What is refractory gold ore?
As a general rule of thumb, any gold ore that gives a CIL (carbon in leach) recovery of 70% or less falls into the class of semi-refractory or refractory gold. This is in stark contrast to free-milling gold ores that give CIL recoveries higher than 85%.
Gold is present in refractory and semi-refractory sulphide gold ores where it occurs both in the chemically bonded state and as nano or micron- size grains of metallic gold. Alternative refractory gold technologies tend to be both Capex and Opex intensive and difficult to operate.
The MACH REACTORTM solution!
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.
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.
The MACH process
During this process, much of the environmentally harmful arsenic is precipitated assisting in an economical and environmentally friendly process.
Read about Refractory Gold Ore from Wiki
A “refractory” gold ore is an ore that has ultra fine gold particles disseminated throughout its gold occluded minerals. These ores are naturally resistant to recovery by standard cyanidation and carbon adsorption processes. These refractory ores require pre-treatment in order for cyanidation to be effective in recovery of the gold. A refractory ore generally contains sulfide minerals, organic carbon, or both. Sulfide minerals are impermeable minerals that occlude gold particles, making it difficult for the leach solution to form a complex with the gold. Organic carbon present in gold ore may adsorb dissolved gold-cyanide complexes in much the same way as activated carbon. This so-called “preg-robbing” carbon is washed away because it is significantly finer than the carbon recovery screens typically used to recover activated carbon. WIKI
Pre-treatment options for refractory ores include: