BIOX® Process

Optimize overall gold recovery and reduce capital costs

Metso BIOX® process was developed for the pre-treatment of refractory concentrates ahead of conventional cyanide leaching for gold recovery. As the gold is encapsulated in sulfide minerals such as pyrite and arsenopyrite, the gold is prevented from being leached by cyanide. The BIOX process destroys sulfide minerals and exposes the gold for subsequent cyanidation, thereby increasing the achievable gold recovery.

Improves rates of gold recovery
Reduces capital cost
Leverages a long track record of commercial operation and continuous process improvement
Offers robust technology suited for remote locations
Is environmentally friendly

The Metso BIOX process for the treatment of refractory gold concentrates has been in commercial operation for over 30 years with 13 successful plants commissioned worldwide. To date, over 22 million ounces of gold have been produced through this process.

The simplicity of operation and scalability of the technology, using a modular design, means the process is especially suitable for remote locations. Commercial Metso BIOX plants operate at treatment capacities in the range of 20 to 2,137 tons per day of flotation concentrate, in various climate conditions.

Robust technology

The plant design can be modified to suit any climatic conditions from extremely cold to hot temperatures, at sea level or high altitude. The process generates exothermic heat, which makes it possible to operate at temperatures below -47 °C without external heating. This has been confirmed by the operation of the Suzdal plant in Kazakhstan, where temperatures below -40 °C are encountered for extended periods during the winter.

Related equipment:

Metso OKTOP BIOX Reactor
Metso OKTOP BIOX Agitator
Metso Thickener
Metso OKTOP Neutralization Reactor

Includes a wide range of concentrate feed material

Flexibility in terms of sulfide sulfur head grade and both low and high sulfur grade concentrates can be treated successfully
The Metso BIOX bacterial culture has been adapted to high arsenic concentrations, for example, the Coricancha plant in Peru treated a concentrate with an arsenic grade of 26%
Most metal sulfide minerals are readily oxidized using the process
Preg-robbing sulfides (in package with HiTeCC process)
Gold-copper sulfides
Other base metal sulfides
Uranium containing sulfide concentrates

To date, more than 150 concentrate and whole ore samples have been tested for amenability to the Metso BIOX process. Over 18 integrated pilot plant runs have been completed to obtain information for the design of commercial plants.

The basic steps normally followed during the development of a project, from the first stages of test work through commissioning of the commercial plant, can vary depending on the needs of the individual client, but this framework can be used as a guideline for scheduling purposes.

The project development framework, shown in the table below, shows the duration and key requirements of each phase of the process. Depending on the schedule for the project, certain functions can overlap or even be omitted to reduce the overall time frame from the start of the test work through the completion of the project.