Smelting of tin/stannum concentrate cannot produce high quality tin directly but crude tin containing several impurities. The refining of crude tin is to remove these impurities and recover valuable metals like indium, bismuth and copper, which helps to reduce production cost to a large extent.

The common purities in crude tin incude iron, arsenic, antimony, copper, lead, bismuth and sulfur. Crude tin is treated by either fire-refining or electro-refining.

Crude tin is obtained by electrical arc furnace smelting. It needs to be further refined by getting rid of some other impurities including removal of iron and arsenic by centrifugal filter, removal of lead and bismuth by continuous spiral finned electrical-heating crystallizer. High purity tin can be obtained directly through refining by spiral finned crystallizer. Alternatives can be electro-refining to treat crude tin with precious metal to produce high quality tin and collect precious metals.

During the refining of crude tin by continuous electrical-heating crystallizer, a kind of byproduct soldering tin is produced. The soldering tin, mainly contains lead and tin, can be refined by vacuum distillation furnace. Metalcess uses multiple-stage distillation to reduce tin loss in lead vapor and get crude tin (Sn >99%) and crude lead (Pb> 98%).