Study of the conditions of forming environmentally sound insoluble arseniferrous products in the course of biohydrometallurgical processing of gold-arsenic concentrates

摘要

Refractory gold-arsenic concentrates or o~ from six deposits, their biooxidation (BO) solid residues and residual bacterial solutions were a-ed for chemical composition and Fe/As molar ratio The effect of the Fe/As ratio on As solubility was examined in two solid BO product types (I)BO solid residues obtained in the course of biooxidation, and (II) precipitates that formed upon the completion of the BO procedure as a result of As precipitation from the bacterial solutions through the jarosite process. Stable arsenic-containing products can be formed provided that the Fe/As molar ratio is greater than 4. The pH governing the BO process and the iron concentration in the bacterial solutions can be varied in order to provide for a controlled increase in Fe/As. Mineragraphic, X-raying and X-ray photoelectron spectroscopic techniques were used to determine the composition arsenic-containing compounds incorporated in insoluble BO residues FeAsO_4 centre dot 2H_2O and Fe_2(AsO_4) centre dot SO_4 centre dot OH centre dot 7H_2O.