The process of crushing and cleaning ore involves several steps to break down raw ore into smaller particles and remove impurities. Here’s a general outline of the process:
1. Crushing the Ore
The goal is to reduce large chunks of ore into smaller, manageable pieces for further processing.
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# Stages of Crushing:
– Primary Crushing:
– Large rocks are fed into a jaw crusher or gyratory crusher to break them into smaller pieces (~6-10 inches).
– Secondary Crushing:
– Smaller pieces are further reduced using a cone crusher or impact crusher to ~1-2 inches.
– Tertiary Crushing (if needed):
– Fine crushing may be done using specialized mills (e.g., ball mills, rod mills) to produce sand-sized particles.
2. Grinding (Optional, for finer processing)
If the ore requires further size reduction for mineral liberation:
– A ball mill, rod mill, or SAG mill grinds the crushed ore into a fine powder.
– Water may be added to form a slurry for wet grinding.
3. Cleaning (Beneficiation)
This step removes impurities and concentrates valuable minerals.
# Common Methods:
1. Screening & Classification:
– Screens separate particles by size.
– Hydrocyclones or spiral classifiers separate fine and coarse material in wet processes.
2. Gravity Separation:
– Used for heavy minerals (gold, tin, tungsten).
– Techniques include:
– Jigging machines
– Shaking tables
– Spiral concentrators
3. Magnetic Separation:
– Used for iron ore or other magnetic minerals.
– A magnet separates magnetic from non-magnetic material.
4. Froth Flotation:
– Chemicals are added to make target minerals hydrophobic (repel water).
– Air bubbles carry mineral particles to the surface, forming froth that is skimmed off.
5. Leaching (for metals like gold, copper):
– Ore is treated with chemicals (e.g., cyanide for gold) to dissolve metals.
6. Washing & Scrubbing:
– Removes clay, dirt, and loose contaminants using water jets or scrubbers.
4. Dewatering & Drying
– Filter presses or thickeners remove
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