Formation and development of electrometallurgy

At the turn of the XIX-XX centuries. In metallurgy, to obtain the best quality grades of steel and non-ferrous metals, the electric current energy is increasingly used. The possibility of electrofusion of metals was first established by the Russian physicist VV Petrov. In 1802 he created the largest at that time galvanic battery, consisting of 2,100 copper-zinc elements. With the help of this source of current, the phenomenon of an electric arc was discovered. Petrov first pointed out the possibility of its practical application for lighting, electric melting and electric welding of metals. The Russian scientist also studied the processes of oxidation of metals and their recovery from ores in the zone of burning of the electric arc.

The patent for the first electrothermal furnace was taken back in 1853 by the Frenchman Pishon. The design of this furnace is to some extent a prototype of electric arc furnaces (E. Stassano, etc.), which found practical application at the end of the last century.

The main element of the Pichon furnace was two pairs of horizontally arranged electrodes, between which an electric arc was excited. A mixture of ore and coal was passed through the arc combustion zone, whose temperature was 3000 to 3500 ° C. The carbon reduced metal melted and collected on the bottom of an electric furnace. However, the insufficient amount of electricity produced at that time by primitive magnetoelectric generators could not ensure the normal course of the metallurgical process, and the Pichon furnace did not receive practical use.

A significant step in the development of electrothermal devices were the experiments of the English engineer W. Siemens, who received in 1878 - 1879. Several patents for their designs of electric furnaces.

One of these structures was a refractory crucible, through the bottom of which passed a bottom electrode of refractory metal. The second metal electrode, which was cooled by water, was passed through the cap of the crucible. An electric arc was excited between these two electrodes. In another design, the hearth electrode was made of iron and cooled during operation, and the upper electrode was formed from coal. The third design was a crucible with two horizontal electrodes mounted one against the other.

The first electric furnaces for steelmaking were installed, as a rule, in areas where the cheapest electric current could be obtained, using for this purpose the hydropower of the rivers in the vicinity. In 1898, the Italian engineer E. Stassano took a patent for obtaining in the electric furnace a cast forged steel with any carbon content. His furnace was installed in Northern Italy, rich in water resources.

In 1899 the Frenchman P. Eru patented his design for a steel-smelting electric furnace with electrodes located above the bathroom. The first furnace Eru was built in Savoy, in the foothills of the Alps. This city in the south-east of France is still one of the centers of French electrometallurgy.

In 1900 the first induction electric furnace of the Cellin design was launched in Sweden. The most important advantage of the induction furnace in comparison with other electric smelting and heating units is that thermal energy occurs in the heated material itself due to the energy of the electric current passing through the primary winding. Induction furnaces provide the most uniform heating of the metal and eliminates the harmful effects of gases generated in conventional furnaces from the combustion of fuel or coal arc.

The first furnace E. Stassano by its design was similar to a blast furnace. It had a shaft, shoulder straps and was loaded from above through a filling funnel. Two horizontally installed carbon electrodes were introduced into its horn. In further designs, Stassano refused the mine-type furnace. From the old design, only the furnace remained. The new furnace had three pairs of electrodes. Forcing one, Two or all three electric arcs to burn, it was possible to regulate the temperature in the melting space. The charge materials for electric smelting were introduced below the combustion zone of the electric arc.

Several years later, E. Stassano built a rotating electric furnace in Turin. In this case, the axis of rotation deviated from the vertical by some angle, which ensured more efficient mixing of the molten materials on the furnace floor. Steelmaking units of the Stassano design were then built in different countries, their optimum capacity was usually from 0.5 to 3 tons.

Electric arc furnaces, created by Era, Giraud and a number of other designers, have been called stoves with direct heating. In them, the electric current is supplied to the vertically arranged carbon electrode and to the metal located on the bottom of the furnace. The electric arc burns between the electrode and the bathroom. Thus, in furnaces with direct heating, thermal energy is obtained from two sources - from burning the arc and heating the bath due to its resistance to the passing electric current. P. Eru received a patent for single- and three-phase electric furnaces, intended for steel smelting and production of ferroalloys.

In 1912 P. Rennerfeldt (Sweden) somewhat modified and improved electric furnaces E. Stassano. His furnace, which operated on a three-phase current, had three electrodes. One of them was located vertically and passed through the arch of the furnace. The other two were introduced through the walls of the furnace with a slight inclination from the horizontal line. During the operation of the furnace, the arc burning zone was slightly deflected by the vertical electrode in the direction of the bath, providing a higher temperature in the surface layers of the melt materials. Rennerfeldt furnaces are widely used for refining steel and cast iron, as well as for melting copper alloys, nickel, silver and aluminum.

In the early XX century. Professor of the Kiev Polytechnic Institute VP Izhevsky proposed a number of designs of laboratory-type electric furnaces for melting metals and heat treatment. The first such furnace, built in 1901, was intended for remelting a small amount of pig iron with iron scraps or with additives of ore. Ceramic walls were heated by an electric current passing through the electrodes embedded in them. The furnace capacity was only 16.5 kg. The furnace made it possible to obtain a uniform metal, it was compact, it could operate on a constant and alternating current of different voltages. In the following years, the Izhevsk furnaces (with a capacity of up to 100 kg) operated at a number of factories in Ukraine.

1909 can be considered the beginning of industrial production of electric steel in Russia. This year, 192 tons of high-grade steel were smelted at the P. Hera arc furnace, launched at the Obukhov plant in St. Petersburg. In 1911 this furnace gave already 1122 tons of metal. In 1913, four electric furnaces worked at Russian factories, which smelted 3,500 tons of steel per year.

In 1915, at the Motovilikha plant in Perm, the first steel-melting single-phase resistance furnace was started, with the bath heated from the above-placed carbon rods heated by an electric current. This furnace was designed by Russian engineers SS Steinberg and AF Gramolin. In the future similar furnaces with a capacity of 0.75 - 1 t were installed at Zlatoust, Nadezhdin and other Ural plants and successfully carried out military orders during the First World War.

The founder of the creation of electrometallurgy of high-quality steels in our country should be considered a prominent metallurgist NI Belyaev-In 1916, at a small foundry near Bogorodsk (now Noginsk, Moscow Region), he received the first alloyed electric steel. Under the leadership of N. I. Belyaev, the construction of a large plant of quality steels with four direct arc furnaces began. In November 1917, the first electric furnace with a capacity of 1.5 tons was put into operation. The Elektrostal plant was the first major enterprise launched under Soviet power.

Since the very beginning of using electric furnaces in the industry, their advantages have not been doubted by anyone. In electric furnaces a higher temperature was reached than in other steelmaking units, scrap of alloyed steels was easily remelted, it was possible to produce special high-quality alloys with refractory alloying elements with the minimum amount of harmful impurities. Therefore, everywhere, where the possibilities of obtaining a sufficient amount of electric power allowed, electrometallurgy was rapidly developed.

In 1910, 114 electric furnaces operated in all countries of the world. In 1915 there were already 213 of them, and by early 1920, 1025 electric furnaces were melted and 362 units were in the stage of installation and commissioning. In developed countries, rich in electricity, the production of electric steel grew at a particularly rapid pace. In the USA, for example, the production of steel in electric furnaces only for 4 years, from 1914 to 1918, increased from 24 to 800 thousand tons, that is, 33 times. A similar picture was observed in Germany and Canada. During the same period, electric furnaces were widely used for the production of ferroalloys, smelting of non-ferrous metals, and also in the chemical industry for the production of calcium carbide, phosphorus and other products.

Shukhardin S. "Technology in its historical development"