How is cassiterite prepared for tin smelting?

To prepare cassiterite for smelting, the ore must first be concentrated and, in the case of complex ores, chemically treated to remove impurities.

Concentration

Because cassiterite is a heavy mineral, it is primarily concentrated using gravity separation methods. This includes:
* Jigging: Pulsing water through a bed of material to separate layers by density.1
* Shaking tables: Using vibration and flowing water to stratify and separate fine-grained particles.21
* Spirals: Utilizing centrifugal force in spiral channels to isolate heavy minerals.1
* Sluice boxes: Used in alluvial mining to allow heavier minerals to settle while lighter waste is washed away.2

For complex sulfide ores, additional processes like froth flotation are required to achieve a clean concentrate.2

Roasting and Leaching

Low-grade concentrates undergo roasting in a furnace at 550–650 °C to drive off sulfur and oxidize impurities. This is often followed by leaching with water or acid solutions to remove any impurities made soluble during the roasting process. Once prepared, the final furnace feed consists of tin oxide mixed with carbon and a flux, such as limestone, for the smelting process.3