Process and plant for the direct reduction of particulate iron-oxide-containing material

Abstract

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 for the reducing gas. The reducing gas is conducted from one fluidized bed zone to another fluidized bed zone in counterflow to the particulate iron-oxide containing material. In order to reduce operating costs and, in particular, the energy demand, the temperature of the iron-oxide-containing material is adjusted in the first fluidized bed zone to be either below 400° C. (and, preferably, below 350° C.), or above 580° C. (and preferably about 650° C.), or to a temperature ranging from 400° C. to 580° C. If the temperature of the iron-oxide-containing material in the first fluidized bed zone is adjusted to be below 400° C., the temperature range in the following fluidized bed zone between 400° C. and 580° C. is passed through 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 be above 580° C., the temperature range in the first fluidized bed zone between 400° C. and 580° C. is passed through within a period of time of maximally 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 in the range of from 400° C. to 580° C., the iron-oxide-containing material remains within that temperature range for a maximum of 10 minutes and, preferably, 5 minutes, and the material is passed on into the following fluidized bed zone immediately after having reached the desired temperature.