Currently, zinc dust (zinc powder) is widely used in various fields of industrial activity, as well as in pyrotechnics to give the flame of fireworks and firecrackers a blue tint. Let us consider in more detail for what purposes this substance is used, its composition and useful properties.
Applications
Wide use of zinc powder received:
- in the chemical industry in the production of polymers, as well as a filler for lubricants;
- in hydroelectrometallurgy and powder metallurgy;
- when mining gold and silver (to displace precious metals from cyanide solutions);
- in hydrogen energy;
- in the production of chemical current sources;
- in the pharmaceutical industry;
- in wastewater treatment;
- for the synthesis of organic compounds.
Zinc powder is widely used for the manufacture of various anti-corrosion compounds that are used in various fields of engineering. In addition, it is part of paints and primers, with the help ofwhich bridges, ships and various structures protect from the aggressive conditions in which they operate.
Types and composition
Currently, the industry produces various grades and modifications of zinc powder, which differ both in chemical composition and in particle size and shape. There are powder particles of spherical, elliptical shape, as well as in the form of flakes.
According to GOST, zinc powder is classified as follows:
- class A includes rectified powder grades with fine grain structure;
- Grade B combines coarse sprayed product.
Zinc powders contain from ninety-five to ninety-eight percent zinc, as well as a small amount of impurities in the form of some other metals.
Storage conditions and precautions
Zinc powder drums should be stored in closed warehouses free of harsh chemicals.
Water should be prevented from getting into the powder container during packaging, transportation and storage, since zinc oxide generates hydrogen by reacting slowly with moisture from the environment.
When working with zinc powder, smoking and the use of open fire are prohibited. In order to ensure safe conditions, it is necessary to clean the premises in the places of sifting and packing of the powder, sweep the walls and equipment at least once a month.
The use of zinc powder inpaint industry
The property of zinc to resist corrosive attack has long been used by manufacturers of paints intended for coating metal surfaces. Such coatings using zinc dust and flakes increase the resistance of metal products to mechanical stress and protect them from corrosion.
A large amount of zinc filler in the composition of the coating increases the protective properties of the paint, but reduces the strength of the coating, which eventually begins to crack and flake off. To solve this problem, it was necessary to reduce the content of the filler to 25 g of zinc powder per hundred grams of the composition, as well as change the structure of the filler and add auxiliary substances to the paint - various organic resins and liquid glass. To improve the useful properties of such coatings, various additives can be added in the form of hardeners, aqueous phosphates, inhibitors, silicates, and s alts of chromic acid. In fact, zinc paint is a special type of primer, since it is used for the primary coating of metal structures and products.
Properties of zinc paint
The paint, which contains a filler in the form of zinc powder, is resistant to moisture, as well as oil products and organic solvents.
Zinc paint can be applied directly to rust without pretreatment of the metal. This paint has high abrasion resistance and increased resistance to mechanical stress.
The use of zinc paint allows you to protect metal structures from the effects of adverse atmospheric factors for up to twenty-five years.
Applying zinc paint
Before applying zinc paint, the surface should be prepared, that is, rid it of loose rust and all sorts of contaminants. To do this, it is cleaned with white spirit or a solvent.
Immediately before use, the paint should be thoroughly mixed to a uniform consistency of medium density. If it has become thick, you can dilute it with toluene. The optimum temperature for dyeing is between five and forty degrees above zero.
To apply the composition to the surface, use a flywheel or medium brush. You can also use a roller. For painting large surfaces, you can use a spray gun. When the first layer dries, after an hour and a half, a second layer of coating is applied. A week after painting, the product is completely ready for use in the usual mode.
