Dissertations / Theses on the topic 'Metal sulphides'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Metal sulphides.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Smit, Timotheus Servaas. "Hydrodesulphurization of thiophenes using transition metal sulphides." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/28084.
Full textMulligan, David John. "Reduction of sulphur dioxide over transition metal sulphides." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61916.
Full textHarrison, Mark Robert. "One-dimensional, mixed-metal sulphides – structural and physical properties." Thesis, University of Hull, 2011. http://hydra.hull.ac.uk/resources/hull:5281.
Full textGreen, Pamela Rose. "The synthesis and structure of ternary transition metal sulphides." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284056.
Full textDavid, Lorraine. "MBE growth and characterisation of metastable transition metal sulphides." Thesis, Heriot-Watt University, 2006. http://hdl.handle.net/10399/197.
Full textEngin, Tahir. "Structural, magnetic and electron transport properties of mixed metal sulphides." Thesis, Heriot-Watt University, 2008. http://hdl.handle.net/10399/2059.
Full textd'Arbeloff-Wilson, Sarah. "Reactions of the phosphaalkyne, PCBu't with metal sulphides, selenides and tellurides." Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324201.
Full textPoole, Mark Charles. "Synthetic and spectroscopic studies of organic sulphides, sulphoxides, sulphones, and their metal complexes." Thesis, University of Exeter, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332281.
Full textSzkoda, Iwona. "Phase relations, structural studies and physical properties of mixed metal oxides and sulphides." Thesis, Heriot-Watt University, 2008. http://hdl.handle.net/10399/2212.
Full textCoimbatore, Dhandayuth Venkatesh. "Cerium chloride inhibition for high strength low alloy steel exposed to sulphide polluted seawater." University of Western Australia. School of Mechanical Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0134.
Full textJordan, Mark Adrian. "The oxidation of base metal sulphides and pyritic gold concentrates with particular reference to mechanism and preferential release of ferrous iron." Thesis, University of Exeter, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357977.
Full textGrobler, Willem Adriaan. "A study into the use of fatty acid and xanthate collector combination in the recovery of base metal sulphides : a holistic approach." Diss., University of Pretoria, 2015. http://hdl.handle.net/2263/50910.
Full textDissertation (MEng)--University of Pretoria, 2015.
tm2015
Materials Science and Metallurgical Engineering
MEng
Unrestricted
Masenya, Mamago Adolphina. "Computational modelling studies of precious mixed metals sulphides." Thesis, University of Limpopo, 2016. http://hdl.handle.net/10386/1725.
Full textThe stabilities of PtS to PdS and PdS to PtS were investigated using density functional theory within the generalized gradient approximation. Their structural, electronic and mechanical properties were determined to show their stability and the effect of pressure on different compositions. We found good correlation of calculations with available ex-perimental data. The lattice parameters were observed to fluctuate with increasing con-centration for both systems. Furthermore, heats of formation were calculated to deter-mine the relative structural stability of the systems. They predict that the most stable structure is Pd50S50 P42/mmc and Pt25Pd25S50 P42/mmc being the least stable. Pd12.5Pt37.5S50 P42/m is the most stable and Pd50S50 P42/m being the least stable struc-ture. The Pt37.5Pd12.5S50 P1 was said to be the most stable structure and Pd50S50 P1 be-ing the least stable. The phonon dispersion calculations show that Pt50S50 P42/mmc, Pd50S50 P42/mmc, Pd12.5Pt37.5S50 P42/m and Pt50S50 P1 (derived from P42/mmc) are me-chanically stable, consistent with calculated elastic constants. The Pt25Pd25S50 P42/mmc show soft modes, which are due to vibrations of Pt and Pd atoms in the x - y plane which suggests the instability of the structure, in agreement with C66 being negative, and consistent with heats of formation. The lattice parameters decreased steadily with increasing pressure. An anomaly was observed in Pt50S50 P1 (derived from P42/mmc), where the c lattice parameter was found to increase with increasing pressure. The elec-tronic density of states (DOS) were performed on all compositions. The DOS were sub-jected to pressure and it was generally noted that the band gap increases with increas-ing pressure. It was observed that the smaller the band gap, the more stable the struc-ture. Furthermore, phonon dispersions under pressure show that compounds with the P42/mmc and P1 (from P42/mmc) symmetries display the mixing of lower and upper en-ergy bands at pressures above 30 GPa.
National Research Foundation
Thangwane, Selaelo Christabel. "Synthesis and characterization of substituted dithiocarbamates ligands and complexes as a source of metal (Pb, Ni & Co) sulphide nanoparticles." Thesis, Vaal University of Technology, 2017. http://hdl.handle.net/10352/396.
