RU2298046C2 - Carbon ferromanganese melting process - Google Patents

Abstract

FIELD: metallurgy, possibly production of ferroalloys.

SUBSTANCE: method comprises steps of loading into melting aggregate charge including manganese-containing raw material, flux, carbon-containing reducing agent; reduction melting; discharging slag and ferromanganese out of furnace. Crucible induction furnace with shaft headpiece is used as melting aggregate. Charge with fraction size 0 - 5 mm and 0 - 16 mm is used; such charge is accurately lumped. Quantity of such charge is to be no more than 50% of the total mass of charge. Before loading to furnace, components of charge are mixed at next relation, mass %: carbon-containing reducing agent, 11.8 - 15.9; flux, 7.9 - 14.0; manganese -containing raw material, the balance. Flux additives provide relation (CaO + MgO)/SiO₂ in final slag equal to 1.35 - 1.80 and content of Al₂O₃ equal to 8 - 20% in slag before adding aluminum to it. Before discharging slag, aluminum is added to it in quantity providing content of Al₂O₃ in final slag equal to 13.0 -30.0%. Invention allows melt carbon ferromanganese at high degree (93 - 97%) of manganese extraction due to reducing its losses together with dump slag and at escaping.

EFFECT: improved degree of manganese extraction, lowered losses of manganese.

3 cl, 1 ex, 3 tbl, 5 dwg

Description

The invention relates to the field of ferrous metallurgy and can be used in the production of ferroalloys, in particular in the production of carbon ferromanganese.

A known method of producing ligatures by the method of aluminothermy (autosw. SU No. 1713964, MKI: C 22 C 33/04, 1992), which includes loading into the electric furnace a charge consisting of manganese-containing, silicon-containing materials, fluxing additives, melting, reduction with aluminum and the release of the melt, the charge together with aluminum is loaded into the crucible of the induction furnace, preheated to 900 ° C, and after the melting of the charge, the melt is kept in the crucible for 5-10 minutes at 1400-1450 ° C.

The disadvantages of this method is the use of an expensive reducing agent - aluminum and obtaining an alloy with a low content of manganese.

A known method of smelting ferromanganese in an induction furnace (ed. St. USSR No. 521340, MKI: C 22 C 33/04, 1976), including the preliminary smelting of converted silicomanganese in an ore thermal furnace, pouring silicomanganese into an induction furnace, heating the melt to 1550 - 1600 ° C and subsequent additives of a mixture of manganese ore and lime.

The disadvantages of this method are the complexity (two-stage), as a result of this, the high energy intensity of the process and the loss of manganese in the fly (evaporation) of 6-10%, in the production of redistributed silicomanganese.

A known method of smelting manganese alloys by the thermal reduction of manganese, iron and other elements from ore and additives containing these elements in oxide form (ed. St. USSR No. 443102, MKI: C 22 C 33/00, C 22 C 7/06, 1974 d), when at the end of the melting one, two or more electrodes are lifted and a mixture of silicon-containing materials and fluxes is introduced into the formed sub-electrode cavities.

The disadvantage of this method is to obtain an alloy with a high silicon content of about 18% and a loss of manganese in the fly 3-10%.

The known method adopted for the prototype of smelting carbon ferromanganese in an ore reduction furnace by flux method (Gasik M.I., Lyakishev N.P. Theory and technology of electrometallurgy of ferroalloys. - M .: SP Intermet Engineering, 1999, pp. 353-356 ), including the loading into the melting unit of a charge consisting of manganese raw materials, a carbon reducing agent, flux, reducing smelting, the release of slag and ferromanganese from the furnace.

The disadvantages of this method are the low extraction of manganese into the alloy (up to 80%), due to the loss of manganese (11-20%) and its losses with dump slag (more than 13%), as well as the low process speed associated with the large size of the charge materials (5 -150 mm).

The objective of the invention is to increase the degree of extraction of manganese in the alloy by reducing its loss with waste slag and fly.

This task is achieved by the fact that in the method of smelting carbon ferromanganese, comprising loading a charge consisting of manganese raw materials, flux, carbon reducing agent, reduction smelting, exhaust slag and ferromanganese from the furnace, according to the invention, a crucible induction furnace with mine extension, while the charge is loaded with a fractional size of 0-5 mm, and the mixture with a fraction of 0-1.6 mm is further pelletized or packaged and its amount should not exceed 50% t total weight of the charge, wherein before loading the charge into the furnace is mixed in the following ratio, wt.%:

Carbon Reducer 11.8-15.9 Fluxing agent 7.9-14.0 Manganese-containing raw materials Rest.

