The principal tin mineral is cassiterite, or tinstone (SnO2), a naturally occurring oxide of tin containing about 78.8 percent tin.
About 80 percent of the world’s tin comes from alluvial or secondary deposits. Most of these occur on land, but in certain areas, notably in Indonesia and Thailand, the deposits are mined offshore by dredging the seabed.
Even in the richest tin fields, the concentration of tin is very low. This means that up to seven or eight tons of ore may have to be mined in order to recover one kilogram of cassiterite.
The alluvial tin ore is often mixed with lots of stones, sand, gravel, soil, and sticky clay; in some ore fields, the tin ore is existing with other minerals like magnetic iron, tungsten, ilmenite, hematite, monazite, and zircon sand, etc.
The alluvial tin ore processing method is similar to placer/soil gold processing.
Generally, the gravity separation method is used. It is the most economical and effective method for processing alluvial tin, as the specific gravity difference between tin ore and barren material is very large, and this method is environmentally friendly and has low investment.
First, alluvial tin ore must be washed by a washing machine before separation.
Generally, alluvial tin ore has large mud content, strong viscosity, and fine particle size. Our rotary washing machines can wash it clean and it is easy to lose fine-grained tin ore particles.
After washing, the alluvial tin ore is screened with a vibrating screen/trommel screen.
As the raw material is often mixed with large stones such as waste rocks and pebbles, screening out these useless materials is much more helpful for the next stage of separation work.
Alluvial tin ore is separated by the gravity separation method.
For alluvial tin ore with a high degree of monomer dissociation, the final concentrate is obtained by the 6-S shaker tables at one time. The concentrate grade is above 60%.
For alluvial tin ore with a low monomer dissociation degree, use a jig machine for primary selection, then concentrate enters 6-s shaking tables for final concentration.
6-S SHAKER TABLE
After the tin concentrate is naturally dry under the sun, send them to a 3-disc magnetic separator for final dry separation of the tin, iron, coltan, and other weakly magnetic minerals.
3-DISC MAGNETIC MACHINE