Process of manufacturing a co-ground calcium carbonate mineral of the GCC and PCC type with a specific steepness factor, obtained products and their uses

1. A process of manufacturing co-ground calcium carbonate material comprising ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC), the process comprising the steps of:

(a) providing GCC in an aqueous suspension;

(b) co-grinding the aqueous suspension of GCC and an aqueous suspension of PCC to obtain a co-ground calcium carbonate material having a steepness factor of at least 30, wherein the co-grinding of GCC and PCC is subjected to a temperature rise to above 60° C.;

(c) optionally screening and/or upconcentrating the co-ground calcium carbonate material obtained following step (b);

(d) optionally drying the co-ground calcium carbonate material obtained following step (b) or (c).

2. The process according to claim 1 , wherein the co-ground calcium carbonate material obtained in step (b) has a steepness factor of at least 40.

3. The process according to claim 1 , wherein the co-ground calcium carbonate material obtained in step (b) has a steepness factor of at least 45.

4. The process according to claim 1 , wherein aqueous suspension in step (a) contains from 20% to 80% by dry weight of calcium carbonate.

5. The process according to claim 1 , wherein aqueous suspension in step (a) contains from 50% to 75% by dry weight of calcium carbonate.

6. The process according to claim 1 , wherein aqueous suspension in step (a) contains from 50% to 70% by dry weight of calcium carbonate.

7. The process according to claim 1 , wherein the co-ground calcium carbonate is present in step (b) at a concentration of from 20 to 80% by dry weight of calcium carbonate.

8. The process according to claim 1 , wherein the co-ground calcium carbonate is present in step (b) at a concentration of from 50 to 75% by dry weight of calcium carbonate.

9. The process according to claim 1 , wherein the co-ground calcium carbonate is present in step (b) at a concentration of from 50 to 70% by dry weight of calcium carbonate.

10. The process according to claim 1 , wherein at least one dispersing and/or grinding aid agent is added before, during or after step (b).

11. The process according to claim 1 , wherein 0.2 to 2% by weight of at least one dispersing and/or grinding aid agent relative to total dry mineral material is added before, during or after step (b).

12. The process according to claim 1 , wherein 0.2 to 1.4% by weight of at least one dispersing and/or grinding aid agent relative to total dry mineral material is added before, during or after step (b).

13. The process according to claim 1 , wherein 0.5 to 1.2% by weight of at least one dispersing and/or grinding aid agent relative to total dry mineral material is added before, during or after step (b).

14. The process according to claim 1 , wherein the co-grinding of GCC and PCC during step (b) is conducted in the presence of at least one other mineral material.

15. The process according to claim 14 , wherein the at least another mineral material is talc, clay, Al 2 O 3 , TiO 2 or any mixtures thereof.

16. The process according to claim 14 , wherein the at least another mineral material is talc, clay or mixtures thereof.

17. The process according to claim 14 , wherein the at least another mineral material is talc.

18. The process according to claim 14 , wherein the at least another mineral material is clay.

19. The process according to claim 1 , wherein the co-grinding of GCC and PCC during step (b) occurs at a pH of above 7.

20. The process according to claim 1 , wherein the co-grinding of GCC and PCC during step (b) occurs at a pH of above 10.

21. The process according to claim 1 , wherein the co-grinding of GCC and PCC during step (b) occurs at a pH of above 11.

22. The process according to claim 1 , wherein the GCC and PCC during co-grinding in step (b) is subjected to a temperature rise to above 90° C.

23. The process according to claim 1 , wherein the GCC and PCC during co-grinding in step (b) is subjected to a temperature rise to above 100° C.

24. The process according to claim 1 , wherein the PCC during the co-grinding in step (b) accounts for 10% to 90% of the total combined PCC and GCC weight.

25. The process according to claim 1 , wherein the PCC during the co-grinding in step (b) accounts for 20% to 80% of the total combined PCC and GCC weight.

26. The process according to claim 1 , wherein the PCC during the co-grinding in step (b) accounts for 30% to 70% of the total combined PCC and GCC weight.

27. The process according to claim 1 , wherein the co-grinding of GCC and PCC during step (b) is conducted in the presence of ceria-containing zirconium oxide grinding beads as grinding media, said beads having:

a ceria content of between 14% and 20% by weight relative to the total weight of said beads; and

an average grain size after sintering of the grains forming said beads of less than 1 μm.

28. The process according to claim 27 , wherein the beads have a ceria content of between 15% and 18% by weight relative to the total weight of said beads.

29. The process according to claim 27 , wherein the beads have a ceria content of about 16% by weight relative to the total weight of said beads.

30. The process according to claim 27 , wherein the beads have an average grain size after sintering of the grains forming said beads of less than 0.5 μm.

31. The process according to claim 27 , wherein the beads have an average grain size after sintering of the grains forming said beads of less than 0.3 μm.

32. The process according to claim 27 , wherein the beads have an original diameter prior to grinding of between 0.2 mm and 1.5 mm.

33. The process according to claim 27 , wherein the beads have an original diameter prior to grinding of between 0.4 mm and 1.0 mm.

34. The process according to claim 1 , wherein step (c) is performed.

35. The process according to claim 1 , wherein step (d) is performed.

36. A process of manufacturing co-ground calcium carbonate material comprising ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC), the process comprising the steps of:

(a) providing GCC in an aqueous suspension;

(b) co-grinding the aqueous suspension of GCC and an aqueous suspension of PCC to obtain a co-ground calcium carbonate material having a steepness factor of at least 30, wherein the co-grinding of GCC and PCC is conducted in the presence of talc;

(c) optionally screening and/or upconcentrating the co-ground calcium carbonate material obtained following step (b);

(d) optionally drying the co-ground calcium carbonate material obtained following step (b) or (c).

37. A process of manufacturing co-ground calcium carbonate material comprising ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC), the process comprising the steps of:

(a) providing GCC in an aqueous suspension;

(b) co-grinding the aqueous suspension of GCC and an aqueous suspension of PCC to obtain a co-ground calcium carbonate material having a steepness factor of at least 30, wherein the co-grinding of GCC and PCC occurs at a pH of above 11;

(c) optionally screening and/or upconcentrating the co-ground calcium carbonate material obtained following step (b);

(d) optionally drying the co-ground calcium carbonate material obtained following step (b) or (c).

38. A process of manufacturing co-ground calcium carbonate material comprising ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC), the process comprising the steps of:

(a) providing GCC in an aqueous suspension;

(b) co-grinding the aqueous suspension of GCC and an aqueous suspension of PCC to obtain a co-ground calcium carbonate material having a steepness factor of at least 30;

(c) optionally screening and/or upconcentrating the co-ground calcium carbonate material obtained following step (b);

(d) optionally drying the co-ground calcium carbonate material obtained following step (b) or (c);

wherein the co-grinding of GCC and PCC during step (b) is conducted in the presence of ceria-containing zirconium oxide grinding beads as grinding media, said beads having:

a ceria content of between 14% and 20% by weight relative to the total weight of said beads; and

an average grain size after sintering of the grains forming said beads of less than 1 μm.