Patent ID: 9650517
Date: 2017-05-16
CPC Classifications: C01F,C01P,C09C,C09D,D21H

Claim:
1. A process for producing ball-shaped spherical surface modified calcium carbonate comprising particles comprising the steps of: a) providing at least one aqueous calcium carbonate containing mineral slurry; b) providing at least one water-soluble acid; c) providing gaseous CO d) contacting the aqueous calcium carbonate containing mineral slurry of step a) with the acid of step b) and with the CO e) optionally dewatering the aqueous slurry, wherein at least one processing agent is added before, during or after the aqueous calcium carbonate containing mineral slurry of step a) is contacted with the acid of step b) and the CO wherein the processing agent is selected from the group consisting of ferrous sulfate, ferric sulfate, ferrous chloride, aluminum sulfate, and their hydrated forms, and wherein the processing agent is added in an amount of up to 8 wt.- % based on the dry weight of the slurry.