Process and plant for purifying red mud

1. A process for purifying red mud, comprising the following steps:

1. reduction of the red mud to reduced material, and

2. at a temperature between 75 and 95° C., traversing the reduced material with an oxygen-containing gas in the presence of a catalyst suitable for iron oxidation creating an at least partially oxidated product.

2. The process according to claim 1 , characterized in that step 1 takes place under continuous or discontinuous addition of a reducing agent, which contains hydrogen, at least one hydrocarbon, carbon monoxide and/or coal.

3. The process according to claim 1 , characterized in that step 1 is carried out at a temperature between 800 and 1500° C.

4. The process according to claim 1 , characterized in that in step 2 an amine compound is used as catalyst.

5. The process according to claim 4 , characterized in that in step 2 the amine compound content lies between 0.5 and 3 wt-% based on the total mass of the mixture of reduced material and catalyst.

6. The process according to claim 1 , characterized in that air is used as oxygen-containing gas.

7. The process according to claim 1 , characterized in that in step 2 the oxygen-containing gas flows into the reduced material with a flow rate of 2 to 20 Nl/min.

8. The process according to claim 1 , characterized in that before step 1 the red mud is washed with washing water, whereby washed mud is obtained.

9. The process according to claim 8 , characterized in that drinking water or sea water is used as washing water.

10. The process according to claim 8 , characterized in that the washing water has a temperature between 30 and 60° C.

11. The process according to claim 8 , characterized in that the washing water is added in a ratio of 0.01 to 0.1 l(H 2 O)/kg(red mud).

12. The process according to claim 8 , characterized in that washing is effected for a period of 1 to 5 hour(s).

13. The process according to claim 1 , characterized in that before step 1, the red mud is subjected to drying.

14. The process according to claim 13 , characterized in that the drying is carried out at a temperature between 80 and 130° C.

15. The process according to claim 13 , characterized in that iron oxide is leached out from the at least partially oxidize product.

16. The process according to claim 15 , characterized in that the iron oxide leached out is removed by a solid-liquid separation.

17. The process according to claim 1 , characterized in that in step 2, water, or optionally a recirculated aqueous solution liberated from dissolved substances, or both is added.

18. The process according to claim 1 , characterized in that after step 2 a product mixture is dried.