JP2006161079A - Method for producing manganese ferroalloy from by-product slag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stably producing manganese ferroalloy with high efficiency from molten slag which is generated as a byproduct at the production of ferromanganese. <P>SOLUTION: The molten slag as a byproduct at the production of ferromanganese is stored in a reactor vessel. A reducing material containing silicon-containing ferroalloy and metal aluminum is put into the above molten slag to undergo agitation so as to reduce at least a part of manganese oxides contained in the molten slag. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing manganese-based alloy iron from molten slag produced as a by-product when producing ferromanganese in an electric furnace by off-reduction reduction smelting.

  Ferromanganese is produced mainly in an electric furnace by melting manganese ore together with coke or the like to melt and reducing the ore. Generally, slag produced as a by-product in the smelting reduction smelting process contains 15 to 35% by mass of manganese. For this reason, various methods for recovering manganese from the molten slag and producing manganese-based alloy iron such as silicomanganese have been proposed.

  Each of these manufacturing methods is a method of reusing molten slag as a by-product as a manganese raw material, and reducing manganese oxide (mainly MnO) in the slag with a siliceous reducing material, thereby producing manganese such as silicomanganese. Manganese alloy iron is produced. In these methods, the reaction is advanced without supplying energy such as electric power from the outside by utilizing the reaction heat of the reduction reaction between manganese oxide and silicon.

  However, in these conventional methods, the reduction reaction cannot sufficiently proceed on a practical production scale, and high-concentration manganese remains in the slag after the reaction. For this reason, it has been proposed to adjust the composition of the molten slag or to preheat the reducing material in order to sufficiently advance the reaction, but this causes a problem that the production efficiency decreases due to an increase in the number of manufacturing steps.

  For this reason, for example, Patent Document 1 proposes to improve the manganese recovery efficiency and shorten the smelting time by strongly stirring the molten slag containing manganese and the alloy iron containing silicon. ing. Specifically, gas is ejected at a high speed from a nozzle installed in the molten slag and agitation is performed to promote the progress of the reaction between the molten slag and the iron alloy containing silicon.

  However, in the method of Patent Document 1, when the temperature of the molten slag is low or the composition has a high viscosity, stirring is not efficiently performed and the manganese recovery efficiency cannot be increased. In particular, when the temperature of the molten slag is low, not only the recovery efficiency of manganese is lowered, but the temperature of the metal produced by the reduction reaction and the temperature of the slag after the reaction cannot be maintained at a high temperature, so that solidification occurs at each outlet. As a result, it may become impossible to discharge, and stable production could not be performed.

  In general, the temperature of molten slag produced as a by-product during the production of ferromanganese in an electric furnace depends on the reaction conditions in the furnace, and is about 1350 ° C. in a stable situation, but is in the range of about 1250 ° C. to 1450 ° C. It fluctuates with. When the temperature of the molten slag is low, even if a reducing material is added, the temperature of the molten slag and the generated metal during stirring cannot be maintained for a long time only by the heat generated by the reduction reaction, so that smelting needs to be interrupted. In addition, when the temperature of the molten slag is lower, out-of-furnace smelting may not be performed.

  Moreover, in the above-mentioned Patent Document 1, when the temperature of the molten slag is low, an oxidizing exothermic substance containing one or more of silicon (Si), aluminum (Al), or carbon (C) as a heat generating agent is used. The reaction vessel is charged with oxygen-containing gas, and the temperature of the charge is raised by the heat of combustion of the exothermic agent and oxygen gas.

However, if the oxidizing exothermic material and oxygen gas are stirred and burned in the molten slag, a vigorous oxidation reaction occurs and the temperature rises locally, so that the refractory provided on the inner wall of the reaction vessel and oxygen gas injection The lance is rapidly melted. Further, since a large amount of silicon oxide (SiO ₂ ) and aluminum oxide (Al ₂ O ₃ ) is generated by combustion, the composition of the molten slag changes greatly, and the reduction reaction which is the next step is inhibited. There is also a problem that the recovery efficiency is reduced.
Japanese Patent Publication No. 3-49975

  An object of this invention is to provide the method which can manufacture manganese-type alloy iron efficiently and stably from the molten slag byproduced at the time of manufacture of ferromanganese.

