Plant for the direct reduction of particulate iron-oxide-containing material

Abstract

In a process for the direct reduction of particulate iron-oxide-containing material by fluidization, a synthesis gas is introduced as a reducing gas into several fluidized bed zones consecutively arranged in series. The reducing gas is conducted from one fluidized bed zone to another fluidized bed zone in counterflow to a flow of particulate iron-oxide containing material through the fluidized bed zones. In order to reduce operating costs and, in particular, the energy demand, various process parameters are varied according to the temperature of the iron-oxide-containing material in the first fluidized bed zone being adjusted to be below 400° C. (and, preferably, below 350° C.), above 580° C. (and preferably about 650° C.), or to a temperature within the range of from 400° C. to 580° C. If the temperature of the iron-oxide-containing material in the first fluidized bed zone is maintained to be below 400° C., the temperature of the iron-oxide-containing material in the following fluidized bed zone is passed through the temperature range between 400° C. and 580° C. within a period of 10 minutes and, preferably, within 5 minutes. If the temperature of the iron-oxide-containing material in the first fluidized bed zone is adjusted to a temperature above 580° C., the temperature range of between 400° C. and 580° C. in the first fluidized bed zone is passed through within a maximum period of time of 10 minutes and, preferably, 5 minutes. If the temperature of the iron-oxide-containing material in the first fluidized bed zone is adjusted to be within the range of from 400° C. to 580° C., the iron-oxide-containing material remains in the first fluidized bed zone within that temperature range for a maximum of 10 minutes and, preferably, 5 minutes, and the material is then passed on into the following fluidized bed zone immediately after having reached the desired temperature.