Tin Ore Processing Solution

Tin is the gravity engineer’s ore. Cassiterite (SnO2) has a specific gravity near 7, far heavier than the quartz and silicate gangue around it, so density-based separation is the natural and lowest-cost route. The catch is that cassiterite is brittle and slimes easily: over-grind it or pump it hard and the tin reports to the minus-20-micron fraction where conventional gravity units cannot catch it. The whole flowsheet is built to liberate the tin without sliming it, and to treat each size fraction with the right device.

Why gravity, and why size control matters

Because of the large density contrast, gravity concentration recovers cassiterite cheaply and without reagents, which is decisive for remote tin projects. But every gravity device, jig, spiral, table or centrifuge, works best over a narrow particle-size band. The governing rule is to size first, then concentrate: feed a unit a mix of coarse and fine particles and the fine heavies behave like coarse lights, and selectivity collapses. So the circuit screens and classifies the feed into fractions and routes each to the device suited to it. Gentle, stage-wise comminution that liberates tin at the coarsest possible size is the other half of the strategy, because every gram of cassiterite turned to slime is tin at risk of loss.

The recommended flowsheet

Comminution and sizing

Hard-rock ore is crushed with a jaw crusher and cone crusher, then ground only as far as liberation requires. Placer feed is scrubbed and screened. Close sizing with screens and a hydrocyclone splits the feed into coarse, sand and fine streams for the gravity units.

Staged gravity concentration

Coarse and middle sizes are preconcentrated on spiral chutes, which reject the bulk of light gangue with no moving parts and low cost. The sand fraction is upgraded on a shaking table, the workhorse for clean tin concentrate at fine sizes. Liberated fines below about 100 micron, where tables lose efficiency, are recovered on a centrifugal concentrator that uses enhanced g-force to catch tin that would otherwise be lost to tailings. The complete gravity concentration range covers each duty. For background on choosing between these devices, see our guide to tables, spirals, jigs and concentrators.

Cleaning and dewatering

The gravity concentrate often still carries iron sulphides and, in some deposits, tantalum-niobium minerals. A cleaning stage, magnetic separation or a small flotation step, removes sulphides and lifts the tin grade, and a magnetic separator can split paramagnetic tantalum-niobium from the cassiterite as a saleable by-product. The finished concentrate is dewatered to a shippable product.

Design choices that drive results

• Comminution philosophy: liberate at the coarsest size and minimize slimes; this is the dominant control on tin recovery.
• Number of size fractions: more, narrower fractions improve recovery but add units and cost; balance is set from sizing analysis.
• Fines circuit: centrifugal concentrators recover tin that tables miss; skipping them is the most common cause of low overall recovery.
• By-products: tungsten, tantalum and niobium can add value and need a dedicated cleaning path.

No two tin ores share the same grain size or slimes behaviour, so the circuit must be designed from sizing and liberation testwork rather than copied. Xinhai runs the ore test, designs the staged gravity flowsheet and delivers the complete processing plant under an EPC+M+O contract. To recover the most tin from your ore, contact us for an ore test.