Raw gypsum (CaSO4.2H2O), whether it is a natural mined gypsum or synthetic Flue Gas Desulphurised gypsum, is delivered to site where it is first ground to the required particle size and dried to remove the vast majority of its free moisture. This dried, ground gypsum is then fed into a calciner, or kettle, where it is heated to a temperature of around 175°C. This will remove ¾ of the gypsum’s chemical, or bound water, and transforms the gypsum into stucco (CaSO4.½H2O).
Once cooled, this stucco is ready to be used in all of Knauf’s plasterboards, plasters and gypsum based jointing compounds.
The stucco and other minor additives are transported via screw conveyors to a series of weigh scales, where the required amounts of the individual components are automatically metered out according to a specific formulation. Once all the ingredients have been weighed out correctly, the batch of powder is transferred into a one tonne batch mixer, where all of the ingredients are combined together to produce the final product.
The product is then bagged off using an automatic bag filling system, stacked onto pallets, and then either placed in the warehouse, or loaded onto trucks for distribution throughout the UK.