  The method for producing manganese-based alloy iron from by-product slag according to the present invention includes storing molten slag produced as a by-product during production of ferromanganese in a reaction vessel, and containing the alloy iron containing silicon and metal aluminum in the molten slag. And reducing the manganese oxide contained in the molten slag to reduce at least part of the manganese oxide.

  ADVANTAGE OF THE INVENTION According to this invention, manganese type alloy iron can be efficiently manufactured stably from the molten slag byproduced at the time of manufacture of ferromanganese.

  As a result of intensive studies on the method for producing manganese-based alloy iron from by-product slag, the present inventors have obtained the following knowledge.

  That is, in the technology for producing manganese-based alloy iron by out-of-furnace smelting from molten slag by-produced when ferromanganese is produced in an electric furnace, the thermal energy (sensible heat) of the molten slag and the molten slag It is important to recover manganese efficiently by utilizing thermal energy (exothermic heat) due to the reduction reaction between manganese oxide (MnO) and a reducing material. The temperature of the molten slag (sensible heat) varies greatly depending on the condition of the electric furnace. Depending on the condition of the electric furnace, the molten slag temperature when charged into the reaction vessel is lowered, and the reaction with the reducing material is stabilized efficiently. And may not progress.

  The inventors of the present invention can improve the recovery rate of manganese from molten slag and enable stable operation by adding metal aluminum in combination with iron-containing alloy iron as a reducing material. I found.

  That is, even when the reaction state in the electric furnace deteriorates, such as when the temperature of the molten slag is low or when the molten slag is small, by using metallic aluminum as the reducing material together with the alloy iron containing silicon, the reducing material The amount of heat generated by the reaction between the molten slag and the molten slag can be greatly increased, and the temperature of the molten slag in the reaction vessel can be maintained. For this reason, the reduction reaction of manganese oxide can be advanced stably, and manganese-based alloy iron can be stably produced with excellent manganese recovery efficiency. Furthermore, according to this method, the silicon content in the manganese-based alloy iron is controlled within a desired range without causing impurities derived from metal aluminum such as aluminum oxide and alumina to remain in the produced manganese-based alloy iron. be able to. Here, the manganese-based alloy iron produced by the method of the present invention particularly refers to a variety (iron-manganese-silicon alloy) called silicomanganese.

  Hereinafter, various embodiments of the present invention will be described.

  In the present invention, as a by-product slag as a starting material, for example, a molten slag produced as a by-product when producing high carbon ferromanganese, medium carbon ferromanganese, or low carbon ferromanganese in an electric furnace or the like can be used. .

  As the iron alloy containing silicon, for example, metal silicon, ferrosilicon, silicomanganese, calcium silicon, aluminum-silicon alloy and the like can be used. These iron alloys containing silicon can be used alone or in combination of two or more.

  The reduction reaction produced by stirring molten slag and a reducing agent containing silicon-containing alloy iron and metallic aluminum mainly consists of manganese oxide (for example, MnO), silicon (Si) and metallic aluminum (Al). This is an exothermic reaction. In particular, the reaction between manganese oxide and metallic aluminum is well known as an aluminum thermite reaction and generates a large amount of heat. The thermochemical equations of MnO, Si and Al as the manganese oxide are shown below.

2MnO + Si → 2Mn + SiO ₂ +34 kcal (1)
3MnO + 2Al → 3Mn + Al ₂ O ₃ +124 kcal (2)
The amount of heat generated by the above reaction is 1.2 kcal per unit mass of Si in the reaction of the formula (1), and 2.3 kcal per unit mass of Al in the reaction of the formula (2). From this, it can be seen that Al generates about twice as much heat per unit mass as Si.

