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Dearsenificating Study during Oxidation of Gold Ore Containing Arsenic by Bacillus

Author: ZhangGuPing
Tutor: YangHongYing
School: Northeastern University
Course: Biochemical Engineering
Keywords: bacterial oxidation gold ore arsenic valence transformation pretreatment
CLC: TD953
Type: Master's thesis
Year: 2008
Downloads: 66
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Abstract


It was studied the bacteria activation and the dearsenification of gold concentrations by setting different grads of pH value in shaking flask. The results show that the optimum initial pH for bacteria activation is 1.3-1.9. Within the optimum initialization, the potential rises quickly and ferrous ion is oxidated well. The optimum initial pH of the bacteria HQ0211 for dearsenification is 1.7-1.9, and it is not good for the concentrations to be oxidated and dearsenificated by bacteria if the initial pH value is outside the scope. The results of X-ray diffraction analysis to oxidation residue show that the phase containing arsenic changed; The arsenic was dissolved into solution when arsenopyrite and lollingite were oxidated, and deposited as the form of scorodite under certain conditions.2# and 3# concentration containing arsenic were processed by bacterial oxidation craft. The results indicated that under low arsenic condition, the bacterial activity was good and oxidation rate was quicker; after 6 days’ oxidation to the 2# concentration,the dearsenificating rate reached 98.33%, and after 5 days’ oxidation to the 3# concentration,the dearsenificating rate reached 98.16%; Under high arsenic condition, period for adaptation of bacteria was long and oxidation rate was slower than the one under low arsenic condition; after 10 days’ oxidation to the 2# concentration,the dearsenificating rate reached 98.25%, and after 10 days’ oxidation to the 3# concentration,the dearsenificating rate reached 97.81%.The process of arsenic valence transformation during oxidation of gold ore containing arsenic by bacillus was analyzed, and concentration of As(Ⅲ)As(Ⅴ)in solution were tested regularly. The results show that during the process of bacterial leaching, arsenic in the ore dissolved into solution as the form of As(Ⅲ) at the first, and then transformed into As(Ⅴ) because of the co-functions of Fe3+、oxygen and bacillus. The potential was low in the earlier period of oxidation to concentration, arsenic in solution existed as the form of (Ⅲ), and the quantity of As(Ⅴ) was few; In the last period, As(Ⅲ)transformed into As(Ⅴ) quickly in the condition of high potential, and arsenic mostly existed as the form of As(V).

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CLC: > Industrial Technology > Mining Engineering > Beneficiation > Metallic Ore Dressing > Precious metal ore beneficiation
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