BIOX® process technology: Creating commercial opportunities from refractory ore

High gold prices and globally depleting levels of oxide ore mean that harder-to-process refractory ore bodies are playing an increasingly important role in global gold production. This dynamic is creating new opportunities for the commercial application of BIOX®. This proprietary Gold Fields technology is licenced to third-parties for the pre-treatment of refractory sulphide gold ores, prior to conventional cyanide leaching.

Refractory ores are naturally resistant to standard recovery methods, as the gold is ‘locked’ within sulphide minerals that inhibit leaching. BIOX® uses naturally occurring bacteria to destroy these sulphide minerals and expose the gold for subsequent cyanidation. Recovery rates for refractory ore typically run at less than 70%. After treatment with BIOX®, however, recovery rates can be as high as 97% – depending on ore characteristics. In addition, the limited environmental impact of BIOX® makes it fully compliant with ever stricter environmental standards around the world.

There are currently 10 BIOX® processing plants in operation in seven countries worldwide, with additional opportunities being explored in the Philippines, Colombia and China – amongst others. Gold Fields portfolio does not currently contain any refractory ore bodies, but opportunities are being explored for the application of BIOX® to recover residual gold in low grade pyrite at its Cerro Corona mine in Peru.

Development of Generation 4 of BIOX® is ongoing and focuses on improving the energy efficiency of the process, enhancing the durability of the tank agitation and bacterial consortium, and achieving a 15% reduction in capital and operating costs. The full roll-out of Generation 4 is scheduled for 2014, whilst many of the planned improvements will be incorporated into Generation 3 of BIOX® within the next two years.

http://goldfields.co.za/com_technology.php