  As a result of the inventors studying the above reaction in more detail, it has been clarified that the thermite reaction between manganese oxide and metal aluminum proceeds rapidly at a temperature of 1000 ° C. or higher. Therefore, if the molten slag is 1200 ° C. or higher, even when metal aluminum at room temperature is added, an aluminum thermite reaction occurs instantaneously without the need for a combustion agent such as oxygen gas, and the temperature of the molten slag can be increased. . The increase in the slag temperature promotes the reduction reaction by the alloy iron containing silicon and improves the production efficiency of the manganese-based alloy iron.

  The input amount of metallic aluminum can be determined in consideration of the following factors.

  The first factor is the quality of the manganese-based alloy iron to be produced. The amount of silicon contained in the manganese-based alloy iron produced can be controlled by the amount of reducing material introduced. Generally, silicomanganese having a silicon content of about 5% to 30% by mass is produced. When the silicon content is increased, the amount of iron alloy containing silicon at room temperature, i.e., low temperature, is increased. Therefore, it is preferable to increase the amount of metallic aluminum having a large calorific value. Moreover, when reducing silicon content, it is preferable to reduce the quantity of expensive metal aluminum.

  The second factor is the temperature of the molten slag charged into the reaction vessel. When the temperature is low, it is preferable to increase the amount of metal aluminum in order to allow the reduction reaction to proceed efficiently. Conversely, when the temperature of the molten slag is high, the temperature does not rise excessively. Furthermore, it is preferable to reduce the amount of metallic aluminum.

As a result of detailed examination under various production conditions, it has been found that it is effective to set the amount of metal aluminum to be in the range of 5% by mass to 25% by mass of the total amount of the reducing material. When the input amount of metallic aluminum is less than 5% by mass, the exothermic effect due to the reaction of metallic aluminum may not be clearly expressed. On the other hand, when the input amount of metal aluminum exceeds 25% by mass, the slag temperature rises excessively, and there is a possibility that the refractory provided on the inner wall of the reaction vessel and the nozzle for stirring gas ejection may be melted. Moreover, since the production amount of aluminum oxide (Al ₂ O ₃ ) increases, it dissolves in the slag, the viscosity of the slag increases, and the produced manganese-based alloy iron hardly settles in the slag. As a result, there is a risk that manganese-based alloy iron cannot be efficiently recovered in a short time, and manganese-based alloy iron is stirred in slag to become spherical and may be discarded together with the slag while floating in the slag. There is also. Silicon oxide (SiO ₂ ) tends to lower the viscosity of the slag. A more preferable range of the input amount of metallic aluminum is 8 to 20% by mass of the total amount of the reducing material. If the amount of metal aluminum input is within this range, the production efficiency of manganese-based alloy iron can be made particularly good.

  In addition, it is preferable to use a particulate aluminum regenerated from waste or the like as the metal aluminum because not only the progress of the reaction is accelerated, but also the manufacturing cost can be reduced because of the low price. For example, a product obtained by baking aluminum foil and then making it spherical by machining, or a product obtained by cutting and drying an aluminum can and then rounding by machining, etc. are particularly suitable because they are spherical and have a large surface area and thus have good reactivity. Also, a regenerated aluminum lump dissolved and then pulverized and granulated is also excellent in reactivity because of its large surface area. The range of the preferable average particle diameter of particulate metallic aluminum is 1 to 10 mm.

  Further, as the metal aluminum, aluminum ash (aluminum dross) generated when aluminum is dissolved can be used. Aluminum ash often has a low content of metallic aluminum, but any aluminum ash containing 60% by mass or more of metallic aluminum can be used as a reducing material. An alloy or a mixture of metallic aluminum and silicon can also be used as a reducing material together with an iron alloy containing silicon.

