SU998567A1 - Charge for smelting low-silicon ferrosilicon - Google Patents

Description

The invention relates to ferrous metallurgy, in particular, to the fermentation of ferroalloys.

The production of low-silicon ferrosilicon containing 25% silicon has recently increased.

This is becoming increasingly used for the deoxidization of steel and especially for the doping of both conventional and synthetic cast iron. The alloy is usually produced by a slag-free process on a charge consisting of quartzite, iron shavings and coke.

The known charge 1 dp of production of low-silicon ferrosilicon, containing the following components, wt.% Iron chips 49-50 Coke .15,5-16,5

Quartzite29-34

The closest in technical essence and composition of ingredients is the charge 2 for melting low-silicon ferrosilicon, containing the following components, wt.%:

Quartzite33.0-35.5

Iron chips 46.5-49.0, Coke, semi-coke 16.5-19.0 However, the known charge is characterized by high electrical conductivity, which leads to a high seating of the electrodes and a significant loss of silicon in the form of monoxide and silicon carbide.

The high electrical conductivity of the charge is due, firstly, to the fact that it contains more than two thirds of the components that conduct the current at both low and high temperatures (iron chips + coke).

ten

Secondly, the high electrical conduction; the charge of this charge is associated with its dense packing, caused by both high bulk density and the lack of processes leading to loosening of solid matter.

15 charge.

Finally, thirdly, the high electrodischarge of this charge is caused by the fact that it heats up quickly both due to its high electrical conductivity,

20 and in particular due to the reaction of coke with silicon monoxide formed in the high temperature zone by the reaction

SiO + 2С 5ЛО + СО (1)

25

The reaction (i is known to be exothermic. It is accompanied by a significant heat release (LF -18600 cal). As a result, the reaction products 30 are heated to 1700-1800 C,

and the charge on the surface of the furnace is up to 800-1100 C.

The aim of the invention is to reduce the electrical conductivity of the charge at the furnace top and to reduce the loss of silicon,

 This goal is achieved by the hem, which is a mixture for smelting low-grade ferrosilicon, which includes: Quartzite, iron shavings, coke, and additionally contains carbonate manganese ore at the next component solubility, wt.% Quartzite25-32

Iron chips 40-47.5 Manganese ore carbonate - 7-12.0 Coke - 16.5-18.0 Manganese carbonate ore is known to decompose according to the reaction

(eleven)

MPO + CO2

Mpso,

The reaction starts near the surface of the top at 500-55 ° C. It absorbs a significant amount of heat HLN +42000 cal / mol). A lot of heat is spent on heating the released carbon dioxide. When carbonate is decomposed, the charge is loosened, which reduces charge current of the conductivity.

As a result of cooling the mixture with an endothermic reaction (11) and its loosening, the temperature of the upper layers of the solid mixture decreases by 200 ° C, which reduces its electrical conductivity by 1.5-2 times.

In addition, manganese oxide, which forms during the decomposition of carbonates, interacts with silica and impurity oxides of the charge and forms a low-melting liquid-mobile slag. The melting of low-melting manganese silicium is also accompanied by a considerable consumption of heat, and therefore also contributes to the cooling of the solid charge.

On the other hand, this slag, a stack in a furnace furnace, contributes to the destruction of silicon carbides formed in the cold zones of the furnace according to reaction 1).

This leads to a decrease in silicon loss during smelting of ferrosilicon. At the same time, the amount of slag does not change, as the liquid slag in the high temperature zones of the hearth is easily restored, including silicon carbide.

When carbonate-manganese ore is introduced into the mixture, not only the temperature conditions change, but also the composition of the alloy. The content of manganese, in particular, in the alloy increases.

Increasing the manganese content in low percentage ferrosilicon to

4-6% at a silicon concentration of 25% does not prevent its use in steelmaking and, in particular, in the foundry industry. On the contrary, this addition of manganese makes 25% of ferrosilicon magnetic, and therefore facilitates the dosing and supply of ferroalloy to the furnace.

On the other hand, the replacement of ferrosilicon and ferromanganese with such an alloy will make the composition of cast iron more stable and reduce the loss of both cream and manganese in cupola furnaces approximately by half. A further increase in the concentration of arganese in the FS 25 alloy again makes it nonmagnetic.

