SU1534086A1 - Method of melting manganese-containing ferroalloys - Google Patents

Abstract

The invention relates to ferrous metallurgy, in particular to the preparation of manganese ore raw materials and the smelting of ferroalloys. The aim of the invention is to increase the recovery of manganese, reduce the phosphorus content in the alloy and the specific energy consumption due to an increase in the electrical resistance of the charge. The method of smelting manganese ferroalloys includes heating a mixture containing manganese ore raw materials and a reducing agent, loading the charge into an electric furnace and smelting. As the reducing agent, when heating the mixture, silicon carbides with carbon are used in an amount that provides a ratio in the silicon carbide mixture to manganese from 0.01 to 0.15. The mixture is heated at a rate of 100–200 ° C / min. to a temperature of 800 ° C and at a speed of 30-75 ° C / min. to the softening temperature of manganese ore raw materials. The smelting of ferroalloys is carried out at a residual content of 0.1-3.0% silicon carbide and 0.1-3.0% carbon in the charge. The use of the method makes it possible to reduce the phosphorus content in the alloy by 2–9%, and to reduce the specific electric power consumption for melting the alloy by 40–80 kW ^. h / t, increase the extraction of manganese in the alloy by 0.4-4.0% and increase the electrical resistance of the charge. 1 tab.

Description

Ferrous alloys are produced at a residual content of 0.1–3.0% silicon carbide and 0.1–3.0% carbon in the charge.

The physico-chemical nature of the proposed method for smelting manganese ferroalloys is as follows.

When manganese ore is heated (roasted) in the presence of a mixture of silicon carbide with carbon, silicon carbide, metallic silicon, silica and carbon play the role of a reagent displacing phosphorus from manganese raw materials. Moreover, the dephosphorization proceeds in a solid phase state without forming a liquid phase (metallic or oxide).

In a mixture of silicon carbide with carbon, silicon carbide and carbon are evenly distributed in elementary volumes and provide a significant increase in the rate of reduction reactions, increase the resistance of the furnace bath and improve other equipment-economic indicators.

In the proposed method of smelting manganese ferroalloys, silicon carbide interacts with oxides in direct contact. Silicon and manganese transition into alloy by reaction

mMnO + nSiC

M4nSln

+ CO

As a result, the slag ratio is reduced and, as a result, the loss of manganese and silicon with slag oxides is reduced.

Along with this advantage of the method is a reduction in the CO output from the reaction zone, which makes it possible to increase the phosphorus content in the exhaust gases, the reduction of 1 mol of Ca (PO4) 2 with silicon carbide requires a loss of 652.0 and 1377 kD of heat in carbon.

All components of the carbon-carbide mixture are useful in the smelting of manganese alloys, since they increase the electrical resistance of the charge and improve the thermodynamic and kinetic conditions for the reduction of manganese.

Silicon and silicon carbide carbon are involved in the reduction of manganese oxides.

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The use of calcined manganese raw materials with a residual content of silicon carbide and carbon is a promising direction for the development of technology for the production of manganese alloys. Residual silicon carbide and carbon, which are in close contact with manganese oxides, are more active reducing agents that contribute to the reduction of elements even in the upper horizons of the furnace. The presence of residual silicon carbide and carbon in the manganese raw material makes it possible to increase the operating voltage and reduce the power consumption by increasing the cos1. The increase in the specific electrical resistance of the charge materials due to the residual content of silicon carbide causes a deep fit of the electrodes, therefore, allows to reduce the loss of manganese by evaporation.

It has been established that the rate of reduction of manganese oxide by the residual content of silicon carbide and carbon increases, and, if the rate of reduction by ordinary water, the rectifier rapidly decreases with increasing temperature, the residual silicon carbide and carbon actively interact with the oxides and P further.

In this way, the use of manganese raw materials with a residual content of silicon carbide and carbon opens up new additional opportunities in electrometallurgy of manganese.

The ratio of SiC / Mn when using the proposed method should be in the range of 0.01-0.15. With an insufficient amount of SiC (SiC / Mn Ј. 0.01) the fly of reduced phosphorus is insignificant. An excessive amount of SiC (SiC / Mn 0.15) in the charge leads to the dilution of the manganese concentrate. As a result, the degree of dephosphorization of the concentrate is reduced.

