MGB studies extracting gold from mine waste using bacteria

The Mines and Geosciences Bureau (MGB) is looking at the possibility of using bacteria to help extract gold from mine waste.

 

The bureau's Metallurgical Technology Division (MeTD) started research on isolating and propagating the bacteria called Thiobacillus ferrooxidans and Thiobacillus thiooxidans to promote bioleaching of refractory gold ores.

 

Bioleaching is the extraction of metal from ores through the use of living organisms, one of the pre-treatment processes used when standard techniques such as straight cyanidation leaching is not feasible.

 

According to the bureau, a refractory gold ore has particles covered with sulfide minerals that prevent contact between the cyanide leach solution and gold particles. 

 

Bioleaching dissolves the unwanted materials, enveloping the precious metal prior to actual cyanidation.

 

The MGB said the inherent capability of Thiobacillus ferrooxidans and Thiobacillus thiooxidans as leaching media to dissolve sulfide minerals has already been established. 

 

"Its possible application here in the Philippines will be in the recovery of gold with grades 0.4 to 0.6 gram per ton present in tailings of old cyanidation plants, where appreciable amount of gold are trapped in sulfide minerals," it added.

 

MGB chemists obtained samples from various areas of Lepanto Consolidated Mining Company in Mankayan, Benguet from May 6 to 10.

 

The samples were brought to the National Institute of Molecular Biology and Biotechnology Laboratory in UP Los banos for proper bacterial propagation, which will then be used in the laboratory scale pre-treatment of refractory ore. — DOR/VS, GMA News