In the chemical industry zinc is used in the form of zinc powders and dusts. These are prepared by pulverizing a stream of molten metal in a jet of compressed air or water. The difference between powder and dust is essentially a matter of fineness, dusts being finer. They are used to purify solutions by cementation or to achieve other reductions. Special grades of zinc powders are also used in alkaline batteries as well as in certain button cells.
The electrochemical properties of zinc account for its essential role as a negative electrode in dry (or Leclanché) batteries.
Zinc oxide ZnO, the most widely used zinc compound, is produced by two different methods: the direct or American process, which starts from oxidized materials and involves a reduction step with carbon, followed by oxidation of the zinc vapor in air, and the indirect or French process, which starts from zinc metal and gives a higher purity end product. Zinc oxide is used in the vulcanization of rubber, as well as in ceramics, paints, animal feed and pharmaceuticals, and many other products and processes. A special grade of zinc oxide has long been used in photocopiers. The oxide is also used in varistors (that provide protection against over-voltages).
Zinc sulphide ZnS mixed with barium sulphate is used as a white pigment known as lithopone. ZnS is also used as a detector of alpha-rays, which render it luminescent.
ZnS and the selenide ZnSe are used in infrared optics.
Zinc salts have various applications: zinc chloride in the textile industry, in the manufacturing of Leclanché batteries, and as a scaling flux in galvanizing; zinc sulphate in agriculture and animal feed; zinc phosphate to passivate steels, etc. Organic salts of zinc are used in paints, and zinc stearate is used in the preparation of plastics as well as in powder metallurgy.