Дисертації: "Geometallurgey"

1

Mwanga, Abdul. "Test Methods for Characterising Ore Comminution Behavior in Geometallurgy." Licentiate thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18689.

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Comminution test methods used within mineral processing have mainly been developed for selecting the most appropriate comminution technology for a given ore, designing a grinding circuit as well as sizing the equipment needed. Existing test methods usually require comparatively large sample amounts and are time-consuming to conduct. This makes comprehensive testing of ore comminution behavior – as required in the geometallurgical context – quite expensive. Currently the main interest in the conduct of comminution test lies in the determination of particle size reduction and related energy consumption by grindability test methods, which provide the necessary information about mill throughput. In this procedure mineral liberation is regarded as a fixed parameter due to missing this information in ore characterization as well as a lack of suitable comminution models. However, ignoring the connection between particle size and mineral liberation prevents the scheduling and controlling of the production process from being optimal.For these reasons new comminution tests need to be developed or alternatively the existing test methods need to be suited to geometallurgical testing where the aim is to map the variation of processing properties of an entire ore body. The objective of this research work is on the one hand to develop small-scale comminution test methods that allow linking comminution behavior and liberation characteristics to mineralogical parameters, and on the other hand establish a modeling framework including mineral liberation information.Within the first stage of the study the comminution of drill cores from Malmberget’s magnetite ore, classified by modal mineralogy and texture information, have been investigated. It was found that there is a direct correlation between the mechanical strength of the rock, as received from unconfined compressive or point load tests, and the crusher reduction ratio as a measure for crushability. However, a negative correlation was found between crushability and grindability for the same samples. The grindability showed inverse correlation with both magnetite grade and the magnetite’s mineral grain size. The preliminary conclusion is that modal mineralogy and micro-texture (grain size) can be used to quantitatively describe the ore comminution behavior although the applied fracture mechanism of the mill cannot be excluded.With crushed ore samples from Malmberget also grindability tests and mineral liberation analyses were conducted using laboratory tumbling mills of different size. Starting from the dimensions of the Bond ball mill a modified test method was developed where small size samples of approximately 220 g were pre-crushed and ground in a down-scaled one-stage grindability test. Down-scaling was done by keeping similar impact effects between the mills. Mill speed and grinding time were used for adjusting the number of fracture events in order to receive similar particle size distributions and specific grinding energy when decreasing mill size by the factor 1.63. A detailed description of the novel geometallurgical comminution test (GCT) is given.With respect to ore crushability and autogenous and semiautogenous grinding (AG/SAG) also drop weight tests were conducted. For a more accurate and precise measurement of the energy transferred to the sample a novel instrumented drop weight was used. Initial tests with fractions of drill cores and pre-crushed ore particles showed that the simple energy calculation based on potential energy needs to be corrected. For the future work these tests will be extended to other ore types in order to investigate the effects of mineralogy and to include mineral liberation in comminution models suitable for geometallurgy.

Godkänd; 2014; 20140402 (abdmwa); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Abdul Mwanga Ämne: Mineralteknik/Mineral Processing Uppsats: Test Methods for Characterising Ore Comminution Behavior in Geometallurgy Examinator: Professor Jan Rosenkranz, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Professor Hakan Benzer, Hacettepe University, Department of Mining Engineering Beytepe, Ankara, Turkey Tid: Torsdag den 12 juni 2014 kl 10.00 Plats: F531, Luleå tekniska universitet

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Guntoro, Pratama Istiadi. "X-ray microcomputed tomography (µCT) as a potential tool in Geometallurgy." Licentiate thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76576.

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In recent years, automated mineralogy has become an essential tool in geometallurgy. Automated mineralogical tools allow the acquisition of mineralogical and liberation data of ore particles in a sample. These particle data can then be used further for particle-based mineral processing simulation in the context of geometallurgy. However, most automated mineralogical tools currently in application are based on two-dimensional (2D) microscopy analysis, which are subject to stereological error when analyzing three-dimensional(3D) object such as ore particles. Recent advancements in X-ray microcomputed tomography (µCT) have indicated great potential of such system to be the next automated mineralogical tool. µCT's main advantage lies on its ability in monitoring 3D internal structure of the ore at resolutions down to few microns, eliminating stereological error obtained from 2D analysis. Aided with the continuous developments of computing capability of 3D data, it is only the question of time that µCT system becomes an interesting alternative in automated mineralogy system. This study aims to evaluate the potential of implementing µCT as an automated mineralogical tool in the context of geometallurgy. First, a brief introduction about the role of automated mineralogy in geometallurgy is presented. Then, the development of µCT system to become an automated mineralogical tool in the context of geometallurgy andprocess mineralogy is discussed (Paper 1). The discussion also reviews the available data analysis methods in extracting ore properties (size, mineralogy, texture) from the 3D µCT image (Paper 2). Based on the review, it was found that the main challenge inperforming µCT analysis of ore samples is the difficulties associated to the segmentation of the mineral phases in the dataset. This challenge is adressed through the implementation of machine learning techniques using Scanning Electron Microscope (SEM) data as a reference to differentiate the mineral phases in the µCT dataset (Paper 3).

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3

Tiu, Glacialle. "Classification of Drill Core Textures for Process Simulation in Geometallurgy : Aitik Mine, Sweden." Thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65207.

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This thesis study employs textural classification techniques applied to four different data groups: (1) visible light photography, (2) high-resolution drill core line scan imaging (3) scanning electron microscopy backscattered electron (SEM-BSE) images, and (4) 3D data from X-ray microtomography (μXCT). Eleven textural classes from Aitik ores were identified and characterized. The distinguishing characteristics of each class were determined such as modal mineralogy, sulphide occurrence and Bond work indices (BWI). The textural classes served as a basis for machine learning classification using Random Forest classifier and different feature extraction schemes. Trainable Weka Segmentation was utilized to produce mineral maps for the different image datasets. Quantified textural information for each mineral phase such as modal mineralogy, mineral association index and grain size was extracted from each mineral map. Efficient line local binary patterns provide the best discriminating features for textural classification of mineral texture images in terms of classification accuracy. Gray Level Co-occurrence Matrix (GLCM) statistics from discrete approximation of Meyer wavelets decomposition with basic image statistical features[PK1] (e.g. mean, standard deviation, entropy and histogram derived values) give the best classification result in terms of accuracy and feature extraction time. Differences in the extracted modal mineralogy were observed between the drill core photographs and SEM images which can be attributed to different sample size[PK2] . Comparison of SEM images and 2D μXCT image slice shows minimal difference giving confidence to the segmentation process. However, chalcopyrite is highly underestimated in 2D μXCT image slice, with the volume percentage amounting to only half of the calculated value for the whole 3D sample. This is accounted as stereological error. Textural classification and mineral map production from basic drill core photographs has a huge potential to be used as an inexpensive ore characterization tool. However, it should be noted that this technique requires experienced operators to generate an accurate training data especially for mineral identification and thus, detailed mineralogical studies beforehand is required.
Primary Resource Efficiency by Enhanced Prediction (PREP)
Center for Advanced Mining and Metallurgy (CAMM)

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Barton, Isabel Fay, and Isabel Fay Barton. "Mineralogical and Metallurgical Study of Supergene Ores of the Mike Cu-Au(-Zn) Deposit, Carlin Trend, Nevada." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/625323.