Full textLead, nickel and cobalt dithiocarbamates complexes were synthesized using methanol and water as solvents. All complexes were refluxed at 60 °C, cooled at room temperature, washed with methanol to remove the impurities and dried under the fume hood. A combination of Fourier transformer infrared (FTIR), elemental analysis (EA) and thermogravimetric analysis (TGA) were used to characterize these complexes. There was shifting of bands from low to high frequencies of the dithiocarbamates complexes compared to benzimidazole derivatives. The absence of the N-H band and the presence of new C=S bands confirmed that the complexes can be used in the preparation of metal sulphide nanoparticles. Elemental analysis showed that there was a percentage mismatch for the complexes I, III, IV and V. Complexes II and VI calculated percentages were within the limits with the found percentages except for sulphur which was low. The TGA curves decomposed to form a mixture of metal and metal sulphides for complex I, II, III and IV except for complex VI which gave metal sulphide only. All benzimidazole complexes decomposed at higher temperatures and were considered as stable complexes. Lead sulphide (PbS) is an important group IV-VI metal chalcogenide semiconductor. It has a direct narrow band gap of 0.41 eV at 300K and a large excitonic Bohr radius of 18 nm. Lead sulphide absorption band can be tuned to anywhere between near IR to UV (0.4μm) covering the entire visible spectrum, while achieving the quantum confinement region. The synthesis of lead sulphide nanoparticles was conducted by varying the effect of the reaction conditions such as the type of capping agents and temperature. Lead dithiocarbamate complex derived from benzimidazole, [Pb(S2N2C8H5)2] was thermolysed in hexadecylamine (HDA) and trioctylphosphine oxide (TOPO) at different reaction temperatures (140, 160 and 180 °C) to produce HDA and TOPO capped PbS nanoparticles. The nanoparticles were characterized using X-ray diffraction (XRD) for structural analysis, transmission electron microscopy (TEM) for shape and size, Ultraviolet visible (UV/Vis) and Photoluminescence (PL) spectroscopy for optical properties. An increase in temperature gave a decrease in the sizes of the nanoparticles when using the HDA capped lead benzimidazole dithiocarbamate complex. The observed morphology was cubes. TOPO capped lead benzimidazole dithiocarbamate complex gave no specific trend when temperature was varied. A cross-like layer with quasi spherical particles on top was observed at 160 °C. At 180 °C, the cross-like layer decomposed into rods- like materials with quasi spherical particles on top for TOPO capped PbS nanoparticles. For lead 2-methylbenzimidazole [Pb(S2N2C9H7)2] dithiocarbamate complex, TOPO capped PbS produced agglomerated cubic morphology at low temperature but as the temperature was increased agglomerated cylindrical shapes were observed. HDA capped PbS produced polydispersed nanocubes which were increasing in size when the temperature was increased. Nanoparticles displayed a blue shift in band edges with good photoluminescence behaviour which was red shifted from their respective band edges all temperatures and capping agents. XRD confirmed the crystal structure of cubic phase (galena) of PbS at all temperatures except for HDA capped PbS nanoparticles at 140 °C from lead benzimidazole dithiocarbamate complex which confirmed the crystal structure of face-centred cubic phase of PbS nanoparticles. Nickel sulphide has much more complicated phase diagram than cobalt sulfides and iron sulfides. Their chemical composition has many crystalline phases such as α-NiS, β=NiS, NiS2, Ni3S2, Ni3S4, Ni7S6 and Ni9S8. Ni3S2 phase has shown potential as a low-cost counter electrode material in dye sensitised solar cells, while the α-NiS phase has been applied as a cathode Material in lithium-ion batteries. The synthesis of nickel sulphide nanoparticles was done by varying the effect of the reaction conditions such concentration and temperature. Nickel benzimidazole dithiocarbamate [Ni(S2N2C8H5)2] and nickel 2-methylbenzimidazole [Ni (S2N2C9H7)2] dithiocarbamates complexes were thermolysed in hexadecylamine (HDA) at different reaction temperatures (140, 160 and 180 °C) and precursor concentrations (0.30, 0.35 and 0.40 g) to produce HDA capped NiS nanoparticles. It was observed that increasing both temperature and precursor concentration increased the size of the nanoparticles. Anisotropic particles were observed for both complexes when varying precursor concentration and temperature. Nickel benzimidazole dithiocarbamate complex produced stable shapes (spheres and cubes) of nickel sulphide nanoparticles. Nickel 2-methylbenzimidazole dithiocarbamate complex produced a mixture of spheres, cubes, triangles and rods nickel sulphide nanoparticles at all concentrations. But when varying temperature, it only produced that mixture at 160 °C. The optical measurements supported the presence of smaller particles at all temperatures and concentrations. XRD showed the presence of C7OS8 and pure nickel as impurities. However, the crystal structure of cubic Ni3S4 was observed at low temperatures and an introduction of monoclinic NixS6 at high temperature (180 °C) when varying temperature for both complexes. When varying concentration using nickel benzimidazole dithiocarbamate complex, XRD showed the presence of NiSO4.6H2O impurities at high temperatures. At 160 °C a mixture of hexagonal NiS and cubic Ni3S4 was observed. At low temperatures only nickel as a metal was found as an impurity and the crystal structure of cubic Ni3S4 was observed. When nickel 2-methylbenzimidazole complex was used, C7OS8 and pure nickel were found as impurities but the crystal structure of cubic Ni3S4 was observed. Cobalt sulphide (CoS) belongs to the family of group II-IV compounds with considerable potential for application in electronic devices. They have a complex phase diagram and their chemical composition have many phases such as Co4S3, Co9S8, CoS, Co1-xS, Co3S4, Co2S3 and CoS2. The synthesis of cobalt sulphide nanoparticles was conducted by varying the effect of temperature on size and shape of the nanoparticles. Nickel benzimidazole dithiocarbamate, [Ni(S2N2C8H5)2] and nickel 2-methylbenzimidazole [Ni(S2N2C9H7)2] complexes were thermolysed in hexadecylamine (HDA) at different reaction temperatures (140, 160 and 180 °C) to produce HDA capped CoS nanoparticles. Cobalt benzimidazole dithiocarbamate complex produced close to spherical shapes nanoparticles at all temperatures. The images showed that as temperature was increased, the size of the particles decreased. All the main reflection peaks were indexed to face-centred cubic Co3S4 and there were some impurities of C7OS8 at all temperatures. The optical measurements supported the presence of smaller particles at all temperatures. Cobalt 2-methylbenzimidazole dithiocarbamate complex produced big and undefined morphology. The optical properties were also featureless and XRD only showed impurities of C7OS8. The impurity is thought to be generated from a side reaction between benzimidazole and carbon disulphide to give this persistent organic moiety.
Alakangas, Lena. "Sulphide oxidation, oxygen diffusion and metal mobility in sulphide-bearing mine tailings in Northern Sweden." Doctoral thesis, Luleå : Division of Applied Geology, Luleå University of Technology, 2006. http://epubl.ltu.se/1402-1544/2006/27/.
