Method for recovering In from Pb-Sn-In alloy

摘要

PURPOSE:To recover high-purity In from Pb-Sn-In alloy scrap at a high yield by adding ammonia chloride to the melt of the Pb-Sn-In alloy scrap and separating In as InCl dross. CONSTITUTION:The scrap of the Pb-Sn-In alloy is put into a graphite crucible and is melted in an electric furnace. While this scrap melt is maintained in a 350 to 500 deg.C range, NH4Cl is added at 0.1 to 1.0wt.% ratio to the melt and the melt is stirred. The In the molten scrap floats as dross on the surface of the molten alloy. This treatment is repeated and continued until the In content in the molten alloy decreases to a desired value or below and until the grater part of the In the molten alloy turns to the dross. Concd. hydrochloric acid and water are added to the resultant dross and the dross is stirred and dissolved. The hydrochloric acid liquid contg. the dissolved In is filtered and separated from the undissolved matter and an NaOH soln. is added thereto. The generated precipitate is removed and thereafter, Zn powder is added thereto to precipitate the high-purity In. This In is separated and recovered.