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This paper presents the results of a mineralogical and metallurgical study of supergene ores at the Mike Cu-Au(-Zn) deposit on the Carlin trend of Nevada, USA, currently held by Newmont Gold Corporation. With a metal endowment totaling >8.5 M oz. Au, 1027 M lbs. Cu, and 809 M lbs. Zn, Mike is one of the largest deposits on the Carlin trend, but it is currently uneconomic to develop. It contains an unusual and complicated suite of metals and ore minerals. This study was undertaken as a first step to investigate process options for recovering both its Cu and Au by 1) comparing the metal recoveries achieved from the supergene ores by six different lixiviants, and 2) identifying which minerals failed to dissolve in each lixiviant. The reagents selected were sulfuric, sulfurous, and methanesulfonic acids, to recover Cu, and cyanide, thiourea, and glycine, to recover Cu and Au. QEMSCAN and SEM study of six samples of different ore types and grades indicate that the Au occurs as varieties of native gold, including auricupride and electrum. Major Cu minerals are native Cu, cuprite, malachite, chrysocolla, and conichalcite (Ca-Cu arsenate), with locally significant Cu in jarosite and goethite. Gangue mineralogy is dominated by quartz, sericite, chlorite, alunite, smectite and kaolinite, K-feldspar, jarosite, and iron oxides. Bottle roll testing indicates that no single-step leaching process is likely to provide economic recovery of both Cu and Au. Sulfuric and methanesulfonic acid both recovered > 70% of the Cu except from the samples dominated by conichalcite, which was not leached effectively by any of the reagents tested. Only cyanide and thiourea recovered significant Au. Reagent consumption for cyanide, sulfuric acid, and methanesulfonic acid was generally within acceptable levels. Glycine and sulfurous acid are both uneconomic based on low recovery. Further work will focus on developing an economic process in two steps. Mineralogical study of QEMSCAN residue indicates that the non-leaching ore minerals are conichalcite and Cu-bearing Fe oxides. In addition, native Cu and cuprite do not leach well in glycine and chrysocolla does not leach well in thiourea or cyanide. Other observed mineralogical changes include the total loss of dolomite and partial loss of alunite and iron oxide from all samples, with apparent gains in jarosite.

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Anderson, Kelvin Frederick Esebewa. "Geometallurgical evaluation of the Nkout (Cameroon) and Putu (Liberia) iron ore deposits." Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/15019.

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The Nkout (Cameroon) and Putu (Liberia) oxide facies iron ore deposits comprise fresh magnetite banded iron formation (BIF) at depth, which weathers towards the surface, forming high grade martite–goethite ores. This study aimed to improve the mineralogical understanding of these deposits in order to predict their metallurgical responses. It concentrated on developing the QEMSCAN® technique and testing its application to these ore types, but also used a variety of other analysis methods. The QEMSCAN® species identification protocol was developed to include three goethite entries: goethite/limonite, phosphorus-bearing and aluminium-bearing goethite. QEMSCAN® was also used to distinguish between the iron oxides using their backscattered electron signals. To test the correlation between the mineralogy and metallurgical characteristics, magnetic separations were carried out. The samples were divided into 4 main groups based on their whole rock Fe content, determined by XRF analysis, and their degree of weathering: enriched material, weathered magnetite itabirite, transitional magnetite itabirite and magnetite itabirite. Quartz and Al oxide and hydroxide minerals such as gibbsite are the major gangue minerals in the magnetite BIF and martite–goethite ores respectively. From the QEMSCAN® analysis it was concluded that the iron oxides are closely associated and liberation of them individually is poor. Liberation increases when they are grouped together as iron oxide. Chamosite concentrations > 6 wt. % significantly lower liberation of the iron oxides. From the metallurgical testing, it was concluded that iron oxide modal mineralogy gives an indication of iron recovery but other QEMSCAN® data such as mineral association and liberation could be important especially if the iron oxide minerals are not liberated. Grain size and instrument characteristics also affect recovery of iron minerals. There is no evidence to show that there is any structural control on the BIF mineralisation at Nkout because metamorphism has significantly affected the lithological characteristics. The BIF mineralised zones occur as stacks with no particular stratigraphic relationship. Alteration and stratigraphy are the main controls on the martite–goethite ores. These results are applicable to most other BIFs so that as direct shipping ores are exhausted, the approach used here can help to develop the lower grade portions of the deposits.

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Schmitt, Raoul. "A Geometallurgical Approach Towards the Correlation Between Rock Type Mineralogy and Grindability: A case study in Aitik mine, Sweden." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-87012.

