How tin ore is mined

Even rich tin fields are so lean that one kilogram of cassiterite can mean digging up to eight tons of ore.

stations: 5
things downstream: 139

The short version

Water does most of the work in tin mining, because cassiterite is far heavier than the sand around it. Jets blast old riverbeds into slurry that runs down sluice boxes, or floating dredges dig flooded fields and sort the ore on board with jigs and shaking tables. Vein deposits in places like Bolivia are mined underground and need froth flotation.

Jet the old riverbed

Draglines or shovels remove the barren overburden. High-pressure water jets then break up the tin-bearing sand, and a submerged gravel pump lifts the muddy slurry. A large share of the world's tin ore is mined this way.
Run the sluice boxes

Slurry flows down sloping boxes with baffles set along their length. Heavy cassiterite drops to the bottom while lighter waste spills over the end to the tailings dump. Every so often the flow stops so crews can take out the crude concentrate.
Float a bucket dredge

Where water is plentiful, the field is flooded and a dredge floats on it, sometimes offshore on the seabed as in Indonesia and Thailand. An endless bucket chain feeds a plant on board, where jigs and shaking tables sort by weight, and waste leaves over the stern.
Tunnel the granite veins

Vein deposits in granite are worked by ordinary hard-rock methods. Deep mines place their first crushers underground, reducing the rock to a manageable size before it travels to the surface.
Float the complex ores

Sulfide-rich vein ore resists simple gravity methods and usually needs froth flotation. Bolivian concentrate may reach only 50 to 60% tin, against 70 to 75% from the alluvial fields of Southeast Asia.

End of the lineTin ore Next it goes into tin.

Worth repeating

Cassiterite is the only commercially important tin ore.
Cornwall and Devon in England have 4500 year old tin workings, in hot quartz veins cooked into the rock around granite.
Alluvial or secondary deposits yield about 80% of all tin, far from the rock where it first formed.