Abstract
Being the most common sulfide minerals, Arsenopyrite and pyrite under oxidizing conditions breaks down to release acids of As and S into the environment, leading to acid mine drainage with high concentrations of dissolved As. In this research, the dissolution of gold ore (with FeS2 and FeAsS as the main sulfides) from Tianli gold mine, Liaoning province, China was investigated. The experiments were conducted in 500mL conical flasks containing 200mL of three different media, 3% pulp density and 1.6 initial pH. The results indicated that treatment with mix culture medium resulted in the dissolution of 99% of Arsenic and 99% of iron, which was higher as compared with when treated in the same culture medium after centrifugation for 20 minutes which in turn higher in comparison with when treated in acidic and pure sterile system. The oxidation potential, Eh of the mix culture medium reached 680mV (vs.SCE) within the first three days of the experiment where as that of centrifuged, acidic and sterile media reached 580, 450 and 445mV (vs.SCE) respectively. The pH tends to increase within the first three days which eventually decreased to nearly one toward ending, courtesy of pyrite which is believed to be net acid releasing sulfide. The dissolution is suggested to be a combined effect of enzymes, ferric iron ions and organic acids. It was observed that enzymes and ferric ions played an essential role in the dissolution process.
Highlights
The innovation of steam engine back in the late 19 the century resulted in an enormous growth of industrial activities globally, which in turn resulted in an increase deterioration of the ecosystem because of the discharge of highly polluted effluents in the forms of solid, liquid, and gas
The experiments were conducted in 500mL conical flasks containing 200mL of four different media, mix bacterial medium, mix centrifuged bacterial culture medium, in acidic medium and in a sterile medium
Within the first 3 day of the experiment, the percentage of the total Fe ion were 86% and 87 for the sample with mixed and centrifuge bacterial culture medium (Figure 4), this clearly indicates that the oxidation rate of the sample is higher at the initial stage, so the increase in pH is apparent
Summary
The innovation of steam engine back in the late 19 the century resulted in an enormous growth of industrial activities globally, which in turn resulted in an increase deterioration of the ecosystem because of the discharge of highly polluted effluents in the forms of solid, liquid, and gas. Bio-hydrometallurgy is a new concept that involves the use of various microorganisms to recover metals from their ores. It is environmentally friendly unlike conventional hydro-metallurgical process [4]. For last several decades bioleaching prioritize in application for metal recovery from ores/ concentrates namely; pyrite arsenopyrite, chalcopyrite, calcite [5]. The recovery of free milling gold by gravity and direct cyanidation proved to be straightforward and well established, refractory ores pose a very different challenge to producers. The first challenge is determining the reason for the poor recovery by direct cyanidation, which can be caused by one or more contributors. Gold ore sample (with FeS2 and FeAsS as the main sulfides) from Tianli gold mine, Liaoning province, China was treated in four different media
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