Pyrites are fired in many countries

Pyrite is the name of a group of minerals that are metal compounds from the group of tin, nickel, iron, cobalt, platinum. The compounds can be both sulfurous and arsenic, and antimony or selenious.

Sulfur calcination assumes that the raw material has a light color, metallic sheen, hardness from 3 to 7. Iron or sulfur pyrite (FeS2 formula), 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 yellowish-gray color with a hardness of 6-6.5. The composition of pure pyrite includes about 47 percent iron and about 53 percent sulfur.

Calcination of pyrites is accompanied by the passage of a number of chemical reactions, of which the first 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 vapor is 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 may include fayalite and other substances, depending on the impurities in the feedstock.

Sulfur burning can give in the gas phase a 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 many countries. 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 an elevated sulfur content), and developments in the USA, France, Norway and Sweden are also in operation. To arsenic pyrite in nature, arsenic varieties of this substance are often mixed, which gives a very harmful admixture in production in chambers. Therefore, manufacturers try to use pure raw materials. For example, Russian plants in St. Petersburg operate on the Swedish pyrite.

Firing of iron pyrite (as well as sulfuric) is carried out in furnaces, where raw materials are fed through a screw or an injector. Further, it mixes 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). Excessive heat is also removed from the furnace by means of water cooling elements.

The pyrites will be fired if the contact surface of the raw material with the air is sufficiently 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.