Ore processing

Digging ore from the earth is only half the battle. The processing of the ore is often just as challenging and expensive, which takes place in refineries, smelters and mills. Ore processing consists of the following stages:

  • 1. crushing and grinding of the ore
  • 2. addition of process water (generally decanted from the tailings pond) to form a slurry
  • 3. addition of lime to the ore, and cyanide solution to the slurry, to leach the gold and silver into solution
  • 4. addition of carbon to adsorb dissolved metals and remove them from the slurry
  • 5. stripping the metals from the carbon by acid washing and circulation of a caustic cyanide solution
  • 6. precipitation of the gold and silver by electro-winning
  • 7. smelting of metal products into bars
  • 8. pumping of the barren slurry (tailings) to the tailings storage facility.

The purpose of ore crushing and grinding is grinding and size classification to reduce the ore down to a fine particle size

The ore crushing process

ore crushing plant

Generally, the complete ore crushing plant consists of jaw crusher, ball mill, classifier, magnetic separator, flotation machines, thickener, dryers and other major equipment, such as vibrating feeder, bucket elevator and belt conveyor. This production line feature with high efficiency, low energy, high capacity, economical and so on.

The primary crusher reduces ore from the trucks to 8-inches or less. That material goes to the primary stock pile directly that you see crushed rock falling onto in your image. Two conveyors (out of view to the right in your image) pull this material directly into each SAG mill where it is combined with water and mill balls (as needed).

Big raw ores are feed to the jaw crusher evenly and gradually by vibrating feeder for primary crushing. After primary crushing, the material will be transferred to other crushers by belt conveyor for secondary crushing, then the crushed materials will be transferred to vibrating screen for separating. Final, the materials will be transferred into the ball mill evenly for ore grinding.

The ore milling process

Following grinding in the ball mill, the material is returned via the sump to the secondary hydrocyclone for resizing. The trash screen removes wood from the old workings that may have found its way into the processing circuit. The slurry that remains after this process has a very fine particle size. Typically, 80% of the ore particles are less than 70 microns in size (about the same consistency as fine beach sand). Such a fine particle size is required for gold liberation C the size required for the cyanide to be able to 'see' the gold in the leaching process.

The remaining slurry passes through a pre-leach thickener, to remove some of the water. The recovered water is reused in the grinding circuit while the thickened slurry moves into the leaching circuit

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Ore Processing