In addition, at more than 6% manganese content in the alloy, in the production of many grades of cast iron in ichtha for cupola melting, along with the alloy, the production of the proposed mixture containing silicon and manganese has to add low percent ferrosilicon without manganese, which complicates the work of the charge span,

Therefore, the consumption of carbonate ore is limited both by its cooling effect and by the composition of the alloy produced. The manganese content of carbonate ores currently used ranges from 26-31%. With such a variation in the content of manganese in the ore, its consumption in the range of 7.0-12.0% makes it possible to obtain an alloy with a content of 4-6% manganese.

When using rich ore, its consumption is taken at the lower limit. When using a poorer ore closer to the upper limit.

On the other hand, such a consumption of ore sufficiently cools the top of the furnace, without causing additional electricity consumption for the decomposition of carbonates and the reduction of manganese Chexides. ..

The latter is related both to the fact that the electric mode of the furnace is improved, and to the fact that the use of silicon is improved primarily by reducing the amount of slag and reducing the concentration of silicon carbide in it.

Example. In the furnace of 100 kVA and 23 MIA melted alloy FS 25 on the charge of the following compositions:

12 3 4 Known

28

32

34

thirty

47.5 43.0

47

40

, 19.0 18.0 16.5 -18.0

No 12.0 8.0 7.0 experimental 4th series swimming trunks used ore with a content of 31% Mn, in the rest - 27%. In the experiments, alloys of the following composition were obtained: 1 234 5,% 25.2 26.2 25.9 26, 0.7 5.7 4.5 4 ,. .Inclusion; silicon 98% 98% 98 Extraction of manganese 92% 95% 95% Energy consumption 2950 2980 | Not op-He6 energy reduced MILN / 1YAL Planting electrodes when smelting ferrosilicon on a mixture containing manganese ore has improved. The top furnace became colder and worked considerably softer, the gases came out colder and more evenly. The amount of slag did not increase. However, slags became more stable in content, CaO. The content of S4 С in them decreased and fluctuated within 4-5%. The content of MpO in the slag was in the range of 0.3-1.0%. Extraction of silicon in the alloy increased by 2%. The alloys obtained from the experimental ones were used in the manufacture of iron in cupola furnaces. At the same time, the consumption of ferromanganese was eliminated from the cupola blend. The yield of cast iron, which meets the requirements of the technical specifications of the chemical composition, increased in content of manganese by 20% in silicon content of 10%. Thus, the proposed mixture dp for melting low-silicon ferrosilicon makes it possible to: improve the electrical and slag regime of melting FS 25 ferrosilicon / reduce silicon loss during smelting of ferrosilica by 2%; reduce the consumption of Plasma ferrosilicon-deficient ferroalloy chips by about 5%, improve the quality of the alloy produced and save the consumer with silicon and manganese. As the calculations show, when using 100 thousand tons of ferrosilicon obtained from the proposed mixture, one can save -f 10 thousand tons of ferromanganese, which will give an ex. effect over 2 million rubles. Formula of the Invention A mixture for smelting low-silicon ferrosilicon, quartzite, iron chips, coke, which, in order to reduce its electrical conductivity at the furnace's top and reduce silicon loss, it additionally contains carbonate manganese ore in the following ratio of components, wt.% 1 .28-32 Zhelezna quartzite 40.0-47.5 chips Carbonate manganese 7.0-12.0 16.5-18.0 Sources of information taken into account during the examination 1.Ryss MA Ferroalloy production. M., Metallurgists, 1968, pp.157-168 ... 2.Ryss MA production of ferroalloys. M., Metallurgists, 1975, p. 4152 ..

Claims (3)

Claim The mixture for melting low-silicon ferrosilicon, including quartzite, iron chips, coke, characterized in that, with the aim. reducing its conductivity on the furnace top and reducing silicon losses, it additionally contains manganese carbonate ore in the following ratio of components, wt.%: Quartzite Iron Chips Carbonate Manganese Ore Coke Sources. _ taken into account in the examination 1. Ryss M.A. Ferroalloy production. M., Metallurgy, 1968, p. 157-168. 2. Ryss M.A. Production of ferro • alloys. M., Metallurgy, 1975, p. 4952. 7.0-12.0 16.5-18.0