, alluvial, marine, glacial and fluvioglacial gold placer deposits are described. Particular attention is paid to the gold grains within these placers. These gold grains have a distinctive morphology and chemical composition which reflect the manner in which they were transported, deposited and concentrated within the placers. The knowledge of the processes which lead to the formation and location of surficial gold placers is then used to guide exploration and target potential deposits, which can then be evaluated.

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Hastings, Matthew H. "Relationship of base-metal skarn mineralization to Carlin-type gold mineralization at the Archimedes gold deposit, Eureka, Nevada". abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1460760.

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Sanchez-Corrales, Victor Manuel. "Electrochemical leaching of gold-bearing arsenopyrite in alkaline cyanide solutions". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184952.

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Rest potential measurements, cyclic voltammetry, linear sweep voltammetry and constant potential coulometry were used to determine the electrochemical response of arsenopyrite in the absence and in the presence of cyanide and to determine its dissolution chemistry. Surface oxidation of arsenopyrite is proposed to proceed by a two-step reaction sequence. FeOOH, H₂AsO₃⁻, and Sᵒ, are produced in the initial step. Oxidation of Sᵒ to SO₄²⁻, and H₂AsO₃⁻ to HAsO₄²⁻ account for the second step. Coulometric results confirmed that 14 electrons are involved in the overall reaction. The implications of these results on the cyanidation of arsenical gold-bearing concentrates were also investigated. The response of four different concentrates to various cyanidation techniques was examined. Alkaline pressure oxidation in 1 M NaOH, at 200°C and under 500 psi of oxygen overpressure followed by conventional cyanidation resulted in 81% gold extraction from a concentrate that yielded only 2% gold extraction after direct cyanidation.

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Roditis, Ioannis Stavros 1960. "A PERFORMANCE EVALUATION OF THE INDICATOR KRIGING METHOD ON A GOLD DEPOSIT: A COMPARISON WITH THE ORDINARY KRIGING METHOD". Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275482.

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Skead, Michael Bethel. "Geological characteristics of selected disseminated sediment-hosted gold deposits in Nevada, U.S.A. : in search of an exploration model". Thesis, Rhodes University, 1995. http://hdl.handle.net/10962/d1007414.

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Sediment-hosted disseminated gold deposits in Nevada, western United States are major gold sources and contain reserves in excess of 1 500 metric tons of gold (Percival et aI., 1988). Discovery of these deposit types continues at a pace, with Placer Dome announcing a mojor discovery, Pipeline, to the south of the Gold Acres Mine, along the Battle Mountain - Eureka Trend in 1994 (The Northern Miner, 1994). Host sediments favoured for disseminated gold mineralisation are thinly bedded silty limestones , carbonate debris flows and to a lesser extent shale, chert and sandstone. The distribution of mineralisation is controlled essentially by the intersection of high-angle faults, which acted as conduits for hydrothermal fluids, with favourable host lithologies, anticlines, low-angle faults and other high-angle faults. Geochemical signature for these deposits is simple being Au, Ag, As, Sb, Hg, Tl, Te, F and Ba, but individual element concentrations vary greatly between and within deposits. Age of mineralisation is cause for considerable debate, and ages ranging between isotopic dates of approximately 117 Ma to early to mid-Tertiary (30-40 Ma) are proposed. Most of these deposits are situated along three major trends namely the Carlin, Battle Mountain - Eureka and Getchell trends. The Battle Mountain - Eureka trend and, to a lesser extent the Carlin trend, are defined by major linear aeromagnetic and gravity anomalies , which are believed to reflect deep-seated structures. Most deposits are hosted in autochthonous Devonian, thinly bedded, silty limestones that occur as windows through what is believed to be allochthonous Ordovician siliciclastic sediments, which were transported from west to east along the Roberts Mountains thrust during the late-Devonian Antler Orogeny. However, recent fossil dating of what were thought to be Ordivician siliciclastic sediments, gives a Devonian age. This questions the age of Ordivician sediments at the other deposits and the interpretation of the structural windows in which deposits are located. Fault-bounded, proximal, carbonate debris-flow breccias are now recognised as a major host to mineralisation. These debris flow breccias, together with interbedded carbonate and siliciclastic sediments, carbonaceous sediments and soft sediment deformation are all characteristics of lithologies in pull-apart basins which develop along a major strike slip faults. It is proposed that sediment-hosted disseminated gold mineralisation is controlled by the distribution of deep-seated long-lived, predominantly right-lateral strike-slip faults. It is along these strike-slip faults that syn-sedimentary pull-apart basins developed, within which sediments favoured by epigenetic gold mineralisation were deposited. These pull-apart basins were then overprinted by post-depositional extensional structures, such as negative flower structures. Igneous intrusions and hydrothermal cells have exploited these extensional structures in both compressional and extensional regional tectonic regimes. This model explains the characteristics of the host sediment at many of the deposits, the spatial relationship between igneous intrusion and mineralisation, spanning the period Cretaceous through to mid-Tertiary, the distribution of deposits as districts along major regional trends and why hydrothermal activity is noted between deposit districts but with no complementary mineralisation. Mineralisation is controlled predominantly by high angle structures and although the recent age for mineralisation at the Betze/Post deposit is ~ 117 Ma (Arehart et aI., 1993a), placing it in the compressional Sevier Orogeny, these high-angle structures would be developed within local extensional tectonic domains as described above. This model can, and should, be applied to other areas of the world where similar geological features exist. In exploring for these deposits in Nevada the distribution of Ordovician siliciclastic sediments should be reviewed, especially where spatially associated with deep regional structures. Ordovician sediments have historically been regarded as unfavourable, hence large areas for potential exploration have been ignored but with new ages for these sediments this opens large areas for potential discoveries.
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Lorenzen, Leon. "A fundamental study of the dissolution of gold from refractory ores". Thesis, Stellenbosch : Stellenbosch University, 1992. http://hdl.handle.net/10019.1/69492.