Full textFredriksson, Andreas. "Adsorption of heptyl xanthate at the metal sulphide/aqueousinterface." Licentiate thesis, Luleå, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16791.
Full textGodkänd; 2004; 20070127 (ysko)
Healy, J. "Some metal sulphide interactions governing copper solubility and availability." Thesis, Robert Gordon University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379262.
Full textFredriksson, Andreas. "Adsorption of heptyl xanthate at the metal sulphide/aqueous interface /." Luleå, 2004. http://epubl.luth.se/1402-1757/2004/01.
Full textHorton, Joseph Hugh. "Surface photo-oxidation and metal film growth processes on amorphous GeSâ†2." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337978.
Full textKnipe, Stephen William. "The role of sulphide surfaces on the deposition of precious metals from hydrothermal fluids." Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260201.
Full textSui, Chihyu Caroline. "Metal ion transfer between sulphide minerals and effect on xanthate interaction with pyrite." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40263.
Full textMetal ion production with minerals in pairs was different from that for single minerals. The amount of metal ion in solution followed a galvanic interaction model, increasing for the anodic mineral and decreasing for the cathodic mineral. However, from the EDTA extraction technique, the concentration of metal ions on the mineral surface increased for both minerals. The mechanism of additional metal ion production on the cathodic mineral is unclear, but may be related to reaction between the mineral and OH ions formed on the surface as a result of galvanic interaction.
Metal ions transferred between two minerals in contact. In the case of pairing with pyrite, the larger proportion of Fe remained on pyrite, while 50% or more of Zn (from sphalerite) and Pb (from galena) transferred to pyrite.
The effect of Pb ions on pyrite in the presence of xanthate, and diethylene triamine (DETA) was investigated by cyclic voltammetry, ex situ spectroelectrochemical analysis and zeta potential measurements.
Once pyrite was contaminated by Pb ions, uptake of xanthate was promoted at pHs 9.2 and 10.5 with lime as pH modifier. The source of Pb--from solution or from contact with galena--was not a factor, and the effect was evident at Pb concentrations as low as 1 ppm. With soda ash as pH modifier, the effect of Pb was suppressed, perhaps due to formation of lead carbonate. The only xanthate product detected was dixanthogen, unless an initial potential less than $-$800 mV/SCE was imposed (when Pb$ sp{2+}$ is reduced to Pb$ sp0)$ and lead xanthate formed.
Xanthate adsorption on Pb-contaminated pyrite was suppressed by DETA, but relatively large concentrations were required. DETA decreased the potential at the mineral/solution interface, which retarded oxidation of xanthate to dixanthogen.
A mechanism of Pb "activation" of pyrite was proposed: adsorption of Pb(OH)$ sp+$ on pyrite provided sites for xanthate adsorption forming Pb(OH)X, on which xanthate ions were attached by hydrophobic interaction and oxidised to dixanthogen.
Khalid, Muhammad. "Gold cyanidation : gold associated with silver minerals embedded within base-metal sulphide matrices." Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27893.
Full textNumerous non-idealities in gold processing are becoming increasingly significant with the depletion of free-milling oxide ores around the globe. Gold is mostly found in nature in metallic form and is associated with silver minerals and bae-metal sulphides. In the present thesis work, the role of silver minerals on gold cyanidation with base-metal sulphides was elucidated in detail on the relative importance of galvanic interactions and passivation phenomena. As the permanent galvanic contacts, inherently present within the ore grains, are hard to achieve between gold rotating disk electrode and slurried base-metal sulphide-rich ores, a packed-bed reactor (PBR) strategy was thus adopted to single out and quantify the virtual contributions of galvanic interaction and passivation effect on the gold and silver leaching rates during gold cyanidation with silver minerals and base-metal sulphides. The mixtures of gold, silver-minerals and sulphides were filled in the PBR to ensure the permanent particle-particle micro-electrical contacts among all ore constituents. Pyrite, chalcopyrite, sphalerite and stibnite were the sulphidic minerals investigated in the present gold-silver cyanidation study. Metallic silver (Ag), acanthite (Ag₂S) and pyrargyrite (Ag₃SbS₃), were the silver-minerals taken into account. Galvanic interactions were found to alleviate the leaching of gold and silver to various extents, for gold and silver minerals associated with pyrite and sphalerite, both under galvanic and passivation impact from the sulphide minerals. Silver minerals were found retarding to the gold leaching for chalcopyrite and stibnite minerals. Strategies were investigated to enhance the gold leaching kinetics in the presence of silver minerals and base-metal sulphides. Lead containing cyanide solution enhanced gold recovery and was found to neutralize significantly the negative effect of sulphidic minerals, particularly for chalcopyrite. Moreover, lead addition enhanced gold leaching kinetics significantly for gold and silver minerals associated with pyrite, chalcopyrite and sphalerite. Pre-treatment with alkaline lead acetate tested on sulphide associated mixtures of gold and silver minerals affirmed enhanced gold recovery in case of pyrite, chalcopyrite and sphalerite minerals. Stibnite found severely retarding towards gold dissolution with silver minerals. Surface obstructing films were observed on gold particles for gold cyanidation with silver minerals and base-metal sulphides in case of chalcopyrite and stibnite.
Mokone, Thebe Phillip. "Metal sulphide precipitation : effect of operational parameters on particle characteristics and process efficiency." Doctoral thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/13429.
Full textAcid mine drainage (AMD) is one of the major, long-term environmental challenges facing the minerals processing industry. Uncontrolled discharges have polluted thousands of kilometres of rivers, as well as surface and groundwater bodies with acidic effluents high in dissolved metals and sulphate. Conventional treatment technologies rely on oxidation, neutralisation and precipitation. While these may be effective they are expensive and not sustainable in the long term. Several biological treatment technologies, based on the activity of sulphate reducing bacteria (SRB), have been successfully developed and applied at both laboratory and industrial scale. The SRB uses sulphate as the terminal electron acceptor and with a suitable electron donor produce bicarbonate alkalinity and sulphide. These can be used to neutralise acidic effluents and effect precipitation of dissolved metal ions as metal sulphides. However, a number of challenges exist around the precipitation step, particularly where the recovery of valuable metals is desired. Metal sulphide precipitation reactions are inherently driven by extremely high levels of supersaturation. As a result, metal sulphide precipitation reactions are difficult to control and a large number of small particles are formed during the process. This leads to significant technical challenges with respect to solid-liquid separation and subsequent recovery of the precipitate. Despite the theoretically high metal removal, related to the low solubility of metal sulphides, practical efficiency is often significantly lower. Previous studies have shown that metal precipitation reactions require controlled physico-chemical conditions and the control of high levels of supersaturation to achieve optimum efficiency. The objective of this study was to extend this approach to metal suphide systems.Initial data indicated that conventional techniques to manage supersaturation were not effective and subsequent work focused on characterising the effect of reaction conditions on particle properties and investigating downstream processing options. The intention of this research was to bridge the gap between highly fundamental studies and practical application of sulphide precipitation technologies.
Haring, Peter G. "The nature of heavy metal contamination in organic lake sediments near the Buchans massive sulphide base metal mines, Central Newfoundland /." Internet access available to MUN users only, 2002. http://collections.mun.ca/u?/theses,25133.
Full textNaylor, Chris. "An investigation of the interactions of metals and sulphide in anoxic sediments." Thesis, Lancaster University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525312.
Full textFredriksson, Andreas. "Kinetics of collector in-situ adsorption on metal sulphide surfaces studied by ATR-FTIR spectroscopy." Doctoral thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26680.
Full textGodkänd; 2006; 20070314 (evan)
McElhinney, Rob. "Style and genesis of base metal sulphide mineralisation of Angas prospect - Strathalbyn area, South Australia /." Title page, table of contents and abstract only, 1994. http://web4.library.adelaide.edu.au/theses/09S.B/09s.bm141.pdf.
Full textHamuyuni, Joseph. "Measurement of surface tension in base metal sulphide mattes by an improved sessile drop method." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71651.
Full textGqebe, Sibongiseni Yamkela. "Improving the settleability of a metal sulphide suspension by the application of a magnetic field." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/20053.
Full textLin, Qingyang. "Use of X-ray computed microtomography to measure the leaching behaviour of metal sulphide ores." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/25274.
Full textShaw, Alan. "Synthesis and reactivity studies on oxo and sulphide compounds of the early transition metals." Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6554/.
Full textGhavami-Riabi, Reza. "Geochemical exploration for base metal sulphide deposits in an arid environment (eastern Namaqua Metamorphic Province), South Africa." Thesis, Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-06192007-100552.
Full textLazarevic, David Andrew. "In-situ Removal of Hydrogen Sulphide from Landfill Gas : Arising from the Interaction between Municipal Solid Waste and Sulphide Mine Environments within Bioreactor Conditions." Thesis, KTH, Industriell ekologi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32770.
Full textwww.ima.kth.se
Kiventerä, J. (Jenni). "Stabilization of sulphidic mine tailings by different treatment methods:heavy metals and sulphate immobilization." Doctoral thesis, Oulun yliopisto, 2019. http://urn.fi/urn:isbn:9789526223964.
Full textTiivistelmä Monet arvometallit kuten kulta, kupari ja nikkeli ovat sitoutuneena sulfidipitoisiin mineraaleihin. Louhittaessa ja rikastettaessa näitä sulfidimineraaleja syntyy miljoonia tonneja sulfidipitoisia rikastushiekkoja vuosittain. Rikastushiekat voivat sisältää myös runsaasti erilaisia raskasmetalleja. Osa rikastushiekoista hyödynnetään kaivostäytössä, mutta suurin osa rikastushiekoista läjitetään edelleen ympäristöön rikastushiekka-altaisiin veden alle. Kun sulfidipitoinen malmi kaivetaan ja käsitellään, sulfidiset mineraalit hapettuvat ollessaan kosketuksissa veden ja hapen kanssa. Hapettuessaan ne muodostavat rikkihappoa, laskien ympäristön pH:ta jolloin useimmat raskasmetallit liukenevat ympäristöön. Muodostuvia happamia kaivosvesiä voi syntyä vielä pitkään kaivoksen sulkemisen jälkeen ja ovat näin ollen yksi suurimmista kaivosteollisuuteen liittyvistä ympäristöongelmista. Lisäksi suuret rikastushiekka-altaat voivat aiheuttaa vaaraa myös ihmisille, mikäli altaan rakenteet pettävät. Rikastushiekkojen kestäviä ja ympäristöystävällisiä varastointimenetelmiä täytyy kehittää, jotta näitä ongelmia voidaan tulevaisuudessa ehkäistä. Tässä työssä tutkittiin menetelmiä, joilla kultakaivoksella syntyvät sulfidipitoiset vaaralliseksi jätteeksi luokitellut rikastushiekat saataisiin stabiloitua tehokkaasti. Työssä keskityttiin kolmeen erilaiseen menetelmään: alkali-aktivointiin, stabilointiin kalsiumhydroksidin ja masuunikuonan avulla ja stabilointiin CSAB sementin avulla. Valmistettujen materiaalien mekaanisia ja kemiallisia ominaisuuksia arvioitiin. Tavoitteena oli ymmärtää, miten eri menetelmät soveltuvat raskasmetallien (erityisesti arseenin) ja sulfaattien sitoutumiseen ja mikä on eri komponenttien rooli reaktioissa. Alkali-aktivoimalla rikastushiekkaa sopivan sidosaineen kanssa saavutettiin hyvät mekaaniset ominaisuudet ja useimmat haitta-aineet sitoutuivat materiaaliin. Ongelmia aiheuttivat edelleen sulfaatit ja arseeni. Kalsiumpohjaiset menetelmät sitoivat raskasmetallit (myös arseenin) ja sulfaatit tehokkaimmin. Sulfaatit ja arseeni saostuivat muodostaen niukkaliukoisia komponentteja kalsiumin kanssa. Samanaikaisesti rakenteeseen muodostui ettringiittiä, jolla on tutkitusti hyvä kyky sitoa erilaisia raskasmetalleja rakenteeseensa. Raskasmetallit myös kapseloituivat rakenteen sisään. Työn tuloksia voidaan hyödyntää, kehitettäessä rikastushiekkojen turvallista varastointia. Kun materiaalille saavutetaan riittävän hyvä lujuus ja kemiallinen stabiilius, rikastushiekat voitaisiin läjittää tulevaisuudessa kuivalle maalle altaan sijaan. Näin vältyttäisiin rikastushiekka-altaiden rakentamiselta ja voitaisiin vähentää happamien kaivosvesien muodostumista pitkällä ajanjaksolla. Saavutettujen tulosten perusteella rikastushiekkoja voidaan mahdollisesti tulevaisuudessa hyödyntää myös erilaisissa betonin tapaisissa rakennusmateriaaleissa
Sheridan, Liam A. "Alternative cadmium source precursors for the growth of cadmium sulphide and cadmium selenide by metal-organic chemical vapour deposition." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339511.
