SU1382867A1 - Method of melting high-silicon ferroalloy - Google Patents

Abstract

The invention relates to the field of ferrous metallurgy, in particular to the production of high-silicon ferroalloys. The aim of the invention is to increase the specific productivity of the furnace without changing its capacity while simultaneously increasing the duration of the ferroalloy melting campaign until the furnace stops for repairs and to reduce the content of non-metallic inclusions in the ferroalloy. After discharge from the furnace melt within 0.1-. 0.15 of the total duration of smelting is carried out by melting the charge without loading it to one of the electrodes, then magnesium oxide in the amount of 0.4-1% of the mass of the ore component is melted into the open crucible obtained under the electrode, and then the charge is charged there required top level. After melting is released, the same order of loading materials is repeated on the next electrode. The method makes it possible to increase the duration of the campaign by 1.39-1.55 times, to increase the specific production, - the furnace duration by 1.15-1.2 times and to reduce the carbon content in the alloy by 2-4 times. 1 tab. (L its 00 tc CX) O5

Description

The invention relates to ferrous metallurgy, specifically to the production of high silicon ferroalloys.

The aim of the invention is to increase the specific productivity of the furnace without changing its capacity while simultaneously increasing the duration of the ferroalloy smelting campaign until the furnace stops for repairs and to reduce the content of non-metallic inclusions in the ferroalloy.

The melting of high-silicon ferroalloy begins with the fact that one of the electrodes for 0 to 1-0.15 of the total duration of the melting mixture is not served, but load it to the other two electrodes. During this period of time remaining with the charge near the unloaded electrode, the melt melts down to form an open crucible, into which magnesium oxide (crushed periclase, magnesite powder, broken magnesite brick) is loaded under the electrode in an amount of 0.4-1% by weight - ore was the knockout for smelting. Upon entering the crucible, magnesium oxide appears on the surface of the ferrosilicon remaining after melt injection and under the action of gravity (magnesia of magnesium oxide is 5 g / cm. The density of liquid ferrosilicon, 5 g / cm) passes through it and settles on the lower surface of the carborundum crucible is displaced by ferrosilicon. Magnesium oxide at the bottom of the crucible interacts with carborundum. The products of reduction are CO and Mg, which is dissolved in ferrosilicon in the form. A high concentration of magnesium in the resulting silicide and a low boiling point of magnesium lead to its evaporation, which is facilitated by the formation of CO bubbles, in which the partial pressure of magnesium is low. The resulting CO-Mg gas bubbles open from the bottom of the crucible and rise to the surface of the ferrosilicon melt in the arc zone.

After the magnesium oxide is supplied to the open crucible, the charge is charged until the furnace top is level in the furnace.

Simultaneously with the reduction of silicon, its carbide is formed, which, in contact with droplets of ferrosilicon, enters the melt. ,

CO-Mg bubbles released in the lower part of the crucible prevent ocay f

Carborundum on the walls of the crucible due to the flotation effect, as particles of carborundum (as well as other nonmetallic inclusions), poorly wetted by ferrosilicon, stick to the rising gas bubbles and are carried to the surface of the melt. On the surface of the melt, gas pug zurki burst and particles of carborundum are absorbed by the slag. When melt is released, most of the slag with carborundum is carried with molten ferroalloy from the smelting furnace. Thus, the evolved CO – Mg gas bubbles simultaneously play a dual role — they cleanse ferrosilicon from nonmetallic inclusions and prevent the intensive overgrowth of crucibles, which contributes to an increase in the duration of the campaign for the melting of high silicon ferrosilicon.

The formation of a non-conductive MgO film on the surface of the reducing agent increases the electrical resistance of the charge, which allows the smelting of ferrosilicon at a higher voltage than with ordinary smelting at the same power, i.e. increase active power and reduce reactive power, while increasing the specific productivity of the furnace.

After the smelting is finished and the melt is released from the furnace at the next smelting operation, melting of the charge without loading it under one electrochemical system, introducing magnesium oxide under the electrode into the crucible and then loading the charge on the other electrode, then the third one, and then again at first, etc.

Since the bulk of the smelting metal accumulates in the crucible under the near-fly-through electrode, in order to avoid premature clogging of it with silicon carbide, the campaign begins by stopping the charge charge to this electrode.

If the amount of injected magnesium oxide is less than 0.4% of the mass of the ore hour; and the charge, then the reduction rate of magnesium will increase significantly. which leads to its rapid and full restoration to the loading of a new portion and to the intensive sedimentation of carborundum on the walls and bottom of the crucible, its rapid overgrowing by the carborundum, i.e. to reduce the smelting campaign of ferrosilicon. At a consumption of 1% magnesium oxide, the ingraining of the crucibles occurs and a sharp slowdown in the reduction of magnesium occurs, which also leads to the overgrowth of the crucible with carborundum.

The period of the melted charge near the electrode for 0.1–0.15 duration of melting is established experimentally and is determined by the composition

charge and power used ELEKT-

ropechey for smelting ferrosilicon. It is important that in the process of melting a funnel is formed in an open crucible, ensuring that the specified magnesium oxide does not get into the crucible on the mirror of the melt.

If the period of melting of the crucible without supplying the charge is less than 0, t is the duration of melting, then the opening of the crucible is not sufficient to supply all of the magnesium oxide on its surface.

The lengthening of the melting more than O, 15 the duration of the melting leads to a tightening of the melting without improving the load of magnesium oxide.

The parameters of the melts are given in the table.

