The effect of solution parameters on the thiosulfate leaching of Zarshouran refractory gold ore
Title: The effect of solution parameters on the thiosulfate leaching of Zarshouran refractory gold ore
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Journal Title: International Journal of Mineral Processing
Publication Date: 10 September 2014
Start Page: 43
End Page: 50
Published online: online 9 August 2014
Author: M. Aazamia, G.T. Lapidusb, Amir Azadehc
a Department of Mining, University of Kurdistan, Kurdistan, Iran
b Depto. Ingeniería de Procesos e Hidráulica, Universidad Autónoma Metropolitana Iztapalapa, C.P. 55-534, 09340 México, DF, Mexico
c Department of Mining Engineering, Engineering Faculty of Azad University, Sciences & Researches Branch, PO Box 14515/775, Tehran, Iran
Abstract: t years, leaching of refractory gold ores has received much attention due to the depletion of oxide ores. Since the gold is usually associated with or encapsulated in sulfide minerals, such as pyrite, arsenopyrite and chalcopyrite, research in this field has focused mainly on these phases. However, the main sulfide mineral in Zarshouran gold mine (Iran) is orpiment, which has received very little attention. In this study, the effect of different additives on the thiosulfate leaching of gold from Zarshouran refractory gold mine (high-grade orpiment) has been investigated, by determining the thiosulfate and arsenic concentration in solution using UV–visible spectrophotometer and the copper and gold ions using atomic absorption.The results indicated that gold recovery in the presence of EDTA is higher than that achieved in the presence of ammonia, which is attributed to the stronger stabilization of Cu (II) and, consequently, the decrease in thiosulfate consumption. Increasing the copper concentration (greater than 0.05 mol/L) decreases the gold recovery, probably due to the increase in the solution potential, which causes higher thiosulfate consumption and, consequently, greater instability of the gold complexes. Although increasing the pH (mainly) and potential enhancement of the orpiment oxidation liberating the gold from the mineral, this also promotes copper and thiosulfate oxidations, which increase copper sulfide and copper oxide precipitation. Consequently, these actions decrease the gold dissolution (to less than 30%) by passivation of the gold surface. The maximum recovery achieved was 71%, with pH = 11, thiosulfate (0.5 mol/L), copper (II) (0.05 mol/L), EDTA (0.05 mol/L), after 24 h with no oxygen injection.
Accepted: 3 August 2014
Received: 11 November 2013
Revised: 12 June 2014
Keywords: Refractory gold ore; EDTA; Thiosulfate leaching; Orpiment
مجریان طرح طلای زرشوران به ترتیب عبارتند از آقایان مهندس نوحی-مهندس یگانلی-مهندس فاطمی نیا و مهندس قوانلو .
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از دیماه سال یکهزار و سیصد و نود و پنج آقای دکتر قدمی به عنوان مدیرعامل شرکت منصوب گردید.