| 摘要 |
1537512 Comminution aids; agitator mills ASSOCIATED PORTLAND CEMENT MFRS Ltd 4 April 1977 [7 April 1976] 14103/76 Heading B2A [Also in Division Cl] Ultrafine chalk whiting for use as a filler free from hard abrasive particles is produced by grinding chalk whiting in aqueous suspension with a grinding medium consisting substantially of calcium carbonate in a form having a crushing strength greater than that of the whiting. The grinding medium may be a limestone or pisolite or a calcium carbonate material derived by precipitation in a watersoftening process. Grinding may be performed in the presence of a dispersing agent e.g. polyphosphates and polysilicates, polyelectrolytes such as water-soluble salts of polyacrylic and polymethacrylic acids, and lignosulphonates. Grinding may be carried out in a sandmill, ball mill or tube mill. |
