KR20020052520A - Method of low-carbon ferromanganese(LCFeMn) manufacturing by recycling dust containing manganese - Google Patents

Abstract

PURPOSE: A method for manufacturing low-carbon ferromanganese(LCFeMn) is provided to minimize oxidation loss of manganese by controlling infiltration depth of an oxidizer into molten metal, and increase product recovery ratio by constantly maintaining refining temperature and supplementing oxidation loss of manganese. CONSTITUTION: The method for manufacturing low-carbon ferromanganese(LCFeMn) by recycling collected dust containing manganese comprises the processes of continuously charging high-carbon ferromanganese into a converter enabling vertical and horizontal blowings at the same time by an oxygen blowing lance(2) and a horizontal blowing tuyere(3); blowing oxygen into an oxidizer through the oxygen blowing lance; blowing a mixed gas of oxygen and nitrogen or argon, and nitrogen or argon gas into inner and outer pipes of the horizontal blowing tuyere having a double pipe structure positioned on the side wall of the converter during the whole process time; and refining high-carbon ferromanganese by injecting calcium oxide into the oxidizer and injecting silicon manganese alloy or ferrosilicon into a reductor, wherein the method further comprises the process of injecting dust lumped after temperature of molten metal(5) is increased to the temperature range of 1600 to 1850 deg.C or more onto all over the oxidizer in an amount of 10 to 20 wt.% of molten metal during the oxidizer operation.

Description

Manufacturing method of low carbon ferromangan by recycling dust collecting dust {Method of low-carbon ferromanganese (LCFeMn) manufacturing by recycling dust containing manganese}

The present invention relates to a method for producing low carbon ferro manganese which can improve the recovery rate of metal components, and in particular, by controlling the penetration depth of the oxidizer to minimize the oxidation loss of manganese and solidifying dust in the furnace during refining. The present invention relates to a method for increasing the product recovery rate by refining the refining temperature and replenishing the manganese lost in oxidation.

Medium carbon ferro manganese can be produced by the silicide method or converter method, but when the low carbon ferro manganese is produced by the silicide method, an electric furnace is used, so the power consumption is too large and it is difficult to control the silicon component, Is somewhat advantageous.

However, in the case of producing low-carbon ferro-manganese by the converter method, the vapor pressure of manganese increases due to the rapid temperature rise in the area where oxygen and the molten metal directly contact, and the manganese easily evaporates, and foaming occurs in the slag according to the intake conditions. (slag foaming) occurs to reduce the recovery of the metal component occurs.

Therefore, in order to solve such a problem in the related art, as specified in Patent No. 129282, the ratio L / H value of the penetration depth of the melt is in the range of 0.3 to 0.5, and the intake oxygen is 150 to 250 Nm ³ / for 1 ton of the melt. It is blown into the oxidizer for 20 to 30 minutes at a flow rate of time, and the mixed gas (1: 1 to 1: 4 weight ratio) and nitrogen or argon gas of oxygen and nitrogen or argon, respectively, in the inner tube and the outer tube through the double tube structured crosswinding tuyer. Was blown, but oxygen was blown from 10 to 30 Nm ³ with respect to 1 ton of the molten metal, and nitrogen or argon gas was blown from 5 to 10 Nm ³ with respect to 1 ton of the molten metal throughout the process. In order to suppress the slope, the slack composition of the oxidizer was kept as low as possible.

However, in the preparation of low carbon ferro manganese, which requires lowering the carbon content to 0.5 wt% or less, the above two methods have the following problems.

end. When the ratio L / H of the molten metal penetration depth is in the range of 0.3 to 0.5, excellent operation results can be obtained for the production of medium carbon ferro-manganese having a carbon content of 1.0 to 2.0 wt%, but low carbon having a carbon content of 0.5 wt% or less In the production of ferro-manganese, the temperature of the molten metal increases rapidly during the deodorization, thereby increasing the steam loss.

I. If the basicity of the slack composition of the oxidizer is kept as low as possible, the slope can be suppressed, but the refining temperature of the oxidizer is excessively increased and the vapor loss of manganese is increased.

All. The condition of "A" is also related to maintaining the temperature in the furnace and the proper decarburization efficiency, so it is impossible to control volatilization.

Therefore, the present invention solves the problems of the prior art described above, and when manufacturing low carbon ferro manganese, while maintaining the proper decarburization efficiency easily lowered the refining temperature, suppressing the slope and replenish the manganese volatile fraction by an appropriate method The purpose is to obtain a method for increasing the recovery rate.

1 is a process chart of a method for manufacturing a low carbon ferro manganese converter;

Figure 2 is a schematic diagram of a composite blowable low carbon ferro manganese production facility for the present invention.

