Hydrometallurgical Recovery of Tin from Harris Dross

Emerged businesses in recycling have been causing the accumulation of impurities in by-processes in base metal smelters. In lead smelters, such impurities are basically removed by drossing. Since drosses comprise several impurity elements of approximately 20 mass% each as well as lead, they require further treatment to separate into each element. Conventional pyrotreatments are, however, not effective due to affinity of impurity elements at high temperatures. The authors have developed a hydrometallurgical process to recover tin and lead separately from Harris dross which is composed mainly of tin, arsenic, and lead. In the process developed, Harris dross is leached to separate lead-bearing residue, then the leachate is mixed with limestone to precipitate burtite (CaSn(OH)(6)) selectively, and the effluent is mixed with slaked lime to precipitate calcium arsenate. Lead-bearing residue can be recycled to the blast furnace while burtite can be payable for tin smelters because impurities in burtite are negligible.