STUDY OF THE PREPARATION OF REDUCED LOW-CARBON IRON POWDER FROM HEMATITE USING THE 'FROZEN FURNACE' EXPERIMENT

摘要

As a rule, the reduction kinetics for hematite in industrial units differs markedly from the process under laboratory conditions. A study is made of the reduction kinetics of hematite concentrate under conditions most closely approximating industrial conditions (in a pilot furnace for annealing powder raw material developed at the Gas Institute of the National Academy of Sciences of Ukraine, and constructed at the Advanced Research Center for Powder Metallurgy and New Materials (Hyderabad, India). The essence of the experiment, called the "frozen furnace" by us, consists of the fact that at a prescribed instant of time the reducing atmosphere in the furnace is replaced by an inert atmosphere stopping the reduction process and fixing its current state. The kinetic reduction curve is obtained for a freely poured fiat dispersed layer of hematatite concentrate. Reduction is separated into three clearly defined periods: quasihomogeneous, diffusion-autocatalytic, and diffusion. The similarity of reduction of a dispersed layer of material and an individual particle is confirmed, and the difference only consists in the geometric and time scales. These studies make it possible to evaluate the role of the scale factor in predicting the reduction of a dispersed layer of material under industrial conditions.