Abstract: Finely divided ferruginous material is intimately mixed with finely divided carbonaceous material and agglomerated and formed into pellets typically of a few cubic centimeters volume to form a feedstock for a smelting operation. The carbonaceous material includes carbon in both high reactivity and low reactivity forms typically provided respectively by sewage sludge or other biosolids and by coke fines, kish graphite, natural graphite, lignite or brown coal. Smelting is conducted in a bath smelting furnace with the bath temperature of at least 1420.degree. C. and preferably 1500.degree. C. in a manner controlled to destroy any organic compounds present, to use carbon as a source of fuel, to carburise the iron to around 4% carbon or higher and to provide an off-gas which can be processed to collect any volatilized metal values.

Abstract: Steelworks dusts or sludge is mixed into sewage preferably in the presence of a flocculating agent to provide a rapid separation of a clear effluent and a sludge which is dewatered and dried to form a solid material adapted to entrap harmful materials in the sewage such as heavy metals, pathogens and organic chemicals. The solid material is supplied to a smelt reduction furnace from which molten iron is recovered and a hot gas discharge is provided from which recovery of zinc and other materials may be achieved, other waste material being removed as a slag.

Abstract: The present invention provides a leaching or smelting precursor method of drying and heating particulate ores or concentrates which have been previously intimately admixed with either an already active form of carbon or with some other carbon-containing material which can be readily dried and heated to charring temperatures by microwave energy comprising irradiating the composite with microwave energy.