Treatment of complex sulfide concentrate

1. A process of treating complex sulfide concentrate, wherein the complex sulfide ore comprises 2 to 20 wt % Ni, 0 to 15 wt % Cu, and 10 to 55 wt % Fe of the total weight of the concentrate and the complex sulfide concentrate is obtained from complex sulfide ores comprising sulfides of two or more metals, comprising the steps of:

(a) roasting wet or slurried complex sulfide concentrate in a furnace at a temperature from 720° C. to 870° C. to obtain a calcine, wherein oxygen is introduced into the roasting step (a) as oxygen enriched air, wherein the oxygen partial pressure is below 1000 Pa; and

(b) smelting the calcine obtained in step (a) at a temperature from 1250° C. to 1500° C. under inert or oxygen free atmosphere in a smelting furnace to obtain a matte.

2. The process as claimed in claim 1 , further comprising:

(c) granulating the matte obtained in step (b) to obtain a granulated matte.

3. The process as claimed in claim 1 , wherein the complex sulfide concentrate comprises Ni, Cu, Co, Fe and/or PGM.

4. The process as claimed in claim 1 , wherein the calcine has sulfur content below 10% w/w.

5. The process as claimed in claim 1 , wherein the furnace in step (a) is a drum furnace or a fluidizing bed furnace.

6. The process as claimed in claim 1 , wherein the roasting temperature in step (a) is from 780 to 820° C.

7. The process as claimed in claim 1 , wherein roasting in step (a) is accomplished in a bubbling bed.

8. The process as claimed in claim 1 , wherein the smelting temperature in step (b) is from 1300 to 1450° C.

9. The process as claimed in claim 1 , wherein a first part of the complex sulfide concentrate is introduced into the roasting step (a) and a remaining second part is introduced into the smelting step (b) after drying.

10. The process as claimed in claim 1 , wherein the smelting furnace is an electric furnace.

11. The process as claimed in claim 1 , wherein the roasting temperature in step (a) is from 750 to 850° C.