In CIL (carbon in leach) process, activated carbon acts like a sponge to aurocyanide and other complex ions in solution. Hard carbon particles (much larger than the ore particle sizes) can be mixed with the ore and cyanide solution mixture. The gold cyanide complex is adsorbed onto the carbon until it comes to an equilibrium with the gold in solution. Because the carbon particles are much larger than the ore particles, the coarse carbon can then be separated from the slurry by screening using a wire mesh.
Working Principle
CIL is cyanide gold extraction process. Firstly, raw material is crushed into less than 10mm by different types of crushers; secondly, crushed material will be ground and classified into 90% of 200mesh, then fine powder will get into thickner, after concentration, add chemical and leach in the leaching tank. After leaching, we can use activated carbon to adsorb gold, then get gold loaded carbon. Finally we can use electrolysis equipment or fire to get gold bar.
Introduction to Flow Chart
A. Raw materials preparation:
Raw ores are sent to primary crusher by vibrating feeder, then sent to the secondary crusher by belt conveyor; the crushed ores will be sent to vibrating screen for separating. Under screen ores will be sent to powder silo. Upper screen ores will be sent to tertiary crusher by belt conveyor for re-crushing, and the crusher ores will be sent to the screen again to be separated. It is named three step one closed circle crushing flow chart.
Raw material from powder silo will be sent to first ball mill by feeder and belt conveyor, ball mill discharges to spiral classifier, bigger size will be returned back for re-grinding. Overflow will be pumped to hydro cyclone by slurry pump for second classifier: bigger size will go to second ball mill, and the discharges are returned to the second classifier. It is named two steps two closed circle grinding flow chart. Overflow from hydro cyclone will be sent to trash screen and thickener.
B. Leaching and adsorption:
The slurry will enter into 8 sets of double impeller leaching tank; well-mixed sodium cyanide agents are added to the first tank; active carbon is added to the tanks from the second to the eighth; active carbon from the second agitator is lifted to carbon screen to get gold-loaded carbon, and after cleaning, the gold-loaded carbon enters into the desorption&electrolysis system; while the slurry left goes back to the second tank; active carbon is lifted by air lifter from the tank next to the tank before against the current; the tailing goes through safety screen to recycle fine-size gold-loaded carbon, and then goes to tail water treatment stage.
C. Tail water treatment:
The tailings are lifted to the filter press, and the filter cake is so called tailings, which are transported by belt conveyor and truck to the yard, while filter liquor goes to circulating water tank for recycling, which helps save the lime and sodium cyanide.
D. Gold-loaded carbon treatment:
The gold-loaded carbon is processed by Desorption&Electrolysis equipment in batches to get gold-dust. The gold-dust goes to gold melting furnace and turns to gold bar. The gold-loaded carbon after Electrolysis process could return to last stage in the flow chart for reprocessing.