Full textBeer, Michael P. "A study of volatile precursors for the growth of cadmium sulphide and cadmium selenide by Metal Organic Vapour Deposition." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303986.
Full textChetty, Deshenthree. "Geochemical fingerprinting of carbonate wall rock alteration at major base metal sulphide deposits in the Otavi Mountain Land, Namibia." Master's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/9555.
Full textThe Otavi Mountain Land is a base metal ore province in which base metal sulphide deposits are hosted by platform carbonates in a foreland fold-and-thrust belt on the northern edge of the PanAfrican Damara Belt. Deposits have been classified as the Berg Aukas- and Tsumeb- types, based on differences in ore association, stratigraphic position and geochemistry of ores and gangue carbonates. Mineralisation at each of these deposits is accompanied by carbonate alteration in the form of dolomite and calcite veins, carbonate recrystallisation, calcitisation and carbonate silicification. Optical cathodoluminescence imaging, electron probe micro analysis, X-ray fluorescence spectrometry, X-ray diffraction, high performance ion chromatography, proton probe micro analysis, stable isotope techniques, and fluid inclusion microthermometry were employed (i) to differentiate between carbonate generations associated with the alteration and mineralisation, particularly for the more economic Tsumeb-type deposits, represented by Tsumeb and Kombat, as well as in comparing between Berg Aukas- and Tsumeb-type deposits; (ii) to set constraints on the fluids effecting such alteration and associated mineralisation; (iii) to determine the relationship of the Khasib Springs deposit, for which little geochemical data exists, to deposits of the Tsumeb-type, and (iv) to identify those parameters which are diagnostic of Tsumeb-type mineralisation.
Markström, Jimmy. "Is mercury mobilized from acid sulfate soils? : Interpreting the mercury record from lake- and marine sediments in Persöfjärden and adjacent sea bay." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-171611.
Full textCherico, Lia. "Development of a geometallurgical data set for the prediction of operating conditions to beneficiate base metal sulphide ore via flotation." Thesis, Cherico, Lia (2017) Development of a geometallurgical data set for the prediction of operating conditions to beneficiate base metal sulphide ore via flotation. Honours thesis, Murdoch University, 2017. https://researchrepository.murdoch.edu.au/id/eprint/40454/.
Full textSyrovetnik, Kristina. "Long-term metal retention processes in a peat bog : Field studies, data and modelling." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-460.
Full textDe, Beer Deon Johan. "The relationship of weld metal hardness residual stress and susceptible to stress corrosion cracking in hydrogen sulphide environment in A516 Grade 70 carbon steel shielded metal arc welded joint." Diss., University of Pretoria, 2002. http://hdl.handle.net/2263/71679.
Full textDissertation (MEng)--University of Pretoria, 2017.
TM2019
Materials Science and Metallurgical Engineering
MEng
Unrestricted
Lopes, Mariângela Vieira. "Desenvolvimento de procedimentos e sistemas automatizados para controle de qualidade de carnes e produtos cárneos." Instituto de Química, 2005. http://repositorio.ufba.br/ri/handle/ri/20507.