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Thesis (PhD)--Stellenbosch University, 1992.
ENGLISH ABSTRACT: The dissolution of gold from refractory ores is a complex kinetic problem involving a number of chemical, mass transport and mineralogical factors. In most Witwatersrand ores in South Africa more than 97 % of the gold is dissolved in cyanide medium after a residence time of about 16 hours in pachuca tanks. This high percentage may be the reason why so little fundamental research has been done into the mechanism and kinetics of the leaching process. With the increasingly lower grades of ore mined, the introduction of backfill mining, and the reduction of profit margins, it has become imperative to increase the efficiency of gold dissolution. The effects of the chemistry and particle size on the dissolution of gold in each sample of ore were studied in detail. The emphasis in this study is on the effect of the leaching behaviour of various ore constituents on the rate of gold dissolution. Interferences with the leaching of gold in contact with other minerals or metals could be attributed to the galvanic interaction (electrical conductivity) between the gold and the mineral and to the formation of a surface film on the gold surface. Sulphide minerals and their oxidation products cause the largest decrease in gold dissolution rate. Galena enhances the rate of gold dissolution owing to dissolved Pb(II)-ions. Gold in contact with conductive minerals passivates as a result of the enhanced magnitude of the cathodic cu1Tent. In all experiments the rotating disc of gold passivated so that the rate of dissolution was much slower than that predicted by a mass-transport limiting model. The various films that form on the surface of the gold and associated minerals, as well as the galvanic interaction, depend largely on the pretreatment of the ore. Pre-elimination of host minerals from the gold bearing ore increases the dissolution rate of gold, and explains the kinetics of reaction on the gold surface to a large extent. The selective destruction of the various minerals with oxidative acid leaches destroys and/or decomposes certain minerals which may form films on the gold surface by precipitation. The chemical composition of these films and precipitates depends on the mineralogy of the sample. These films may be oxides, sulphides, carbonates and cyanide complexes. The complexes can be destroyed, depending on the nature of the film, by interstage dilute acid and/or cyanide washes in an agitated vessel. The destruction of the films exposes the gold surface for cyanidation. A simple distribution function similar to the King liberation model is proposed and tested to describe the dissolution step in the multi-step leaching mechanism. For the King model, good agreement is shown with experimental results. For the liberation results obtained by leaching in this study, the trend is co1Tect, but calibration is required for a close fit. A potentially important use for the liberation model by leaching is to predict the leachable or free gold in an ore from the free gold in the complete sample. This approach for studying the leaching behaviour of different gold bearing minerals has provided reasons why some ores leach better than others.
AFRIKAANSE OPSOMMING: Die loging van goud vanuit weerbarstige ertse is 'n komplekse kinetiese probleem wat verskeie faktore soos massa-oordrag, chemiese aspekte en mineralogiese ingeweefdheid insluit. Goud ekstraksies so hoog as 97 % in sianied oplossings in Pachuca reaktore na ongeveer 16 uur logingstyd word behaal in die meeste Witwatersrand ertse in Suid-Afrika. Hierdie hoë ekstraksies mag dalk die rede wees vir die min fundamentele navorsing oor die ekstraksie van goud vanuit minerale in 'n spesifieke erts. Die dalende erts grade, die verlaging van winsgrense en die terugplaas van geloogde erts in die myn noodsaak verbeterde goud ekstraksie. Verkeie faktore nl., chemie, diffusie, partikelgrootte en oplosbaarheid van goud in elke monster erts is in hierdie studie ondersoek. Die sentrale tema was om die logingsgedrag van goud vanuit verskeie minerale in 'n erts te bepaal. Galvaniese interaksie (hou verband met elektriese geleidingsvermoeë) en film vorming is die belangrikste faktore wat die loging van goud in kontak met minerale nadelig beïnvloed. Sulfied minerale en hul oksidasie produkte speel die grootste rol in die verlaging van die tempo van goudloging. Galena verhoog die tempo van goudloging as gevolg van die Pb (II)- ione in oplossing. Goud in kontak met geleidende minerale passiveer as gevolg van die verhoogde katodiese stroomdigtheid. In alle eksperimente met die roterende skyf (goudskyf) apparaat, passiveer die goudskyf in so 'n mate dat die logingstempo baie stadiger is as wat voorspel word met die massa-oordrags model. Die onderskeie films wat vorm op die goud- en geassosieerde minerale se oppervlaktes, asook die galvaniese interaksies, is 'n funksie van die voorafbehandeling van die erts. Die selektiewe eliminering van minerale vanuit 'n gouddraende erts verhoog die tempo van goudloging drasties en dit beskryf die kinetika van goudloging op die goudoppervlak in 'n groot mate. Die selektiewe eliminering van minerale deur gebruik te maak van oksiderende suurlogings, vernietig sekere van die minerale wat films op die goudoppervlakte kan veroorsaak deur middel van presipitasie. Die chemiese samestelling van hierdie films hang af van die mineralogie van die monster. Dit bestaan meestal uit oksiedes, sulfiedes, karbonate en sianiedkomplekse en hulle kan vernietig word deur middel van inter-stadia verdunde suur-en/of sianied wasse. 'n Eenvoudige distribusiefunksie, soortgelyk aan die King bevrydingsmodel word voorgestel en eksperimenteel getoets om die logingstap in die multi-stadia logingsmeganisme te beskryf. Vir bevryding deur loging, is die neiging van King se model korrek, maar kalibrasie word benodig vir goeie passing. 'n Potensiele gebruik van die aangepaste model is om vrye of loogbare goud in 'n spesi fieke partikel grootte fraksie van 'n erts te voorspel as die vry goud in die totale fraksie bekend is. Die resultate uit hierdie studie kan gebruik word om die logingsgedrag van gouddraende minerale te voorspel en te beskryf, en dus veduidelik hoekom goud uit sekere ertse beter loog as uit ander.

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18

Jourdain, Vincent. "Géologie des amas sulfures aurifères de la province de Grenville /". Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1993. http://theses.uqac.ca.

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Thèse (D.R.Min.)-- Université du Québec à Chicoutimi.
Programme offert à l'Université du Québec à Montréal en vertu d'un protocole d'entente avec l'Université du Québec à Chicoutimi. CaQCU Document électronique également accessible en format PDF. CaQCU

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19

Chandraprabha, M. N. "Studies On Bio-Oxidation A Refractory Gold Containing Sulphidic Concentrate With Respect To Optimization And Modeling". Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/188.

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Although bacterial leaching of sulphidic minerals is a well-known phenomenon, it is only in the last ten years that full-scale bacterial leaching plants have been commissioned for gold processing. In order for bacterial leaching to compete successfully with other pretreatment processes for refractory ores, particularly with established technologies such as roasting and pressure leaching, it needs to be efficient. This requires the optimization of the parameters affecting the leaching reaction and the growth of bacteria. The entire biotreatment process is agitation leaching, carried out in stirred reactors or Pachuca type reactors. The bacterial oxidation is a complex reaction involving gaseous, liquid and solid phases. The interactions are highly complex, and analysis is complicated by the presence of solids in the leaching medium. Inspite of the amount of research that has been performed, kinetic and process models are underdeveloped. Since kinetic data varies widely with the type and source of concentrate, experimental data should be generated before doing the full-scale reactor design. In sizing reactors for a commercial scale process, it would be useful to have a mathematical model that one could use to predict the amount and rate of release of metal, as a function of the various operating parameters of the system. G.R.Halli arsenical gold sulphide concentrate obtained from Hutti Gold Mines Ltd., Karnataka, was chosen for our study, because of its high refractoriness. An indegenous strain of Thiobacillus ferrooxidans was used for biooxidation. The experiments were conducted in a well-agitated stirred tank reactor under controlled conditions. Sparged air was supplemented with carbon-dioxide for optimized growth. In this work, more than 90% gold and 95% silver could be recovered from the sulphidic gold concentrate when bioleaching was used ahead of cyanidation, compared to 40% and 50% by direct cyanidation. A generalized model, which accounts for both direct bacterial attack and indirect chemical leaching, has been proposed for the biooxidation of refractory gold concentrates. The bacterial balance, therefore, accounts for its growth both on solid substrate and in solution, and for the attachment to and detachment from the surface. The overall process is considered to consist of several sub-processes, each of which can be described in terms of a mechanism and related rate expressions. These sub-processes were studied seperately under kinetically controlled conditions. The key parameters appearing in the rate equations were evaluated using the experimental data. Since the refractory concentrate contains pyrite and arsenopyrite as the major leachable entities, leaching studies have been done on pure pyrite and arsenopyrite as test minerals and the key parameters in the rate equations are evaluated using this data. The model so developed is tested with the leaching kinetics of the concentrate. The growth of bacteria is dependent on the availability of the substrate, ferrous iron, and the dependence is modelled by the widely accepted Monod equation. The effect of carbon dioxide supplementation on the bacterial activity was studied and the optimal concentration for growth was found to be l%(v/v). Studies on indirect chemical leaching showed that the rate is sensitive to surface area of concentrate. Indirect rate constant of arsenopyrite was found to be greater than that of pyrite, since pyrite is more nobler than arsenopyrite. Conditions of direct leaching alone was obtained at high pulp density and using substrate adapted bacteria. The rate constant of arsenopyrite was found to be greater than that of pyrite. The parameters obtained were tested with the overall batch leaching data of the concentrate and favourable comparision was obtained. Thus, it has been possible to isolate the various simultaneous sub-processes occurring during the leaching and propose useful models to describe these processes in some detail. The model has been extended successfully to predict the continuous leaching behaviour using the parameters obtained from the batch data. Studies on the effect of residence time and pulp density on steady state behaviour showed that there is a critical residence time and pulp density below which washout conditions occur. The critical residence time at 10% pulp density was found to be 11 hrs. Operation at pulp densities lower than 5% and residence times lower than 72 hrs is not favourable for efficient leaching. Studies on the effect of initial ferric iron concentration showed that there exists an optimum concentration of ferric iron at which the time required to reach steady state is minimum.

