Condition optimization for bio-oxidation of high-S and high-As gold concentrate

Abstract:

Abstract:［Objective］To study the effects of temperature and lixivium return on the concentrate bio-oxidation and rate of gold cyanide leaching.［Methods］ The bioleaching of a high-sulphur (S) and high-arsenic (As) refractory gold concentrate was conducted，and we studied the effects of different temperature (40 ℃ and 45 ℃) and lixivium return (0 and 600 mL) on the bio-oxidation efficiency．The bacterial community structure also was investigated by 16S rRNA gene clone library.［Results］ The results showed that both the temperature and lixivium return significantly influenced the oxidation system． The temperature rising elevated the oxidation level，while the addition of lixivium depressed the oxidation． Dissimilarity and DCA (detrended correspondence analysis) indicated the effect of temperature on oxidation system was much greater than lixivium． The bacterial community was comprised by Acidithiocacillus caldu (71%)，Leptospirillum ferriphilum (23%) and Sulfobacillus thermosulfidooxidans (6%) indicated by the clone library，and the OTU coverage based on 97% sequence similarity was as high as 93.67%.［Conclusion］Temperature rising to 45 ℃ would improve the oxidation efficiency while lixivium return would decrease it．This study is helpful to provide an important guiding value for the industry cost optimization of mesophile bacterial oxidation and reduction process.

Key words:Keywords: high-sulphur and high-arsenic gold concentrate，continuous bio-oxidation，leaching rate of Au，rate of sulfur oxidation，detrended correspondence analysis (DCA)，16S rRNA gene clone library