(Explanation of symbols for the main parts of the drawing)

1 ... Magnesia Carbon (MgO-C), Magnesia Chromium (MgO-Cr) Refractory,

2 ... fraud lance, 3 .... fraud tuyer,

4 ... slack, 5 ... molten metal,

6. Melt penetration depth.

In order to achieve the above object, in the present invention, by reducing the ratio L / H value of the molten metal penetration depth in the range 0.2 ~ 0.3 it was possible to suppress the volatilization of the molten metal. That is, 1) the number of holes in the lance nozzle was increased, 2) the injection angle was increased, and 3) the gap between the melt and the lance was increased to increase the flash point / bath diameter value, thereby reducing the volatilization loss of manganese. However, the operating conditions of 1) to 3) are also related to the temperature maintenance and the proper decarburization efficiency in the furnace, so there is a limit to the adjustment. Therefore, it is necessary to supplement manganese volatiles in an appropriate way. It was noted that supplementing manganese by incorporating the agglomerated dust of ferroalloy furnaces and refining furnaces was most advantageous in terms of environmental and economical aspects. .

In the present invention, the change of utility of L / H value and the utility of agglomerated dust as a charge were verified by the following method.

After charging the high carbon ferro-manganese molten metal into the refining converter that can be stowed and stolen, the oxygen gas is injected through the wicking lance and at the same time the inert tube such as oxygen, nitrogen, or argon as the inner tube of the double tubing. A mixed gas with a gas is blown outwardly with an inert gas such as nitrogen or argon to lower the carbon content in the molten metal. At this time, dust of the solidified ferroalloy electric furnace and the refining furnace was introduced. When the molten metal reaches the predetermined carbon content, the blowing of the oxygen is stopped and the molten metal is flowed only by the gas of the gas, and the manganese oxide is recovered by charging silicon manganese alloy and ferrosisil through the raw material inlet at the top of the furnace into the converter.

At this time, the optimum value was obtained by adjusting the L / H value by changing the hole number, injection angle, gap between the melt and the lance, and comparing the utility by changing the input time and the input amount of the solidified dust.

While changing the L / H value and the timing and amount of the solidified dust during operation, the vapor loss of manganese in the oxidizer and manganese recovery in the reducer were observed. I came up with a method.

Low carbon ferro manganese suitable for the purpose of the present invention is prepared in the temperature range of 1,550 ~ 1,850 ℃. At this time, the decarburization reaction when oxygen is blown into the high carbon ferro-manganese molten metal can be expressed as follows.

MnO + C = CO + Mn

LogK = -11600 / T + 7.623

The temperature dependence of the reaction is that oxygen blown to oxidize manganese first below the critical temperature Tc, but carbon is first oxidized above Tc to enable the decarburization reaction as described above. Increasing above will minimize the loss of manganese. However, if the temperature is excessively high, the vapor pressure of manganese is increased, so that manganese is evaporated, and thus there exists a temperature range suitable for decarburization of high carbon ferro-manganese, and in the case of low carbon ferro-manganese, it has a temperature range of 1,550 to 1,850 ° C. When efficient decarburization is possible.

The temperature of the melt is controlled by the blowing conditions of oxygen through the upper lance. In the present invention, 15 tons of actual production test, the depth of the irregularities (hereinafter referred to as "melt penetration depth") generated on the molten surface by the injection of fresh oxygen is found to be the most important factor in the temperature of the molten metal It was. The melt penetration depth is represented by the following equation.

L = L _h exp (-0.78 × h / L _h )

L _h = 63.0 [Kq / (nd)] ^2/3

L: molten metal penetration depth, L _h : molten metal penetration depth at h = 0, h: distance between the upper lance and the molten metal surface,

Q: oxygen flow rate, n: number of nozzles, d: nozzle diameter, k: correction constant

When the penetration depth of the melt is smaller than the appropriate value, the flow of the melt is weakened, and the injected oxygen heats only the surface of the melt, so that it takes a long time for the inside of the melt to rise above 1,550 ° C., thereby reducing the reaction efficiency. The greater the penetration depth of the melt, the better the flow of the melt and the easier temperature control, but the more the melt is splashed out of the furnace, resulting in a lower manganese recovery rate. Therefore, it is possible to expect excellent decarburization efficiency and recovery rate by adjusting the penetration depth of molten metal in an appropriate range.

