REDUCTION OF A METAL OXIDE-CONTAINING MATERIAL ON THE BASIS OF AMMONIA NH3

Abstract

A method for the reduction of a metal oxide-containing material in which a reducing gas that is obtained using ammonia (NH.sub.3) is used. The reducing gas is supplied to a reduction reactor containing the metal oxide-containing material, and a top gas is discharged from the reduction reactor. At least one sub-quantity of the top gas is used as components in the preparation of the reducing gas, optionally after the top gas is prepared. A device for the reduction of the metal oxide-containing material that includes a reduction reactor, a top gas discharge line for discharging top gas, a supply line for an ammonia contribution, a preparation system for preparing the reducing gas, a supply line for the ammonia contribution leading into the preparation system, and a feed line for feeding the reducing gas and/or a precursor of the reducing gas to the reduction reactor.

Claims

1. A process for reducing metal-oxide-containing material, wherein a reducing gas obtained with the use of ammonia NH.sub.3 is employed, wherein the reducing gas is supplied to a reduction reactor containing the metal-oxide-containing material, and a top gas is discharged from the reduction reactor, wherein at least a part-amount of the top gas, optionally after a treatment of the top gas, is used as a component in the preparation of the reducing gas.

2. The process as claimed in claim 1, wherein the treatment of the top gas withdrawn from the reduction reactor includes a process step to lower the nitrogen content.

3. The process as claimed in claim 1, wherein at least one member of the first group consisting of: ammonia, hydrogen obtained from ammonia, is added to the top gas and/or to the treatment gas during the preparation of the reducing gas.

4. The process as claimed in claim 1, wherein at least one member of the second group consisting of: natural gas, hydrocarbons, hydrogen, carbon monoxide, coke oven gas, syngas comprising two or more constituents from the group of constituents consisting of CO, H.sub.2, CH.sub.4, C2-C6 hydrocarbons, N.sub.2, CO.sub.2, is added to the top gas and/or to the treatment gas during the preparation of the reducing gas.

5. The process as claimed in claim 4, wherein at least one member of the second group is added to the gas mixture obtained after combining the top gas or treatment gas and at least one member of the first group.

6. The process as claimed in claim 4, wherein at least one member of the first group is added to the gas mixture obtained after combining the top gas or treatment gas and at least one member of the second group.

7. The process as claimed in claim 1, wherein it is carried out in a reduction reactor having a cooling zone and/or a product cooler, wherein ammonia is introduced into the cooling zone of the reduction reactor and/or into the product cooler.

8. A device for reducing metal-oxide-containing material, comprising: a reduction reactor, a top gas discharge line for discharging top gas from the reduction reactor, at least one inlet line for the ammonia input, a preparation unit for preparing the reducing gas, into which leads at least one inlet line for the ammonia input, a supply line for the supply of the reducing gas and/or of a reducing gas precursor to the reduction reactor, wherein the top gas discharge line leads into the preparation unit.

9. The device as claimed in claim 8, wherein the top gas discharge line includes at least one treatment unit that is a device for lowering the nitrogen content.

10. The device as claimed in claim 8, wherein the preparation unit includes at least one feed line for feeding in one or more members of the group consisting of: natural gas, hydrocarbons, hydrogen, carbon monoxide, coke oven gas, syngas.

11. The device as claimed in claim 8, wherein the reduction reactor has a cooling zone and/or a product cooler, wherein an ammonia supply line leads into the cooling zone and/or the product cooler.

12. A signal processing means comprising a non-transitory medium having recorded thereon a machine-readable program code, wherein the code includes closed-loop control commands for carrying out a process as claimed in claim 1.

13. A computer product comprising a non-transitory computer-readable medium that has recorded thereon machine-readable program code for a signal processing means, wherein the program code includes closed-loop control commands that cause the signal processing means to carry out a process as claimed in claim 1.

14. (canceled)

15. An open-loop and/or closed-loop control of a device for reducing metal-oxide-containing material with a computer containing a computer program product including commands that, when the computer program is executed by the computer, cause the computer to execute the steps of a process as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0132] The present invention will be described by way of example hereinbelow with reference to several schematic figures.

