Reaction Smelting

a method for the production of metals based on either the reaction between the sulfide and oxide of the metal to be extracted (MeS + 2MeO = 3Me + SO₂) or the reaction between the metal’s sulfide and sulfate (MeS + MeSO₄ = 2Me + 2SO₂). Reaction smelting is also called ore-hearth smelting in the case of lead metallurgy. The process is performed in a special crucible charged with a rich lead concentrate and coke. The charge is blown with compressed air, and the temperature in the crucible increases to 700°-900°C from the combustion of coke and the heat liberated in the oxidation of metallic sulfides. The principal processes of reaction smelting occur at this temperature and result in the formation of crude lead. The charge must remain in a porous state during the reaction, and contact between the components is achieved by continuous raking with a mechanical rake.

The crude lead contains 70 percent of the metal from the charge, the gray slags contain 10—15 percent, and the dust 15–20 percent. The gray slags are treated in blast furnaces to achieve additional extraction of lead, and the dust is returned to a new charge of the reaction smelting process.

The principles of reaction smelting are being applied to new processes for producing lead from partly roasted sulfide concentrates. Examples are smelting through the methods of electrometallurgy (Sweden), smelting in suspensions (Sweden, Finland), and injecting concentrates into the molten bath of a converter (USA). Reactions characteristic of reaction smelting are used in the metallurgy of antimony for the smelting of oxide and sulfide concentrates and in the converter blowing of copper mattes.