LLC Research Center Hydrometallurgy (Saint-Petersburg, Russia)

V. А. Puchkina, Researcher, puchkina-v@gidrometall.ru
N. А. Кravchenko, Leading Engineer, kravchenko-n@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

LLC Giproniсkel Institute (Saint Petersburg, Russia)
N. М. Vostrikova, Senior Researcher, Candidate of Technical Sciences, VostrikovaNM@nornik.ru

The paper presents the results of laboratory investigations into the effect of limestone addition on the processing of the Pioneer deposit concentrate using autoclave hydrometallurgical technology. Secondary phases formed during the pressure oxidation of pyrite concentrates with low arsenic content exhibit a relatively low dissolution rate during the hot cure process. Due to the limited hot curing time, this process remains incomplete, and during the neutralization of the pressure oxidation residue prior to cyanidation, the secondary phases react with lime, substantially increasing lime consumption and reducing the efficiency of concentrate processing. The implementation of a particular processing route for the Pioneer deposit concentrate and other concentrates of similar composition requires the development of new technological solutions. One of them is the addition of limestone to the autoclave feed slurry, which reduces slurry acidity in the initial autoclave compartments and enables control over the composition of the secondary phases formed. The obtained results demonstrate the influence of limestone addition and its dosage on the key process indicators, including the proportion of cyanidable gold, the degree and kinetics of sulfide sulfur oxidation, solid residue yield, lime consumption for neutralization prior to cyanidation, and hot curing time. Chemical analysis showed that limestone addition decreases the content of basic ferric sulfate in the hot-cured pressure oxidation residue while increasing the hematite content. Such changes in the phase composition reduce the minimum hot curing time required for the oxidized slurry and significantly lower lime consumption during slurry neutralization prior to cyanidation.

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