Pyrites are fired in many countries

The pyrite is the name of a group of minerals,which are compounds of metals from the group of tin, nickel, iron, cobalt, platinum. The compounds can be either sulphurous and arsenic, or antimony or selenious.

Calcination of pyrite suggests that the raw materialhas a light color, metallic luster, hardness from 3 to 7. Iron or sulfur pyrite (formula FeS2), which is pyrite, is a valuable technical raw material from which sulfur dioxide is produced (production in chambers). In appearance, the mineral represents a mass of fine crystals of regular form, yellowish-gray in color with a hardness of 6-6.5. The composition of pure pyrite includes about 47 percent iron and about 53 percent sulfur.

The pyrite burning is accompanied by the passage of a series ofchemical reactions, the first of which gives the decomposition of the mineral into iron sulfide and sulfur in the vapor state (at a temperature of about 500 C). Then the sulfur fumes are burned, giving sulfur dioxide, and the iron sulphide gives oxide or nitrous oxide. Moreover, the sulphide does not completely burn out, forming a "cinder", which can include fayalite and other substances, depending on the impurities in the feedstock.

Pyrites can be fired in the gas phasea certain amount of SO3 mixed with SO2. This substance acts on the equipment in a corrosive manner, so to reduce SO3, the temperature of the gas at the outlet from the furnace equipment should be about 850 ° C, and then rapidly decrease to 400 ° C.

Burning sulfur pyrite is practiced in manycountries, because this element belongs to the number of widespread. In Russia, this mineral is mined at the Soimskaya dacha, the Kalitvinsky deposit, near Kushva, at Bogoslovsky plants, in the Caucasus, in the Ryazan and Smolensk regions, and elsewhere. Abroad, Spanish deposits are especially famous (especially Aguas Tenidas, where the material does not contain copper, but has a high sulfur content), and in addition to the development in the US, France, Norway and Sweden. To arsenic pyrite in nature, arsenic varieties of this substance are often mixed, which gives a very harmful admixture in production in chambers. Therefore, producers try to use pure raw materials. For example, Russian plants in St. Petersburg operate on the Swedish pyrite.

The annealing of iron pyrites (as well as sulfuric)is produced in furnaces, where the raw material is fed through an auger or an injector. Further it is mixed with the mass of solid material that already exists in the unit (in the fluidized bed on the grate, under which air is fed from below), after which chemical reactions occur that give the gas (removed) and the cinder (it is partially poured by special pipes). Also, excess heat is removed from the oven by means of water cooling elements.

Pyroealing will be successful if the surfacethe contact of raw materials with air will be quite large. Therefore, the mineral is often processed in a pulverized state (in appropriate furnaces), when the particle size is so small that oxygen freely penetrates into the mass of the substance. In addition, the temperature regime is important, because minerals of this class are often sintered at temperatures above 900 C. To solve this problem, recycling is also used in the form of a dust-air mixture, which allows burning raw materials at temperatures up to 1000 C, which increases the efficiency of production.