The best technical and economic indicators of the smelting of silicon manganese are achieved with a residual content of 0.1–3.0% SiC in the manganese ore raw material and 0.1–3.0% carbon. By reducing the amount of residual silicon carbide in manganese ore raw materials (below 0.1 wt.%) The necessary increase in the electrical resistance of the charge is not achieved, there is no decrease in the specific energy consumption,

since it is not possible to increase the working voltage and increase the balance.

An increase in the amount of residual silicon carbide (above 3.0 wt.%) Leads to an increase to an unacceptable amount of silicon in the alloy, which is limited in some manganese alloys.

By reducing the amount of residual carbon in manganese feedstock after heat treatment together with the carbide coal mixture (below 0.1 wt.%), There is no noticeable improvement in the process of manganese recovery, there is no increase in the degree of manganese recovery. I

An increase in the content of residual carbon in manganese ore raw materials (above 30 wt.%) Contributes to an increase in the electrical conductivity of the charge, which causes a deterioration of the technical and economic indicators of the smelting process.

The process of dephosphorization of manganese ore raw materials begins to actively proceed after 800 ° C. In this case, the rate of temperature rise for a more complete process of dephosphorization should be in the range of 30-75 ° C. In this regard, the rate of temperature rise to 800 ° C, when the process of defosguration of the charge is not yet proceeding, is 100–200 ° C / min and is determined by the possibility of the firing unit.

The rate of temperature rise after 800 ° C less than 30 ° C / min is impractical because the productivity of the process decreases without a proportional increase in the process of dephosphorization. When temperatures rise after 800 ° C at a rate of more than 75 ° C / min, the process of dephosphorization proceeds incompletely.

Under identical conditions, I test the proposed and known methods.

Carbonate concentrate containing, May. %: Mp 28.1; Si02 16.7; Fe 2.0; CaO 18.4; Mr, 0 3.3; P 0.197; R / Mp 0.00701, mixed with the carbide-coal mixture and agglomerate it (option 1, limestone method), and in the second series of experiments, the same mixture is heated in an electric furnace to 800 C at a rate of 150 ° C per minute and then at a speed of 50 ° C per minute to soften manganese concentrate temperature.

P and Mn are determined in the resulting sinter and concentrate, calcined with a carbide coal mixture.

The degree of dephosphorization of the concentrate is calculated by the formula

h1 P / MPoEC .c-ta-R / Mn «x

100%.

k-t

five

0

five

0

five

0

The test results are presented in the table.

The agglomerate and calcined concentrate are used for smelting manganese in an electric furnace of 160 kVA.

As the test results show (table), the most stable electric mode is observed during smelting according to option 3-5, the electrodes are deeply seated in the furnace, the melt comes out easily, it is easily mobile

When testing a known variant and beyond the limits of SiC / Mn ratios, there is some disorder in the smelting process. The melt in the furnace is viscous, the electrodes are sitting high, the furnace top is sintered as a result of this, all technical and economic indicators deteriorate.

Thus, the use of the proposed method for smelting manganese ferroalloys makes it possible to reduce the phosphorus content in the alloy, to increase the electrical resistance of the charge and to extract manganese.

In addition, the invention makes it possible to efficiently dispose of waste electrode and abrasive plants.

Claims (1)

Invention Formula A method of smelting manganese ferroalloys, including heating a mixture containing manganese ore raw materials and a reducing agent, loading the mixture into an electric furnace and smelting, characterized in that, in order to increase the recovery of manganese, reduce phosphorus in the alloy and the specific energy consumption due to an increase in electrical resistance of the mixture, as a reducing agent when the mixture is heated, a mixture of silicon carbide with carbon is used in an amount that provides a ratio of silicon carbide to manganese in the mixture of 0.01-0.15, while the mixture is heated at a rate of 100–200 ° C / min to 800 ° C and then at a rate of 30–75 ° C / min to the softening temperature of manganese ore 15340868 raw materials, and the smelting of ferroalloys is carried out at a residual content of silicon carbide and carbon in the mixture of 0.1-3.0%, respectively. SiC / Mn ratio in charge0, 009 0.01 0.08 I 0.15 0.16