Full textApproved for entry into archive by NUBIA OLIVEIRA (nubia.marilia@ufba.br) on 2016-09-14T20:43:57Z (GMT) No. of bitstreams: 1 Tese Mariangela V Lopes.pdf: 3032469 bytes, checksum: 36404d46d79768ab384fb49c544f496e (MD5)
Made available in DSpace on 2016-09-14T20:43:57Z (GMT). No. of bitstreams: 1 Tese Mariangela V Lopes.pdf: 3032469 bytes, checksum: 36404d46d79768ab384fb49c544f496e (MD5)
Neste trabalho, foram desenvolvidos procedimentos e sistemas automatizados para o controle de qualidade de carnes e produtos cárneos quanto à presença de aditivos (NO2- e NO3-), degradação (evolução de H2S), presença de adulterante (SO3-) e riscos de contaminação pela capacidade sortiva de metais. O desenvolvimento destes procedimentos vem contrapor as metodologias clássicas recomendadas pelos órgãos oficiais brasileiros. Os métodos e procedimentos aqui desenvolvidos obedecem às recomendações da Química Analítica moderna, as quais priorizam precisão, exatidão, sensibilidade, custos operacionais, versatilidade, robustez, rastreabilidade, minimização de resíduos e produtividade analítica. O sistema de analise por injeção em fluxo (FIA), para análise seletora e discriminatória de H2S evoluído pela carne, foi desenvolvido baseado no método do azul de metileno. O emprego da multicomutação, associado à câmara de pervaporação, conferiu versatilidade ao sistema com produtividade analítica de 30 determinações h-1. Paralelo a isto, foi realizada uma avaliação da degradação de carnes empregando a espectroscopia no infravermelho próximo (NIR) para averiguação das condições de conservação de carnes. Os resultados foram concordantes para as duas metodologias (NIR e FIA), sendo possível detectar indícios de deterioração após 30 min de exposição da carne à atmosfera em temperatura ambiente. O desenvolvimento de sistema em fluxo para análise seqüencial de NO2- e NO3-, em produtos cárneos, utilizando câmara de tubos concêntricos (CTC) foi baseado no método de Greiss. A CTC proporcionou a divisão da zona da amostra, facilitando as determinações seqüenciais de NO2- e NO3-. A subzona da amostra que passava pelo tubo central da CTC resultava apenas na determinação do NO2-. A amostra que passava pelo tubo externo (coroa) da CTC, percolava grãos de cádmio coperizado, resultando na redução do NO3- existente à NO2-. Este sistema ofereceu boa sensibilidade para a quantificação dos analitos, apresentando limites de detecção de 0,018 e 0,036 mg L-1 para NO2- e NO3-, respectivamente. O procedimento proposto atingiu produtividade analítica de 120 determinações h-1. O desenvolvimento de sistema automatizado em fluxo para análise discriminatória de sulfito em carnes foi baseado no método da p-rosanilina. Foi empregado câmara de permeação gasosa, onde o SO3- presente na amostra, permeava através de membrana de PTFE para a reação com o reagente cromogênico. O sistema foi satisfatório para screening analysis, com produtividade analítica de 12 determinações h-1. A capacidade sortiva de metais pela carne bovina foi também avaliada. Foi avaliado o contato estático da carne com soluções de referência de Cd e Pb, preparadas com água de torneira, a pH 6. Foi empregada válvula multiportas, com oito canais para execução dos experimentos, enquanto que metais foram determinados por ICP OES. Os resultados indicaram um elevado poder sortivo, cerca de 80% para ambos os metais, evidenciando risco potencial de contaminação para as carnes submetidas a práticas inadequadas de abate e comercialização
In the present work automated systems and procedures to control the quality of meats and meat products had been developed, in concern to the additive presence (NO2- and NO3-), degradation (H2S evolution) and presence of adulterating species (SO32-). Also the metal sorption capacity on meat was evaluated. The development of these methods comes to oppose classical methods recommended by brazilian official agencies. The developed procedures follow the recommendations of the modern Analytical Chemical, which prioritizes the precision, exactness, sensitivity, traceability, robustness, reduced operational costs, lesser production of residue and raised analytical productivity. The flow analysis (FIA) procedure to discriminate H2S in meat sample was developed based on methylene blue method. Multicommutation, associated to gas permeation conferred versatility to the system with analytical throughput of 30 determinations h-1. Parallel to this, the spectroscopy in the near infrared region (NIR) was carried out to evaluate meat degradation. A flow system for sequential NO2- and NO3- analysis in meat products, using concentric tubes chamber (CTC) was based on the Greiss method. The CTC provides the division of sample zone, permitting the sequential analysis. The sample sub zone that passed for the central pipe of the CTC resulted in the determination of the NO2-. The sample that passed through external CCP pipe, percolated the cadmium column, allowing the reduction of the NO3- to NO2-. This system offers sensitivity in the quantification of anilities with detection limits of 0.036 for NO3- and 0.018 mg L-1 for NO2-, reaching 120 determinations h-1. The flow system for the screening analysis of SO32- in meat sample was based on p-rosanilne method. Chamber for gas permeation was employed. The system revealed efficient for screening analysis with analytical throughput of 12 determination h-1. The metal sorption capacity on meat was evaluated. The investigated species comprised Cd and Pb from solutions prepared with tap water at pH 6. In the experimental set, it was employed an eight channels multiport valve in order to prepare part of the samples, while the metal determinations was carried out by using ICP OES technique. The results obtained demonstrated an expressive retention capacity of meat for Cd2+ and Pb2+ ions with percentages ca. 80% (m/m) for both metals, indicating the potential risks related to the consumption of meat submitted to inappropriate conditions of abattoir, handling, storage and commercialization.
Mattisson, Emmy. "Increased leaching of metals as a result of foundation work." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232049.
Full textFörorening av tungmetaller i naturen är ett globalt problem som troligtvis kommer öka i framtiden. Den här rapporten undersöker en byggarbetsplats där ökade koncentrationer av metallerna kadmium, kobolt, koppar, nickel och zink samt ett minskat pH-värde har observerats i ytvattenrecipienten. Fokus ligger på att analysera föroreningskaraktärer och identifiera lämpliga åtgärdsmetoder för att undvika att en å nedströms som är skyddad av miljökvalitetsnormer ska förorenas. Berggrunden i området är sulfidförande och släpper ut surt lakvatten när den oxiderar, vilket är antaget har hänt till följd av plansprängning och utfyllnad av överblivet bergmaterial. Föroreningskaraktärerna analyserades med de statistiska metoderna modified double mass analysis och principalkomponentsanalys. En vattenbalans etablerades för att ta fram flöden, volymer och för att bestämma massorna av de frigjorda metallerna i ytvattnet. Identifiering av lämpliga åtgärdsmetoder gjordes med en litteraturstudie av tillgängliga metoder som grund. Resultaten visade att det är en signifikant ökning av metallkoncentrationer och minskning i pH-värde runt samma tid som sprängning och utfyllning av bergmaterial påbörjades samt att det är förhöjda halter av sulfid och svavel, men de kunde inte bli associerade med ett specifikt media. De årliga massorna av frigjorda metaller som släpps ut från området i ytvattnet är mellan 77-98 % högre än tillåtet av de etablerade riktlinjerna. Genom att separera vattnet som kan antas innehålla majoriteten av föroreningarna från det naturliga vattenflödet i avrinningsområdet kan volymen som behöver renas halveras. Eftersom föroreningen är så omfattande föreslås en kombination av åtgärdsmetoder; installation av gröna tak för att minska avrinningen från området, inneslutning av utfyllnadsmaterialet med bentonit och installation av ett filter för snabb, effektiv reduktion. För mer långsiktig rening föreslås det att optimera de existerande sedimentationsdammarna och våtmarken. Slutsatsen är att det kommer bli väldigt dyrt att åtgärda föroreningen på grund av dess omfattning, och hantering av sulfidförande berg för exploateringssyfte borde vara lagstadgat för att undvika miljömässiga och ekonomiska kostnader.
