Study effects of conventional flotation reagents on bioleaching of zinc sulfide

Abstract

Although flotation and bio-extraction of metals from its products are extensively investigated, there are few studied which evaluated the effects of reagents on bioleaching process. Both structure and concentration of flotation reagents are effective factors on microorganism activities. In this study, Kendall’s tau (τ) as a statistical method was used to statistically access the effect of typical sulfide flotation surfactants (collectors: potassium amyl-xanthate, potassium isobutyl-xanthate, sodium ethyl-xanthate, potassium isopropyl-xanthate, and Dithiophosphate), and frothers: pine oil and methyl isobutyl carbinol) on the bioleaching of Zn sulfides in a mixed culture (Leptospirillum ferrooxidans, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans). To consider both structure and concentration of these reagents, their molarities were used for the statistical evaluations. The Kendall assessments indicated that by increasing in the molarity of reagents, the pH value (the most effective factors of bioleaching) was increased (τ: 0.56) while the ORP value (τ: −0.54), Fe3+Fe2+ ratio (τ: −0.51) and numbers of oxidizing bacteria (τ: −0.38) in the solution were decreased. Therefore, as a result of these multi-interactions, by increasing the molarity of reagents, Zn recovery was decreased (τ: −0.45). These results potentially can be used for selection of flotation reagents when bioleaching would be the metallurgical metal extraction method.