| 摘要 |
<p>A batch of aluminium silicate-containing raw materials, soda and calcium carbonate is sintered and extracted. The resulting aluminium solution is separated from a belite slurry, and the aluminate solution is freed from the silicate in two steps. The second of these involves the treatment of the solution with a lime-containing mass comprising CaO, Al2O3, SiO2, Fe2O3 and Na2O. The ratios between these oxides (by weight) are as follows: CaO : (SiO2 + Fe2O3) = 1.000-5.000 : 1 and Na2O : Al2O3 = 0.25- 0.60 : 1. Furthermore, CaO is active, and Na2O is carbonized. The mass is used in such an amount as to ensure that the amount of active CaO in the solution is equal to 5-10 g/l. The calcium hydroaluminium silicate that separates out after the removal of the silicate can be used to prepare two types of cement: 1) cement for the preparation of foundry moulds and foundry cores and 2) cement with a high alumina content. To prepare a cement for foundry moulds and cores, the calcium hydroaluminium silicate is heated to 250-600 degrees C and finely ground. To prepare a cement with a high alumina content, the calcium hydroaluminium silicate is mixed with aluminium hydroxide in a ratio by weight of 0.25-0.50 : 1 (calculated for CaO : Al2O3), and the mixture is sintered at 1350-1450 degrees C, after which the sintered material is subjected to fine grinding.</p> |
