The QSL Lead Process

The QSL continuous lead smelting process incorporates two basically different pyro- metallurgical operations: roast-reaction, smelting of galena concentrate, followed by carbothermic reduction of some by-product lead oxide slag. Both steps are performed simultaneously in separate compartments of a long horizontal cylindrical reactor, which is lined with fused chrome-magnesite bricks. This converter-type reactor contains a liquid bath consisting of a shallow layer of lead bullion with a superimposed layer of slag, the lead content of which is gradually reduced from about 50% to discardible levels. Metal relative to slag, and slag relative to the gas phase are in continuous countercurrent motion. A lead well is arranged at the flue end of the reactor, and an overflow tap for slag at the opposite end. Tonnage oxygen for oxidation and smelting of the charge, and sub- stoichiometric mixtures of pulverized coal and oxygen for reduction and heating of the slag, are directly blown into the bath using fluid-protected Savard-Lee injectors. High gas-liquid momentum transfer ensures intensive local mixing, and enables rapid mass and heat transfer.