In the present invention, the number of holes of the lance nozzle is increased from three to five, and the injection angle is 9 to 12 degrees, and the distance between the molten metal and the lance is increased during the operation of low carbon ferromangan with a carbon content of 0.5 wt% or less. Increases the flash point / bath value and maintains the ratio L / H of the melt penetration depth to the total melt depth in the 0.2-0.3 range, which is smaller than the conventional 0.3-0.5 range, thereby reducing the volatilization loss of manganese to more than 85%. Low carbon ferro manganese can be produced with recovery.

The deodorizing oxygen is blown for 25 to 35 minutes at a flow rate of 100 to 300 Nm ³ / hour for 1 ton of molten metal. According to the present invention, a mixed gas of oxygen and nitrogen or argon (1: 1 to 1: 4 weight ratio) and nitrogen or argon gas are respectively blown into the inner tube and the outer tube through the double-pipe structured tubing, but oxygen is the molten metal 1 10 to 30Nm ³ with respect to the tone, wherein the nitrogen or argon gas is blown over the 5 to 10Nm ³ the entire process with respect to the molten metal ton. When the intake of the oxygen is stopped, the mixing ratio of the gas to be fed through the inner tube of the gas is changed to 1: 5 weight ratio, and the reduction machine operation to recover the ferro-manganese is added by adding quicklime, silicon manganese alloy or ferrosilicon. .

In the present invention, the dust of the ferroalloy furnace and the refinery furnace (hereinafter referred to as " solidified dust ") which has been agglomerated during the operation of the oxidizer is introduced to suppress the slope occurring in the oxidizer, keep the refining temperature constant, and volatilization loss. Manganese supplemented to increase the recovery rate.

Dust is there the form of a most _{Mn 3 O 4, Mn 3 O} 4 is added when the molten metal leads to the following dissociation reaction.

Mn ₃ O ₄ => 3 MnO + 1/2 O ₂

The reaction occurs at a relatively high temperature, so accurate measurement of the generated temperature is difficult, but considering the free energy, it is estimated to occur around 1,500 ° C. Accordingly, the dust is supplied not only manganese but also surplus oxygen. When decarburization efficiency is low in the low temperature region, the excess oxygen oxidizes Fe first, so that a high temperature condition of a certain level or more is required to efficiently reduce dust. It can be seen that.

In the present invention, it was found that the melt temperature and the input amount of the dust injection timing is an important operating condition, since 10 to 20% by weight of dust in the molten metal is continuously maintained throughout the oxidizer after the temperature during the oxidizer operation rises to 1,600 to 1,850 ° C or more. The best results were obtained when the solution was added. While the operating temperature at the time of injecting the dust is higher than 1600 ° C, the introduced dust is reduced at a high rate, whereas if the molten metal temperature is excessively increased, the steam loss of manganese due to oxygen blowing is increased and the recovery rate is reduced. In addition, when dust is added in a relatively low temperature region of less than 1,600 ℃, the above reaction does not occur is not preferable.

In the reducer, only the flow of the molten metal by the stolen gas exists, so it is important to establish proper flow conditions. In the present invention, it can be seen that the ratio of the depth H of the total melt and the height h of the stowing tuber is the most important operating condition among the reducing flow conditions. When the h / H value is in the range of 0.2 to 0.3, the best operation result can be obtained. there was. If the h / H value is more than the appropriate range, there is a stagnation zone in which the flow of the molten metal does not reach, the chemical composition of the molten metal in the reaction vessel is non-uniform, not only increases the carbon concentration of the final product but also reduces the manganese recovery, If the h / H value is lower than the appropriate range, the gas being brought into contact with the furnace wall due to the increase in the melt pressure, and the refractory in the vicinity of the gas duct is severely damaged.

Throughout the entire reaction, the composition and loading conditions of the preparation are closely related to the slope. In the present invention, when the slope generated during the decarburization of high carbon ferro-manganese appears slag foaming due to the CO gas bubbles generated by the decarburization reaction at the slag and the metal interface, in order to prevent this, It was found that the basicity of the slack composition should be kept as low as possible. Accordingly, in the present invention, after the temperature rises to 1,600 to 1,850 ° C during the operation of the oxidizer, a portion of the solidified dust and quicklime is continuously added to the end of the oxidizer, and then the remaining amount of quicklime is added just before the transition to the reducing machine. Slope of the oxidizer is suppressed, and in the reducer, smooth reduction of manganese is possible. At this time, the total amount of quicklime added is 10-20% by weight of the molten metal, and 1/3 of the total input amount is added to the oxidizer together with the solidified dust, and the remaining 2/3 is added immediately before the transition to the reducing machine.

