| 摘要 |
<p>Granules are made of CaSO4, 2H2O(I), opt. with additives, in a granulating and drying plant in which the time, travelling speed of the granules, and the drying temp., are controlled so the core of the granules loses a part of its moisture which is not chemically bonded; and the outer zone of of the granules crystallises as the semihydrate (I) opt. with anhydrite. During rehydration of the outer zone with the surface water still on the core, the desired strength is reached on the surface of the (II) granules. Pref. plant uses a granulating drum na) travelling at a peripheral speed of 0.5-2.0 m/second, followed by a drying drum (b) with peripheral speed of 0.15-0.5 m/sec. Drum (b) may be heated by gases flowing in the same or opposite direction as the granules; and waste air from (b) may flow through drum (a). Strong granules of (II) can be made for use in gypsum, cement or fertilisers, starting from raw materials which can include waste CaSO4 obtd. in the chemical industry.</p> |
