The present invention refers to a process to modify at least part of the surface of at least one mineral material, and to the use, as an additive in an aqueous suspension of mineral materials having a pH between 5 and 10, of at least one agent, wherein the additive allows for the formation of a low volume, high solids content filter or centrifuge cake on dewatering the suspension.

The present invention relates to a process for producing a surface-reacted calcium carbonate, wherein a calcium carbonate-comprising material is treated with at least one inorganic acid and carbon dioxide in an aqueous medium to form an aqueous suspension of surface-reacted calcium carbonate, wherein the at least one water-soluble, inorganic magnesium salt is added before, during and/or after the treatment step. Furthermore, the present invention relates to a surface-reacted calcium carbonate obtained from said process and its use.

The present invention is related to ball-shaped spherical surface modified spherical calcium carbonate comprising minerals, the process for preparing such ball-shaped spherical surface modified spherical calcium carbonate comprising minerals, and their use.

The present invention refers to a process to modify at least part of the surface of at least one mineral material, and to the use, as an additive in an aqueous suspension of mineral materials having a pH between 5 and 10, of at least one agent, wherein the additive allows for the formation of a low volume, high solids content filter or centrifuge cake on dewatering the suspension.

The present invention refers to a white UV-absorbing surface-reacted calcium carbonate doped with a titanium species, comprising calcite and hydroxyapatite in a weight ratio of from 99:1 to 1:99 based on the dry weight of the calcite and the dry weight of the hydroxyapatite and having a specific surface area of from 15 m.sup.2/g to 200 m/.sup.2g, wherein the titanium species is present in an amount from 0.01 to 20 wt.-% of titanium element, based on the total dry weight of the surface-reacted calcium carbonate. Furthermore, the present invention refers to a process for producing the white UV-absorbing surface-reacted calcium carbonate doped with a titanium species, the use of said white UV-absorbing surface-reacted calcium carbonate doped with a titanium species as well as an article comprising said white UV-absorbing surface-reacted calcium carbonate doped with a titanium species.

The present invention relates to a process for producing an aqueous suspension of surface-reacted calcium salt particles by mixing a calcium salt excluding monocalcium phosphate and dicalcium phosphate, a calcium phosphate selected from monocalcium phosphate and/or dicalcium phosphate, with water, and grinding the obtained aqueous suspension at a pH value of at least 4.2 to form an aqueous suspension of surface-reacted calcium salt particles.