The natural property and usage of zinc

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Zinc, of which the chemical symbol is Zn, belongs to the subgroup element of II group in the periodic table of chemical element and is one of the six kinds of base metals. Zinc is a kind of metal element distributed widely in the nature which is mainly existed in the state of sulfide and oxide. Its minerals include blende, smithsonite, willemite, calamine, hydrozincite and so on. Due to its low melting point, it is mainly smelted by blast furnace method and electrolytic method. As zinc has good drawability, corrosion resistance and abrasive resistance, it is the third important nonferrous metal in ten kinds of commonly used nonferrous metals. Currently, the consumption of zinc is only second to copper and aluminum and is widely used in the colored, metallurgy, building materials, light industry, electromechanical, chemical engineering, automobile, military industry, coal, oil and other industries and departments.

Zinc has good drawability, corrosion resistance and abrasive resistance, which can form various alloy of excellent performance with many metal. Chief of all, zinc can be made into brass together with copper, tin and lead, which can be used in the machine building industry; the die-casting alloy made with zinc together with aluminum, magnesium and cooper can be used in making various precision casting; the surface of steel and various cast iron coated with zinc can prevent corrosion, in addition, zinc coating material and various corrosion-resistant material are widely used; besides, zinc processing material is the main material of manufacturing dry batteries. Zinc chemicals, such as zinc oxide and lithopone are indispensable raw materials for the medicine, rubber, pigment, oil paint and other industries. About 50 percents of zinc consumption are used in anti-corrosion coating, 15 percents are used in producing brass (including direct applications of renewable raw material zinc), about 15 percents are used in producing casting alloy, the rest is used in rolling zinc plate, the production of zinc chemical and pigment, etc. The main products of native zinc enterprises include: metal zinc, zinc base alloy and zinc oxide. These products have very wide applications which are mainly as follows:

Galvanization

Zinc metal powder, used as the coating (such as the galvanized sheet) for corrosion resistance, are widely used in automobile, construction, shipping, light industry and other industries and occupies about 46 percents of zinc dosage. As zinc has good atmospheric corrosion resistance, it is mainly used as the surface coating of steel and steel structure. After the oxidation of electroplating hot dip galvanized alloy in its surface, it will form a uniform and dense basic zinc carbonate oxide film layer which can prevent the growth of mould. As zinc alloy plate has good atmospheric corrosion resistance, recent years the western countries are trying to use it as the roof cover materials that has the durable years up to 120-140 years and can be recycled. Besides, the roof cover material used with galvanized iron sheet can have the durable years of about 5-10 years.

Manufacturing copper alloy material (such as brass)

About 15 percents of zinc are used in automobile making and machinery industry. Zinc has applicable mechanical property, but it has not very high strength and hardness. By adding aluminum, copper and other alloy elements, its strength and hardness will be greatly improved. Especially with the emergence of zinc-copper-titanium alloy, its synthesized mechanical properties have approached or reached the level of aluminum alloy, brass and gray cast iron. Its creep resistance is also largely improved. Therefore, zinc-copper-titanium alloys currently are widely used in the production of nails.

Casting zinc alloy

About 15 percents of zinc are made into die pressed casting that used in the automobile, light industry and other industries. Many zinc alloys have good processability, of which the pass reduction is up to 60-80 percents. As it has excellent medium pressure performance, it can be used in deep drawing. It also has self-lubrication which can be used in extending the die life. It can be welded with braze, electric resistance welding or electric-arc welding (should be conducted in helium condition), while its surface can be treated with electroplate and japanning. It has good machinability and superior superplasticity under certain conditions.

Except for the above performance, zinc also has favourable resistance to electromagnetic fields. Its electric conductivity is 29 percents of the standard electrician-copper. Under the condition of radio-frequency interference, zinc can be used as a very effective shielding material. As zinc is non magnetic, it can be made into the instrument parts material, caseter and coins. Meanwhile, as no spark will be produced by zinc or by collision with other metals, it can be applied in the mine explosion-proof equipment.

About 11 percents of zinc are used in producing zinc oxides which are widely applied in the rubber, coating, enamel, medicine, printing, fibre and other industries. About 13 percents of zinc are made into dry cells with the forms of zinc cake and zinc plate.

Zinc has appropriate chemical performance. It can react with NH4CI and release H+ positive ion, this theory is applied in making zinc-manganese dioxide battery. The battery shell made by zinc alloy can be both used as the containers of battery electrolyte and battery anode participating in the cell reaction. This performance of zinc is also widely used in the medicine industry.