Albany, OR: U.S. Department of the Interior, Bureau of Mines, RI 9199, 1988 Jan; :1-8
Effective recycling or disposal of flue dusts is a continuing problem, particularly for secondary smelters treating low-grade cu scrap. The Bureau of Mines investigated a variety of flue dust treatment approaches and demonstrated the technical feasibility of a bench-scale alkaline method that includes leaching, cementation, precipitation, and roasting. Flue dust was leached at room temperature with an alkaline solution of (nh4)2co3 and nh4oh to solubilize zno and zn metal. Some copper, lead, tin, and most of the zinc were dissolved in the leach step. Copper, lead, and tin were recovered in the cement product. The zn in the filtrate was precipitated by ph adjustment to neutral using co2 injection. The zn salt was filtered from solution and roasted to give high-purity zno. The leach residue, enriched from 4.3 to 10.4 pct sn, could find a ready market; the metallic cement product can be recycled back to the copper converter; and the high-purity zno product can be sold in several markets, leaving no material for disposal. The possibility for recycling of reagents, lower energy demand, and low environmental impact make this method economically and environmentally attractive for recycling secondary copper smelter flue dusts.
Albany, OR: U.S. Department of the Interior, Bureau of Mines, RI 9199