Calcium Application Areas

Industrial field
It is used to make alloys with aluminum, copper, and lead. It is also used as a reducing agent for beryllium, a deoxidizing agent for alloys, and a dehydrogenating agent for oils.
It is used as a deoxidizing agent for alloys, a dehydrating agent for oils, a reducing agent for metallurgy, a desulfurizing and decarburizing agent for iron and ferroalloys, and a getter in electron tubes.
Biological field
Calcium is used as a high-temperature thermal reducing agent to produce metal chromium, thorium, uranium, rare earth elements, zirconium, magnetic materials samarium-cobalt alloys, hydrogen-absorbing materials lanthanum-nickel alloys, and titanium-nickel alloys from oxides and halides. Ca-Si alloys are added to steel to prevent the formation of carbides. Lead-calcium alloys containing 0.04% calcium have high hardness and corrosion resistance, and are used as cable sheaths and battery lead plates; adding calcium to aluminum alloys can enhance plasticity. Calcium is also used as a deoxidizer for smelting tin bronze, nickel, and steel, a degassing agent in electron tubes and television picture tubes, a dehydrating agent for organic solvents, a desulfurizing agent for petroleum refining, a denitrifying agent for pure inert gases (such as helium), and decomposition of odorous thiophenes and mercaptans. Calcium fluoride is used as a raw material for optical glass, optical fiber, and enamel, and as a flux. Calcium peroxide is a mild oxidant, used as a sterilizing, preservative, and bleaching agent, and is also used as a quick-drying agent for sealing glue.
Humans:
Calcium is an essential element for organisms. For the human body, there are proteins bound to Ca2+ in muscles, nerves, body fluids, and bones. Calcium is the main inorganic component of human bones and teeth, and is also an essential element for nerve transmission, muscle contraction, blood coagulation, hormone release, and milk secretion. Calcium accounts for about 1.4% of the human body mass and participates in metabolism. Calcium must be supplemented every day; insufficient or excessive calcium in the human body will affect growth and health.
Calcium is the most abundant inorganic salt element in the human body. The total amount of calcium in a healthy adult is about 1000-1300 grams, accounting for about 1.5%-2.0% of body weight. 99% of calcium exists in bones and teeth in the form of bone salts, and the rest is distributed in soft tissues. Calcium in extracellular fluid accounts for only 0.1% of the total calcium. Bones are the main site of calcium deposition, so they are known as "calcium stores". Bone calcium mainly exists in two forms: amorphous calcium hydrogen phosphate (CaHPO4) and crystalline hydroxyapatite (3Ca3PO4×Ca(OH)2). Its composition and physical and chemical properties change constantly with the physiological or pathological conditions of the human body. There is more calcium hydrogen phosphate in new bone than in old bone, and it gradually turns into hydroxyapatite during bone maturation. Bones maintain a dynamic balance between bone calcium and blood calcium through continuous osteogenesis and osteolysis.
Under normal circumstances, almost all of the calcium in the blood exists in plasma. Under the action of various calcium regulating hormones, blood calcium is relatively constant at 2.25-2.75 mmol/L. It is slightly higher in children and is often at the upper limit. Calcium exists in plasma and extracellular fluid in the following ways: (1) Protein-bound calcium. It accounts for about 40% of the total blood calcium. (2) Diffusible bound calcium. Calcium bound to organic acids, such as calcium citrate, calcium lactate, and calcium phosphate, can diffuse through biological membranes and accounts for about 13%. (3) Serum free calcium. That is, ionized calcium (Ca), which is constantly exchanged with the above two types of calcium and is in dynamic equilibrium. Its content is related to blood pH. When pH decreases, [Ca] increases, pH increases, and ionized calcium decreases. In the normal physiological pH range, ionized calcium accounts for about 47%. Among the three types of blood calcium, only ionized calcium has a direct physiological effect. Hormones also regulate ionized calcium and are regulated by the feedback of ionized calcium levels.
The intracellular ionized calcium concentration is much lower than the extracellular ionized calcium concentration. Extracellular ionized calcium is the storage reservoir of intracellular ionized calcium. Calcium exists in three forms within cells: stored calcium, bound calcium, and free calcium. About 80% of the calcium is stored in organelles (such as mitochondria, sarcoplasmic reticulum, endoplasmic reticulum, etc.). Calcium in different organelles does not diffuse freely with each other. 10% to 20% of the calcium is distributed in the cytoplasm, bound to soluble proteins and membrane surfaces, while free calcium accounts for only 0.1%.