Combined method for production of reducing gases and processing galena-containing concentrate

Abstract

A combined method for production of reducing gases by gasification of coal and pyrometallurgical processing of galena-containing concentrate is proposed. The coal is preliminarily cleaned from the components accompanying carbon in the reactor, which is heated through the inner walls of the double vessel by the heat of the stream of heated gases of metallurgical production. When coal is heated to 300–350 оC, moisture evaporates from it, CO and CO2 are desorbed and volatile components are released, and when the temperature rises to 500–550 оC, the graphitization of coal begins with the release of resinous substances. As the temperature rises to 700 оC, coke is formed, which is subjected to gasification with water vapor in the ratio C:H2O = 1:1 in a gas generator at a temperature of 1000–1050 оC. The resulting generator gas of equimolar composition H2:CO = 1:1 with a temperature of up to 1050 оC initially heats the reaction mixture from the galena-containing concentrate and air through the reactor wall. Part of the heat is used to obtain water vapor, and at a temperature of 350–380 оC as a reducing gas to obtain crude lead. Oxidation gases of sulphide minerals with a temperature of 1050 оC are used to heat coal in a double-vessel reactor to a temperature of 700 оC, then they give off part of their heat to produce water vapor and, with a temperature of 400 оC, enter the sulfur dioxide oxidation reactor, where the catalytic oxidation of SO2 to sulfuric anhydride, used to produce sulfuric acid, takes place. The remainder of the gas mixture, consisting of inert nitrogen and argon, is separated into individual components by a membrane method. The proposed method is implemented using a waste-free technology: incidentally formed water vapor and condensate, CO2, sulfuric acid and inert gases are used as useful products. Heat supply of the method is realized due to heat exchange between flows of substances within the technological scheme. The method is low-cost and environmentally friendly, emissions into the environment are excluded.