Sulfuric acid is widely used in various fields of human activity. The modern chemical industry includes it in the list of main production products, the level of its output is an indirect indicator of the chemical production potential of a particular country. About 160 million tons of this substance are produced annually in the world.
According to its physicochemical properties, sulfuric acid is a dibasic acid; in this compound, sulfur reaches the highest oxidation state (+6). Under normal conditions, in a concentrated state, sulfuric acid is a heavy, oily liquid that has neither color nor odor. Sulfuric acid in solution is used. As a solvent, both ordinary water and sulfuric anhydride can be used. It is considered to be an aqueous solution if the ratio of the number of sulfuric anhydride molecules to the amount of water is less than unity. If this indicator is exceeded, the expression is used - a solution of sulfuric anhydride in sulfuric acid or oleum.
The production of sulfuric acid provides this valuable product with the technological process of creating mineral fertilizers, it is used as an electrolyte in lead batteries, acid is the main component in the production of various mineral salts and acids. Chemical fibers, dyes, smoke-generating and explosive substances use sulfuric acid in the technology of their production. Without it, it is impossible to imagine the oil, metalworking, textile, leather and other industries.
Even the food industry could not do without the use of this substance - obtaining food supplement E513 (emulsifier). Industrial organic synthesis, dehydration (the process of producing esters, diethyl ether), hydration (production of ethanol from ethylene), sulfonation (the production of synthetic detergents and intermediates in the preparation of dyes), alkylation (synthesis of isooctane, caprolactam, polyethylene glycol), resin recovery filters on distilled water production lines - none of these processes can do without the use of sulfuric acid.
The production of sulfuric acid provides the most basic consumer of this substance - the synthesis of mineral fertilizers. For example, to get a ton of phosphate fertilizer, you need to spend from two to three and a half tons of sulfuric acid. For this reason, sulfuric acid enterprises, which are responsible for the production of sulfuric acid, are building in conjunction with plants producing mineral fertilizers.
Two technological methods are used to produce sulfuric acid. The production of sulfuric acid by the contact method is the main one and amounts to ninety percent, the nitrous (tower) method has received less prevalence. Despite the shortcomings and advantages of each, the production of sulfuric acid from pyrites displaced nitrous due to more attractive indicators of cost, purity and high concentration of the finished product at the output.
The development of a contact synthesis method by sulfuric acid plants and the production of sulfuric acid can be divided into three stages. At the first stage, pyrite is fired; for this, special firing furnaces in the so-called "fluidized bed" are used. The second stage involves the oxidation of sulfur gas to sulfur oxide (VI), and the third stage is the production of oleum, which is poured into tanks and sent to customers.
The production of sulfuric acid by the nitrous method was not widely used due to the insufficient purity of the output product, which limits its use.
Regardless of the methods and methods of production, the production of sulfuric acid requires manufacturers to pay increased attention to environmental protection.