Process and plant for producing calcine products

1. A process for producing calcine products comprising:

dead roasting a metal sulfide concentrate having a low sulfur content, the concentrate being roasted in a circulating fluidized bed at a temperature of about 950 to 1050° C.;

passing a waste gas of the fluidized bed through at least one of: a recuperator so as to preheat at least a portion of fluidizing air of the fluidized bed and a Venturi drier so as to dry at least a portion of the concentrate to be roasted; and

providing for further processing calcine product obtained in the fluidized bed with a sulfur content of less than 1 wt-%.

2. The process according to claim 1 , wherein the concentrate is a platinum-group metal sulfide concentrate.

3. The process according to claim 1 , wherein the roasting is performed in the fluidized bed at a temperature greater than 1000° C.

4. The process according to claim 1 , wherein at least one of additional air and oxygen are supplied to the fluidized bed.

5. The process according to claim 1 , wherein at least a portion of the waste gas is cleaned and recirculated to the fluidized bed.

6. The process according to claim 1 , wherein solids contained in the waste gas are separated and at least partially recirculated to the fluidized bed.

7. The process according to claim 6 , wherein the solids that are recirculated to the fluidized bed are at least partially treated in a microgranulation so as to obtain a desired mean grain size of the solids.

8. The process according to claim 1 , wherein an oxygen concentration in the waste gas of the fluidized bed reactor is adjusted to about 1 to 4 vol-%.

9. The process according to claim 8 , wherein the oxygen concentration in the waste gas of the fluidized bed reactor is adjusted to about 2 to 3 vol-%.

10. The process according to claim 1 , wherein the waste gas, upon release of heat, is cooled in the at least one of the recuperator and the Venturi drier in less than 1 min to a temperature below about 350° C.

11. The process according to claim 10 , wherein the waste gas is cooled in less than 10 sec.

12. The process according to claim 1 , wherein the calcine product obtained in the fluidized bed, upon roasting, is molten in an electric arc furnace prior to a hydrometallurgical treatment.

13. The process according to claim 12 , wherein the calcine product obtained in the fluidized bed is supplied directly to the electric arc furnace.

14. The process according to claim 1 , wherein SO 2 -containing waste gas is provided to a sulfuric acid plant.

15. A plant for producing calcine products comprising:

a fluidized-bed reactor configured to dead roast a metal sulfide concentrate having a low sulfur content;

at least one of a recuperator and a Venturi drier disposed downstream of the fluidized-bed reactor in a waste gas stream of the fluidized-bed reactor and configured to recover heat of the waste gas to fluidizing air of the fluidized bed reactor, the fluidizing air being subsequently provided to at least one of the fluidized-bed reactor and the concentrate to be roasted; and

a microgranulation configured to treat solids recirculated to the fluidized-bed reactor.

16. The plant according to claim 15 , further comprising a cooler disposed downstream of the at least one of the recuperator and the Venturi drier in the waste gas stream.

17. The plant according to claim 16 , wherein the cooler includes an evaporation cooler.

18. The plant according to claim 15 , further comprising a solids separator disposed in the waste gas stream.

19. The plant according to claim 18 , wherein the solids separator is configured to operate electrostatically.