| 主权项 |
1. A high solids aqueous suspension of mineral material obtained by the process consisting of the steps of:
a) providing at least one mineral material comprising calcium carbonate, b) preparing an aqueous suspension comprising the at least one mineral material of step a), c) grinding the aqueous suspension of the mineral material of step b) so that from 20 to 70 wt % of particles of the mineral matter are <2 μm, d) optionally subjecting the aqueous suspension of ground mineral material to one or more of a separation step, screening, filtration and centrifugation; and e) concentrating the aqueous suspension of ground mineral material of step c), or of d) if performed, by flash cooling in a flash cooler comprising an inlet and an outlet, wherein the temperature of the aqueous suspension at the inlet of the flash cooler is from 70 to 105° C., and the temperature of the aqueous suspension at the outlet of the flash cooler is less than 60 to 30° C., to obtain an aqueous suspension having a final solids content of 80 to 85 wt % and a Brookfield viscosity, measured at 23° C. after 1 minute of stirring at 100 rpm, of from 100 to 750 mPa·s, wherein at least one dispersing agent is added to the aqueous suspension of step b), wherein the at least one dispersing agent is added completely before grinding step c), or stepwise before and during grinding step c), or before and during and/or after grinding step c), wherein the at least one dispersing agent is a homopolymer or copolymer of a polycarboxylic acid, acrylic acid, methacrylic acid or maleic acid, a partially or completely neutralized acid salt thereof that is neutralized with sodium, lithium, potassium, ammonium, calcium, magnesium, strontium, aluminium or any mixture thereof, a derivative of a polycarboxylic acid, an ester based on acrylic acid, methacrylic acid, maleic acid, fumaric acid, or itaconic, an acryl amide or acrylic ester, a methylmethacrylate, or any mixture thereof, an alkali polyphosphate, or any mixture thereof, wherein the total amount of the at least one dispersing agent added before grinding step c), or before and during step c), or before and during and/or after grinding step c), is from about 0.01 to 1.25 wt %, based on the dry weight of the mineral material, wherein optionally before, during, or after step c), but before step e), at least one earth alkali oxide and/or hydroxide is added to the aqueous suspension of step b), and wherein optionally before, during, or after step c), but before step e), lime and/or burnt dolomite is added to the aqueous suspension of step b). |
