Large Volume Inorganic Chemicals - Ammonia ... - ammk-rks.net

Chapter 66.4.3 Valorisation of anhydriteDescriptionA substantial amount of calcium sulphate is co-produced with hydrogen fluoride in theanhydrite form (CaSO 4 without the crystallisation of water). The preferred use of this product isas a raw material. The potential uses for synthetic anhydrite are numerous: plaster, binder forfloor screed, cement industry additives, agriculture, fillers of plastics, porous bricks. Anhydriteis the preferred material in some of these applications but for many reasons such as other rawmaterial competition, fear of change, and quality reasons, the quantities of anhydrite producedare always in excess of demand. For the excess quantities, landfilling is the most commondisposal option and three plants in Europe apply dispersion in surface waters or into the sea.Achieved environmental benefitsUse of anhydrite as a raw material reduces the need for disposal to the environment.Cross-media effectsNone believed likely.Operational dataNo information provided.ApplicabilityGenerally applicable. Still, calcium sulphate co-products have to compete in open markets withnatural and synthetic anhydrite and cement, hence, recovery is of course eased in countries inwhich natural anhydrite or gypsum availability is limited. Anhydrite is sometimes not of anequivalent quality to other products. Conditions for its re-use as a raw material depend on itsphysical properties and on the pattern of its impurity concentrations. In many cases, anhydritequality upgrading is necessary, increasing the cost. Anhydrite has to compete with naturalmaterial. For example, even though anhydrite as a binder for floor screed has proven advantagesover the commonly used cement, to develop a market is difficult because of local ways andcustoms, leading to market resilience.EconomicsCost benefits.Driving force for implementationCost benefits.References to literature and example plants[22, CEFIC, 2000]270 Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers