Utilising waste gypsum obtd. in phosphoric acid mfr. - by mixing with low CA3 cement and hardening, e.g. to make foundation material

摘要

In a process for utilising gypsum, esp. that obtd. as a by-product in the prodn. of phosphoric acid, the gypsum is mixed with a low-CA3 cement, opt. with the addn. of water, and the mixt. is allowed to harden. The hardened pieces, opt. after being broken up, are used e.g. as a foundation material. The process utilises waste gypsum obtd. in large amts. as a by-product in the prodn. of phosphoric acid and artificial fertilisers. The by-product gypsum may contain traces of heavy metals such as Cd, Ni, Hg, Cu, Zn, As, Pb, U, etc., and may possess som radioactivity, so that serious environmental pollution can occur if it is dumped. The process transforms the potentially hazardous waste material into a safe, useful, water-resistant material.