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Chandraprabha, M. N. "Studies On Bio-Oxidation A Refractory Gold Containing Sulphidic Concentrate With Respect To Optimization And Modeling". Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/188.

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Although bacterial leaching of sulphidic minerals is a well-known phenomenon, it is only in the last ten years that full-scale bacterial leaching plants have been commissioned for gold processing. In order for bacterial leaching to compete successfully with other pretreatment processes for refractory ores, particularly with established technologies such as roasting and pressure leaching, it needs to be efficient. This requires the optimization of the parameters affecting the leaching reaction and the growth of bacteria. The entire biotreatment process is agitation leaching, carried out in stirred reactors or Pachuca type reactors. The bacterial oxidation is a complex reaction involving gaseous, liquid and solid phases. The interactions are highly complex, and analysis is complicated by the presence of solids in the leaching medium. Inspite of the amount of research that has been performed, kinetic and process models are underdeveloped. Since kinetic data varies widely with the type and source of concentrate, experimental data should be generated before doing the full-scale reactor design. In sizing reactors for a commercial scale process, it would be useful to have a mathematical model that one could use to predict the amount and rate of release of metal, as a function of the various operating parameters of the system. G.R.Halli arsenical gold sulphide concentrate obtained from Hutti Gold Mines Ltd., Karnataka, was chosen for our study, because of its high refractoriness. An indegenous strain of Thiobacillus ferrooxidans was used for biooxidation. The experiments were conducted in a well-agitated stirred tank reactor under controlled conditions. Sparged air was supplemented with carbon-dioxide for optimized growth. In this work, more than 90% gold and 95% silver could be recovered from the sulphidic gold concentrate when bioleaching was used ahead of cyanidation, compared to 40% and 50% by direct cyanidation. A generalized model, which accounts for both direct bacterial attack and indirect chemical leaching, has been proposed for the biooxidation of refractory gold concentrates. The bacterial balance, therefore, accounts for its growth both on solid substrate and in solution, and for the attachment to and detachment from the surface. The overall process is considered to consist of several sub-processes, each of which can be described in terms of a mechanism and related rate expressions. These sub-processes were studied seperately under kinetically controlled conditions. The key parameters appearing in the rate equations were evaluated using the experimental data. Since the refractory concentrate contains pyrite and arsenopyrite as the major leachable entities, leaching studies have been done on pure pyrite and arsenopyrite as test minerals and the key parameters in the rate equations are evaluated using this data. The model so developed is tested with the leaching kinetics of the concentrate. The growth of bacteria is dependent on the availability of the substrate, ferrous iron, and the dependence is modelled by the widely accepted Monod equation. The effect of carbon dioxide supplementation on the bacterial activity was studied and the optimal concentration for growth was found to be l%(v/v). Studies on indirect chemical leaching showed that the rate is sensitive to surface area of concentrate. Indirect rate constant of arsenopyrite was found to be greater than that of pyrite, since pyrite is more nobler than arsenopyrite. Conditions of direct leaching alone was obtained at high pulp density and using substrate adapted bacteria. The rate constant of arsenopyrite was found to be greater than that of pyrite. The parameters obtained were tested with the overall batch leaching data of the concentrate and favourable comparision was obtained. Thus, it has been possible to isolate the various simultaneous sub-processes occurring during the leaching and propose useful models to describe these processes in some detail. The model has been extended successfully to predict the continuous leaching behaviour using the parameters obtained from the batch data. Studies on the effect of residence time and pulp density on steady state behaviour showed that there is a critical residence time and pulp density below which washout conditions occur. The critical residence time at 10% pulp density was found to be 11 hrs. Operation at pulp densities lower than 5% and residence times lower than 72 hrs is not favourable for efficient leaching. Studies on the effect of initial ferric iron concentration showed that there exists an optimum concentration of ferric iron at which the time required to reach steady state is minimum.

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21

Huang, Jian Hui. "The applications of microwave energy to improve grindability and extraction of gold ores". Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369344.

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Oxidation developed from the surfaces into the cores of the microwaved particles. Metallic particles were also formed during microwave exposure. Lihir gold ore, in which gold was finely disseminated in pyrite and marcasite, was an extremely refractory gold ore. Without pretreatment, only 37-39% of the gold could be extracted with sodium cyanide. However, this was improved after the head ores or floatation concentrates were pretreated by microwave radiation. 74.581.2% of the gold was extracted from the microwave treated head ore. The hydrometallurgical pretreatment of pyrite and marcasite in a microwave field and a conventional heating environment was also investigated.I,n a nitric acid solution, pyrite and marcasite can be rapidly leached. Reaction temperature and the concentration of HNO3 had a significant influence on decomposition rate. Marcasite had a substantially higher i decomposition rate than pyrite. Microwave heating could promote the dissociation of marcasite and pyrite, compared with conventional heating. This was caused by special volumetric heating during microwave exposure that may induce local overheating or improve the interactions between the high dielectric loss minerals and the leaching solution. Kinetic investigations show that the decomposition of both the minerals in a nitric acid medium is controlled by chemical reactions on the surfaces of particles. The decomposition is a second order reaction with respect to nitric acid concentration. Less than 5- 7% of the decomposed sulphur was transformed into elemental sulphur during the leaching of both the minerals

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Veselinović, Milica. "Genetic models for epithermal gold deposits and applications to exploration". Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1005562.

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Epithermal gold deposits are the product of large-scale hydrothermal systems in tectonically active regions. They form at shallow crustal levels where the physico-chemical conditions change abruptly. Two major groups of epithermal gold deposits can be distinguished based on their genetic connection with: A) Copper-molybdenum porphyry systems and B) Geothermal systems related to volcanic centres and calderas. Epithermal gold deposits connected with geothermal systems encompass three major types: adularia-sericite, acid-sulphate and disseminated replacement (the Carlin-type). Their essential ingredients are: high heat source which leads to convection of groundwater in the upper crust; source of hydrothermal fluid, metals and reduced sulphur; and high-permeability structures which allow fluid convection and metal deposition. Mixing of these ingredients leads to the formation of epithermal gold deposits throughout crustal history, without any restriction on age. The ores were deposited from near-neutral (adularia-sericite type and some of the Carlin-type) to acidic (acid-sulphate type and porphyry-related epithermal gold deposits), low-salinity, high C0₂ and high H₂S fluids, which were predominantly meteoritic in origin. The transport capability of deep fluids in epithermal hydrothermal systems may be shown to be dependent largely on their H₂S content and, through a series of fluid mineral equilibria, on temperature and on C0₂ content. The most common mechanisms of ore deposition are boiling (phase separation), mixing of fluids of different temperatures and salinities, reaction between them and wall rocks, dilution and cooling. An understanding of genetic models for epithermal gold deposits provides the basis for the selection of favourable areas for regional to prospect-scale exploration.