Bonel, Kevin Anthony. "The mode of occurrence, recovery characteristics and petrogenesis of platinum-group and base metal sulphide minerals in the UG2 chromitite at Northam Platinum Mine, South Africa." Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297790.
Full textRobinson, Oliver B. "A critical review of the phenomenon of bond-stretch and distortional isomerism in oxo and sulphido complexes of transition metals." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5758/.
Full textParker, Andrew Donald. "Oxidative dissolution of chalcopyrite in ferric media: an x-ray photoelectron spectroscopy study." Thesis, Curtin University, 2008. http://hdl.handle.net/20.500.11937/140.
Full textParker, Andrew Donald. "Oxidative dissolution of chalcopyrite in ferric media: an x-ray photoelectron spectroscopy study." Curtin University of Technology, School of Science and Computing, 2008. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=118673.
Full textXPS analysis was performed on chalcopyrite massive fractured under anaerobic atmosphere and chalcopyrite massive and concentrate oxidised in 0.1 M ferric sulphate (pH 1.9) and 0.2 M ferric chloride (pH 1.6) at 50, 65 and 80ºC. Quantitative XPS analysis of the chalcopyrite surfaces required the development of programs that accounted for the observed XPS spectra. The output of these programs was used to construct profiles of the chalcopyrite surfaces and the deposited phases. These surface profiles were correlated with copper recoveries determined for chalcopyrite concentrate dissolution under the same conditions.
The surface of chalcopyrite before oxidative dissolution reconstructs to form a `pyritic' disulphide phase. This phase is oxidised in ferric media to form thiosulphate via the incorporation of oxygen atoms from the hydration sphere. The thiosulphate reacts in the oxidising conditions of low pH to form elemental sulphur, sulphite and sulphate. The sulphate complexes with ferric to produce hydronium jarosite. This reaction occurs at the surface during the initial stages of dissolution and in the bulk solution during the latter stages. This precipitation of hydronium jarosite during the latter stages of dissolution corresponds to inhibition of the dissolution reaction. It is therefore concluded hydronium jarosite is responsible for inhibiting the oxidative dissolution of chalcopyrite in ferric media.
The identification of hydronium jarosite as the inhibiting phase is consistent with the industrial practice of removing `excess' iron from the ferric solution before oxidative dissolution. However, additional iron and sulphate are generated at the chalcopyrite surface during oxidative dissolution. These high iron and sulphate concentrations combine with the low pH and high temperatures favoured for the oxidative dissolution of chalcopyrite to produce ideal conditions for jarosite precipitation. Therefore, pH must be lowered further to prevent jarosite precipitation and enhance copper recoveries from chalcopyrite in ferric media.
Cuthbert, Edwin. "The synthesis of metal chalcogenide volatile precursors in the formation of antimony and bismuth sulphide thin films and the synthesis of amine adducts for the formation of gallium nitride by MOCVD." Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250737.
Full textMariga, Valentina. "Sustainability analysis in the mining sector: a case study on new recycling technologies for sulphidic mine residues valorisation." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23270/.
Full textStalder, Marcel. "Petrology and mineral chemistry of sulphide ores and associated metalliferous rocks of the Gamsberg Zn-Pb deposit, South Africa : implications for ore genesis and mineral exploration." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16072.
Full textENGLISH ABSTRACT: The Gamsberg Zn-Pb deposit is a metamorphosed and multiply deformed sediment-hosted base metal deposit in the central Namaqua Province of South Africa. The deposit is hosted by the Bushmanland Group, a late Palaeoproterozoic (2000-1600 Ma) supracrustal succession of quartzite, metapelitic schist and interbedded metavolcanic rocks. Mineralisation occurs within the central part of the Gams Formation, a heterogeneous sequence of metamorphosed metalliferous sediments and fine-grained organic-rich shales. The ore horizon is subdivided into a lower unit of metapelite-hosted ore, an intermediate layer of phosphorite-hosted ore, and an upper unit of banded garnet-apatite ore. The ore body is enveloped by unmineralised silicate-, carbonate- and oxide-facies metalliferous rocks, which originally represented mixtures of Fe-Mn-rich hydrothermal precipitates, authigenic carbonate, and variable concentrations of detrital material. Based on mineralogical and geochemical characteristics, the metalliferous host rocks are subdivided into iron formations, coticules, Fe-Mn silicates, impure marbles and barite/Ba-rich quartzite. Minerals of the Gams Formation mostly represent solid solution between the Fe and Mn end-members of garnet, pyroxene, pyroxenoid, amphibole, olivine, spinel and ilmenite. Calcium-rich rock types are a typical feature and characterized by the occurrence of manganoan calcite, clinopyroxene, andradite-rich garnet and titanite. A successive increase in the (Mn+Ca):Fe value of rocks and minerals is evident with increasing distance from the ore horizon. Amphibole is restricted to Fe-rich ore-bearing assemblages, whereas orthopyroxene, clinopyroxene, Fe-rich pyroxenoid and olivine are present in intermediate assemblages, and Mn-rich rhodonite and pyroxmangite in the most manganiferous assemblages. These variations are mimicked by an increase in the Mn:Fe value of coexisting garnet and ilmenite group minerals with increasing distance from ore. LA-ICP-MS analyses have been used to constrain the REE patterns of garnet and apatite. In the ore-body, these minerals display a positive Eu anomaly, which is interpreted to reflect a distinct hydrothermal signature. In contrast, garnet and apatite in unmineralised metalliferous rocks display nil or a negative Eu anomaly. Primary features of the Gams Formation, such as REE patterns, the banded nature of garnet-apatite ore, the presence of diagenetic apatite nodules, and the distribution of the redox-sensitive elements Ba and Mn have been used to constrain palaeo-environmental conditions. The results indicate that metapelitehosted ore has been deposited in a stratified ocean that was characterised by anoxic bottom waters and precipitation of Fe and Zn sulphides into organic matter-rich shales. These rocks were superceded by phosphorite-hosted ore, garnet-apatite ore and metalliferous host rocks that developed in a suboxic to oxic environment. The large size of the deposit, the internal lamination of the ores and the predominance of sphalerite and barite are consistent with a vent-distal setting and precipitation of the ore-forming constituents from dense and reduced hydrothermal fluids, which originated due to reactivation of dormant growth faults. Collectively, the geological evidence indicates that Gamsberg is bridging the gap betweenthe SEDEX and BHT classifications. The relationships demonstrate that differences between these two classes of sediment-hosted Zn-Pb deposits are predominantly related to environmental conditions within localised third order basins and not to fundamental differences in ore-forming processes.
