Alleviation of organic solvent inhibition with improved copper recovery from low grade sulphide ore by bioaugmentation with newly isolated Candida sp. OR3 and OR6

• The organic SX (0.75%) resulted in low Cu bioleaching at low grade sulphide ore.
• Candida sp. OR3 and OR6 were isolated from solvent extraction (SX) process.
• The 2 isolates can grow at 1% organic SX, oil, decane and hexadecane at pH 2.
• The organic SX inhibition in ore bioleaching was alleviated by the 2 isolates addition.

Organic compounds used in solvent extraction (SX) processes severely inhibit copper bioleaching microorganisms. In this experimental study, it was found that bioleaching microorganisms at 0.5% and 0.75% organic (SX) resulted in lower Cu recovery from low grade sulphide ore. Two new Candida species OR3 and OR6 were isolated from the liquid phase in solvent extraction process and these isolated strains were tolerant and capable of growing on 1% organic phase. The inhibition of organic phase to bioleaching microorganisms was alleviated by the addition of the 2 isolates and as a result the Cu recovery remained at high level. This is the first study which shows that the organic SX mixture inhibition to acidophilic microorganism can be overcome by the addition of other microorganisms.