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Rankine, Graham M. "Gold metallogeny of Australia". Thesis, Rhodes University, 1987. http://hdl.handle.net/10962/d1004676.

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The gold metallogeny of Australia is predominantly confined to the Archaean and Palaeozoic Provinces. The Archaean gold occurrences are predominantly hosted in ultramafic-mafic dominated greenstone belts, with less associated tofelsic-volcanic and sedimentary sequences. Most gold occurrences are confined to shear zones or faults, and adjacent discoveries of economic laterite-hosted deposits, host rocks. Recent are presently under investigation and will supply a significant proportion of production in the future. The Proterozoic gold deposits of Australia , are confined to geosyncinal sequences, commonly turbidites (eg: Telfer), with other hydrothermal deposits associated directly to granites. An important feature of the North Australian Craton deposits, is the spatial association of most deposits to granite bodies, although a genetic link has not been established conclusively. The Roxby Downs deposit in South Australia is a unique occurrence of gold in association to copper, uranium and R.E.E. This deposit is tentatively related to intraplate alkaline-magmatism, with further work necessary. The most significant recent discovery of gold mineralization in Australia is in the Drummond Basin in Queensland. This epithermal is tentatively related to mineralization within the Georgetown Inlier. The latter mineralization is Permo-Carboniferous, in a Proterozoic (and possibly Archaean) sequence of schists. It is tentatively suggested that all the gold mineralization in northern Queensland may be related to single tectonic event, a feature which requires further study . Other mineralization in the Phanerozoic includes the turbidite-hosted metamorphogenic deposits of Victoria, the rift related deposits in New South Wales and magmatic related deposits in Queensland. The gold deposits in Australia may in the future be classified in a tectonogeological framework, similiar to the layout of this dissertation, particularly once further data becomes available on recent discoveries.

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Couture, Jean-François. "Géologie et gitologie du gisement de la rivière Eastmain, Ungava, Québec /". Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1993. http://theses.uqac.ca.

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Breedt, Machiel Christoffel. "Gold exploration in tropical and sub-tropical terrains with special emphasis on Central and Western Africa". Thesis, Rhodes University, 1996. http://hdl.handle.net/10962/d1005578.

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The aim of this dissertation is an attempt to' provide a general guide for future gold exploration in tropical and sub-tropical terrains. The dissertation includes a brief discussion of the various exploration techniques used in regional and local exploration. This provide the necessary background knowledge to discriminate between the constraints and applications and to be able to select the techniques which are more suitable for gold exploration in tropical and sub-tropical terrains. Weathering, gold geochemistry and soil formation, fields often neglected, are emphasized to illustrate the importance of the mobility and dispersion of gold in the weathering of the lateritic soil profile. A sound knowledge and experience in regolith mapping is to the advantage of the explorationist. Case studies with special emphasis on Central- and Western Africa are included to illustrate the effectiveness of some of the gold exploration techniques in tropical and sub-tropical terrains. Gold exploration is a highly complex and demanding science and to be successfull involves the full intergration of all geological, geochemical and geophysical information available. An intergrated exploration method and strategy would enhance the possibility of making viable discoveries in this highly competative environment where our mineral resources become more depleted every day. Where applicable, the reader is refered to various recommended literature sources to provide the necessary background knowledge which form an integral part of gold exploration.

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26

Lu, Guan-Qing. "Le lien génétique entre la minéralisation en or et en mercure et l'évolution pétrolifère : le cas de dépôt d'or et mercure de Danzhai = A genetic link between the gold-mercury mineralization and petroleum evolution : a case of the Danzhai gold-mercury deposit /". Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1994. http://theses.uqac.ca.

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Campbell, Keith Bryan. "The geology, alteration, and mineralization of the True North gold deposit, Fairbanks, Alaska". abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3239880.

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Sener, A. K. "Characteristics, distribution and timing of gold mineralisation in the Pine Creek Orogen, Northern Territory, Australia /". Connect to this title, 2004. http://theses.library.uwa.edu.au/adt-WU2005.0102.

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Harlap, Ariel. "Alteration and ammonium enrichment vectors to low-sulphidation epithermal mineralization : insights from the Banderas gold-silver prospect". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112633.

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The alteration at the low-sulphidation epithermal Banderas Au-Ag prospect, Guatemala, was characterized using a portable infrared mineral analyzer (PIMA) spectrometer and shown to comprise illite, buddingtonite and, on surface, kaolinite associated with gold mineralization. The Spextract python program, developed by the author, was used to measure variations in the short-wave infrared spectra (SWIR) which were then mapped as equal-area-of-influence or voronoi diagrams. Voronoi maps of the 2200 and 2350 nm absorption features, position and depth, respectively, for illite and 1560 and 2120 nm feature depths for buddingtonite indicate that illite crystallinity and ammonium alteration intensity increase towards gold mineralization. The latter observation suggests that gold transport and deposition may have been controlled by ammonia complexation. At conditions likely to have prevailed during mineralization, i.e., temperatures between 150° and 250°C, a pH between 5 and 8.5, an oxygen fugacity ( fO2 ) near the hematite-magnetite buffer, a chlorinity of 0.5 m, a total sulfur activity of 0.001 m, and a total nitrogen activity of 0.004 m, AuNH3 +2 is the dominant ammonia complex and gold solubility at optimal pH- fO2 conditions reaches ∼65 ppm at 250°C. In contrast, the maximum solubility of gold as AuHS -2 , the species normally assumed to control gold transport in epithermal systems, is approximately four orders lower at 250°C; at 150°C the solubility of AuNH3 +2 and AuHS -2 are essentially the same, i.e., ∼9 ppb. A model for Au-Ag mineralization is proposed in which hydrothermal fluids were focused along NW-SE extensional faults and at the contacts of rhyolite domes and tuffs, and gold transport and deposition were controlled mainly by ammonia-dominated complexation and boiling-induced temperature decrease, respectively.

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Daglioglu, Yasar Mehmet. "A review of sediment-hosted gold deposits of the world with special emphasis on recent discoveries outside the U.S.A". Thesis, Rhodes University, 1996. http://hdl.handle.net/10962/d1005609.

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Most of the Great Basin sediment-hosted gold deposits are located along well defined, northwest-striking trends. Trends coincide with faults, intrusive rocks and magnetic anomalies. Sedimentary host rocks are siltstone, sandstone, conglomerate, argillic, interbedded chert and shales. Silty bedded silty dolomites, limestone and carbonaceous shales are the most favourable hosts. High, and locally, low-angle faults are very important structural features related to the formation of the ore bodies. High-angle faults are conduits of hydrothermal fluids which react, shatter and prepare the favourable host rock. Decalcification, silicification, and argillization are the most common hydrothermal alteration types. Jasperoid (intense silica replacement) is a significant characteristic; not all of these deposits are gold-bearing. Most deposits contain both oxidized and unoxidized ore. Fine grained disseminated pyrite, arsenian pyrite, and carbonaceous material are the most common hosts for gold in many deposits. These deposits are also characterized by high Au/Ag ratios, notable absence of base metal and geochemical associations of Au, As, Sb, Hg, Ba and TI. Recently numerous sediment-hosted gold deposits have been recognized in different regions of the world. They vary in their size, grades, textwe, host rock lithology, degrees of structural control and chemical characteristics. However, they have many common features which are very similar to the general characteristics of sediment-hosted gold deposits in the Great Basin, U.S.A. Besides these similarities, several unusual features are recorded in some newly discovered deposits elsewhere, such as predominant fault controlled paleokarst related mineralization and the lack of two very common trace elements (Hg, TI) in Lobongan/Alason, Indonesia; and Early Proterozoic age metamorphosed host rocks and lack of Sb in Maoling, China. The discovery of the deep ores in the Post-Betze and Rabbit Canyon, Nevada, proposed sediment-hosted Au emplacement at deeper level (4 ± 2 km; Kuehn & Rose, 1995) combined with a lack of field evidence for paleowater table and paleosurface features has ruled out a shallow epithermal origin. Recent discoveries in other parts of the world throw important new light on the ongoing genetic problems. Intrusive rocks are present in nearly all sediment-hosted gold deposits. Numerous intrusion-centred districts worldwide are characterized by tWo or more different mineralization types and consequently by metal zoning. Sediment-hosted gold deposits are proposed as a distal part of intrusion-centred magmatic hydrothermal systems (Sillitoe &Bonham, 1990).

