Production of surface-reacted calcium salts by grinding induced conversion

A process for producing an aqueous suspension of surface-reacted calcium salt particles comprising the steps of:

• a) providing a calcium salt excluding monocalcium phosphate and dicalcium phosphate,
• b) providing a calcium phosphate, wherein the calcium phosphate is dicalcium phosphate and is produced by contacting a calcium ion source and a phosphate ion source,
• c) forming an aqueous suspension by mixing the calcium salt of step a), and the calcium phosphate of step b) with water, and
• d) grinding the aqueous suspension of step c) at a pH value from 4.2 to 14 and at a temperature of 0° C. to 100° C. to form an aqueous suspension of surface-reacted calcium salt particles,
• wherein the calcium salt of step a) and the calcium phosphate of step b) in combination have a calcium ion to a phosphate ion molar ratio (Ca2+:
• PO43−) in the range from 2.2:1 to 100:1;
• wherein grinding of step d) is carried out:
• (1) in a ball mill, a rod mill, a vibrating mill, a centrifugal impact mill, a vertical bead mill, an attrition mill, a sand mill, or combinations thereof;
• and
• (2) at a specific grinding energy from 50 to 500 kWh per dry metric ton of (2) surface-reacted calcium salt particles.