A processing flowsheet has been developed for treating substandard lead-containing polymetallic bulk concentrates and intermediate flotation products containing precious metals, which comprises oxidizing roasting in a calcination kiln and electrothermic smelting generating low volumes of off-gas. The proposed flowsheet also incorporates a dust collection system and sulfur dioxide recovery from off-gas. It is proposed to implement this process by using a reaction smelting technique. For this purpose, the charge to be fed to the smelting furnace after its calcination in a drum-type rotary kiln must have a ratio of sulfide sulfur to sulfate sulfur of at least 1:2. Electric smelting makes it possible to produce lead bullion that also collects the precious metals contained in the feed, as well as copper-lead matte and slag containing zinc. The recovery of lead into lead bullion and into matte is approximately 83 percent and 14 percent, respectively (thus the overall recovery is 97 percent); the total recovery of gold and silver into lead bullion and matte is 98 percent; that of copper into matte is 89 percent; the recovery of zinc into slag is 96 percent; and that of sulfur into sulfuric acid or gypsum is 90 percent. After the recovery of zinc from slag, the latter can be utilized in the construction industry.
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