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Aitik is a large copper porphyry type deposit located in northern Sweden, currently exploited at an annual rate of approximately 45Mt. The ore's exceptionally low head grade of 0.22 % Cu and varying degrees of hardness across the entire deposit pose challenges to the two fully autogenous grinding lines, each of which comprises a 22.5 MW primary autogenous mill in series with a pebble mill. The variability in ore grindability frequently leads to fluctuations in mill throughput. Within the framework of a geometallurgical approach, the present study investigated the relationships between ore grindability and modal mineralogy. For this purpose, drill core samples from different lithologies were subjected to Boliden AB's in-house grindability tests. This laboratory-scale autogenous grinding test generates a grindability index Ks mainly related to abrasion breakage, which is a significant breakage mechanism within autogenous mills. The test results suggested divergent degrees of grindability within and across the selected rock types. Furthermore, subsequent sieve analyses identified a relationship between the grindability index, PSD, and the proportions of fines generated by abrasive grinding. A combination of scanning electron microscopy, X-ray powder diffraction, and X-ray fluorescence analyses was performed for the grinding products and bulk mineral samples. The resulting mineralogical and elemental properties were correlated to the parameters from the grindability tests. It was shown that the main mineral phases, such as plagioclase, quartz, and micas, correlate well with the grindability indices. Similar correlations were found regarding the sample's chemical composition, attributable to the main mineral phases. Derived from the previous findings, two exemplary linear empirical models for the calculation of grindability based on either mineral contents or chemical composition were presented. Careful examination of the mineralogical data revealed that the prevalent abrasion breakage mechanism leads to constant and continuous removal of mineral particles from the sample's surface. No indications for a preferential abrasion of any mineral phases were found. A further inverse correlation between the sample's calculated average weighted Mohs hardness based on modal mineralogy and the grindability index Ks was established. Hence, it was proposed that a higher Mohs hardness results in a finer grinding product, oppositional to the Ks-values. Since Ks can be interpreted as a measure of abrasiveness, it can be stated that abrasiveness decreases with an increasing average sample hardness and vice versa. Moreover, mineral liberation information provided by scanning electron microscopy was associated with the parameters mentioned earlier. It was determined that different degrees of mineral liberation were reached within specific particle size classes. The identified relationships between grindability, modal mineralogy, and element grades may help Boliden develop a predictive throughput model for Aitik to be integrated into the mine's block model. Based on this information, a strategy for smart blending could be developed, where run of mine material from ore blocks of varying grindabilities could be blended to attain the target plant throughput.

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Patton, William. "Modelling of unequally sampled rock properties using geostatistical simulation and machine learning methods." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2022. https://ro.ecu.edu.au/theses/2530.

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Important orebody characteristics that determine viability of the mineral resource and ore reserve potential such as physical properties, mineralogical and geochemical compositions often vary substantially across an ore deposit. Geometallurgical models aim to capture the spatial relationships between mineral compositions, physical properties of rock and their interactions with mechanical and chemical processes during mining extraction and processing. This characterisation of physical and chemical properties of ores can in turn be used to inform mining and processing decisions that enable the extraction of the maximum value from the ore deposit most efficiently. During the construction of such spatial geometallurgical models, practitioners are presented with many challenges. These include modelling high-dimensional data of various types including categorical, continuous and compositional attributes and their uncertainties. Decisions on how to segregate samples data into spatially and statistically homogeneous groups to satisfy modelling assumptions such as stationarity are often a requirement. Secondary properties such as metallurgical test results are often few in number, acquired on larger scales than that of primary rock property data and non-additive in nature. In this thesis a data driven workflow that aims to address these challenges when constructing geometallurgical models of ore deposits is devised. Spatial machine learning techniques are used to derive geometallurgical categories, or classes, from multiscale, multiresolution, high dimensional rock properties. In supervised mode these methods are also used to predict geometallurgical classes at samples where rock property information is incomplete. Realisations of the layout of geometallurgical classes and the variabilities of associated rock properties are then mapped using geostatistical simulations and machine learning. The workflow is demonstrated using a case study at Orebody H; a complex stratabound Bedded Iron Ore deposit in Western Australia’s Pilbara. A detailed stochastic model of five compositions representing primary rock properties and geometallurgical responses in the form of lump and fine product iron ore quality specifications was constructed. The predicted product grade recoveries are realistic values that honour constraints of the predicted head grade compositions informed by more abundant and regularly spaced sampling than metallurgical tests. Finally, uncertainties are quantified to assess risk following a confidence interval based framework. This could be used to identify zones of high uncertainty where collection of additional data might help mitigate or minimise risks and in turn improve forecast production performances.

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Westberg, Fredrik. "Textural characterization of gold in the Björkdal gold deposit, northern Sweden." Thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-82496.

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The Björkdal gold deposit is located in the eastern part of the Skellefte district, northern Sweden. Twenty thin sections from four production areas in the open pit and four drifts from the underground mine were analysed for mineral association and grain size distribution of gold. In addition, the texture of gold was investigated in order to find out how that affects the recovery of gold. The overall gold grain size distribution shows an interval from very fine-grained (2 μm) to coarse grained(856 μm) while the overall median size is 7 μm. Gold from the Quartz Mountain production area displays the smallest median size of 4 μm, whereas gold from the sampled drifts at 340m- and 385m- level has the largest median size of 14 μm. Gold at grain boundary is the dominant textural mode of gold from all sampled locations and varies from 62% to 92%. This is followed by intergrown which ranges between 8% and 29%. Of the sulfides, pyrite, chalcopyrite and pyrrhotite are the most common. Galena and was also present in the samples. Gold is significantly and positively correlated with tellurium (Appendix 10.1.1), and weakly positive correlated to silver and mercury. Gold show a close association to bismuth-tellurides in the samples. Apart from native gold, which is the dominant mineral phase of gold, two additional gold-bearing tellurium minerals were detected with SEM-EDS, a Au-Te-mineral and a Ag-Au-Te-mineral. One additional bismuth-telluride mineral aside from the most commonly occurring tsumoite (BiTe) was also detected with SEM, with a elemental composition of Bi-Te-S. Liberated gold in the tailings was optically identified in two thick sections, TB1-02feb-1 and TB1-07feb-1 (Fig. 32A and B), where the flotation circuit failed to float the free gold. One grain of gold was also identified intergrown with bismuth-telluride as an inclusion in silicate (Fig. 33), where the flotation properties of the larger silicate grain likely dominated in the flotation process. This thesis highlights the importance of further quantitative analysis utilizing SEM/QEMSCAN/MLA to retrieve representative mineralogical data to benefit the mineral processing of the ore from the active mine. Keywords: Björkdal gold deposit, gold, gold-telluride, SEM, mineral association, grain size,geometallurgy.

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Koch, Pierre-Henri. "Particle generation for geometallurgical process modeling." Licentiate thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63270.

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A geometallurgical model is the combination of a spatial model representing an ore deposit and a process model representing the comminution and concentration steps in beneficiation. The process model itself usually consists of several unit models. Each of these unit models operates at a given level of detail in material characterization - from bulk chemical elements, elements by size, bulk minerals and minerals by size to the liberation level that introduces particles as the basic entity for simulation (Paper 1). In current state-of-the-art process simulation, few unit models are defined at the particle level because these models are complex to design at a more fundamental level of detail, liberation data is hard to measure accurately and large computational power is required to process the many particles in a flow sheet. Computational cost is a consequence of the intrinsic complexity of the unit models. Mineral liberation data depends on the quality of the sampling and the polishing, the settings and stability of the instrument and the processing of the data. This study introduces new tools to simulate a population of mineral particles based on intrinsic characteristics of the feed ore. Features are extracted at the meso-textural level (drill cores) (Paper 2), put in relation to their micro-textures before breakage and after breakage (Paper 3). The result is a population of mineral particles stored in a file format compatible to import into process simulation software. The results show that the approach is relevant and can be generalized towards new characterization methods. The theory of image representation, analysis and ore texture simulation is briefly introduced and linked to 1-point, 2-point, and multiple-point methods from spatial statistics. A breakage mechanism is presented as a cellular automaton. Experimental data and examples are taken from a copper-gold deposit with a chalcopyrite flotation circuit, an iron ore deposit with a magnetic separation process. This study is covering a part of a larger research program, PREP (Primary resource efficiency by enhanced prediction).
PREP

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Parian, Mehdi. "Development of a geometallurgical framework for iron ores - A mineralogical approach to particle-based modeling." Doctoral thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-62515.

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The demands for efficient utilization of ore bodies and proper risk management in the mining industry have resulted in a new cross-disciplinary subject called geometallurgy. Geometallurgy connects geological, mineral processing and subsequent downstream processing information together to provide a comprehensive model to be used in production planning and management. A geometallurgical program is an industrial application of geometallurgy. Various approaches that are employed in geometallurgical programs include the traditional way, which uses chemical elements, the proxy method, which applies small-scale tests, and the mineralogical approach using mineralogy or the combination of those. The mineralogical approach provides the most comprehensive and versatile way to treat geometallurgical data. Therefore it was selected as a basis for this study. For the mineralogical approach, quantitative mineralogical information is needed both for the deposit and the process. The geological model must describe the minerals present, give their chemical composition, report their mass proportions (modal composition) in the ore body and describe the ore texture. The process model must be capable of using mineralogical information provided by the geological model to forecast the metallurgical performance of different geological volumes and periods. A literature survey showed that areas, where more development is needed for using the mineralogical approach, are: 1) quick and inexpensive techniques for reliable modal analysis of the ore samples; 2) ore textural characterization of the ore to forecast the liberation distribution of the ore when crushed and ground; 3) unit operation models based on particle properties (at mineral liberation level) and 4) a system capable of handling all this information and transferring it to production model. This study focuses on developing tools in these areas. A number of methods for obtaining mineral grades were evaluated with a focus on geometallurgical applicability, precision, and trueness. A new technique developed called combined method uses both quantitative X-ray powder diffraction with Rietveld refinement and the Element-to-Mineral Conversion method. The method not only delivers the required turnover for geometallurgy but also overcomes the shortcomings if X-ray powder diffraction or Element-to-Mineral Conversion were used alone. Characterization of ore texture before and after breakage provides valuable insights about the fracture pattern in comminution, the population of particles for specific ore texture and their relation to parent ore texture. In the context of the mineralogical approach to geometallurgy, predicting the particle population from ore texture is a critical step to establish an interface between geology and mineral processing. A new method called Association Indicator Matrix developed to assess breakage pattern of ore texture and analyze mineral association. The results of ore texture and particle analysis were used to generate particle population from ore texture by applying particle size distribution and breakage frequencies. The outcome matches well with experimental data specifically for magnetite ore texture. In geometallurgy, process models can be classified based on in which level the ore, i.e. the feed stream to the processing plant and each unit operation, is defined and what information subsequent streams carry. The most comprehensive level of mineral processing models is the particle-based one which includes practically all necessary information on streams for modeling unit operations. Within this study, a particle-based unit operation model was built for wet low-intensity magnetic separation, and existing size classification and grinding models were evaluated to be used in particle level. A property-based model of magnetic beneficiation plant was created based on one of the LKAB operating plants in mineral and particle level and the results were compared. Two different feeds to the plant were used. The results revealed that in the particle level, the process model is more sensitive to changes in feed property than any other levels. Particle level is more capable for process optimization for different geometallurgical domains.

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Mwanga, Abdul-Rahaman. "Development of a geometallurgical testing framework for ore grinding and liberation properties." Doctoral thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-59904.

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Efficient measurement methods for comminution properties are an important prerequisite for testing the variability of an ore deposit within the geometallurgical context. This involves the investigation of effects of mineralogy and mineral texture on the breakage of mineral particles. Breakage properties of mineral particles are crucial for the liberations of minerals and the energy required for that. For process optimization and control purposes, comminution indices are often used to map the variation of processing properties of an entire ore body (e.g. Bond work index). Within the geometallurgical approach this information is then taken up when modelling the process with varying feed properties. The main focus of this thesis work has been to develop a comprehensive geometallurgical testing framework, the Geometallurgical Comminution Test (GCT), which allows the time and cost efficient measurement of grinding indices and their linkage to mineralogical parameters (e.g. modal mineralogy or mineral texture, mineral liberation). In this context a small-scale grindability test has been developed that allows estimating the Bond work index from single pass grinding tests using small amounts of sample material. Verification of the evaluation method and validation was done with different mineral systems. For selected samples the mineral liberation distribution was investigated using automated mineralogy. By transferring the energy-size reduction relation to energy – liberation relation new term liberability has been established. As part of the experimental investigations, mineralogical parameters and mineral texture information were used for predicting breakage and liberation properties. Patterns for describing the breakage phenomena were established for a set of iron oxide ore samples. The determined breakage patterns indicated that the specific rate of mineral breakage slows down when reaching the grain size of mineral particles, thus allowing maximizing mineral liberation significantly without wasting mechanical energy.
CAMM

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Belo, Fernandes Ivan. "Geometallurgical approach to understand how the variability in mineralogy at Zinkgruvan orebodies affects the need for copper activation in the bulk rougher-scavenger flotation." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65392.

