After carrying to the dressing centre the ore is roughly crushed down to the size below cca 25- 30 mm at first.
The next step is crushing in metallic mortars resulting in diminution of 85%-90% of ore under 1 (0,8) mm size (local flour sieve mesh). This base material is locally referred to as "gnaka". The remaining portion - oversize fraction (cca 10-15 %) forms badly crushable quartz grains of 1-4 mm size (locally known as "kricy").
"Gnaka" is directly washed on simple sluice boxes. Comparatively high efficiency of sluices (in the case of supervision by specialists of washing) direction of well is reached due to slow washing under conditions of lack of water. The water is perfectly utilized (recycled) and real consumption may decrease below 0.5 ton of water per 1 ton of ore. Washed material is usually retained and washed again. "Gnaka" (rich ores) is than dried and grinded in simple corn mills (grinding mill). The product of grinding is washed again. In case of low gold content detected at the first washing the "gnaka" is not grinded but stored at the dump.
"Kricy" high-grade ores are directly grinded in mills and than washed. "Kricy" low-grade ores are neither washed or grinded but deposited at dumps. Tailings resulting from multiple washing form small and bigger dumps at the processing site.
Concentrates taken from sluices are panned. Gained black concentrate is dried, cleaned using magnetic separation and air blowing. Amalgamation is used routinely and nitric acid leaching is used in some areas. The processing results in comparatively pure concentrate of gold dust (with impurities < 5 %) or "amalgam sponge" or directly gold bullion.
Copyright © 2002 - 2018 EXPLO-MINE Ltd.