Specific features of the use of pulverized coal fuel in combined chemical processing

Abstract

Expanding the applications of combined thermochemical processing of mineral raw materials is one of the priority development areas in the non-ferrous metals industry. In particular, combined processes involving reduction roasting and the Waelz process are considered very promising, for example, for additional recovery of non-ferrous and accessory metals from metallurgical cakes. The first chemical stage of these reduction processes is the conversion of carbon fuel into carbon monoxide and carbon dioxide in the presence of oxygen and water vapor. The urgency of a detailed study of this stage is due, among other reasons, to the many problems related to CO2 emissions into the environment. Carbon dioxide emissions into the atmosphere are largely associated with the operation of furnace units that consume a significant amount of carbon-containing utility products. Operation of tubular rotary furnaces involves high temperatures, achieved by burning various types of fuels. This article discusses the process of burning pulverized coal fuel that results in an incomplete burnout of coal particles. Subsequent exposure of the unburned solid phase to the combustion products leads to the formation of a multicomponent heterogeneous system that maintains the synthesis reactions for CO and H2. These reactions, occurring at high temperatures, change the equilibrium composition of the combustion products dramatically. An algorithm is proposed for calculating the equilibrium composition by solving a system of nonlinear equations. The calculation was made by the iterative Newton’s method at a constant temperature, assumed on the basis of the calculated theoretical combustion temperature of the fuel of a given composition.