| 摘要 |
1,250,670. Synthetic wollastonite. RHEINISCHE KALKSTEINWERKE G.m.b.H. 15 Sept., 1969 [19 Sept., 1968], No. 45310/69. Heading C1A. Wollastonite is produced from lime and silica which are reacted in substantially equivalent quantities, in the presence of water at over 100‹ C., to give calcium hydrosilicates, which are then dehydrated to give #-wollastonite. The reaction is preferably carried out at between 170‹ and 200‹ C. and accompanied by grinding of the reaction mixture. Coarser #-wollastonite may be obtained by heating the #-wollastonite produced to around 1200‹ C., when α-wollastonite is formed, which can then be re-converted to coarser crystalline #-wollastonite by maintaining a slightly lower temperature. |
