in nonferrous metallurgy, a process for the treatment of lead sulfide concentrates with soda ash (80–100 percent of the weight of the concentrate) in an ore heat-treating furnace. In the process, lead (up to 96–97 percent), antimony, arsenic (approximately one-third), bismuth, gold, and silver are converted into black lead, copper is converted to copper-sodium matte, zinc (approximately two-thirds) and the remaining metals (except cadmium) and sulfur are converted to soda slag (melt), and zinc (approximately one-third) and cadmium are converted to a recoverable dust. The soda slag is leached with hot water; copper, zinc, and the other metals remain in the precipitate, which is separated and treated in an electric furnace. Sulfur is separated from the solution, and the soda is regenerated. With the soda process, the production cycle for the smelting of lead is shortened (by eliminating the sintering process necessary to agglomerate the particles of lead concentrate), the volume of waste gases is reduced, the apparatus for collecting the dust is simplified, and a high level of lead extraction is obtained. Among the disadvantages of the process are the large quantities of soda required and the complexity of the soda regeneration process. The soda process is also used for treating dusts and intermediates of lead production.
B. L. GRANOVSKII