| 摘要 |
<p>Process for prop preparing shaped articles from gypsum (CaSO4.2H2O),by compressing calcium sulphate dihydrate and additives to form articles. The process is characterized in that in moist, non-calcined calcium sulphate dihydrate of any origin one or several addivites, with the exception of calcium sulphate hemihydrate, is admixed and the gypsum slurry compressed at a pressure of at least 200 kg/cm2 and thereafter dried. Chemical gypsum containing soluble phasphates, fluorides and/or ammonium sulphate up to about 2% by weight or cement the ground blast-furnace sing in a quantity of up to 10% by weight, referred to the dry gypsum is started form. Preferred as a additive is urea formaldehyde resin in a quantity of less than 3% by weight referred to the dry gypsum, preferably 1-4% by weight, and more preferably approximately 1% by weight in the combination of chemical gypsum of acid reaction.</p> |
