Extraction of Gold from Refractory Gold-Bearing Ores by Means of Reducing Pyrometallurgical Selection
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EXTRACTION OF GOLD FROM REFRACTORY GOLD-BEARING ORES BY MEANS OF REDUCING PYROMETALLURGICAL SELECTION R. S. Seisembayev,1 S. M. Kozhakhmetov,2 S. A. Kvyatkovsky,3 and A. S. Semenova4
UDC 669.21/23
Problems related to the effective processing of refractory gold ores containing carbon and arsenic are discussed. In the search for technologies for the extraction of gold from such ores, including those obtained from the Sayak-4 gold deposit, pyrometallurgical processing represents a possible direction. The results of an experimental study of the Reducing Pyrometallurgical Selection (RPS) process carried out in relation to this ore are presented. To this end, the ore was smelted with flux additives and a reducing agent leading to the extraction of noble metals in the metallized phase. The experiments were carried out using the following ore composition, wt. %: 3.5 g/ton Au; 1.76 g/ton Ag; 3.95 Fe; 0.01 Cu; 1.93 C; 1.0 S; 3.3 As; 0.05 Co; 38.30 SiO2; 23.6 CaO; 4.56 Al 2O 3 ; 0.73 MgO with addition of iron, copper oxides, and coke. The optimal temperature conditions of melting were determined. The possibility of obtaining a metallized phase containing 16.2–16.4 g/ton gold with gold recovery of ∼ 90% was demonstrated. Preliminary calculations show that the economic efficiency of the new process can be achieved with a gold content of more than 5 g/ton in ore. Pyrometallurgical processing is shown to be promising for treating ores obtained from refractory and double-refractory gold deposits. Keywords: refractory gold ore, reduction smelting, flux, coke, slag, matte, iron and copper alloys, gold recovery.
One of the unresolved challenges facing the gold mining industry is the organization of highly efficient processing of refractory and double refractory lode gold ores containing about 50% of the world’s reserves. Such ores are characterized by the presence of submicroscopic gold, as well as the presence of other minerals including copper, arsenic, iron, and carbonaceous matter [1–4]. A brief analysis of the existing and developed methods for processing refractory- and double-refractory gold raw materials showed the futility of focusing on the existing modern technological schemes, which, despite being considered effective, in many cases are fundamentally incapable of providing efficient processing of such ores [5–15]. A novel approach for ensuring the efficient extraction of gold from such ores consists in the Reducing Pyrometallurgical Selection (RPS) process. RPS is independent of the forms of gold content as well as the characteristics of the chemical and mineralogical compositions of the feedstock. In tests carried out on gold ores derived from various deposits in Kazakhstan, the RPS technology demonstrated a high recovery rate (Table 1). The problem of processing such raw materials is relevant for the Republic of Kazakhstan (RK), which has large gold deposits, including the Sayak-4 “Zolotoy” deposit. During gravity and flotation concentration of ores obtained from this deposit, a satisfactory level of extraction of gold
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