- Calcium sulfate, with the chemical formula CaSO₄, is an inorganic compound composed of calcium, sulfur, and oxygen.
- It occurs naturally in several mineral forms, the most common being gypsum (CaSO₄·2H₂O)—the dihydrate form—and anhydrite (CaSO₄)—the anhydrous form. It is typically a white or colorless crystalline solid that is odorless and non-toxic, and has limited solubility in water. Calcium sulfate is widely used in construction, agriculture, food, and industrial processes due to its stability and abundance.
- One of the most prominent uses of calcium sulfate is in the construction industry, particularly in the form of gypsum, which is used to produce plaster, plasterboard (drywall), and cement. When heated, gypsum loses its water of crystallization and forms plaster of Paris (CaSO₄·½H₂O). This material, when mixed with water, hardens upon setting and is used extensively for molding, casting, and wall finishing. Its quick-setting nature and ease of application make it ideal for use in architectural and decorative applications.
- In agriculture, calcium sulfate serves as a soil conditioner and calcium and sulfur source for crops. It helps improve soil structure, reduce soil compaction, and enhance water penetration in heavy clay soils. Unlike lime, it does not significantly alter soil pH, making it useful for providing calcium without raising alkalinity. The sulfur content is beneficial for plant metabolism and protein synthesis, particularly in sulfur-deficient soils.
- Calcium sulfate also plays a role in food production, where it is recognized as a food-grade additive (E516). It is used as a firming agent, dough conditioner, and calcium fortifier in products like tofu (where it acts as a coagulant), baked goods, and beverages. Because it is generally regarded as safe, it is commonly included in food and dietary products to enhance nutritional value or texture.
- In the medical and dental fields, calcium sulfate is used in orthopedic applications as a bone graft substitute or filler material due to its biocompatibility and resorbable nature. It provides temporary scaffolding for new bone growth in cases of bone defects or fractures. In dentistry, it can be used in surgical packing materials and for periodontal treatments.
- In industrial applications, calcium sulfate is involved in water treatment, especially in the removal of contaminants and as a coagulant in some filtration processes. It is also a common byproduct of flue gas desulfurization, where sulfur dioxide emissions from power plants are treated to form synthetic gypsum, which can then be used in construction materials.
- While calcium sulfate is generally safe, its limited solubility in water can lead to scaling in pipes, boilers, and industrial equipment, particularly in areas with hard water. Managing calcium sulfate precipitation is important in industrial water systems to prevent clogging and inefficiencies.