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Zinkgruvan is a Pb-Zn-Ag deposit located in south-central Sweden, owned and operated by Lundin Mining. The ore is beneficiated by a collective-selective flotation circuit, recovering both galena and sphalerite in a bulk rougher-scavenger flotation stage and later on separating them into two final products. Opportunities for increase in zinc recovery in the bulk rougher scavenger flotation stage have been identified as the plant is relying on natural Pb-activation to process the ore. Process mineralogical tools were used to characterize four different orebodies from Zinkgruvan (Burkland, Borta Bakom, Nygruvan and Sävsjön) and evaluate the metallurgical performance for flotation and magnetic separation, following a geometallurgical approach to better understand and predict the behavior of such ore types in processing plant. The first hypothesis in this thesis is that by addition of copper sulfate and increased collector dosage, Zn recovery will be improved without being detrimental to galena flotation. Results demonstrated that there is a significant increase in Zn recovery by further increasing collector dosage and copper-activating the flotation pulp in the scavenger stage. For instance, an increase in zinc recovery up to 16% has been achieved after addition of copper sulfate. Galena is readily floatable while sphalerite takes longer to be recovered. In addition, iron sulfides take longer to be recovered and, after addition of copper sulfate, there was an increase in iron sulfide recovery. The amount of iron sulfides reporting to the concentrate should still not be a problem to the plant. Most of the Fe in the concentrate is still coming from the sphalerite lattice. However, it might be that some orebodies coming into production in the near future have higher amounts of pyrrhotite, which might be a problem. Therefore, magnetic separation methods have been tested to remove pyrrhotite from the bulk ore. The second hypothesis is that the high Fe content in the concentrate might be due to the presence of iron sulfides, in which case they could be selectively removed by magnetic separation. XRD analyses demonstrated that Sävsjön is a highly variable orebody, and that its high Fe content varies with the location inside the orebody, being caused by either iron sulfide or iron oxide minerals. Both monoclinic and hexagonal pyrrhotite have been observed. Davis Tube could remove monoclinic pyrrhotite but it was very inefficient when dealing with hexagonal pyrrhotite. WHIMS, on the other hand, performed well for both types of pyrrhotite. When applying Davis Tube on Sävsjön OLD feed, a concentrate with up to 52.3% pyrrhotite is achieved, at a recovery of 35.32%. However, sphalerite is also reporting to the magnetic concentrate, which would generate Zn losses for the overall process. Zinc losses were up to 15.3% when the highest field strength was applied. Therefore, the applicability of magnetic separation for Zinkgruvan ore must be further evaluated.

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Cárdenas, Efraín. "Particle tracking in geometallurgical testing for Leveäniemi Iron ore, Sweden." Thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65988.

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In a particle based geometallurgical model, the behavior of the particles can be used for forecast the products and quantify the performance of the different ore types within a deposit. The particle tracking is an algorithm developed by Lamberg and Vianna 2007 whose aim is to balance the liberation data in a mineral processing circuit composed by several processing units. Currently, this tool is being developed for the HSC Chemistry software by Outotec.The objective of this study is to understand and evaluate the particle tracking algorithm in a geometallurgical test for iron ore. To achieve this objective, the liberation data is balanced in a Davis tube test circuit. A total of 13 samples from Leveäniemi iron ore were process in a Davis tube circuit.The magnetite is the main mineral in the Leveäniemi iron ore samples. Its high recovery in the Davis tube circuit along with the V, Ti and Mn suggest that these elements are present in the magnetite lattice. These penalty elements in the iron concentrates cannot be avoided at the stage of mineral concentrations.The washing effect of the Davis tubes controlled by the rotational and longitudinal agitation of the tube perturb the particles agglomeration between the pole tips of the electromagnet. A higher agitation frequency and amplitude will wash away most of the gangue minerals and also fine grained magnetite.In this work, the particle tracking is depicted and implemented in a magnetic separation circuit for high liberated material. The liberation data was balanced in a way that the particle classes can be followed through circuit and their recoveries can be calculated. Nevertheless, the algorithm requires further validation and analysis of its limitations in terms of resolution and reproducibility.

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14

Lood, Stark Gustav. "A process mineralogy study of grinding characteristics for the polymetallic orebody, Lappberget Garpenberg." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-86988.

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Most of the high-grade ores have been depleted globally, thus the effective processing of the low-grade and complex ores require a comprehensive mineral characterization through the process mineralogy/ geometallurgical approaches. 30-70 % of the total energy consumption in mining comes from the comminution step in mineral processing. This study, is aimed to investigate how different mineral domains in Lappberget, Garpenberg affect the grinding energy and throughput of an autogenous grinding mill (AG) and how blending different mineralogical domains will have an effect on throughput. The results were obtained through automated mineralogy using a Zeiss Sigma 300 VP at the QANTMIN scanning electron microscope (SEM) laboratory (Luleå University of Technology) and an in-house grindability test developed by Boliden Mineral AB. There is approximately a multiple of three times differences in the amount of energy consumption and throughput between the hardest and softest mineralogical domains. This difference is attributed to mineral composition of the individual domains and mineral characteristics. Blending different samples indicate that a higher throughput can be achieved and one possible hypothesis is that the harder minerals act as grinding media.

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15

Contessotto, Renato. "Classificação de domínios mineralógicos e caracterização de minérios de níquel da mina de Santa Rita - BA, em apoio à geometalurgia." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3134/tde-22062017-141549/.

