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

No description available.

M.Tech. (Minerals Engineering) / This report deals with the feasibility study of a novel concept whereby a lead sulphide concentrate and a solid reductant are reacted with a manganese ore at a temperature of approximately lOOO=C. The manganese oxides are reduced to their lower oxides, which, having a higher affinity for sulphur than lead. scavenge the sulphur from the lead sulphide. A manganese sulphide mane is formed. and liquid lead metal is tapped off. The manganese sulphide mane is then leached with sulphuric acid. After a purification step to remove the base metals from solution, the electrolyte proceeds to an electrolytic manganese metal or manganese dioxide facility where the manganese is recovered. The benefits of this process are fourfold: firstly, lead ores may be beneficiated locally; secondly, the separate and often lengthy processes for the recovery of lead and manganese are combined into a simplified process, thereby reducing the capital expense: thirdly, the Leadman process can be applied to any scale of operation: and fourthly, no 502 is produced. Details of the investigation included the following: a literature survey. a laboratory scale study where the operating conditions were narrowed down, a smelting campaign on a rotary kiln, a mineralogical study, a brief leaching study, a leach liquor purification step and a techno-economic assessment. This study has shown the technical and economical feasibility of the Leadman process. The lead and manganese recoveries were both approximately 93%, with good accountability of all the other elements of interest. Depending on the operating conditions, between 80 and 100 per cent of silver, originally in the galena, was recovered with the lead bullion. The purity of the lead metal produced was good with a lead content of approximately 97 per cent, and low levels of contaminants. It was also shown that the manganese matte produced is suitable for use as feed to an existing manganese electrowinning operation. The techno-economic assessment showed a return of R 3 118/t of Pb, compared with R 939/t and R 240/t for the conventional manganese and lead blast processes, respectively.

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 1990. / The static Rand gold price has put pressure on the South African gold mines to improve efficiency. Superior metallurgical performance and lower costs attributed to column flotation prompted the construction of a pilot plant (238 millimetres by 10 metres) at ERGO, an Anglo American tailings retreatment plant [Abbreviated Abstract. Open document to view full version] / MT2017

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. Title from title screen (viewed Mar. 27, 2007). Includes bibliographical references (leaves 47-50). Online version of the print original.

Six distinct types of mafic igneous rocks are present within the ca. 2714-2690 Ma Woolyeenyer Formation of the Norseman Terrane, East Central Yilgarn Superterrane (ECYS), Yilgarn Block, Western Australia. (1) Tholeiitic basalts and gabbros comprise the bulk of the formation, and are characterized by flat to slightly depleted mantle-normalized incompatible element patterns, and å_Nd values of +2 to +3. (2) High-MgO tholeiite dykes (HMT) with normalized REE and multielement patterns like those of tholeiites, albeit at slightly lower abundances. (3) Enriched high-MgO tholeiite dikes (EHMT) with MgO, Cr similar to HMT but with extreme Al-depletion, enrichment in incompatible elements and HREE depletion, and å_Nd values of -2.0 to -1.2. (4) High-MgO tholeiites with characteristics transitional to HMT and EHMT (THMT). Incompatible element enriched tholeiites transitional between HMT, HMT and tholeiite, subdivided into (5) ET1, characterized by enrichment in incompatibleelements and LREE, with relatively flat HREE patterns and ENd values ranging from -0.1 to 1.0, and (6) ET2, characterized by Al-depletion and pronounced HREE depletion. The HMT and tholeiites are comagmatic, and positive ENd values and comparable normalized trace element patterns suggest derivation of these rocks from a similar depleted source. Conversely, detailed modelling demonstrates that EHMT compositions cannot be generated by alteration or crustal contamination of HMT, Al-undepleted or Al-depleted komatiitic magmas, and require a source (1) that was enriched in incompatible elements by small volume partial melts prior to melting, and (2) where garnet was retained during melting. Generation of the above mafic lithologies require that incompatible element enriched and depleted sources existed at 2.7 Ga in the Norseman Terrane. The EHMT are the first report of such severely Al-depleted 2.7 Ga rocks from ECYS. The Archean lode-gold deposits at Norseman, Western Australia, consist of auriferous quartz veins in dextral-reverse ductile shear zones within tholeiitic metabasalts of upper-greenschist to amphibolite facies metamorphic grade. Three types of deposits (northern, central, southern) are delineated on the basis of their spatial distribution, veining style, alteration mineralogy and metamorphic grade of host rocks. All deposits exhibit variable ductile deformation of veins and contiguous alteration haloes, implying a syn-deformational genesis at high temperatures. From Northern to Southern deposits, the alteration assemblages are indicative of higher temperatures, and there are progressively greater degrees of dynamically recovered textures in quartz. Initial Pb isotope compositions of galena and altaite from lode gold deposits of the Norseman Terrane yield the most variable initial Pb-isotopic compositions for these minerals of any Archean lode gold deposit. Interpreted initial Pb isotope compositions of galena and altaite are systematically more radiogenic with increasing proximity to felsic intrusive rocks and older crust.

Thesis (Ph. D.)--University of Queensland, 2003. / Includes bibliographical references.

No description available.

No description available.