  Examples of the stirring method of the molten slag and the reducing material include a method using an inert gas ejected at high speed, a method using a rotating stirring blade, and a method of vibrating a reaction vessel. Among them, a method of stirring the molten slag and the reducing material by ejecting an inert gas from a nozzle provided in the molten slag at a high speed is preferable. Compared with the method using a stirring blade, the method using the inert gas can stir the charged material in the reaction vessel more uniformly, so that the production efficiency of manganese-based alloy iron can be improved. The local excessive temperature rise of the molten slag by aluminum can be prevented, and damage to the reaction vessel or the like can be prevented.

The method of vibrating the reaction vessel reduces the amount of molten slag that can be stored as compared with the method using an inert gas, which may reduce the production efficiency and may increase the load on the inner wall of the reaction vessel. A stirring method using an inert gas is preferable because the surface of the molten slag can be waved and the rapid reaction between the reducing material and the molten slag can be promoted. In addition, there is an advantage that the stirring force can be appropriately controlled in accordance with the situation by changing the gas ejection amount. Nitrogen gas is optimal as the inert gas. The ejection amount of the inert gas is preferably in the range of 5 to 15 Nm ³ / min, and the ejection pressure of the inert gas is preferably in the range of 1 to 2 MPa.

  A preferable temperature range of the reaction slag (remaining part of the charge in the reaction vessel excluding the produced manganese-based alloy iron) is about 1410 to 1520 ° C. Here, the reaction slag temperature is a temperature at which the temperature of the reaction slag becomes substantially constant after sufficiently stirring the reducing material and the molten slag. The higher the temperature when the molten slag and the reducing material are stirred, the faster the reaction rate, the higher the temperature of the reaction slag and the lower the viscosity. Therefore, when the reaction slag is hot, not only the production of manganese-based alloy iron is accelerated, but also the production efficiency is improved because the reaction slag and the produced manganese-based alloy iron are quickly separated from each other by the specific gravity difference. Also, the Mn recovery rate tends to be improved. However, if the reaction is performed such that the reaction slag reaches a high temperature exceeding 1520 ° C., the refractories of the reaction vessel and the stirring gas ejection nozzle may be damaged, and stable production may not be possible. In particular, a stirring gas nozzle shaped like a straw is severely damaged at high temperatures and may have an extremely short life. For this reason, it is desirable to determine the temperature of the reaction slag in consideration of the balance between productivity and durability of the refractory. A more preferable temperature range of the reaction slag is about 1430 to 1480 ° C. In this temperature range, the production efficiency can be made the best. However, since the preferable temperature range of the reaction slag differs depending on the type of manganese-based alloy iron to be produced, it is not limited to this temperature range.

  The amount of reducing material input (total amount of silicon-containing alloy iron and metallic aluminum) depends on the Mn content in the molten slag, the ratio of metallic aluminum in the reducing material and the target quality of manganese-based alloy iron, for example, The amount of the molten slag can be in the range of 8% by mass to 20% by mass. However, the input amount of the reducing material is not limited to this range, the Mn content is measured, the ratio of metallic aluminum is defined, and the theoretical amount is calculated from these results according to a predetermined reaction formula. The final input amount can be determined by adding a correction value in consideration of the operation status to the value of. For example, when manufacturing manganese-based alloy iron having a high silicon content, the amount of silicon-containing alloy iron and metal aluminum increases, so the amount of reducing material input also increases. In addition, when it is necessary to particularly improve the manganese recovery rate, there is a tendency to increase the input amount of the reducing material. On the other hand, when manufacturing manganese-based alloy iron with a low silicon content or when it is necessary to manufacture inexpensive manganese-based alloy iron, such as when the price of silicon rises, reduce the amount of reducing material used. Is desirable.

  FIG. 1 shows an example of a manganese alloy iron production apparatus used for producing manganese alloy iron from byproduct slag according to the present invention.

