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

A process for the direct reduction of particulate iron-oxide-containing material by fluidization, wherein synthesis gas such as reformed natural gas is introduced as a reducing gas into several fluidized bed zones consecutively arranged in series for the reducing gas and is conducted from one fluidized bed zone to another fluidized bed zone in counterflow to the particulate iron-oxide containing material, and wherein heating of the iron-oxide-containing material is effected in the fluidized bed zone arranged first in the flow direction of the iron-oxide-containing material and direct reduction is carried out in the further fluidized bed zone(s), characterized

• in that a temperature of the iron-oxide-containing material of either below 400° C. and, preferably, below 350° C.,
• or above 580° C. and, preferably about 60° C.,
• or a temperature ranging from 400 to 580° C. is adjusted in the first fluidized bed zone,
• wherein, at a temperature adjustment to below 400° C., the temperature range between 400° C. and 580° C. in the fluidized bed zone following the first fluidized bed zone in the flow direction of the iron-oxide-containing material is passed through within a period of 10 minutes and, preferably, within 5 minutes. and
• wherein, at a temperature adjustment to above 580° C., the temperature range between 400° C. and 580° C. is passed through within a period of maximally 10 minutes and, preferably, 5 minutes, and
• wherein, furthermore, at a temperature adjustment 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 is passed on into he fluidized bed zone following next immediately after having reached the desired temperature.