[Biooxidation of a Double-Refractory Gold-Bearing Sulfide Ore Concentrate]

Area of Science:

• Metallurgical Engineering
• Environmental Science
• Geochemistry

Background:

• Double-refractory gold ores present significant processing challenges.
• The Bakyrchik deposit in East Kazakhstan contains gold-bearing sulfide ore with high organic carbon, pyrite, and arsenopyrite content.
• Conventional cyanidation shows very low gold recovery (2.8%) from this concentrate.

Purpose of the Study:

• To evaluate the efficiency of biooxidation for treating a double-refractory gold-bearing sulfide ore concentrate.
• To compare biooxidation performance in a standard medium versus a medium mimicking local groundwater chemistry.

Main Methods:

• Biooxidation experiments were conducted using two different liquid media.
• One medium was standard, while the other simulated Bakyrchik deposit groundwater with high sodium, magnesium, and chloride concentrations.
• Gold recovery was assessed after biooxidation and subsequent cyanidation.

Main Results:

• Biooxidation achieved high efficiency in both tested media, oxidizing approximately 90% of sulfide sulfur.
• Despite high sulfide oxidation, subsequent cyanidation efficiency remained low (39% and 32%).
• The ore concentrate contained 17.5% organic carbon, 6% pyrite, and 13% arsenopyrite, with a gold content of 57.5 g/t.

Conclusions:

• Biooxidation is highly effective at sulfide mineral oxidation in refractory gold ores.
• High biooxidation efficiency alone does not guarantee efficient gold recovery from double-refractory ores.
• Further research is needed to optimize gold liberation and recovery from such complex ore types.