Gypsum is an evaporite mineral most commonly found in layered sedimentary deposits in association with halite, anhydrite, sulfur, calcite and dolomite. Gypsum (CaSO4.2H2O) is very similar to Anhydrite (CaSO4). The chemical difference is that gypsum contains two waters and anhydrite is without water. Gypsum is the most common sulfate mineral. Gypsum is available in two forms, viz, mineral gypsum and by-product gypsum.The mineral gypsum is mined from land deposits.By-product gypsum includes marine gypsum, phosphor-gypsum, fluoro-gypsum, boro-gypsum, scrubber gypsum,etc. Marine gypsum is recovered from sea-water as a by-product while producing common salt, whereas the other types are obtained as by-product from different chemical plants. The quality of mineral gypsum available in India is very inconsistent and the percentage of calcium sulphate varies even in the same deposit. The ratio between high grade gypsum containing above 80% calcium sulphate content and the rest is generally 1:3. The quality of gypsum also depends on the size of the particles, the large particles generally have higher percentage of calcium sulphate. The average difference in calcium sulphate content between lumps ( above 5 cm) and fines(5 cm and less ) has been found to vary considerably and is generally of the order of 6 percent. Investigations have further shown that it is due to more friable material containing silica which crumbles, leaving lumps (above 5 cm) which is more concentrated in calcium sulphate. In gypsum calcium or magnesium carbonate, chlorides, other sulphate minerals, clay minerals or silica are considered as deleterious constituents. As a result most mine production of gypsum will have the purity ranging between 70 and 95%. Often it is used as mined, although in certain cases, one or more methods of mineral beneficiation are employed to upgrade the product.
Cement
Gypsum is a mineral and is hydrated calcium sulfate in chemical form. Gypsum plays a very important role in controlling the rate of hardening of the cement. During the cement manufacturing process, upon the cooling of clinker, a small amount of gypsum is introduced during the final grinding process. Gypsum is added to control the setting of cement. If not added, the cement will set immediately after mixing of water leaving no time for concrete placing.
Construction
Gypsum building materials are used in all construction types (residential, non-residential, new or refurbished), ranging from complex high-tech systems to easy to install products adapted for use by the general public.
Plasterboard
Plasterboard is used for partitions and the lining of walls, ceilings, roofs and floors. The properties of plasterboard can be modified to meet specific requirements, such as fire resistance, humidity resistance, shock resistance, etc
Decorative Plaster
Plaster powder, mixed with water, manually or through the use of silo-supplied spray systems, are used to create an effective and aesthetically-pleasing lining for brick and block walls, and for ceilings. Gypsums adaptability in application lends itself to moulding and shaping. Since time immemorial, Gypsum has been used by skilled craftsmen to create decorative plaster mouldings.
Building plasterGypsum plaster is used for walls and ceilings.
Plaster blocks
Gypsum blocks are used for partitions and Gypsum tiles for ceilings.
Plaster
Plaster of Paris is a white powder which hardens after coming in contact with water. The most important use of this product is in plastering in broken bone surgery. It is also used in making decorative tiles, sculpture, etc. Other uses of plaster of Paris include making slip cast refractory blows, architectural decoration for the formation of decorative friezes, cornics, columns, and other decorative features in interior finishes, making impression for dentures, inlays and for the casting of metal fillings, etc... Plaster of Paris is made from gypsum which is a non-metallic mineral. When gypsum is heated to 1210C, it loses a property of its water of crystallization and forms a quick setting cement of plaster of Paris.
As a soil additive (sometimes called land plaster) to improve the soil’s workability and receptivity to moisture, and to overcome the corrosive effect of alkalinity. Gypsum specifically benefits such crops as alfalfa, corn, cotton, wheat, and peanuts where substantial amounts of sulfate sulphur are required
As an additive in turbid water, particularly ponds, to settle dirt and clay particles without injuring aquatic life.
To create surgical and orthopedic casts
As a food additive. Gypsum (calcium sulfate) is recognized as for use as a dietary source of calcium, to condition water used in brewing beer, to control the tartness and clarity of wine, and as an ingredient in canned vegetables, flour, white bread, ice cream, blue cheese, and other foods
As a color additive for drugs and cosmetics
A primary ingredient in toothpaste