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A Mina de Santa Rita, situada no complexo máfico-ultramáfico Fazenda Mirabela, é uma intrusão máfica-ultramáfica, mineralizada a sulfetos de níquel e cobre, situada no sudeste do Estado da Bahia, município de Itagibá. Esse depósito é composto por rochas de idade Paleoproterozóica, metamorfizadas em fácies granulito. Os sulfetos de níquel e cobre ocorrem disseminados e, preferencialmente, associados a harzburgitos, olivina ortopiroxenitos e ortopiroxenitos. O minério é composto por uma grande variedade de Mg-silicatos, sendo que o níquel ocorre essencialmente como pentlandita nos peridotitos, além de se apresentar como elemento menor em silicatos e espinélios em rochas mais máficas. Informações de processo demonstram a impossibilidade de se estabelecer uma correlação robusta entre a composição química do minério e seu comportamento na etapa de beneficiamento mineral. Desta forma, o conhecimento da variabilidade mineralógica no depósito é de fundamental importância para o planejamento de lavra e processamento mineral. Mais de 300 amostras do plano de mineração de curto prazo (2013-2017) relativas a intervalos de furos de sondagem considerados no estudo de viabilidade econômica (período de 1985-2004) foram agrupadas em domínios mineralógicos, utilizando a análise estatística multivariada de dados de difração de raios X (DRX-AEM). Dezessete domínios mineralógicos inicialmente definidos são essencialmente diferenciados com base na presença e conteúdos relativos dos principais minerais de ganga: serpentina, olivina e piroxênio. Amostras representativas dos principais domínios mineralógicos, pré-definidos por DRX-AEM, foram submetidas a estudos de caracterização mineralógica de detalhe por análise de imagens (MEV-MLA). Os resultados indicam que os grupos com composições mais peridotíticas e/ou carbonáticas, com maiores conteúdos de serpentina, apresentam menor tempo de moagem para atingir P95 igual a 0,15 mm; maior alteração dos grãos de pentlandita; maior parcela de total de níquel associado a silicatos; menor grau de liberação dos sulfetos; e maior quantidade de sulfetos abaixo de 10 ?m, em relação aos grupos de composição mais piroxenítica.
The Santa Rita mine, located in the mafic-ultramafic complex Fazenda Mirabela, is a mafic-ultramafic intrusion mineralized to nickel and copper sulphides located in the southeast of Bahia state, Itagibá municipality. The nickel sulphide deposit comprises a portion of a mafic-ultramafic layered complex under granulite metamorphism facies. Disseminated Ni and Cu sulphides form a stratiform body parallel to the lithostratigraphic contacts extending upwards essentially from the harzburgite unit and through the olivine orthopyroxenite unit. The nickel content is mainly associated to pentlandite in peridotitic rocks but also enriched in silicates and spinels in mafic rocks (dunites). Industrial plant benchmark data have shown the unfeasibility of establishing a strong relation between the ore chemical composition and its behavior in the mineral beneficiation process. Therefore, the knowledge of the mineralogical variability in the deposit is crucial for mine planning and mineral/metallurgical processing. More than 300 samples from drill core samples from the feasibility studies (period of 1985-2004) included in the short-term mining plan (2013-2017) were clustered into geological domains applying multivariate statistical analysis (MSA) of X-ray diffraction data (XRD). Results discriminated seventeen initial mineralogical domains considering the content of major gangue minerals: serpentine, olivine and pyroxene. Representative samples of the main mineralogical domains pre-defined by XRD-MSA ore-types were later subject to sieve size analysis followed by detailed mineralogical studies by automated SEM image analysis (MLA). The results indicate that groups with more peridotite and / or carbonatic compositions, with higher content of serpentine, have less time of grinding to reach P95 equal to 0,15 mm; high level of pentlandite alteration; greater portion of nickel associated into silicates; lower sulphides liberation degree; and a higher amount of sulphides below 10 ?m; in relation to the most pyroxenic composition groups.

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16

Guiral, Vega Juan Sebastian. "Textural and Mineralogical Characterization of Li-pegmatite Deposit: Using Microanalytical and Image Analysis to Link Micro and Macro Properties of Spodumene in Drill Cores. : Keliber Lithium Project, Finland." Thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70422.

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Lithium represents one of the strategic elements for the rest of the 21st century due to its increasing demand in technological applications. Therefore, new efforts should be focused on the optimization of mineral characterization processes, which link the ore properties with its behaviour during downstream processes. These efforts should result in reducing operational risks and increasing resources utilization. The methodology presented in this study is based on the application of several classification techniques, aiming the mineral and textural characterization of two spodumene pegmatite deposits within the Keliber Lithium Project. Twelve textural classes have been proposed for the textual classification of the ore, which have been defined through the recognition of the main mineral features at macro- and micro-scale. The textural classification was performed through the application of drill core logging and scanning electron microscopy. Six classes are proposed to describe the characteristics of the spodumene ore. Six additional classes describe the main properties of the rocks surrounding the ore zone. Image analysis was implemented for the generation of mineral maps and the subsequent quantification of spodumene and Li2O within the analysed drill core images. The image segmentation process was executed in Fiji-ImageJ and is based on eight mineral classes and a set of seven feature extraction procedures. Thus, quantification of spodumene and Li2O is estimated by textural class. Hyperspectral images were used as a reference for assessing the estimations made through images analysis. A machine learning model in Weka allowed forecasting the behaviour of the twelve textural classes during spodumene flotation. This model is fed by metallurgical data from previous flotation tests and uses Random Forest classifier. The proposed methodology serves as an inexpensive but powerful approach for the complete textural characterization of the ore at Keliber Lithium Project. It provides information about: (1) mineral features at different scales, (2) spatial distribution of textures within the pegmatite body, (3) quantification of spodumene and Li2O within the drill cores and (4) processing response of each textural class. However, its application requires wide knowledge and expertise in the mineralogy of the studied deposits.

Thesis Presentation.

Textural and Mineralogical Characterization of Li-pegmatite Deposit: Using Microanalytical and Image Analysis to Link Micro and Macro Properties of Spodumene in Drill Cores. Keliber Lithium Project, Finland.

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17

Owen, Nicholas Daniel. "The mineralogical deportment of radionuclides in South Australian Ca-Au-(U) ores." Thesis, 2019. http://hdl.handle.net/2440/123640.

