Analyzing how ions tend to form in the aqueous phase of the slurry and how they affect the bacterial oxidation of sulphide minerals

Abstract

This paper describes the results of a study that relied on chemical and physico-chemical analysis techniques to examine the qualitative and quantitative composition of anions during bacterial oxidation of flotation concentrate. It was found that bacterial oxidation of flotation concentrate results in the production of anions of sulphate, thiosulphate, arsenate, selenate, nitrate, chloride and amino acids (cysteine, threonine and arginine). Anions of amino acids, as well as thiosulphate and selenate anions form chelates with precious metals, which get carried away with the biocake wash to the neutralization stage. The findings helped determine how the concentration of gold ions changes at different process stages. This research aims to analyze the behavior of anions during bacterial oxidation of sulphide minerals. The research material included samples of processed sulphide ores taken from active bacterial oxidation reactors at 12 different points (classifier overflow, flotation concentrate from the thickener, exit from reactors 1, 2, 3, 4, 5, 6; solids of counterflow wash-1 and wash-3, top of the sorption cyanidation tank, cyanidation tailings). The concentrations of amino acids were determined during sample analysis. Three amino acids were mainly detected in the solution: cysteine, threonine and arginine. These amino acids are capable of binding with gold ions and forming chelates. Under the effect of cyanides, cysteine and arginine were found to decompose while threonine remained intact.