Lime is the same as calcium oxide, which is obtained from the extreme heating of limestone (natural calcium carbonate).Lime and gypsum are among the materials whose efficacy from ancient times was known by mankind and used in different types of buildings. Materials such as lime, cement were used to connect tighter pieces of stone or wood. Dead lime ,hydrated lime or slaked lime Whenever water is poured on calcium oxide (quicklime), it creates heat due to the reaction with water, which causes a portion of water to vaporize. In this action, the lime is swollen by water absorption, then it becomes whitened, called "dead lime" (because it does not react in contact with water any more).Whenever a little water is added to the dead lime, it turns into lime putty, which if it is smooth, a clear solution, which is actually a water-saturated solution of calcium hydroxide, is called lime water. Lime water has many applications in the chemical industry. For example, in the preparation of sodium hydroxide, ammonia, metal hydroxides, perchlorin and especially in the extraction of magnesium from seawater. Lime types Usually three types of lime are used in construction work. Pure or Fat Lime This type of lime has about four percent impurities, and its most important feature is that swell in contact with water and its volume increases by about 2.5 times its initial value. Mixing it with sand in contact with carbon dioxide is rapidly absorbed and hardened (for 15 days in the vicinity of the air). Hence, pure lime is also called air limestone. Poor lime This type of limestone is made up of limestone with 5 to 6 percent lime, and its major impurities are iron oxide (II), silicon oxide (silica) and aluminum oxide (aluminum). The characteristics of this type of lime are that it is richly flocculated and the resulting mixture is mixed with sand, slowly become hard in the air. Hydraulic or water lime This type of lime is usually made from limestones, which make up about 6% to 22% of clay. One of the important features of this type of lime is that it is slowly tightened away from the air and even underwater, in contact with water is very expanded and it produces a low gum paste with water. In general, this type of lime can be intermediate between air limestone and cement.
Lime has a lot of uses in the construction and procurement of industrial and chemical products, and many of them are mentioned: porcelain dishes: Porcelains are actually ceramic types and they are divided into two types of origin porcelain or hard and artificial porcelain. Conventional glasses: mainly includes of silica, calcium carbonate (or lime), sodium carbonate and carbon coke. Cement: At first, a grinding mill was used to mix the mixture and to use fixed furnaces. Suruj: Suruj or Malat is a mixture of lime, sand and water, which, unlike cement, does not absorb itself inside water and does not tighten, it is gradually hardened in the vicinity of the air due to the absorption of carbon dioxide gas and the formation of limestone. Sugar making: Sugar can be extracted from the roots of sugar beet. Skin Tanning: Before tanning the skin should be applied to remove the remaining residue on the skin. Another major use of lime in the chemical industry and in chemical laboratories is the production of sodium hydroxide from sodium carbonate and ammonium hydroxide from ammonium chloride.