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Iron-oxide copper gold (IOCG)-uranium deposits represent South Australia’s primary resource base for copper production. The presence of daughter radionuclides (RN) from the 238U decay series within the ores necessitates a detailed understanding of their mineralogical deportment as a pre-requisite for attempts to remove or reduce RN concentrations. Research presented in this thesis contributes towards this knowledge by identifying and characterising potential RN-carriers, migration of radiogenic lead via geological processes, and provides evidence for RN sorption during processing. Novel approaches to RN reduction are proposed based on mineralogical-geochemical results. Evidence for migration of Pb within the deposit and during processing is relevant for any assessment of RN deportment, especially since the Pb-chalcogenides galena, clausthalite (PbSe) and altaite (PbTe) are often hosted within Cu-(Fe)-sulphides. Lead isotope values measured in-situ by laser ablation inductively coupled plasma mass spectrometry suggest an overwhelmingly radiogenic origin for Pb and thus extensive decoupling of radiogenic Pb from parent U- and Th-minerals. Calculated 207Pb/206Pb ratios suggest Pb mobilisation during an event that postdates the initial Mesoproterozoic Fe-Cu-Au-U mineralisation event, an interpretation consistent with other studies in the Olympic Cu-Au province which indicate cycles of replacement-remobilization-recrystallization. A nanoscale study of the most common of the three Pb-chalcogenide minerals, clausthalite, by high-angle annular dark field scanning transmission electron microscopy, proved highly instructive for identifying mechanisms of remobilization and overprinting. Characteristic symplectite textures involving clausthalite and host Cu-(Fe)-sulphides are indicative of formation via reaction between Se that pre-existed in solid solution within Cu-(Fe)-sulphides and migrating Pb. Observed superstructuring of clausthalite nanoparticles within chalcopyrite provides a direct link between solid solution and symplectite formation. Sr-Ca-REE-bearing aluminium-phosphate-sulphates (APS) of the alunite supergroup are a minor component of the Olympic Dam orebody. They appear paragenetically late, often replacing earlier REE-minerals. Characterisation of these compositionally zoned phases allowed them to be defined as minerals that span the compositional fields of woodhouseite and svanbergite, and also a REE- and phosphate-dominant group displaying solid solution towards florencite. A nanoscale secondary ion mass spectrometry study of RN distributions in APS minerals in acid-leached copper concentrate revealed that APS minerals readily sorb products of 238U decay, notably 226Ra and 210Pb, whereas U remains in solution. Many APS phases, particularly those that are Pb-bearing, are stable over a wide range of pH and Eh conditions and at temperatures up to 450 °C. As such, synthetic APS phases represent viable candidates not only for the removal of radionuclides from metallurgical streams, but also for their safe storage and isolation from surrounding environments. Ca-Sr-dominant phases display preferential enrichment by Pb (notably 210Pb) during flotation. 210Pb uptake then increases during subsequent acid leaching. Mixed Ca- and Sr-bearing APS phases were synthesised by modifying existing recipes to test the role of compositional variability of APS phases on the sorption rate of Pb from dilute Pb(NO3)2 solution. Lead incorporation by the synthetic APS phases was confirmed, whereby Pb replaces Ca, but not Sr, within the APS crystal structure. Extended X-ray absorption fine structure analysis of the resulting solids reveals the nature of Pb sorption by the synthesized material. The data showed that the dynamic incorporation of Pb by APS phases occurred overwhelmingly at pH 3.5, thus verifying that uptake of Pb by synthetic APS phases may represent a robust mechanism to achieve both reduction and immobilisation of 210Pb within metallurgical processing streams.
Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering & Advanced Materials, 2020

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18

Chibaya, Ashley. "Geometallurgical analysis - Implications of operating flexibility (A case for Geometallurgy for Orapa A/K1 deposit)." Thesis, 2014.

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Historically, many mining investments have demonstrated inability to meet projected cash-flows despite detailed and costly project evaluations. The risk in mining projects can be attributed to the fact that decisions are made in situations involving high levels of uncertainty. The cash-flow uncertainty is driven by commodity price fluctuations and by the uncertainty of the geometries and grades of ore deposits. Accurately predicting future prices can be very difficult, however, better knowledge of the orebody will allow for improved strategic planning and an ability to build in flexibility into the design of the operation to deal with veiled uncertainty, orebody variability and operational constraints. Geometallurgy provides a platform for cross-functional collaboration between geology and metallurgy, providing better inputs to mine planning and strategic decision making. Understanding variability in the orebody enables optimum operational designs and extraction methods that maximize value recovery. Geometallurgical programs allow for material characterization that is based on metallurgical responses instead of just geological zones, enabling informed design decisions and building in flexibility to handle variability. On the other hand, metallurgical design decisions made without full appreciation of the resource can limit ability to deal with variability, constraining the process right from design. Geometallurgical risk exists as a result of uncertainty in metallurgical characteristics of the ore resulting in treatability challenges. Projects such as the Cawse Nickel Project in Western Australia and the Voorspoed Diamond Mine in South Africa are given as illustrations of geometallurgical risk at various phases of projects. Canahuire Project in Peru and the Kemi Chromite and Ferrochrome mine in Finland exemplify how successful geometallurgical programs have and can be implemented. This report demonstrates a case for geometallurgy at the Orapa A/K1 deposit. Two rock types comprising the kimberlite, SVK_M and NPK_GG, previously not apparent in geological models, have introduced a constraint in the Orapa 2 treatment plant. This treatability challenge is due to the generation of non-settling slurries from the rock types. A metallurgical design decision in the selection of the thickeners has limited the plant’s ability to deal with the changes in the ore blend. The Orapa case proves how design decisions can limit flexibility to deal with orebody variability, constraining the process from achieving the design capacity and limiting forecast cash-flows. The case demonstrates existence of geometallurgical risk and illustrates the consequences of this risk in operational and financial terms.

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19

Sepúlveda, Escobedo Exequiel Manuel. "Quantification of uncertainty of geometallurgical variables for mine planning optimisation." Thesis, 2018. http://hdl.handle.net/2440/114242.

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Interest in geometallurgy has increased significantly over the past 15 years or so because of the benefits it brings to mine planning and operation. Its use and integration into design, planning and operation is becoming increasingly critical especially in the context of declining ore grades and increasing mining and processing costs. This thesis, comprising four papers, offers methodologies and methods to quantify geometallurgical uncertainty and enrich the block model with geometallurgical variables, which contribute to improved optimisation of mining operations. This enhanced block model is termed a geometallurgical block model. Bootstrapped non-linear regression models by projection pursuit were built to predict grindability indices and recovery, and quantify model uncertainty. These models are useful for populating the geometallurgical block model with response attributes. New multi-objective optimisation formulations for block caving mining were formulated and solved by a meta-heuristics solver focussing on maximising the project revenue and, at the same time, minimising several risk measures. A novel clustering method, which is able to use both continuous and categorical attributes and incorporate expert knowledge, was also developed for geometallurgical domaining which characterises the deposit according to its metallurgical response. The concept of geometallurgical dilution was formulated and used for optimising production scheduling in an open-pit case study.
Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2018

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Addo, Junior Emmanuel. "Multivariate Modelling of Geological and Geometallurgical Variables." Thesis, 2019. http://hdl.handle.net/2440/120164.

