Patent ID: 8563642

Claim:
A product obtained by the process of 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 a grinding aid agent having a weight-average molecular weight (Mw) of 20,000 to 50,000, wherein the grinding aid agent comprises a polymer formed by radical polymerization of: (a) polyethylene glycol methacrylate, acrylic acid and maleic acid; (b) polyethylene glycol methacrylate and maleic acid; (c) polyethylene glycol methacrylate and acrylic acid in which the carboxylic acid groupings of acrylic acid are fully neutralized by sodium; (d) a monoether of maleic acid with lateral chains of polyethylene glycol methacrylate, and maleic acid; or (e) polyethylene glycol methacrylate functionalized with hexyl 1-decanyl and acrylic acid in which the carboxylic acid groups of acrylic acid are fully neutralized by sodium; (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 stage d) if performed, and stage e) if performed, has a d 50 of 0.5 to 500 microns and comprises said grinding aid agent.