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Zheng, Jialong. "An electrochemical study of the copper-gold-cyanide system with reference to the processing of copper-gold ores". Thesis, Zheng, Jialong (2000) An electrochemical study of the copper-gold-cyanide system with reference to the processing of copper-gold ores. PhD thesis, Murdoch University, 2000. https://researchrepository.murdoch.edu.au/id/eprint/52721/.

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Gold and copper often occur together in ores, an occurrence which creates processing difficulties since cyanide leach solutions are not selective for gold. Copper contamination can result in serious problems throughout the conventional carbon-inpulp process, often making the operation uneconomic. This thesis describes electrochemical studies of two ways of dealing with copper contamination. One concerns the selective electrodeposition of gold from coppercontaining cyanide solutions; the second concerns the possibility of selectively leaching gold from copper-containing ores using an aerated ammoniacal cyanide solution. In the electrowinning study, a rotating disc electrode technique was combined with a method of chemical analysis to investigate the codeposition behaviour of copper and gold. In these experiments, the variables were gold concentration, agitation, free cyanide concentration, pH and temperature. The experimental results obtained have provided an improved understanding of the electrolytic codeposition of copper with gold in cyanide solutions. The major factors influencing copper codeposition with gold are the free cyanide concentration, the operating temperature and the pH of the electrowinning solution. By controlling these variables in the electrowinning operation, it is possible to minimise the copper deposition. Pulsed potential control was employed as an alternative to constant potential electrodeposition as a means of reducing copper codeposition in the gold electrowinning process. It was demonstrated in this work that by simply varying the parameters of the applied pulsed potential waveform, all other operating conditions being the same as for the constant potential case, copper contamination was greatly reduced. This improvement is due to the high instantaneous gold deposition rate during the cathodic potential pulse period and the copper redissolution during the anodic potential pulse period. A rotating electrochemical quartz crystal microbalance (REQCM) technique was developed in this research work. It was demonstrated that this REQCM technique is capable of measuring the partial current of a metal deposition in the potential region where the hydrogen evolution reaction is involved.. Thus, obtaining information outside the electrochemical window of a solid electrode become possible. The REQCM was used to study the mechanism of copper and gold deposition from cyanide solution. One of the findings from this work is that when using the chronopotentiometric method to study metal dissolution or cementation reactions, the effect of the inert substrate must be taken into account. It was found that the substrate has no influence on the rate if the reaction is diffusion controlled; however, it markedly affects the rate of chemically controlled reactions. The magnitude of the effect is related to the catalytic activity of the substrate. The REQCM technique was also used to study the mechanism of selective leaching of gold from copper contaminated ores using ammoniacal cyanide. Experimental results show that in copper containing cyanide solutions, the copper-cyanide complex species takes part in the gold dissolution reaction. The addition of ammonia to solutions containing copper and cyanide greatly diminishes the rate of gold dissolution. However, when the cyanide to copper ratio is close to 2:1, the rate of gold dissolution increases on addition of ammonia. This may be due to the formation of some goldammonia complex or the involvement of the formation of Cu(II)- cyanide-ammonia complex which can act as an oxidant in the gold leaching process.

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Coxon, Brian Duncan. "Lateritisation and secondary gold distribution with particular reference to Western Australia". Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1005586.

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Lateritisation is associated with tropical climates and geomorphic conditions of peneplanation where hydromorphic processes of weathering predominate. Laterites are products of relative (residual) and absolute(chemical) accumulation after leaching of mobile constituents. Their major element chemistry is controlled by the aluminous character of bedrock and drainage. Bauxitisation is characterised by residual gibbsite neoformation and lateritisation, by both residual accumulation and hydromorphic precipitation of goethite controlled by the redox front at the water table. The laterite forms part of a weathering profile that is underlain by saprock, saprolite, the mottled zone and overlain by a soil horizon. The secondary gold in laterites has its source invariably with mineralised bedrock. The distribution of secondary gold is controlled by mechanical eluviation and hydromorphic processes governed by organic, thiosulphate and chloride complexing. The precipitation of secondary gold is controlled by pH conditions, stability of the complexing agent and ferrolysis. Gold-bearing laterites are Cainozoic in age and are best developed on stable Archean and Proterozoic cratons that have suffered epeirogenesis since lateritisation. Mechanical eluviation increases in influence at the expense of hydromorphic processes as a positive function of topographic slope and degradation rate. Gradients greater than 10⁰ are not conducive for lateritisation, with latosols forming instead. High vertical degradation rates may lead to the development of stone lines. In the Western Australian case, post-laterite aridification has controlled the redistribution of secondary gold at levels marked by stabilisation of the receding palaeowater table. Mineable reserves of lateritic ore are located at Boddington, Westonia and Gibson toward the south-west of the Yilgarn Block. A significant controlling variable appears to be the concentration of chloride in the regolith. Based on the Boddington model, the laterite concentrates the following elements from bedrock gold lodes: i) Mo, Sb, W, Hg, Bi and Au as mobile constituents. ii) As and Pb as immobile constituents. Geochemical sampling of ferruginous lag after bedrock and laterite has provided dispersed anomalies that are easily identifiable. "Chalcophile corridors" up to 150 km in length are defined broadly by As and Sb but contain more discrete anomalies of Bi, Mo, Ag, Sn, W, Se or Au, in the Yilgarn Block. The nature of the weathered bedrock, the tabular distribution of secondary gold ore deposition and the infrastructural environment lends the lateritic regolith to low cost, open-cut mining. The western Australian lateritic-gold model perhaps can be adapted and modified for use elsewhere in the world.

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Gaspar, Luis Miguel Guerreiro Galla. "The Crown Jewel gold skarn deposit". Online access for everyone, 2005. http://www.dissertations.wsu.edu/Dissertations/Summer2005/l%5Fgaspar%5F072805.pdf.

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Olivo, Gema Ribeiro. "Les gites d'or palladifères des mines de Caue et de Conceicao, dans les formations de fer du type lac Supérieur du district d'Itabira, Craton Sao Francisco, Bresil : structure, minéralogie, géochronologie et métallogenie = (Palladium-bearing gold deposits of the caue and conceicao mines, hosted by lake superior-type iron-formations of the Itabira district, Sao Francisco craton, Brazil : structure, mineralogy, geochronology and metallogeny) /". Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1994. http://theses.uqac.ca.

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Tanda, Bennson Chemuta. "Glycine as a lixiviant for the leaching of low grade copper-gold ores". Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/56525.

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The continuous depletion of high grade gold ores has shifted research focus towards the processing of low grade, complex ores containing impurities such as copper which is detrimental to the traditional cyanidation process. Alkaline glycine solution selectively leached copper and gold over impurity elements such as Fe, Ca, Mg and Si from copper – gold ores. Copper was recovered from solution by solvent extraction and gold could be recovered by carbon adsorption while glycine is recycled.