  As shown in FIG. 1, the manganese-based alloy iron manufacturing apparatus includes a storage tank 10 for storing silicon-containing alloy iron, a storage tank 11 for storing metal aluminum, and a refractory for performing furnace smelting. A reaction vessel 14 attached inside is provided. In the reaction vessel 14, molten slag by-produced in the electric furnace is stored. A lid 17 is provided in the upper opening of the reaction vessel 14, and an exhaust port 22 is provided in the lid 17.

  A reaction slag discharge port 16 is provided at the lower part of the reaction vessel 14, and a manganese-based alloy iron discharge port 15 is provided further below. A nitrogen gas ejection nozzle 18a extending from the nitrogen gas supply device 18 passes through the lid 17 and is inserted into the reaction vessel 14, and the tip of the nozzle 18a is charged with molten slag or the like for stirring. It is immersed in things. The nitrogen gas ejection nozzle 18a is coated with a refractory, and for example, a lance can be used. The nitrogen gas ejection nozzle 18a is preferably installed such that its ejection port is located in the vicinity of the bottom in the reaction vessel 14, and a plurality of the nozzles can be installed.

  The lid 17 of the reaction vessel 14 is provided with a charging hopper 13, and the silicon-containing alloy iron contained in the storage tank 10 and the metal aluminum stored in the storage tank 11 are sent to the charging hopper 13 by the charging conveyor 12, The reaction vessel 14 is charged from the charging hopper 13.

  When manufacturing manganese-based alloy iron from byproduct slag using such a manganese-based alloy iron manufacturing apparatus, for example, it can be performed as described below.

  First, molten slag is charged into the reaction vessel 14 from an electric furnace (not shown). In that case, the mass of molten slag, temperature, and manganese content are measured. The amount of reducing material required is determined from these measurement results, and the alloy iron and metal aluminum containing silicon are extracted from the respective storage tanks 10 and 11 according to this amount, and sent to the input hopper 13 by the input conveyor 12. Is fed into the reaction vessel 14. At the same time, nitrogen gas is supplied from the nitrogen gas supply device 18, and the nitrogen gas is ejected at a high speed from the nozzle 18a immersed in the slag. The nitrogen gas foam 21 generated thereby stirs the molten slag and the reducing material to advance the reduction reaction. Stirring is continued for about 5 minutes after all the predetermined amount of reducing material has been charged. The agitation time is determined by manufacturing conditions such as the quality of the target manganese-based alloy iron and the amount of molten slag. Usually, it is preferable to continue stirring for 5 minutes to 10 minutes after adding the reducing material.

  The metal generated by this reaction settles in the mixture of the molten slag and the reducing material (reaction slag 20) and is stored as manganese-based alloy iron 19 at the bottom of the reaction vessel. After the stirring is completed, the reaction slag 20 is discharged from the discharge port 16 and the manganese-based alloy iron 19 is recovered from the discharge port 15.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

[Example]
Next, the present invention will be described in more detail with reference to examples.

Example 1
Using the manganese-based alloy iron manufacturing apparatus shown in FIG. 1, silicomanganese was manufactured as manganese-based alloy iron as described below.

  10,000 kg (10 tons) of molten slag produced as a by-product when high carbon ferromanganese was produced in an electric furnace was charged into a reaction vessel having a storage capacity of 20 tons of molten slag. The temperature and manganese content of the charged molten slag were measured, and the results are shown in Table 1. Further, 870 kg of metal silicon (Fe; 0.8 mass%, Si; 96.8 mass%) at room temperature and 200 kg of metal aluminum (Al; 97.0 mass%) were added as reducing materials to the reaction vessel. As the metallic aluminum, particles having a diameter of 1 to 2 mm regenerated from aluminum foil were used. Table 1 shows the ratio of metallic aluminum in the reducing material at this time. The metal silicon input was determined according to the target silicomanganese composition, and the metal aluminum input was determined according to the determined metal silicon input.

