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Tar is what it is. Composition and application

To create a high-quality and reliable road surface, various materials and materials are used. One of them is tar. What is this substance, what properties it has and where it is applied, is very well known first of all to builders and road workers. People of the older generation, whose childhood was spent in the Soviet Union, probably remember what their first chewing gum - tar was. Outwardly, it is a resinous substance formed after the processing of petroleum products , having a viscous structure and pronounced black color. The output of tar is 8 to 45 percent of the mass of oil.

Tar - what is it?

The basis of this substance is petroleum products, so the composition of tar is very similar to oil fractions. The mandatory components are:

- Petroleum resins, which consist of complex hydrocarbons and impart viscidity and viscidity to tar.

- Asphaltenes are solids that increase temperature stability.

- Asphalt acids and their anhydrides, having a gummy consistency and related to polynaphthenic acids.

- Also an obligatory component of tar is the high content of metal impurities present in the oil.

Properties of tar

They depend mainly on the properties of oil, as well as the technologies used in its processing. The nature of oil fractions also affects some characteristics of tar, such as density, melting point and flare, coking ability. A better tar is obtained from heavy resinous oil and is about 8% of its mass.

Application of tar

In a wide variety of industries, tar is used. That this is an indispensable component for the production of road and construction bitumen is known, perhaps, to all. But in addition, tar is also needed in the manufacture of motor fuel, fuel oil and combustible gases. In the construction and rubber industries it is used as a softener. Tar oils with a high tar content can be processed into diesel fuel using the hydrogenation and cracking method.

In order to remove tar-asphaltene components and polycyclic hydrocarbons, which have a low viscosity index and a high degree of coking, tar deasphalting is applied. The solvent, as a rule, is propane. But along with it, when it is required to obtain a feedstock for hydrocracking or catalytic cracking plants , pentane and butane can be used. Sometimes a two-stage deasphalting is carried out, when the asphalt produced in the first stage gives off a more viscous component, deasphalting 2.

When carrying out road works, tar is transported in a solid form, and immediately before use, it is heated to a liquid state.

Secondary resources

In the production of detergents, light oils, purification of paraffins and other technological processes, where sulfuric acid is used as a reagent , a byproduct, called acidic tar, is formed. This is a valuable secondary resource in the form of a resinous black mass containing mainly sulfuric acid and organic compounds. A ton of sour tar allows 600 kg of liquid fuel, 230 kg of gypsum, 110 kg of coke or 60 kg of gaseous hydrocarbons.

The Danger of Acid Tar Oil for Ecology

Despite its value as a raw material for bituminous binders, one of the most serious factors posing a threat to the environment is acid sludge. That this substance is really a source of danger for the plant and animal life, it is easy to imagine if you recall its composition - resinous substances and free sulfuric acid, the content of which can be up to 70% of the total mass.

Danger is also a way of storing acid tar. Due to the fact that today there are no rational methods for their utilization, these wastes simply fall into storage ponds, sometimes occupying quite large areas. As a result of oxidation-reduction processes, which spontaneously occur on the surface of these storage facilities, a large amount of sulfur dioxide is released. After heavy rain or melting snow in the spring, acidic waters, draining from overcrowded ponds, acidify the soil and underground water.

All this negatively affects the ecological situation near the location of such ponds, adversely affects the health of people living in the adjacent territory. Millions of tons of acid tar are stored in open storage ponds in Russia. Virtually all refineries have such wastes. In Nizhny Novgorod alone, they accumulated more than 250 tons.

Recycling

With the current development of construction, the demand for such products as bitumen, tar, bitumen mastic, asphalt is constantly growing. Accordingly, the number of producers increases. Many of them try to solve the problem of acid sludge utilization, using the sulfuric acid cleaning method, but this is still not enough, because it is a rather complicated technological process. It requires expensive acid-resistant materials, the development of special technical methods and storage conditions. Today, the most effective technologies for the utilization of acid sludge are being developed.

Almost all specialists engaged in road construction, rightly consider the tar to be the most unique material. Its repeated melting makes it possible to create various connections, which are successfully used in the construction of roads. And the use of tar in roofing and construction work, to produce fuel oil, lubricating oils and liquid fuels further enhances its value.

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