In addition, flux additives provide the ratio (CaO + MgO) / SiO ₂ in the final slag equal to 1.35-1.80, and the content of Al ₂ About ₃ in the slag before the additive Al in the amount of 8-20%.

In addition, before the release of the slag, aluminum is added to it in an amount providing an Al ₂ O ₃ content in the final slag of 13.0-30.0%.

Using for smelting ferromanganese induction furnace with a mine extension allows you to reduce the manganese emission from 11-20% (prototype) to 0.5-1.8%.

Pre-mixing of the components of the charge before loading into the furnace allows to increase the speed and completeness of the recovery processes.

The use of materials, the fraction size of which is more than 5 mm, in this process is impractical due to a decrease in furnace productivity, an increase in the fractional size of the charge materials leads to a decrease in the area of the reaction surface, as a result of which the reduction processes are greatly slowed down and the melting time increases.

The use of materials with a fraction of less than 1.6 mm leads to emissions from the furnace. Rounding or packing materials with fractions smaller than 1.6 mm prevents emissions. With an increase in the fraction of “fines” in the charge (charge materials of which fractions <1.6 mm) from 0 to 50%, the degree of extraction of manganese into the alloy increases, this is due to an increase in the reaction surface area of charge materials, which increases the speed and completeness the course of recovery processes. A subsequent increase in the share of "fines" in the charge leads to a decrease in the degree of extraction of manganese due to increasing emissions of the charge, a fraction of less than 1.6 mm from the furnace. When using both anthracite and grade Zh coal as a reducing agent, the degree of manganese extraction increases in the interval from 0 to 50% of the "fines" in the charge, and in the interval from 50 to 100% of "fines" in the charge, the degree of manganese extraction decreases.

Increasing the basicity of slag ((CaO + MgO) / SiO ₂ ) to 1.35-1.8 leads to easier reduction of manganese into the alloy due to an increase in MnO activity in the slag, but increasing the basicity of the final slag above 1.80 leads to its excessive viscosity, due to which the process of reducing manganese from the slag is inhibited and the slag discharge from the furnace is difficult. When the final slag basicity is less than 1.35, the degree of manganese extraction into the alloy decreases due to insufficient MnO activity in the slag.

The addition of fluxes containing aluminum oxides improves the slurry fluidity, increases the MnO activity in the slag, which leads to an improvement in the conditions for the transition of manganese from slag to metal. In the absence of these additives, the slag contains 4.5-5.5% Al ₂ O ₃ , while it is thick, slightly reactive, and subsequent reduction of manganese from it will be difficult. Therefore, an increase in the content of Al ₂ O ₃ in the slag, before Al is added to it, up to 8%, makes it possible to increase the reactivity of the slag, an increase in the content of Al ₂ O ₃ above 20% is impractical, because leads to an increase in the multiplicity of slag and a decrease in furnace productivity.

Additive Al in the slag can increase the degree of extraction of manganese. According to the results of experimental swimming trunks it is clear that the optimal content of Al ₂ O ₃ in the final slag is 13-30%. When the content in the final slag is less than 13% Al ₂ O _{3, the} degree of extraction of manganese into the alloy and the productivity of the furnace are reduced. An increase in the content of Al ₂ O ₃ in the final slag up to 30% leads to maximum extraction of manganese. A further increase in the content of Al ₂ O ₃ does not lead to an increase in the degree of extraction of manganese in the alloy.

- уголь марки Ж, • - антрацит). На фиг.4 показана зависимость степени извлечения марганца от основности шлака ((СаО+MgO)/SiO₂). На фиг.5 показана зависимость степени извлечения марганца от содержания в конечном шлаке Al₂О₃.The method is illustrated by the following figures: figure 1 shows an induction furnace. Figure 2 presents the dependence of the reaction surface area of the charge materials on the size of their fractions (data are for a vessel with a volume of 5 dm ³ , the numbers at the points show the reaction surface area of the charge materials). Figure 3 shows the dependence of the degree of extraction of manganese on the amount of fines in the charge for different reducing agents (

- coal grade Zh, • - anthracite). Figure 4 shows the dependence of the degree of extraction of manganese on the basicity of the slag ((CaO + MgO) / SiO ₂ ). Figure 5 shows the dependence of the degree of extraction of manganese on the content in the final slag Al ₂ About ₃ .

The method is as follows.