AFRIKAANSE OPSOMMING: Die Gamsberg Zn-Pb afsetting is ‘n meerfasig vervormde en gemetamorfiseerde sedimentgesetelde onedel metaal afsetting in die sentrale Namakwa Provinsie van Suid Afrika. Die afsetting word geherberg deur die Boesmanland Groep, ‘n laat Paleoproterosoïse (2000 – 1600 Ma) bokors-opeenvolging van kwartsiet, metapelitiese skis en tussengelaagde metavulkaniese gesteente. Mineralisasie word gevind in the sentrale deel van die Gams Formasie. Die Gams Formasie is ‘n heterogene opeenvolging van gemetamorfiseerde metaalhoudende sediment en fynkorrelrige organiese skalie. Die erts horison word onderverdeel in ‘n onderste laag van metapeliet-gesetelde erts, n sentrale laag van fosforiet-gesetelde erts, en ‘n boonste laag van gebande granaat-apatiet erts. Die erts-liggaam word omhuls deur ongemineraliseerde silikaat-, karbonaat- en oksied-fasies metal-ryke rotse. Hierdie gesteentes word geinterpreteer as oorspronklike mengsels van Fe-Mn-ryke hidrotermale partikels, outigeniese karbonaat, en verskeie hoeveelhede detritale materiaal. Gebaseer op mineralogiese en geochemiese kenmerke word hierdie rotse onderverdeel in ysterformasies, „coticules“, Fe-Mn silikate, onsuiwer marmer en barite/Ba-ryke kwartsiet. Minerale van die Gams Formasie form meestal soliede oplossingsreekse tussen die Fe en Mn endlede van granaat, pirokseen, piroksenoid, amfibool, olivien, spinel en ilmeniet. Kalsium-ryke rots tipes is ‘n tipiese kenmerk van die Gams Formasie en word gekenmerk deur mangaan-ryke kalsiet, klinopirokseen, andradiet-ryke granaat en sfeen. Daar word ‘n stapsgewyse vergroting van die (Mn+Ca):Fe verhouding in gesteentes en minerale gevind met toeneemende afstand van die erts horison. Amfibool is beperk tot Fe-ryke ertsdraende gesteentes, ortopirokseen, klinopirokseen, Fe-ryke piroksenoid en olivien tot intermediêre gesteentes, en Mn-ryke rodoniet en piroksmangiet tot Mn-ryke gesteentes. Hierdie variasies gaan gepaard met vergroting van die Mn:Fe verhouding in granaat en ilmeniet-groep minerale met toeneemende afstand van die erts. LA-ICP-MS analises was gebruik om die skaars-aarde element patrone van granaat en apatiet te bepaal. In die erts-liggaam wys hierdie minerale ‘n positiewe Eu anomalie, wat geinterpreteerd word as ‘n hidrotermale kenmerk. In ongemineraliseerde gasheer gesteentes wys granaat en apatiet geen of ‘n negatiewe Eu anomalie. Primêre kenmerke van die Gams Formasie, soos skaars-aarde patrone, the gebande voorkoms van granaat-apatiet erts, die teenwoordigheid van diagenetiese apatiet knolle, en die verspreiding van die redox-sensitiewe elemente Ba en Mn, was gebruik om afleidings oor die paleo-omgewing te maak. Die resultate het gewys dat metapeliet-gesetelde erts afgeset was onder anoksiese bodem water deur presipitasie van Fe en Zn sulfiedes in organiese skalie. Hierdie erts gaan oor in fosforiet-gesetelde erts, granaat-apatiet erts en metaal-ryke gasheer gesteente wat in ‘n suboksiese tot oksiese omgewing ontstaan het. Die grootte van die afsetting, die interne gelaagdheid van die erts, asook die teenwoordigheid van sfaleriet en bariet dui op ‘n distale omgewing relatief tot die hidrotermale bron en presipitasie van die ertsuit digte en gereduseerde hidrotermale vloeistowwe, wat ontstaan het deur die heraktiveering van rustende groeiverskuiwings. Gesaamentlik bewys die geologiese kenmerke van Gamsberg dat gemetamorfiseerde SEDEX en Broken Hill-tipe mineralisasie binne die perke van ‘n enkele afsetting kan voorkom. Die geologiese verhoudings dui aan dat verskille tussen hierdie twee tipes van sedimentgesetelde afsettings meestal veroorsaak word deur omgewings-toestande binne in gelokaliseerde derde orde komme en nie deur fundamentele verskille in ertsvormende prosesse nie.