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Fundamental And Technological Studies On Bioleaching Of Refractory Arsenical Gold Concentrates By Thiobacillus Ferrooxidans

Posted on:2001-02-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:X B MinFull Text:PDF
GTID:1101360002950847Subject:Non-ferrous metal metallurgy
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Fundamental and technological studies on bioleaching of arsenic-bearing refractory gold concentrates by 77 ferrooxidans were carried on, with GuanXi JinYa gold concentrates being the developed objective of this research. The main subjects in this dissertation are as follow抯:The relationship between the oxidation of ferrous ion and 77 ferrooxidans growth has been studied systematically. Factors affecting biooxidation of ferrous ion were discussed, a response model for bacterial growth in the substrate containing ferrous ion was also built. It can be expressed as,p梉(p~IY)+p01 +K_______________p0梉(p~/Y)+p0] (p~/Y)+p0 p{p0梉(p~/Y)+p0]}The model shows the variation of ferrous ions concentration with the kinetics parameters of bacterial growth such as Li m ,K and P b/1~ Via the computer simulation to the concentration of ferrous ion during Tferrooxidans growth, the kinetic parameters of the bacterial growth were determined. The model, furthermore, can predict the influences of these parameters on the biooxidation of ferrous ion, with changing the parameter valuesAccording to the aspect of bioleaching process, the potential ?pH diagrams for arsenopyrite-water and pyrite-water systems were drawn, with which was combined the potential-pH diagram for TJ鑢rooxidans activity. A thermodynamic behavior for the bioleaching of pyrite and arsenopyrite has been examined. Tferrooxidans is active in the regions for dissolving pyrite and arsenopyrite, so pyrite and arsenopyrite is possible to be bioleached thermodynamically. It is easy to form element sulfur during the leaching of pyrite and arsenopyrite. If there is no direct action of Tferrooxidans on the formed sulfur, it is impossible for ferric ion to dissolve the element sulfur because of existing a high-energy obstacle in the furtherVIcontinues way, by which a process for biooxidation ?cyanidation of Guangxi Jinya refractory gold arsenical concentrate was studied. An arsenic extraction rate reaches 82.5% after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0, ferric ion concentration 6.5 gIL and pulp density 10%. And leaching rate of gold in the following gold cyanidation is over 90%. The parameters of three series fluid-bed reactors exhibit stability during the semi-continues bioleaching of the concentrate. Arsenic in the concentrate can be got rid of 91% after 6-day leaching. Even after 4 days, 82% of arsenic extraction rate was still obtained. The recovery rates of gold are 92% and 87.5% respectively in cyaniding the above bioleached sludges. The results will provide a base for further commercial production of gold development.
Keywords/Search Tags:refractory arsenical gold concentrate, Tferrooxidans, thermodynamics, micro-electrode of mineral powder, oxidation mechanism, band model, fluid-bed reactor, semi-continuous bioleaching.
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