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The mining and minerals industry is confronted with several challenges that were not common some decades ago. Deep-seated and complex orebodies, low metal grades, and fluctuating commodity prices have an increasingly high impact on the mining industry, potentially reducing profit margins. It follows that accurate modelling of geological and geometallurgical variables is needed to reduce risks associated with most mineral prospects. This modelling needs to include uncertainty in predictions, as well as outcomes, so that mining companies can use value at risk, for example, to make informed business decisions. This thesis, comprises three journal papers and one conference paper. Several mathematical formulations have been used to model geological and geometallurgical variables. These novel modelling methodologies provides more versatile modelling techniques to traditional modelling techniques which are currently employed in the mining and minerals industry. In Chapter 2 (Paper 1) and Chapter 3 (Paper 2), spatial pair-copula models are used to predict the geological grades of an anisotropic gold deposit within and outside a main field. These models are compared with a traditional kriging approach and results show that pair-copulas models provide improved modelling of error structure than kriging. In Chapter 4 (Paper 3), different trivariate copulas were used to model and predict geological variables from a drill core. The models provided better estimates and prediction intervals of geological variables. In general, geological variables have a large number of outlying values and also exhibit tail dependence. Copulas provide a means of dealing with these practical issues. D-vine copula models, which are able to address the massive multivariate nature and non-linear bivariate relationships of geometallurgical variables, are employed to model geometallurgical variables. In most cases, geometallurgical variables have several missing data, which makes modelling and prediction of these variables difficult. Chapter 5 (Paper 4), a novel data imputation algorithm is developed as part of this thesis to address the issue of missing data of geometallurgical variables. The outcomes of this thesis are an improved geostatistical modelling framework and novel data imputation algorithm techniques, providing better estimates and prediction intervals for geological and geometallurgical variables, and with demonstrated application to practical mining case studies.
Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental & Mining Engineering, 2019

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Singh, Kartikay. "A Geometallurgical Forecast Modelfor Predicting Concentrate Quality in WLIMS Process for Leveäniemi Ore." Thesis, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65970.

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Previous studies have suggested that Davis tube (DT) experiment can used to study wet low intensitymagnetic separation (WLIMS) for magnetic iron ores. But DT process has never been used to mapWLIMS process, specifically in a geometallurgical framework. This thesis work is a step towardsfulfilling this gap by studying the Davis tube experiment performed on 13 different samples fromLeveäniemi iron ore deposit. The methodology adapted to map WLIMS concentrate quality includesstudy and analysis of feed, DT and WLIMS. Analyses were made using experimental data, processingdata using some analytical tools, some data-processing tools and post processing tools. For coveringthe geometallurgical aspect the analysis was done for both elements and minerals. The results fromthis study has reviled that DT can be used to predict WLIMS concentrate quality to an acceptablelevel of confidence. Furthermore, results show that a combination of DT and WLIMS informationproduce very accurate and highly reliable models for predicting and mapping WLIMS concentratequality. This work serves as the first step towards studying an unexplored field pertaining to magneticiron ore concentrate and has opened door to possible future work that could take this work a stepfurther. Supplementing this study with more data from different sample is required not only tovalidate the model but also to make it better. A better modal mineralogy of the samples is needed tounlock the full potentials of mineralogical modelling approach used in this work.

I am a graduate from the of Erasmus Mundus masters in Georesource Engineering, 2017.

Primary Resource Efficiency by Enhanced Prediction (PREP)

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22

Loidl, Gernot C. "The Elura Orebody: a multidisciplinary study investigating geochemical mineralogical & geometallurgical ore characteristics." Thesis, 2012. http://hdl.handle.net/2440/82375.

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The Elura Zn-Pb-Ag deposit 43km NNW of Cobar, NSW, contained a pre-mining resource of 50.7 Mt at 8.8 wt% Zn, 5.6 wt% Pb, 107 g/t Ag and 0.2 wt% Cu. Sediment-hosted ore within a turbiditic sequence is strongly structural controlled. It is sheet-like with several elongated, subvertical massive zoned sulphide bodies with central pyrrhotitic cores surrounded by pyrite ore which is enclosed by semi-massive and breccia-stringer mineralisation. This study showed pronounced grain sizes, texture, mineral composition and trace element geochemistry heterogeneity. The pyrite-pyrrhotite-galena-sphalerite ore has minor marcasite, chalcopyrite and arsenopyrite and trace tetrahedrite (±freibergite), native silver and magnetite. Enrichment trends towards the surface and peripheral pyrite-dominated ore zones are in Ag, As, Tl, Hg, Sb, Sn, Mo and Au. The first Re-Os whole rock massive sulphide isochron age is 378±15 Ma. Initial ϒOs of ~170 is either caused by juvenile continental crust of the Lachlan Fold Belt as metal source or by a contribution of primitive mantle Os. Zinc isotope compositions of sphalerite (δ⁶⁶ZnJMC 0.220- 0.450‰) suggest effectively leached average continental crust as the source for metals, chlorite thermometry showed temperatures at 314-343°C, high Cu concentrations coincide with light Zn isotopes that define two major zones of fluid influx and the isocon method showed host lithology replacement was negligible during ore genesis. Sulphides formed in sites of increased dilation and fracture-induced permeability during prolonged periods of fracturing and fluid pulses. Decreasing fluid pressure and adiabatic cooling initiated precipitation of sulphides. No evidence for fluid mixing was identified. Initially, lower parts of the orebody formed in dilational zones in sandstone-rich sequences along a transpressional fault corridor. Major fracturing then caused the formation of upper main lode and upgrading of the lower main lode ore zones. Changing fluid temperatures, internal refinement via dissolution-reprecipitation and temporal fluid composition change created vertical mineralogical and geochemical ore zonation. The orebody was modified during post-depositional compression during continued basin inversion resulting in sulphide remobilisation, upgrading and amplified ore zonation. Zinc and, in particular, Pb recovery rates significantly fluctuated since production began in1983. Fluctuating recovery rates resulted from grain size variability and subsequent poor particle liberation during grinding. Silver recoveries rarely exceeded 50%. Poor Ag recoveries were due to fine-grained argentian tetrahedrite, common associations with gangue phases and alteration of tetrahedrite. High concentrations of Bi were encountered recently in lead concentrate. A galenamatildite solid solution contains Bi (max. 5,645ppm). High Bi is limited to the lower most main lode ore zone. Geometallurgical ore characterisation via QEMSCAN® was undertaken to predict mineral processing characteristics of ore sourced from parts of the same stope. On the stope scale there are significant variations in flotation characteristics from different parts of the stope which enables prediction of recoveries, concentrate qualities and mill throughput. Theoretical recovery calculations suggest that ore from the western part will have10% lower recovery. Theoretical and long-term average recoveries are similar for Zn but not for Pb. Theoretical data may over- estimate recovery because sample preparation may liberate more particles than plant grinding. An overview of mineralogy and trace elements allows geometallurgical ore characterisation on the stope scale to better predict mill performance. Investigation of geometallurgical ore characteristics and penalty element concentrations are recommended on a stope-by-stope basis within life-of-mine planning.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2012

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Дисертації з теми "Geometallurgey"

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