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36

Magnan, Martin. "La zone 87 du gisement d'or et de cuivre du lac Troilus : pétrographie et géochimie /". Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1993. http://theses.uqac.ca.

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37

Witne, John Yagbinan. "The effects of oxygen and carbon dioxide enriched air on the bacterial oxidation of sulphide concentrates". Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302672.

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Biohydrometallurgical techniques are quite established for the treatment of certain sulphide minerals and others have been demonstrated at laboratory or pilot plant scale level, where iron and sulphuroxidising bacteria are utilised for the leaching of low grade sulphide ores and the pretreatment of gold ores and concentrates. The majority of the microorganisms which are used for bacterial leaching are autotrophic aerobes, therefore carbon dioxide and oxygen are essential nutrients for their growth and survival, adequate supplies must be ensured in order for the oxidation process to be successful through an effective gas mass transfer process from air or other sources to the gas/liquid/solids interface in the pulp which can then be readily available to the microorganisms. Gas mass transfer limitation is one of the major problems faced by the industry therefore, most commercial biooxidation plants currently operate at low pulp densities at around 20 - 25% to minimise gas mass transfer limitations. Three cultures, a mesophile (DSM 583), a moderate thermophile (Y1FI) and a extreme thermophile iSulfolobus BC65) were used to bioleach the Ok Tedi copper concentrate under optimum Ch and CO2 enriched air (30% Ch and 10% CO2) based on volume ratios. The positive effect of using oxygen and carbon dioxide enriched air to bioleach the copper mineral was clearly demonstrated where an increase in Cu leaching rate by a factor of2.8, 2.1 and 1.9 for DSM 583, YTFI and Sulfolobus respectively were observed compared with the shake flask tests. The lag phase observed with the other test conditions such as in shake flask or with air, was eliminated when leached under optimum gas enrichment and 1t;80%of the Cu was extracted in the first 120 to 150 hours of leaching for all three cultures. The average dissolved oxygen concentrations observed in the pulp for these tests were 11.8, 8.0 and 7.2 mgll for DSM 583, YTFI and Sulfolobus respectively, indicating that O2 was not limiting in these tests. The Fe released during the bioleaching of copper was non stoichiometric for a predominantly chalcopyrite concentrate and the low redox potential values (max 638mV) suggested galvanic interaction during the leaching of copper where chalcopyrite was leached preferentially due to the presence of pyrite. Bioleaching of copper under optimum gas enrichment at different pulp densities showed near total copper extraction occurred for pulp densities of 3, 10 and 20% (w/v). At high pulp densities, more so at 40% than 30% (w/v), the leaching rate decreased rapidly for tests with YTFI and Sulfolobus. Monitoring of dissolved Ch shows that O2 demand increased with increasing pulp density and the average dissolved O2 concentration observed for DSM 583, YTFl and Sulfolobus at 40% solids concentration were 3.0, 2.6 and 2.4 mgll respectively, suggesting that oxygen and carbon dioxide are not limiting. The decrease in leaching rate observed at high pulp densities (30 & 40%) under optimum gas enrichment was accompanied by low metal dissolution and low redox potential values which was attributed to shear stress due to attrition of cells by high solids concentration, toxicity of metal ions especially Ag, Fe and Cu, and the formation of precipitates and jarosites as confirmed from XRD analysis of leach residues hence impeding the leaching process rather than as a result of O2 and C~ limiting conditions. The addition of flowing air increased the overall iron release rate for the Porgera gold-bearing pyrite concentrate by a factor of AJ 2.8, 1.8 and 1.5 for DSM 583, YTFl and Sulfolobus respectively compared with the shake flask tests, and the lag time was observed to decrease by about 80% for all cultures, suggesting O2 and CO2 limiting conditions in the shake flask. The average dissolved ~ concentration observed for the pulp with the different cultures were 8.7, 5.8 and 5.0 mgll for DSM 583, YTFI and Sulfolobus respectively indicating oxygen was not limiting in these tests. Biooxidation of pyrite concentrate under optimum gas enrichment at various pulp density shows DSM 583 performing well exhibiting the highest oxidation rate for all pulp densities, followed by YTFt and Sulfolobus, except at 3% pulp density where the rates are similar for all cultures. At high pulp density, above 30%, the oxidation rate decreased rapidly for YTFt and Sulfolobus, with DSM 583 showing a moderate decrease. Monitoring of dissolved oxygen showed that oxygen demand increased with increasing pulp density and at one point the dissolved oxygen concentration for the test with YTFI at 40% and Sulfolobus at 30 and 40% solids concentration decreased below t.O mgll, suggesting oxygen and carbon dioxide limiting conditions. The decrease in leaching rate at high pulp densities above 30% under optimum gas enrichment was accompanied by low Fe dissolution and low redox potential which was attributed to shear stress due to attrition of cells by high solids concentration, toxicity of metal ions especially Ag, and Fe. and the formation of precipitate andjarosites hence impeding the leaching process. Oxygen and CO2 limiting conditions due to high pulp density and viscosity were only observed for YTFt and Sulfolobus cultures. The cyanide leaching of the pretreated pyrite concentrate shows that the extent of gold and silver recovery increased with the degree of pyrite oxidation and Au and Ag recoveries in excess of 80% were achieved compared with that of only 18.1% and 35.94'10 for gold and silver respectively, from the original. untreated concentrate by direct cyanidation.

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Ruiz, Párraga Juan Antonio. "Geology of the Chukar Footwall Mine, Maggie Creek District, Carlin Trend, Nevada /". abstract and full text PDF (UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1447807.

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Thesis (M.S.)--University of Nevada, Reno, 2007.
"May, 2007." Geological maps on eleven folded leaves in pocket. Includes bibliographical references (leaves 143-154). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2008]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

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39

Sapiie, Benyamin. "Strike-slip faulting, breccia formation and porphyry Cu-Au mineralization in the Gunung Bijih (Ertsberg) mining district, Irian Jaya, Indonesia /". Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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Thesis (Ph. D.)--University of Texas at Austin, 1998.
Vita. Four folded plates in pocket. Includes bibliographical references (leaves 285-303). Available also in a digital version from Dissertation Abstracts.

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40

Sibbick, Steven John Norman. "The distribution and behaviour of gold in soils in the vicinity of gold mineralization, Nickel Plate mine, southern British Columbia". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28862.

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Sampling of soils and till are conventional methods of gold exploration in glaciated regions. However, the exact nature of the residence sites and behaviour of gold within soil and till are poorly known. A gold dispersion train extending from the Nickel Plate mine, Hedley, southwest British Columbia, was investigated in order to determine the distribution and behaviour of gold within soils developed from till. Three hundred and twelve soil, till and humus samples (representing LFH, A, B and C horizons) were collected from fifty-two soil pits and thirty-four roadcut locations within the dispersion train. Soil and till samples were sieved into four size fractions; the resultant -212 micron (-70 mesh) fraction of each sample was analysed for Au by FA-AAS. Humus samples were ground to -100 micron powder and analysed for Au by INAA. Based on the analytical results, each LFH, A, B and C horizon was subdivided into anomalous and background populations. Detailed size and density fraction analysis was carried out on soil profiles reflecting anomalous and background populations, and a mixed group of samples representing the overlap between both populations. Samples were sieved to six size fractions; three of the size fractions (-420+212, -212+106, -106+53 microns) were separated into two density fractions using methylene iodide and analysed for Au by FA-AAS. The Au content of the -53 micron fraction was analysed by FA-AAS and cyanide extraction - AAS. Results indicate that the Au content of soil profiles increase with depth while decreasing with distance from the minesite. Heavy mineral concentrates and the light mineral fraction Au abundances reveal that dilution by a factor of 3.5 occurs within the till over a distance of 800 metres. However, free gold within the heavy mineral fraction is both diluted and comminuted with distance. Recombination of size and density fractions indicate that the Au contents of each size fraction are equivalent; variation in Au abundance is not observed with a change in grain size. Seventy percent of the Au in the -53 micron fraction occurs as free gold. Chemical activity has not altered the composition of gold grains within the soil profiles. Compositional and morphological differences between gold grains are not indicative of glacial transport distance or location within the soil profile. Relative abundances of gold grains between sample locations can be used as an indicator of proximity to the minesite. The sampling medium with the best sample representivity and contrast between anomalous and background populations is the -53 micron (-270 mesh) fraction of the C horizon. Geochemical soil sampling programs in the vicinity of the Nickel Plate mine should collect a minimum mass of 370 grams of -2000 micron (-2 mm) soil fraction in order to obtain 30 grams of the -53 micron fraction.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate

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41

Salier, Brock Peter. "The timing and source of gold-bearing fluids in the Laverton Greenstone Belt, Yilgarn Craton, with emphasis on the Wallaby gold deposit". University of Western Australia. School of Earth and Geographical Sciences, 2004. http://theses.library.uwa.edu.au/adt-WU2005.0013.

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[Truncated abstract] The Laverton Greenstone Belt (LGB), located in the northeastern part of the Eastern Goldfields Province (EGP) of the Yilgarn Craton, Western Australia, has a total contained gold endowment of over 690t. An important feature of the gold deposits in the LGB is their close spatial association with granitoids, with many gold deposits located adjacent to, or hosted by, granitoids. Recently-proposed genetic models for Archaean orogenic gold deposits have emphasised the role of granitoids in the formation of ore-deposits, but differ significantly in the nature of that role. Some models suggest that the granitoids are a source of ore-fluids and solutes, whereas others suggest that granitoids exert an important structural control on gold mineralisation. Such competing genetic models for gold mineralisation variably propose either a proximal-magmatic or distal-metamorphic, or less commonly distal-magmatic, source for goldbearing fluids, or mixing of fluids from multiple sources. Isotope geochemistry and geochronological studies are used to constrain the source and timing of auriferous fluids at nine gold deposits in the LGB in an attempt to differentiate between conflicting genetic models. To overcome the lack of detailed deposit-scale geological constraints inherent to any regional study, hypotheses generated from regional datasets are tested in a detailed case-study of the Wallaby gold deposit. The Pb-isotope compositions of ore-related sulphides from deposits in the LGB plot along the line representing crustal-Pb in the Norseman-Wiluna Belt of the EGP, with individual deposits clustering with other nearby deposits based on their geographic location. This trend is similar to that recorded in the Kalgoorlie-Norseman region in the southern EGP, and is consistent with a basement Pb reservoir for gold-bearing fluids. As such, data are consistent with a similar fluid source for all gold deposits. The Nd and Sr isotopic composition of goldrelated scheelite in the LGB clusters very tightly. The inferred ore-fluid composition has a slightly positive εNd, similar to ore fluids at other gold deposits in the EGP for which a proximal magmatic source is highly improbable. As such, Sr and Nd data are consistent with a similar fluid source for the gold deposits analysed in the LGB, but cannot unequivocally define that source. The median S, C and O isotopic compositions of ore minerals from all nine different gold deposits studied in the LGB fall in a very narrow range

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42

Day, Stephen John. "Sampling stream sediments for gold in mineral exploration, southern British Columbia". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27869.

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The problems encountered by mineral explorationists when sampling stream sediments for gold were investigated by considering the sparsity of free gold particles and their tendency to form small placers at certain locations in the stream bed. Fourteen 20-kg samples of -5-mm sediment were collected from contrasting energy and geochemical environments in five streams draining gold occurrences in southern British Columbia. The samples were sieved to six size fractions (420 µm to 52 µm) and gold content was determined by neutron activation analysis following preparation of two density fractions using methylene iodide. Gold concentrations were converted to estimated number of free gold particles and the Poisson probability distribution was used to show that much larger field samples (>100 kg of -1 mm screened sediment) would be required to reduce random variability due to nugget effects to acceptable levels. However, in a comparison of conventional sampling methods, the lowest probability of failing to detect a stream sediment gold anomaly is obtained using the sampling method described in this study. Small-scale placer formation was investigated by collecting twenty 60-kg samples of -2-mm sediment from ten locations along five kilometres of Harris Creek in the Okanagan region, east of Vernon. Samples were prepared and analysed as described above though heavy-mineral concentrates were only prepared for two size fractions. Gold was found to be considerably enriched in sandy-gravel deposits compared to sand deposits, with the effect decreasing as sediment size decreased. The level of enrichment varies on the stream in response to changing channel slope and local hydraulic conditions. Gold anomaly dilution is apparent in sand deposits but not apparent in sandy-gravel deposits since gold is preferentially deposited in gravels as channel slope decreases. These results are presented in the framework of H.A. Einstein's sediment transport model. Sediment collected from gravels may represent the best geochemical sample since placer-forming processes produce high gold concentrations, however in very high energy streams, the small quantities of fine sediment in gravels may lead to unacceptable nugget effects. In the latter case, a sample collected from a sand deposit is a satisfactory alternative.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate

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43

Korkalo, T. (Tuomo). "Gold and copper deposits in Central Lapland, Northern Finland, with special reference to their exploration and exploitation". Doctoral thesis, University of Oulu, 2006. http://urn.fi/urn:isbn:951428108X.

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Abstract At least 30 gold deposits verified by means of one or more notable diamond drill hole results have been discovered in Central Lapland in the last 20 years, and these can be divided spatially into groups, between which the metal composition varies. The deposits contain varying amounts of sulphides and sulpharsenides as well as gold. Pyrite is the most common sulphide mineral in the gold deposits associated with volcanic rocks, and usually pyrrhotite in those associated with sedimentary rocks. The principal sulphide minerals in those connected with banded iron formations are pyrite and arsenopyrite. A separate group of formations consists of the palaeoplacer gold deposits associated with the molasse-like quartzites and conglomerates of Central Lapland. The iron oxide-copper-gold deposits of Central Lapland, which are a significant potential source of copper and gold, are mostly associated with skarn rocks at the eastern contact of the acidic intrusive rocks of Western Lapland and with skarn rocks occurring as interlayers in metavolcanic and metasedimentary rocks. The gold deposits that have led to actual mining activities in Central Lapland are Saattopora in Kittilä and Pahtavaara in Sodankylä. Apart from the Laurinoja iron oxide-copper-gold ore body in Kolari, copper concentrate has been produced from the Saattopora gold ore deposit and the Pahtavuoma copper ore deposit. Only one gold ore in Central Lapland is being actively exploited at present, that of the Pahtavaara mine, which was worked in 1995–2000 and reopened in 2003. The best starting point for successful gold ore exploration in Central Lapland can be achieved through a thorough knowledge of the deformation zones and their structures and alteration processes and the application of geochemical methods. Magnetic surveys can be of help in identifying and locating deformation zones of interest for exploration purposes and the majority of the associated shear zones and faults. Ore-critical zones usually feature graphite-bearing schists and iron sulphide-bearing sequences that can be traced by electrical methods and used as marker zones to verify the results of geological mapping. Geological, geophysical and geochemical techniques have been used in great diversity, and in particular till geochemistry and bedrock drilling have been methods by which the gold and copper deposits in Central Lapland have been discovered. A total of 7.6 million tonnes of gold and copper ores, including the Laurinoja iron oxide-copper-gold ore, were extracted in Central Lapland over the period 1982–2000. The resulting production of gold during this period was 10 800 kg, together with 21 000 tonnes of copper in concentrates and 4500 kg of silver. The gold and copper ores have been concentrated by gravity separation and/or flotation, since the ores so far taken into production has been of the free milling type. However, a substantial proportion of the deposits in the area contain copper, nickel, cobalt and arsenic as well, in the form of sulphides or sulpharsenides, so that the achievement of commercially saleable products calls for the use of different leaching processes. Deposits have also been found in Central Lapland that have consisted partly or entirely of refractory gold ore in which gold is lying in the crystal lattice of pyrite and/or arsenopyrite, the processing of which by the above-mentioned methods is not economic, as it requires pre-treatment by bio-oxidation or pressure oxidation in order to convert the gold to a cyanide-soluble form.

