Stability of arsenical bacterial oxidation products

Summarization: In the present study the stability of the arsenical solid residues emanating from the bacterial oxidation of auriferous arsenical pyrites was evaluated in relation to the operating parameters in the bioleaching circuit. The material examined as a case study was a refractory arsenopyrite concentrate assaying As: 21.0%, Fe: 26.0% and Au: 30.0g/t. The effect of pH-EMF and solution chemistry on precipitate formation during biooxidation and the subsequent stability of the arsenical solid residues was evaluated. The composition and morphology of oxidised precipitates was examined with acid treatment of the bioresidues, chemical and particle size analyses and scanning electron microscopy. Arsenic solubility of the solids under study was evaluated with the standard EPA leachability test. Based on the results of this study, an optimised set of biooxidation operating conditions was derived, including Fe/As ratios in the feed material and oxidised products and Fe3+ levels in solution, aiming at the production of stable arsenical bacterial oxidation products, suitable for environmentally safe disposal.Παρουσιάστηκε στο: Hydrometallurgy ’9