Coal - processing yesterday, today and tomorrow

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Once Mendeleev said that drowning with oil is like throwing banknotes into the furnace. The same can be said about coal. Recycling reduces the burden on the environment and practically eliminates sulfur-containing harmful impurities from coal. Let us consider the main methods and processes of coal processing, as well as the result and the products obtained from it.

Coal past

Mankind has been familiar with coal as a fuel since ancient Greece. But as an independent industry, the coal industry stood out only in the 18th century. At the beginning of the 19th century, coal began to be used very actively - fuel for transport, electricity production, metallurgy, the chemical industry, automobile and shipbuilding, etc. Better raw materials were required.

Methods for processing coal were developed in the 20th century so that the quality of the extracted raw materials was higher. They were with disadvantages, such as low yield of products, rigid framesimplementation of the process. But with the introduction of various catalysts into the process, the yield of the product became higher, and therefore cheaper, and the passage of the process no longer required strict compliance with all conditions.

Today, mining and processing of coal is a step into the future. It is carried out in five ways. The choice of method depends on the desired end product.

Pyrolysis

This method of coal processing has been used for a long time. Back in the late 90s. In the 19th century, they knew how to heat coal without air access to cause the destruction of polymer molecules, followed by their transformation. Thermochemical processing products come in solid, liquid and gaseous states.

Modern coking (another name for pyrolysis) is carried out at temperatures between 900 and 1100 °C. The product of the process is coke, which is used in the metallurgical industry, both ferrous and non-ferrous, as well as a by-product in the form of a mixture of gases and vapors.

About 250 chemicals are later recovered from the high temperature coking mixture, including benzene, naphthalene, phenols, ammonia and heterocyclic compounds. The introduction of a catalyst into the process contributed to the formation of coke with a fine-grained internal structure - a more valuable type of commercial coke.

Semi-coking

In order to obtain fuel (liquid or gaseous) from coal by processing, low-temperature coking at 500 °C is used. The process is also not innovative, it has been known for a long time. Previously, the goal was to get solid fuel from brown coal, more valuable energetically. Today, the process of coal processing by semi-coking with the use of an oxidation catalyst has increased the environmental friendliness of the final product, it has reduced the concentration of carcinogens and harmful substances. The resulting resin is used to produce solvents and fuels.

Destructive hydrogenation

This method of processing coal is aimed at converting solid fuel into "synthetic oil" at a temperature of 400-500 °C and under the influence of hydrogen. The idea of such processing appeared in the 20s of the last century. In the 1930s and 1940s, the first industrial enterprises were built in Germany and Great Britain, but in the USSR the process was used on an industrial scale only in the 1950s.

A mixture of aluminum, molybdenum and cob alt is used as catalysts in oil refining. Initially, it was also used for coal, but, as it turned out, the process can be made much cheaper, without loss of efficiency, using a widespread iron ore - magnetite, pyrite or pyrrhotite - as a catalyst. Such a result was easy to calculate if you know that catalysis occurs indirectly. Coal passes into the liquid phase not under the action of hydrogen molecules, but through the transfer of hydrogen atoms from the organic solvent molecules to the molecules of the coal component. The catalyst is needed only to restore the solvent properties lost during the elimination of hydrogen atoms.

Gasification

Under the influence of high temperatures, but in an air environment where oxygen, hydrogen, carbon dioxide and steam are present, solid coal passes into a gaseous state. This is the whole point of the process. There are about 20 technologies. We will not dwell on each of them in detail, but consider how the introduction of a catalyst can help.

In addition to increasing efficiency, with a catalyst it becomes possible to lower the temperature while maintaining the speed at the same level, it is also possible to regulate the end product of gasification. The most common are alkali and alkaline earth metals, as well as iron, nickel and cob alt.

Plasma chemical processing

One of the most promising, since in addition to liquid fuels, such valuable compounds as ferrosilicon, technical silicon and other silicon-containing substances are extracted from hard and brown coal during processing, which, under other methods, were simply thrown away with ash.

What about tomorrow

Given how quickly oil and gas deposits on earth are being depleted, the fuel issue will soon become quite acute. And one of the simplest solutions would be coal mining. Scientists are conducting their research work in search of new recycling processes - more efficient, inexpensive, but at the same time environmentally friendly.

Work is also underway to obtain "synthetic oil". In Krasnoyarsk, for example, it was tested to obtain it from a mixture of coal and water in equal proportions. Synthesis was carried out underhigh pressure, the treatment was carried out mechanical, electromagnetic and cavitation. Energy consumption is low - only 5 kW per ton of oil. In terms of its chemical composition, the resulting fraction is close to natural.

So do not rush to dispose of your iron horse, there will be something to feed. And one more good news - coal is replenished, which means it will serve humanity for a long time.