Tests of the proposed method of smelting high-silicon ferroalloy are carried out in an industrial furnace with a transformer of 15 MVA. Campaigns for smelting high-silicon ferroalloy according to various options are carried out after conducting melts of ferroalloy with a low silicon content (FS65 grade ferrosilicon). In the three main options of heats (at the boundary and medium parameters) and the well-known variant, FS90f grade ferrosilicon is produced (the lower limit of the silicon content is 87%, the base silicon content is 89%), an additional campaign is carried out (at medium parameters of the proposed technology) of ferrosilicon smelting with barium grades FS85F according to change No. 1 VTT 139-38-86 (the lower limit of the silicon content is 83%, the base content of the sum of silicon and barium is 85%).

As charge materials for the smelting of ferroalloys use quartzite fraction 50-120 mm, coke nut fraction 5-25 mm, charcoal fraction less than 100 mm, coal semi-coke fraction 5-40 mm, used magnesite brick, fraction 5-20 mm (as magnesium oxide), ba ore

Jq

fj

20

25

go, g

35

50

five

|) jtroHyi j 4 | p; | 1c is less than 300 mm (only c.pn slats option 4).

The optimum level of melting for melts is determined in preliminary campaigns for the smelting of ferrosilicon (an increase in the voltage of the more optimal in the melts of the variants leads to a decrease in the electrode planting depth, to an intensive overgrowth of the silicon carbide bottom due to a decrease in the temperature post campaign).

Melting ferrosilicon FS90f is carried out on a mixed charge consisting of 300 kg of quartzite, 80 kg of coke, 30 kg of charcoal, 65 kg of semi-coke, and 20 kg of quartzite is replaced by barite ore in FS85f of ferrosilicon.

The charge is loaded as it melts onto the surface of the top furnace. The duration of each melt is 2 hours. After this time, the furnace is made to release ferrosilicon. After termination of the release from the furnace of ferroalloy in the bottoms of the proposed fitting (options 1-4), about one of the electrodes are penetrated without penetration into the furnaces, respectively, according to options 1.2 (and 4) and 3, for 12, 15 and 18 minutes (0.1; 0.125 and 0.15 of the total duration of melting). As a result, the crucible opens around the electrode and a bricks of magnesite brick is loaded into it, the amount of which for these variants is 27, 50 and 69 kg, respectively (i.e. 0.4, 0.7 and 1% by weight of the ore component — quartzite and barite ore — for smelting). Then, the charge, the amount of which is 0.76, 0.98 and 1.15 colos, respectively, is charged to the electrode before the furnace top is leveling.

The melting of the charge with the subsequent loading of magnesite bo into the crucible, and then the charge begins at each variant of the melting with a circulating electrode with alternating electrodes.

The working voltage level in the trunks of option 1 is the second (145.5 V), in the trunks of options 2-4, the first (150 V). The amount of charge processed for smelting is respectively according to options 22.71; 23.6 and 23.01 Kolosh.

The end of the rumination of smelting ferrolycium is determined by a sharp reduction in the output of the ferroalloy furnace from the furnace until complete cessation due to the intense overgrowth of the bottom of the silicon carbide.

Campaign duration for melting of ferrosilicon according to options 1-3 is 26, 28, and 10 25 days, respectively, for option 4 30 days.

Known melting is carried out on the same composition of the charge, as in options 1-3. The optimum voltage level is one third (141.5 V). The melting of this variant is carried out without melting the mixture under the electrode and loading the magnesium oxide into the crucible, i.e. The charge is fed uniformly throughout the entire heat of melting over the whole furnace top. Consumption of charge 20 for smelting is 17.97 Kolosh, the duration of the campaign is (18 days). A comparison of the melts performed shows that the smelting of ferrosilicon according to the proposed method as compared with the known one is characterized by an increase in the duration of the campaign by 1.39-1.55 times, an increased specific furnace productivity of 1.15- | 1.2 times, reduced content of carbon-39 i kind in the alloy in 2-4 times.

i: S828b76

Claims (1)

Invention Formula The method of smelting high-silicon ferroalloy by a coal-thermal process in an ore-thermal electric arc furnace, including continuous as the charge melts the charge on the surface of the furnace top to the electrodes, periodically discharging the melt from the furnace and pouring it into molds, characterized in that, in order to increase the specific productivity of the furnace without changing its capacity while simultaneously increasing the duration of the ferroalloy smelting campaign until the furnace is shut down for repairs and reducing the content of non-metallic inclusions in the ferroalloy after melting is released, the charge is melted without loading it to one of the electrodes, then magnesium oxide is loaded into the open crucible obtained under the electrode in an amount of 0.4-1% of the mass of the ore component to be melted, and then the charge is loaded there the required level, top and after the release of this melting the same order of loading materials is repeated on the next electrode. The method of smelting high-silicon ferroalloy by a coal-thermal process in an ore-thermal electric arc furnace, including continuous as the charge melts the charge on the surface of the furnace top to the electrodes, periodically discharging the melt from the furnace and pouring it into molds, characterized in that, in order to increase the specific productivity of the furnace without changing its capacity while simultaneously increasing the duration of the ferroalloy smelting campaign until the furnace is shut down for repairs and reducing the content of non-metallic inclusions in the ferroalloy after melting is released, the charge is melted without loading it to one of the electrodes, then magnesium oxide is loaded into the open crucible obtained under the electrode in an amount of 0.4-1% of the mass of the ore component to be melted, and then the charge is loaded there the required level, top and after the release of this melting the same order of loading materials is repeated on the next electrode.