METHOD OF REPROCESSING LEAD-CONTAINING MATERIALS

A method is disclosed of reprocessing lead-containing materials in which simple and complex metal sulphates and oxides, including higher oxides of iron, predominate, examples of such materials being the sludges and dust obtained during the conversion of mattes and similar materials. The raw material is mixed with fluxes, and sulphide or carbon-containing material in powder form is added, the moisture content of the resulting charge being approximately 2-16 %. The charge is dried and mixed with reversible oxidized powders and crushed carbon-containing material and then fused in suspension in an oxygen atmosphere. During the fusion process, the powder reduces the sulphate sulphur and the higher iron oxides and a low-melting point oxide melt is thus formed, while a heated layer is formed from the carbon-containing material under the flame. At the same time, the lead oxide is reduced within that layer to metal, while the zinc remains in the slag. The oxidized dust is removed from the gases produced by the fusion and returned to the melt. The powder material added to the charge can be either: sulphide (such as lead ore or low-grade concentrate), which is added to the charge until the weight ratio of the sulphur in sulphide, elemental and pyrite form to the total sulphur content of the charge is approximately 0.08-0.87; or a carbon-containing substance, with approximately 4-12 kg of pure carbon to every 100 kg of trivalent iron and approximately 20-140 kg of pure carbon to every 100 kg of sulphate sulphur. A third possibility is to add the sulphide and carbon-containing substance simultaneously in the amounts indicated.