MesoTHERM BIOX Process

The Metso® MesoTHERM BIOX® process is a sustainable solution for the treatment of refractory gold ores that significantly reduces cyanide consumption, and therefore costs, in the leaching of certain bio-oxidation product residues. It is based on Metso’s proven and highly successful mesophile BIOX process and offers an easy, cost-effective upgrade path for plants already using this process.

Benefits

Reduces cyanide consumption by up to 50% and lowers reagent storage requirements
Produces cleaner BIOX product solids
Offers easy, cost-effective upgrade for existing BIOX operations
Based on proven technologies and standard processing equipment

Improved bio-oxidation performance with a reduced environmental footprint

Metso’s conventional mesophile BIOX process is an economical and environmentally attractive process for liberating occluded gold hosted in refractory sulfidic material by oxidatively leaching the sulfides to soluble sulfates. Metso MesoTHERM BIOX enhances this established process by combining mesophile bio-oxidation technology with a higher-temperature thermophile oxidative stage to enable an even more effective overall sulfide oxidation step.

Reduced cyanide consumption and simplified process operation

Traditionally, cyanide consumption with conventional bio-oxidation residues is higher than with residues produced through other oxidative technologies. By using a higher-temperature thermophile microbial species, Metso MesoTHERM BIOX process can cut cyanide consumption by as much as 50% compared to conventional bio-oxidation and significantly reduce the formation of thiocyanate – a common and stable cyanide species traditionally formed as a further by-product. Furthermore, inter-stage thickening between the two oxidative processes is used to decant off various solubilized species prevalent in the mesophile stage, thus simplifying operation of the thermophile stage.

A simple, cost-effective upgrade path

Upgrading an existing BIOX process to BIOX MesoTherm process is a relatively simple process and is based on proven Metso technologies, which are integrated in a reconfigured circuit. The upgrade involves the addition of an inter-stage thickening step using Metso High Rate Thickeners and Metso OKTOP® Atmospheric Reactors for the thermophile step.