Satbayev University, «Institute of Metallurgy and Ore Beneficiation» JSC (Almaty, Republic of Kazakhstan):

Koyzhanova A. K., Head of Laboratory, Candidate of Engineering Sciences, aigul_koizhan@mail.ru
Kenzhaliev B. K., General Director, Doctor of Engineering Sciences, Professor, bagdaulet_k@mail.ru
Kuldeev E. I., Deputy General Director, Candidate of Engineering Sciences, Associate Professor
Kamalov E. M., Senior Researcher, kamalov@mail.ru

The paper presents the results of leaching of the ore mass of spent HL (heap leaching) piles aimed at recovering gold associated with sulfides. A sample was taken and its phase composition was studied. The chemical and mineral composition of the leaching tailings were studied using the semi-quantitative X-ray fluorescent, chemical (assaying), mineralogical and rational (phase) analysis methods. It was established that the sample contained 1.6 g/t Au and 0.14 g/t Ag. The particle size analysis demonstrated that the bulk of gold (46.73%) was concentrated in the size class of –0.8+0.25 mm, with its content being 1.56 g/t. The main minerals of the original sample were quartz, albite, muscovite, and microcline. Sulfides were represented by arsenopyrite, pyrite, chalcopyrite, iron oxides and hydroxides (goethite, magnetite, hematite). The gold particle sizes varied from 0.8 to 10.2 μm. The amounts of free gold and gold in splices with the host rock were 55.56 and 44.44 %, respectively. According to the phase analysis data, a significant portion of gold (46.43%) was in association with sulfides. Various processing methods for the ore mass of spent HL piles were studied, such as regrinding with subsequent cyanidation and preliminary oxidation with a chemical reagent. The possibility of processing tailings by cyanidation was established. Preliminary oxidation and liberation of refractory gold enabled increasing the gold recovery rates in the cyanidation of the oxidation residue. It was shown that, for the particle size of 90 % class –0.071 mm, under optimal cyanidation conditions with preliminary oxidation, 61.3 % of gold was recovered within 24 hours.
The work was performed with the financial support of the Ministry of Education and Science of the Republic of Kazakhstan under the financial grant No. AP05130143.

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