METHOD OF PROCESSING LEAD-BEARING MATERIALS

A method of processing low grade lead-bearing materials where mostly simple and complex sulphates and oxides of metals are present, including higher iron oxides, su ch as for example, lead residues, dusts of matte converting and other similar materials. The startin g material is mixed with fluxes, and powder sulphide and/or carboniferous material is inserted with a moisture content of resulting charge from about 2 to about 16%. The charge is dried, mixed wi th oxidized recycle dust, crushed carboniferous material and subjected to flash smelting in oxyg en atmosphere. During smelting, the powder material reduces sulphate sulphur and higher iro n oxides and, therefore a low melting oxide melt is produced and the crushed carboniferous material formes a heated bed under the torch of flame. Lead sulphate in this bed is reduced ou t of the melt and zinc stays in slag. Smelting off -gas is cleaned of oxidised dust which is return ed to smelting. The following material is inserted to the charge as a powder material: either sulphide material (e.g. lead ore, low grade concentrate), which is added to the charge to obtain a mass ratio of the sum of sulphide, elemental and pyrite sulphur to a total sulphur content within the range from about 0.08 to about 0.87 or carboniferous material rated at about 4 to about 12kg of uncombined carbon per 100 kg of ferric iron and from about 20 to about 140 kg of uncombined carbon per 100 kg of sulphate sulphur, or both materials are inserted at the same time in amounts indicated above