Tin circuits must manage both liberation and fragility
Cassiterite is dense and often suitable for gravity concentration, but density alone does not guarantee a simple plant. The valuable mineral can occur across a broad size range and may break into difficult fine particles during unnecessary crushing or aggressive recycling.
The flowsheet should recover coarse liberated tin as early as practical, then classify and treat the remaining fractions with equipment suited to their size and expected grade.
Classification is part of the separation
A gravity separator is sensitive to particle size because settling behavior changes rapidly as particles become finer. Sending a broad mixture of coarse sand, fine sand and slime to one machine makes it difficult to maintain a useful operating condition.
Classification also makes losses easier to diagnose. If the tailings are sampled by size fraction, the process team can see whether the problem is incomplete liberation, poor washing, overloaded roughing or ineffective fine recovery.
Cleaning depends on the concentrate mineralogy
Gravity roughing may produce a mixed heavy-mineral concentrate. Shaking tables, magnetic separation or sulphide removal may be considered depending on the minerals present and the final product requirement.
The correct sequence should be tested. Adding every available separator increases cost and recirculating load without guaranteeing a better saleable concentrate.
Typical process logic
- 01
Wash and protect the valuable mineral
Remove clay and oversize while avoiding unnecessary breakage of brittle cassiterite.
- 02
Classify into narrow ranges
Separate coarse, medium and fine fractions so each gravity device receives a suitable feed.
- 03
Recover coarse tin early
Use appropriate gravity stages before repeated handling creates more fines.
- 04
Treat fine fractions separately
Apply controlled fine-gravity treatment only where testing demonstrates economic recovery.
- 05
Clean the concentrate
Upgrade gravity products and assess removal of magnetic minerals or sulphides as required.
Equipment roles, not a shopping list
Scrubber and screens
Disaggregate clay and establish controlled size fractions without excessive comminution.
Jig
Recovers suitable coarse liberated cassiterite from a classified feed.
Spiral concentrator
Provides high-capacity roughing for appropriate medium and fine sand fractions.
Shaking table
Cleans and upgrades pre-concentrated tin fractions under a stable feed rate and size range.
Frequently asked questions
Why is tin often lost in the fine fraction?
Cassiterite can be brittle, and excessive crushing, scrubbing or recycling creates slimes that conventional gravity equipment treats less efficiently.
Can one jig treat the full feed size?
Wide feed-size distributions reduce separation control. Classification into suitable fractions normally improves both recovery and concentrate quality.
Is magnetic separation always required?
It depends on the gangue and concentrate specification. Mineral identification and concentrate cleaning tests should determine whether it adds value.