[0133] FIG. 1 shows in schematic form the performance of a variant of the process of the invention in a variant of the device of the invention for reducing metal-oxide-containing material.

[0134] FIG. 2 shows a further variant in schematic form.

[0135] FIG. 3 shows a further variant.

[0136] FIG. 4 shows a further variant in schematic form.

[0137] FIG. 5 shows a further variant in schematic form.

DESCRIPTION OF THE EMBODIMENTS

Examples

[0138] FIG. 1 shows in schematic form the performance of a process of the invention in a device of the invention 1 for reducing metal-oxide-containing material. Metal-oxide-containing material 3, in this case iron-oxide-containing material, is introduced into a reduction reactor 2, in this case a reduction shaft, where it forms a fixed bed 4. A reducing gas is used to reduce the metal-oxide-containing material 3 in the reduction reactor 2. Top gas is discharged from the reduction reactor 2 via top gas discharge line 5. The top gas discharge line 5 leads into the preparation unit 6 for preparing the reducing gas. An inlet line for the ammonia input 7 leads into the preparation unit 6. In the preparation unit 6, reducing gas is prepared with the use of ammonia NH.sub.3 and with the use of top gas as a component. The reducing gas obtained with the use of ammonia and top gas is supplied to the reduction reactor 2 containing the metal-oxide-containing material 3 via the supply line 8. In the preparation unit 6, top gas is mixed with ammonia and the resulting gas mixture is the reducing gas. The top gas is thus used directly in the preparation of the reducing gas.

[0139] FIG. 2 shows in schematic form a variant largely analogous to FIG. 1, in which the top gas is used indirectly in the preparation of the reducing gas. The preparation unit 6 is supplied with treatment gas via the top gas discharge line 5. The treatment gas is obtained by the treatment of the top gas; in the top gas discharge line 5 there is a device for lowering the nitrogen content 9a stream of treatment gas depleted in nitrogen is supplied to the preparation unit 6 via the top gas discharge line 5. In the preparation unit 6, the treatment gas is mixed with ammonia and the resulting gas mixture is the reducing gas. In FIG. 2, the lowering of the nitrogen content thus results in a part-amount of the top gas being used as a component in the preparation of the reducing gas.

[0140] FIG. 3 shows in schematic form a variant largely analogous to FIG. 2, in which the preparation unit 6 includes a feed line for natural gas 10. This makes it possible to admix natural gas with the gas mixture obtained after combining treatment gas and ammonia, or to admix ammonia with the gas mixture obtained after combining treatment gas and natural gas. The gas mixture thereby obtained can serve as a reducing gas precursor and be converted into a reducing gas in a reformer (not specifically shown).

[0141] FIG. 4 shows in schematic form a variant largely analogous to FIG. 2, in which an ammonia supply line 11 leads into the cooling zone 12 of the reduction reactor 2. This allows ammonia to be introduced into the cooling zone during direct reduction in the reduction reactor 2.

[0142] FIG. 5 shows in schematic form a variant largely analogous to FIG. 1, in which the bustle 13 of the reduction reactor is also shown. Reducing gas is supplied to the bustle 13 via supply line 8. For the preparation of the reducing gas, ammonia is supplied to the top gas conduit 14 via an inlet line for the ammonia input 7. The supply line 8 also counts here as a preparation unit and mixing device, since ammonia and top gas are mixed therein.

LIST OF REFERENCE SIGNS

[0143] 1 Device for reducing metal-oxide-containing material [0144] 2 Reduction reactor [0145] 3 Metal-oxide-containing material [0146] 4 Fixed bed [0147] 5 Top gas discharge line [0148] 6 Preparation unit [0149] 7 Inlet line for ammonia input [0150] 8 Supply line [0151] 9 Device for lowering the nitrogen content [0152] 10 Feed line for natural gas [0153] 11 Ammonia supply line [0154] 12 Cooling zone [0155] 13 Bustle [0156] 14 Top gas conduit