When the quicklime is added immediately before transition to the reducing machine, dolomite and fluorspar may be added together in the form of a single or a mixture, where dolomite and fluorspar are used effectively at 3 to 7% by weight of the total weight of the quicklime, respectively. to be. The amount of silicon manganese alloy or ferosilicon introduced into the reducing machine as the reducing agent is preferably such that 50 to 100 kg of silicon per ton of molten metal.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

(Example)

10 tons of high-carbon ferro-manganese, which reduced 20 tons of manganese ore, 2 tons of dolomite and 4.2 tons of carbonaceous material to 22,000KWH, was charged into a converter containing MgO-C-based refractory. The molten metal had the composition shown in Table 1 below, and charged with fresh oxygen with a lance attached to a five-hole nozzle at the end after charging, and made of a double tube at a height equal to 1/5 of the total height of the molten metal from the bottom of the furnace. Two percolating tuyers were installed at an angle of 60 °, but a mixed gas of oxygen and argon was blown into the inner tube and argon gas was blown out from the outside. The initial flow rate of fresh oxygen was maintained at 2,500 Nm ³ / hour for 15 minutes, after which 10 minutes were 2,000Nm ³ / hour, and the next 10 minutes were maintained at 1,500Nm ³ / hour, after which the blowing of oxygen was stopped and reduced. In addition, 800Kg of quicklime was added as a preparation. During oxidizer operation, the lance height was adjusted so that the melt penetration depth was in the range of 25% of the total melt height. The composition of the gas for the first 15 minutes of the oxidizer was made to have an oxygen: argon flow rate ratio of 1: 2, the following 10 minutes were changed to 1: 3, and the subsequent 10 minutes was set to 1: 4. The amount of fresh oxygen was maintained at 8%. At this time, 1 ton of agglomerated dust was continuously added so that the temperature of a molten metal was maintained at 1,750 degreeC. As a rejuvenating agent, quicklime was added and divided into 800Kg for 5 minutes at the end of the oxidizer, and 1.5 tonnes of silicon manganese alloy was used as the reducing agent. The weight ratio of oxygen to argon was 1: 5, and the ratio of the height of the stowing tuyer and the entire molten metal was maintained for 20 minutes with h / H = 0.25, followed by tapping. The final low carbon ferro manganese product thus obtained was 11.2 tons, the chemical composition thereof is shown in Table 2. At this time, the ratio of inputs and outputs, that is, the recovery rate of manganese obtained from the mass balance was 87%.

(Comparative example)

In the same manner as in the above embodiment, the molten metal penetration depth was 35% of the total melt height, and was operated without the addition of dust solidified in the oxidizer to obtain a low carbon ferro manganese of the components shown in Table 2. In addition, the chemical composition of the charges in Examples and Comparative Examples is shown in Table 1.

The final low carbon ferro manganese product obtained in the comparative example was 10.3 tons, and the manganese recovery obtained from the mass balance between the input and the output was 83%.

division Mn Si C Fe metal High carbon ferro manganese molten metal (Example) 78.15 0.35 6.76 Residual amount High carbon ferromanganyongtang (comparative example) 78.28 0.32 6.78 Residual amount Silicon manganese 65.52 16.80 2.03 Residual amount Preparation division Mn ₃ O ₄ Fe ₂ O ₃ SiO ₂ CaO MgO Al ₂ O ₃ lgnition loss Solidified dust 73.79 5.02 7.85 3.02 0.36 0.40 Residual amount quicklime - - - 88.0 - - Residual amount

division Mn Si C Fe Low Carbon Ferro Manganese (Examples) 81.29 0.29 0.45 Residual amount Low Carbon Ferromanganese (Comparative Example) 79.88 0.25 0.47 Residual amount

As described above, in the present invention, by adjusting the operating parameters such as the molten metal penetration depth and the aggregated dust input time and input amount in an appropriate range, it is possible to realize a high manganese recovery rate at an environmentally friendly and low price. In addition, in the case of applying this to the production of medium-carbon ferro-manganese it was obtained by the addition of 100kg of agglomerated dust per ton of molten metal to improve the recovery of manganese of 3%.

Claims (1)

A high-carbon ferro-manganese is continuously charged into the converter which can be simultaneously picked up and stowed by the injector lance and the takeover tuyer, and oxygen is injected into the oxidizer through the intake lance. Through the inner tube and the outer tube, the mixed gas of oxygen and nitrogen or argon and nitrogen or argon gas are blown through the whole process, quicklime is added to the oxidizer, and silicon manganese alloy or ferrosilicon is introduced to the reducer. In the process of refining high carbon ferro manganese to produce a low carbon ferro manganese, Method for producing low-carbon ferro-manganese by recycling dust collection dust, characterized in that 10 to 20% by weight of the molten metal is added to the entire oxidizer after the melt temperature rises to 1,600 to 1,850 ℃ or more during the oxidizer operation. .