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44

Schmauder, Gretchen C. "Thermal and chemical profiling of the Bald Mountain District, White Pine County, Nevada /". abstract and full text PDF (free order & download UNR users only), 2005. http://0-wwwlib.umi.com.innopac.library.unr.edu/dissertations/fullcit/1433099.

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Thesis (M.S.)--University of Nevada, Reno, 2005.
"August, 2005." Includes bibliographical references. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2005]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

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45

Doyle, Jessica B. "Geology and structure of Winters Creek, Jerritt Canyon District, Elko County, Nevada". abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1447627.

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46

Papangelakis, V. G. (Vladimiros George) 1958. "Aqueous pressure oxidation of arsenopyrite". Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65435.

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47

Linklater, Michael Anthony Leonard Flanders. "The exploration for and possible genesis of, some Archaean granite/gneiss-hosted gold deposits in the Pietersburg granite-greenstone terrane". Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1005557.

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Abstract The gold mineralization event within Archaean granite-greenstone terranes occurred during the late Archaean, and followed the intrusion of syn- to late-tectonic granitic plutons into previously deformed greenstone belts. An Archaean granite/gneiss-hosted gold deposit, in terms of this project, is classified as having a gold-assay cutoff of 1g/metric ton over widths of at least several metres, or higher grades over narrower widths and/or verbal descriptions that indicate such values. Fluid inclusion studies and isotopic data identify two possible origins for the auriferous fluids; namely magmatic and metamorphic. The exploration target according to the magmatic model, is a late-Archaean, hydrothermally altered, mineralized and fractured granitic intrusion preferably with a granodioritic or quartz-dioritic composition. The exploration target according to the metamorphic replacement model is a granitic stock that has intruded a zone of crustal weakness such as a shear zone, active during the late Archaean. Alternatively, the granitic intrusion should be affected by regionally extensive late-Archaean shearing. It should be hydrothermally altered, deformed and mineralized. Five areas within the Pietersburg granite-greenstone terrane were selected for the 'Regional Area Selection' phase of exploration for Archaean granite/gneiss-hosted gold deposits; namely Roodepoort, Waterval, Ramagoep, Moletsie and Matlala. Roodepoort contains a known granodiorite-hosted gold deposit; the Knight's Pluton, and served as an orientation survey for this project. The use and interpretation of LANDSAT images formed an integral part of exploration techniques; to assess their usefulness in the exploration of Archaean granite/gneiss-hosted gold deposits. Area selection criteria for granite/gneiss-hosted gold mineralization at Roodepoort are the major ENE-trending shear zone, the NNW-trending lineament and hydrothermal alteration, shearing, quartz-stockworks and sulphide mineralization within the Knight's Pluton. The origin of the gold within the Knight's Pluton is uncertain; both magmatic and metamorphic models are possibilities. Ongoing exploration is in progress at Roodepoort. The only area selection criterion for granite/gneiss-hosted gold mineralization at Waterval is the sericitized, subcropping granites located within trenches. Gold mineralization is insignificant. No area selection criteria for Archaean granite/gneiss-hosted gold mineralization were located at Ramagoep, Matlala and Moletsie. No further exploration is recommended for all these areas. The MES image interpretations were successful in identifying lineaments, granitic outcrops, greenstones, vegetation and soil cover. The Clay-iron images adequately differentiated betweeen iron-rich and clay-bearing areas. However, not all clay-bearing areas were associated with hydrothermal alteratian; field checks were necessary to discriminate between weathered granites and hydrothermally altered granites. The Wallis images served to locally enhance the contrasts of the MES and Clay-iron images.

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48

Voicu, Gabriel. "Géologie, géochimie et métallogénie du gisement d'or Omai, Bouclier Guyanais, Amérique du Sud = Geology, geochemistry and metallogeny of the Omai Gold Deposit, Guiana Shield, South America /". Thèse, Montréal : Chicoutimi : Université du Québec à Montréal ;. Université du Québec à Chicoutimi, 1999. http://theses.uqac.ca.

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49

Patterson, Lucia Maria. "Hydrothermal footprint of Carlin-type gold deposits at the district scale : Jerritt Canyon Mining District, Elko County, Nevada /". abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1464422.

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Thesis (M.S.)--University of Nevada, Reno, 2009.
"May, 2009." Includes bibliographical references (leaves 202-215). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2009]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

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50

House, MJ. "Gold distribution at the E26 porphyry copper-gold deposit, Goonumbla N.S.W". Thesis, 1994. https://eprints.utas.edu.au/20154/7/whole_HouseMichaelJohn1995.pdf.

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The E26 porphyry copper-gold deposit is the largest of several copper-gold deposits discovered to date in the Goonumbla region of central west N.S.W. Cu and Au mineralisation occurs in areas of strong pervasive potassic alteration and quartz veining, associated with a small pipe-like quartz monzonite porphyry (QMP1). The mineralisation occurs both within the porphyry and the covolcanic late Ordovician trachyte-latite lavas and volcanic breccias that it has intruded. The deposit is bounded at depth and to the east by a biotite quartz monzonite, while to the immediate north, is another younger QMP (QMP2) which has stoped out the Cu-Au mineralisation. Several other QMP's occur to the northwest and at deeper levels in the E26 deposit. Copper mineralisation occurs principally as bornite with lesser chalcopyrite and chalcocitedigentite. Two bornite phases have been identified based on colour and mineral associations. Gold occurs principally as fine inclusions in bornite. The sulphides are zoned from a bornite-rich core, through a chalcopyrite zone to an outer pyrite halo associated with propylitic alteration. A weak base metal/gold association occurs in thin structurally controlled zones of quartz-sericite-pyrite alteration, away from the main E26 mineralisation. Within E26 itself, the bulk of the Au is confined to the central and deeper parts of the system and immediately around QMP 1. Cu however, continues to shallower depths and laterally further away from QMP 1 . This pattern is reflected in the Cu/Au ratios, and has led to the definition of two distinct vertical domains within the higher grade areas of E26. The upper domain is characterised by high copper grades but low gold grades; the lower domain contains similar copper grades but much higher gold grades. Sulphide composition, timing and alteration are similar within the Cu/Au domains defined. A geochemical model developed shows that the Cu/Au relationships observed at E26 can be explained by coprecipitation of Cu and Au, but at different rates due to differing changes in saturation levels between the two metals. Deposition of both metals from chloride complexes in high temperature, saline fluids was in response to a decrease in T, and changes in f02nand pH associated with hematisation of secondary magnetite associated with earlier biotite (potassic) alteration. The deposits at E22, E27 and E31N do not show the same degree of magnetite destruction as E26 and E48, are more deeply eroded, and therefore not as enriched in copper.

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