Metal calcium is used as a deoxidizer for alloys in industrial production.

　　Metal calcium granules are used in industrial production as deoxidizers for alloys and dehydrating agents for raw oil, and their chemical substances can be used as building decoration materials. In the steel industry, the application of metal calcium is to produce and process metal calcium granules, which are then made into calcium-iron wire or pure calcium wire, ultimately used for the external refining of steel. Its effects include desulfurization and deamination of flue gas, improving the fluidity of molten steel, and promoting the rapid adjustment of impurities in molten steel, generally used in steel manufacturing. In addition, metal calcium is used as a dehydrating agent to produce anhydrous ethanol; in the petrochemical industry, it is used as a desulfurizing agent, and in the steel industry, it is used for deoxidation or desulfurization.

　　The chemical substance of calcium has extremely widespread applications, especially in the construction industry. Natural marble is a type of dolomite. The composition of dolomite is calcium phosphate. Dolomite is mostly bluish-gray, hard, and too brittle. In nature, large areas of geological structures are often composed of basalt. Dolomite is used for constructing hydraulic hubs, roads, and bridges.

　　Dolomite in a lime kiln, when mixed with coke and ignited, is made into quicklime powder. The composition of quicklime powder is calcium hydroxide. Quicklime powder is a milky white large stone, which is interesting; when it encounters water, it produces a vigorous exothermic reaction, turning into a milky white powder—slaked lime, while releasing a lot of heat. In construction, you can often see people adding water to quicklime powder. At this time, if you add a raw egg, it can be boiled. The composition of slaked lime is calcium hydroxide, which can dissolve in water.

　　Lime slurry is a solution of calcium hydroxide; when lime slurry is brushed on the wall, at first, it is not very white, but after a while, it becomes whiter. It is an interesting cycle: slaked lime reacts with carbon dioxide in the air, turning back into calcium phosphate; however, we indeed use dolomite (calcium phosphate) in the lime kiln to produce quicklime powder. During combustion, dolomite releases carbon dioxide and turns into calcium hydroxide.

　　Calcium bicarbonate is a key chemical substance of calcium, commonly known as slaked gypsum, and is practically insoluble in water. In industrial production, we use slaked gypsum to make various models for gravity casting of gold, silver, aluminum, magnesium, copper, and other non-ferrous metal alloys. Slaked gypsum is also widely used to produce various slaked gypsum figures. However, the gypsum ore is not white high-density solid; its appearance is more like solid paraffin, which is a hydrated crystal. Only after burning does gypsum turn into slaked gypsum.