LLC Research Center Hydrometallurgy (Saint-Petersburg, Russia)
V. А. Kuzas, Researcher, puchkina-v@gidrometall.ru
М. V. Klementiev, Deputy General Director for Project Support and Implementation, klementev-m@gidrometall.ru
I. V. Fomenko, General Director, Candidate of Technical Sciences, fomenko-i@gidrometall.ru
N. А. Кravchenko, Leading Engineeer, kravchenko-n@gidrometall.ru
LLC Giproniсkel Institute (Saint Petersburg, Russia)
N. М. Vostrikova, Senior Researcher, Candidate of Technical Sciences, VostrikovaNM@nornik.ru
The paper presents the results of pilot-scale testing of the pressure oxidation (POX) process applied to the Pioneer deposit concentrate blended with limestone. The objective of the study was to evaluate the effects of limestone dosage and oxidation intensity on the key performance indicators of pressure oxidation, subsequent hot curing of the oxidized slurry, neutralization, and cyanidation. Six continuous pilot-scale autoclave tests were carried out under moderate and intensive oxidation conditions, with the specific limestone consumption varied from 50 to 100 kg/t of concentrate. It was found that pressure oxidation under moderate conditions (Fe2+ concentration in the liquid phase of the autoclave discharge slurry of 1.5–3.0 g/dm3) reduced the hot curing time and provided the lowest solid yield and lime consumption during neutralization of the pressure oxidation residue slurry prior to cyanidation. In contrast, intensive oxidation (Fe2+ concentration in the liquid phase of the autoclave discharge slurry of 0.3–0.7 g/dm3) resulted in a several-fold increase in both the solid yield and lime consumption during slurry neutralization before cyanidation. In addition, the effect of limestone consumption on the key process performance indicators was determined. At a specific limestone consumption of 50 kg/t of concentrate, high values of cyanidable gold recovery and sulfide sulfur oxidation degree (98–99%) were maintained. Under these conditions, the solids yield after hot curing reached 64%. Furthermore, the lime consumption required for pulp neutralization prior to cyanidation was reduced dramatically, from 43 to 1.3 kg/t of concentrate.
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