In a graphite crucible of an induction furnace 1 heated to 800–1600 ° C, with a removable shaft extension 2, a pre-mixed charge of a fraction of 0-5 mm is loaded, a charge of fractions of 0-1.6 mm is fed into a packaged furnace, and its quantity should not exceed 50 % of the total mass of the charge. The size of the extension shaft is chosen so that its volume is 2-2.5 times the volume of the crucible. The composition of the loaded charge (wt.%): Carbon reducing agent 11.8-15.9; flux 7.9-14.0; Manganese-containing raw materials - the rest. After completion of the recovery processes and the formation of liquid slag, Al is added to it. Then, after holding for 2-3 minutes, metal and alloy are released.

An example implementation of the proposed method.

Preparation of charge materials for smelting.

Burden materials (manganese-containing raw materials, flux, carbon reducing agent) were crushed to a fractional size of 0-5 mm and dispersed into fractions of 0-1.6 and 1.6-5 mm. Then, separate mixing of the charge materials of the selected fractions was carried out, and the charge materials with a fraction of 0-1.6 mm were packaged.

Melting. The IST-016 induction crucible furnace, with a mine extension, was charged with a mixture of charge materials with a fraction of 0-5 mm, consisting of 200 kg of manganese ore, 29.8 kg of anthracite, 20 kg of lime, 1.5 kg of bauxite. Burden materials, the fraction size of which was less than 1.6 mm, were fed into the furnace in batches, and their amount did not exceed 50% of the total mass of the charge. The chemical composition of the charge materials is given in table 1. After the formation of liquid-mobile slag, 5.1 kg of aluminum was added to it, then, after holding for 2 minutes, the alloy and slag were drained. As a result of melting lasting 35 minutes, 102.6 kg of alloy and 59.6 kg of slag were obtained.

Table 1
The chemical composition of the charge materials Materials The content of elements,% MnO ₂ MnO SiO ₂ Al ₂ O ₃ Cao MgO P ₂ O ₅ Fe ₂ O ₃ S moisture FROM ash volatile yield CO ₂ SO ₃ TiO ₂ Na ₂ O K ₂ O Manganese ore 58.0 10.7 8.8 2.18 2.18 1,0 0.09 8.57 0.01 8.47 Anthracite 1,0 91.2 4.8 3.0 Anthracite Ash 28,2 15.0 7.85 3.95 0.15 33.9 7.7 0.7 1.31 1.28 Lime 1,0 1,0 92.0 2.0 1,0 3.0 Bauxite 9.81 61.3 2,33 0.08 2,31 0.1 rest 2.7

The chemical composition of the alloy and slag are given in tables 2 and 3.

table 2
The chemical composition of the alloy The content of elements,% Mn Si FROM S P Fe Alloy 81.7 0.82 5.91 0.012 0.064 rest

Table 3
The chemical composition of the slag The content of elements,% MnO Al ₂ O ₃ Cao MgO SiO ₂ Slag 9.78 26.41 32.04 4.12 25.5

Data analysis shows that when implementing this method, it is possible to increase the degree of extraction of manganese from 80% (according to the prototype) to 93.23%, and with a more complete recovery of manganese from slag and up to 97%, it is possible to use manganese ore with a lower content manganese than in the method adopted for the prototype. Due to the fact that any solid carbonaceous reducing agent is suitable for the inventive method, the need for expensive metallurgical coke is eliminated.

Thus, it is shown that the proposed method can be smelted carbon ferromanganese with a high degree of extraction of manganese (93-97%).

Claims (3)

1. The method of smelting carbon ferromanganese, including loading into the melting unit a charge consisting of manganese-containing raw materials, flux, carbon reducing agent, reduction smelting, slag and ferromanganese discharge from the furnace, characterized in that a crucible induction furnace with a shaft extension is used as a melting unit, load the mixture with a fractional size of 0-5 mm, while the mixture with a fraction of 0-1.6 mm in an amount of 50% of the total mass of the mixture is additionally pelletized or packaged, and before loading into the melting unit the mixture is mixed in the following ratio of components, wt.%: Carbon Reducer 11.8-15.9 Fluxing agent 7.9-14.0 Manganese-containing raw materials Rest 2. The method according to claim 1, characterized in that the addition of flux to the mixture provides a ratio (CaO + MgO) / SiO ₂ in the final slag of 1.35-1.80 and an Al ₂ O ₃ content _of 8-20% in the slag before an additive in it aluminum. 3. The method according to claim 1, characterized in that before the release of the slag, aluminum is added to it in an amount providing an Al ₂ O ₃ content in the final slag of 13.0-30.0%.

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