Much of the refractory gold ores widely distributed in the southwest, northwest and northeast of China is now expected to be put to commercial use. A gold extraction technology called bio-oxidation developed by China National Gold Group Corporation (CNGC) recently passed the national authentication. Wang Dianzuo, chief member of the authentication commission, deputy president of the Chinese Academy of Engineering and academician of the CAS and CAE, believes this technology has taken the leading place in China and is advanced in the world. Particularly the oxidative activity and temperature adaptability scope of the bacteria strains used have reached the leading position in the world. With more than ten years' effort scientists and engineers engaged in the systematic research and commercial application of the technology have won the commendation and award of the CNGC on August 30.

China is a major gold production country in the world. However gold resources that are relatively easy to extract are declining in recent years whilst refractory sources account for one third of the ascertained resources. Moreover the perspective reserves of refractory gold ores are even more promising. For more than ten years the Changchun Gold Research Institute of the CNGC conducted systematic research in a major mine of refractory gold in the Fengcheng region of Dandong in Liaoning province. They collected, cultivated and domesticated composite bacteria strains; tackled key technologies such as the highly energy-efficient biological reactor and established the Liaoning Tianli Gold Ltd., which can process 100 tons of refractory gold ores each day. The plant was officially put to trial run last July and has been operating smoothly for a year. The various indices have either reached or surpassed the design level.

Cheng Fumin, director-general of the CNGC, pointed out the authentication of this technology with independent intellectual property right indicates that China has made a major breakthrough in extracting refractory gold ores. It can not only drastically raise the exploitation rate of domestic gold resources and improve China's resource utilization level, but also provide opportunities for exploitation of refractory gold ores in neighboring countries and improve the international competitiveness of China's gold industry.

Background links

Bio-oxidation gold extraction is a technology arising in the 1980s for treating refractory gold ores. It can solve the dressing problem of low-grade gold ores that could not be used commercially due to their low recovery rate using conventional technologies. It makes use of biological technology and oxidizes the arsenic and sulfur-containing metal minerals covering the gold ore surface through bacteria, so that the gold ores can be exposed and extracted.

The biological gold extraction technology is characterized by less investment, low cost, simple procedure and light environmental pollution etc. Currently there are 10-odd biological gold extraction plants in operation worldwide. China has set up two biological gold extraction plants. Liaoning Fengcheng Tianli Gold Ltd. is located in a region where climate is colder than any other region in which the existing plants are located. The oxidative ability and temperature adaptability of bacteria strains is leading the world.

As learned from Wang Dinzuo this technology can not only be used in extracting gold from arsenic and sulfur-containing gold ores but also on other rare metal ores that contain arsenic and sulfur. Currently this technology has been applied in some copper mines. In addition the technology reclaims value for important mineral resources that formerly were too low in grade to be listed as resources. It is of great significance and has remarkable social, economic and environmental benefits.

By People's Daily Online