Institute of Chemistry named after V. I. Nikitin (Academy of Sciences of Republic of Tajikistan), Dushanbe, Republiuc of Tajikistan:

Sh. R. Samikhov, Leading Researcher
Z. A. Zinchenko, Head of Laboratory of Mineral Processing, phone: +992-918-65-05-15

“Joint Enterprise “Zeravshan” LLC, Penjikent, Republic of Tajikistan:

O. M. Bobomurodov, Deputy Head of Chemical Laboratory

Involving of manufacturing of refractory gold containing ores (which share is continuously increased in nature) in industrial sphere is an urgent problem of gold mining branch. Preparation of gold arsenic containing ores is a difficult technological problem. Thiourea leaching methods are prospective with ecological point of view. Researches of thiourea leaching of gold and silver from Chore deposit concentrates (Tajikistan) were carried out in laboratory conditions. Experiences were spent with a concentrate, preliminary processed by sulfuric acid, within 2 hours with periodic mixing until reaching of рН value to 2,0–4,0. After that, 26,41% of Au and 37,58% of Ag was leached into the thiourea solution for 8 hours of recovery. For the purpose of improvement of thiourea leaching process, concentrates were exposed to roasting at the temperature of 600 ^oС during 2 hours. During the roasting process, pyrite and arsenopyrite are oxidized, which leads to opening of gold, containing in them. After roasting, gold and silver recovery is sharply raised and makes >80% for 8 hours. On the basis of the carried out researches, there were found optimum conditions of thiourea leaching of gold from roasted flotation concentrates, obtained from Chore deposit ore. The reached recovery of Au is 87,77%, while the recovery of Ag is 87,22%. The principle flowsheet of processing of gold and arseniccontaining concentrates of Chore deposit is offered. The developed flowsheet includes flotation, crushing and grinding of ore to the content of 90% of –0,074 mm of the grain size fraction with obtaining of bulk concentrate. The concentrate is roasted at the temperature of 600 ^oС with subsequent leaching by thiourea and obtaining of “Dore” alloy from gold containing solutions. Barren solutions are sent to reclamation of arsenic with addition of Ca(OH)₂ and Na₂S. The formed residue goes to special refuse, and solution can be an object for reception of lime milk.

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