Patent ID: 8152079

Claim:
A process for dry grinding a mineral material comprising at least calcium carbonate, wherein the process comprises the stages of: a) crushing the mineral material in at least one crushing unit until a crushed material is obtained with a d 95 of less than 10 cm; b) optionally subjecting the material crushed according to stage a) to a flotation stage and/or a magnetic separation stage and/or a sieving stage and/or a chemical treatment stage; c) dry grinding the material according to stage a) and/or b) in at least one grinding unit: (i) in the presence of at least one comb-type hydrophilic polymer containing at least one polyalkylene oxide function grafted on to at least one unsaturated ethylene monomer, (ii) in such a manner that the quantity of liquid in the grinding unit is less than 15% by dry weight of the material crushed in the crushing unit; d) optionally classifying the material dry ground according to stage c) with at least one classification unit; and e) optionally repeating stages c) and/or d) on all or part of the dry ground material resulting from stages c) and/or d); wherein the material recovered following stage c) and/or d) and/or e) has a d 50 of 0.5 to 500 microns.