CALCIUM HYDROXIDE or HYDRATED LIME
Commercial hydrated lime is a dry powder obtained by treating quicklime (see calcium oxide) with sufficient water to satisfy its chemical affinity for water, thereby converting the oxides to hydroxides. Depending upon the type of quicklime used and the hydrating conditions employed, the amount of water in chemical combination varies, as follows:
High calcium hydrated lime: high calcium quicklime produces a hydrated lime containing generally 72 to 74 percent calcium oxide and 23 to 24 percent water.
Dolomitic hydrated lime (normal): under atmospheric hydrating conditions only the calcium oxide fraction of red dolomitic quicklime hydrates, producing a hydrated lime of the following chemical composition: 46 to 48 percent calcium oxide, 33 to 34 percent magnesium oxide, and 15 to 17 percent water.
Dolomitic hydrated lime (pressure treated): this lime is produced from dolomitic quicklime under pressure, which results in hydrating almost all of the magnesium oxide as well as all of the calcium oxide, producing the following chemical composition: 40 to 42 percent calcium oxide, 29 to 30 percent magnesium oxide, and 25 to 27 percent water.
Hydrated lime, though only slightly soluble in water, forms suspensions easily; the resulting solution and suspension is strongly alkaline, possessing a pH of 12.4
USES OF LIME
METALLURGY: Steel Manufacture, Steel Products Manufacture, Magnesium Manufacture, Alumina Manufacture, Ore Flotation and Non-Ferrous Metal Smelting.
PULP AND PAPER: Sulfate Process, Sulfite Process, Bleaching, Precipitated Calcium Carbonate, Strawboard Manufacture, and in the treatment of pulp and paper mill liquid wastes, as a coagulant in color removal.
CHEMICALS: Alkalis, Calcium Carbide and Cyanimide, Petrochemicals, Bleaches, Dye and Dyestuff Intermediates and Coke-By-Products. In addition, it is used in the purification of citric acid, glucose and dextrin; metallic calcium; soda-lime, an adsorbent; and for countless other minor or isolated purposes, such as for CO, absorption.
WATER TREATMENT: Scope, Softening, Purification, Coagulation, Neutralization of Acid Water, Silica Removal and Removal of other impurities.
SEWAGE TREATMENT: Maintain proper pH and Stabilizing Sewage Sludge.
INDUSTRIAL WASTES: Treatment of industrial trade wastes to abate pollution from Steel and Metal Fabricating Plants, Chemical and explosives Plants, Acid Mine Drainage, Paper and Fibers, Food Plants and in clarifying “water gas” acid waste effluents.
FLUE GAS DESULFURIZATION
SOLID WASTES DISPOSAL
CERAMIC PRODUCTS: Glass, Refractories, and in the production of white ware pottery, lime is sometimes employed to bind the kaolin and ball clays present.
BUILDING MATERIALS: Calcium Silicate Brick, Concrete Products, Miscellaneous Building Units, and Insulation Materials.
PROTECTIVE COATINGS: Pigments, Water Paints, and Varnish.
FOOD AND FOOD BY-PRODUCTS: Dairy Industry, Sugar Industry, Animal Glue and Gelatin Industries, Baking Industry, and CA (controlled atmospheric) Storage of Fresh Fruit and Vegetables. All tortillas are made with lime treatment.
MISCELLANEOUS USES: Petroleum, Leather, and Rubber.