Method of treatment of zinc-containing by-products and waste materials

A method for treating a waste material which contains zinc and heavy metals to form an inert slag and to separate the zinc from the heavy metals and recover the zinc and heavy metals, said method comprising:

• supplying to a gas-tight electric smelting furnace a waste material and a sulfur-containing compound, said waste material obtained from a process used to produce a non-ferrous metal, said waste material containing oxidized zinc and one or more heavy metals selected from the group consisting of copper, nickel, lead, arsenic, bismuth, antimony and silver;
• adding a metallic reduction material to the furnace to reduce said oxidized zinc to zinc;
• maintaining the furnace at a temperature of about 1200.degree. C. to about 1700.degree. C. to form a gas phase of zinc, a slag phase, and a molten sulfide phase, said molten sulfide phase containing said heavy metals, thereby separating the zinc from said heavy metals;
• a first tapping step to remove the sulfide phase and thereby recover the heavy metals from the waste material in the form of a sulfur compound;
• a second tapping step to remove the slag phase as an inert slag suitable for deposit in a landfill;
• and
• condensing the gas phase and recovering the zinc.