Pre-oxidation with the MACH oxidises ferrous to ferric and precipitates ferric hydroxide and even more stable ferric oxyhydroxides. Sulphide is oxidised to sulphate in an exothermic reaction that produces sulphuric acid. Pre-oxidation also forms a surface film of ferric hydroxide on the surface of the reactive mineral which prevents it from leaching out when cyanide is added for the gold leach.
For semi-refractory gold ores, the MACH is also able to improve gold recovery. Thanks to the MACH REACTOR’s aggressive pre-oxidation techniques, much of the sulphide matrix is destroyed, releasing the bulk of the solid solution or chemically bonded gold. During this process, much of the environmentally harmful arsenic is precipitated assisting in an economical and environmentally friendly process. In order to achieve the best recovery results, the chemistry and grind of pre-oxidation can be adjusted to suit the specific characteristics of the ore as required. GoldOre has trade named this process as the GoldOre FerrateTM process.