Boliden Aktiebolag

Torsten E Jensfelt

Stig A Petersson

Lead is recovered from sulphidic lead raw-material containing impurities of the kind bismuth, arsenic, antimony and tin, by flame-smelting the material with an oxygen-containing gas. The oxygen potential and temperature are adapted during the flame-smelting process so that the product formed thereby comprises substantially a lead-sulphide melt substantially free of volatile, sulphidic and metallic impurities of the said kind. The lead-sulphide melt is brought into contact with an oxidic lead material substantially free of impurities of the aforementioned kind, while oxidizing the sulphide-sulphur content of the material and forming a melt substantially free of sulphur. Lead is recovered from the melt by separation, optionally after subjecting the melt or a part thereof to a reducing process.

Manufacture of lead from sulphidic lead raw material

The metal content of complex sulphidic metal raw material is recovered therefrom by means of an autogenous flame-smelting process, preferably carried out in a vortex, with an oxygen-containing gas. The raw materials are smelted in a furnace in the presence of an excess of oxygen and together with an addition of an acid slag former, such as silica, to form a melt which is rich in metal-oxide silicate and poor in sulphur. Any metal phase formed in the furnace is separated from the silicate phase, and non-iron metals present in the silicate phase are recovered therefrom by selective reduction.

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Stocksund, Sweden

Torsten E Jensfelt