Lead, accompanying copper ores, passes tocopper concentrate during flotation of the ores. Its presencemakes further metallurgical processing difficult. Research,done in various scientific centres in Poland, is aimed atdeveloping a method to lower the content of lead in theseproducts. This paper presents the results of research on acopper concentrate from the Rudna Processing Plant. Thesample contained on average 30 percent copper and 1.5 percentlead and was very fine grained. As much as 62 percent was inthe - 45 #mu#m grain class. The study aimed to assess thepossibility of lowering lead content in copper concentrate bytwo methods: chemical treatment of the concentrate with anammonium acetate solution, pre-treatment of the feed withdiluted inorganic acid, or with hot water, followed by flotation.It was found that lead content in the concentrate could hereduced from 1.5 percent to about 0.2 percent by leaching withammonium acetate. Copper was leached at the same time,which impoverished the concentrate. The best results wereachived by leaching the raw sample and washing the filter cake.By doing so, the lead content could be lowered to 0.6 percentwith minimum lost of copper- only 3.5 percent in solution,regarding the initial sample. Surface pre-treatment of theconcentrate with nitric acid or hot water, followed by flotation,resulted in two products with different copper and lead content.One of them contained 25÷36 percent copper and about 1.7percent lead, at yields ranging from 75 to 90 percent. The other,with a lead content lowered to 0.8÷1 percent, contained 13÷16percent copper, at yields ranging from 25÷10 percent.
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