Setting calcium sulphate - fabricated by processing calcium sulphate fines

摘要

Preparing setting plasters from finely divided calcium sulphate, fragmented by double firing on a conveyor passing through firing zones, and then crushing the final product. The pieces of calcium sulphate are divided after firing into two batches, the part which the hot gases pass through first being crushed as a final product, while the layer through which the gases pass through last is recycled, crushed and divided into two quantities, one of which is mixed with finely divided calcium sulphate in the presence of free water and fired on the conveyor as the layer through which the hot gases pass last, whereas the other quantity is mixed with free water and calcium sulphate and fired on the conveyor as the layer which the hot gases pass through first. Converting various forms of calcium sulphate into a setting plaster. In the firing zone the temp. should reach 700 degrees C for 5 mins. and 350 degrees C for 1 hr. Air at room temp. is sucked or blown over the calcium sulphate to cool it to below 100 degrees C.