PROCESS OF PREPARING VIRTUALLY CADMIUM-FREE CALCIUM SULPHATE AND CALCIUM SULPHATE PREPARED ACCORDING TO THIS PROCESS

摘要

AE 5400 22772-1093 Virtually cadmium-free calcium sulphate is produced in the preparation of a liquid medium containing phosphoric acid, which comprises digestion with a mineral acid of cadmium-containing phosphate rock and separation from the liquid medium containing phosphoric acid of at least a portion of the calcium in the phosphate rock after precipitation by means of a solution containing sulphate ions in the form of calcium sulphate, in which process halogen ions are present in an amount of 50-20.000 ppm during precipitation of the calcium sulphate to be separated.