During and after the introduction of the reducing material, the molten slag and the reducing material were agitated by jetting nitrogen gas from a stirring nozzle inserted into the molten slag. The nitrogen gas ejection pressure was 1.5 MPa, and the ejection amount was 10 Nm ³ / min. The stirring time was 10 minutes after the introduction of the reducing material, but the reaction was intense and the molten slag temperature was observed to rise significantly, so the time was shortened, and after stirring for 5 minutes after the reducing material was added. Stopped. Thereafter, the produced silicomanganese was recovered from the reaction vessel, and the reaction slag was recovered.

(Examples 2 to 7)
Using the molten slag having the mass, temperature, and Mn content shown in Table 1, the amount of metal aluminum input, the amount of metal silicon input, the ratio of metal aluminum in the reducing material, and the stirring time were other than the values shown in Table 1. In the same manner as in Example 1, silicomanganese was produced.

(Example 8)
Using the molten slag having the mass, temperature and Mn content shown in Table 1, the input amount of metal aluminum, the input amount of metal silicon, and the ratio of metal aluminum in the reducing material were set to values shown in Table 1. Further, instead of stirring using nitrogen gas, a stirring blade made of a refractory was inserted into the molten slag and rotated at a speed of 50 rotations per minute to stir the molten slag and the reducing material. At this time, the stirring time was set to the time shown in Table 1. Except for these, silicomanganese was produced in the same manner as in Example 1.

(Comparative Example 1)
Using the molten slag having the mass, temperature, and Mn content shown in Table 1, the amount of metal silicon input and the stirring time were as shown in Table 1, and the same as in Example 1 except that metal aluminum was not added. Thus, silicomanganese was produced.

  Table 2 shows the mass, the Mn content, and the Si content of the silicomanganese obtained in Examples 1 to 8 and Comparative Example 1. Further, the Mn content in the recovered reaction slag was measured, and the results are also shown in Table 2. Furthermore, the ratio of the mass (kg) of manganese contained in silicomanganese to the mass (kg) of manganese contained in the molten slag is also shown in Table 2 as the Mn recovery rate.

  Moreover, the temperature of reaction slag was measured after completion | finish of stirring and before collection | recovery, and this result is shown in Table 2. Further, a value obtained by subtracting the temperature of the molten slag (° C.) from the temperature of the reaction slag (° C.) is also shown in Table 2 as a temperature change ΔT (delta T).

  As is clear from Tables 1 and 2, the methods of Examples 1 to 8 according to the present invention had a high Mn recovery rate, and could efficiently recover the manganese in the molten slag to produce silicomanganese. Moreover, the slag temperature after reaction was as high as 1412 degreeC-1514 degreeC, and the stable manufacture was possible. Furthermore, as is clear from Examples 1 to 5, the silicon content in the silicomanganese is in the range of 14% by mass to 30% by mass by adjusting the input amount of the reducing material (metal silicon, metal aluminum). It was controllable.

  Although the molten slag used in Example 1 was a standard temperature of 1350 ° C., the amount of the molten slag was 10 tons, which was as small as half of the storage capacity of the reaction vessel (about half of normal operation). Nevertheless, by introducing metal aluminum corresponding to 19% of the reducing material, the molten slag temperature could be raised sufficiently, and as a result, a high Mn recovery rate could be realized.

  From the results of Examples 2 to 4, even when molten slag having a wide temperature range of 1342 ° C to 1375 ° C is used in the range of 12,040 kg to 16,090 kg, sufficient temperature rise can be achieved by introducing metal aluminum. It was possible and it was confirmed that an excellent Mn recovery rate could be realized.

Moreover, in the method of Examples 1-4 which made the ratio of the metal aluminum in a reducing material in the range of 5 mass%-25 mass%, compared with Examples 6 and 7 in which the ratio of metal aluminum deviates from this range. A high Mn recovery rate was obtained. This is considered to be because the calorific value could be increased while suppressing the excessive production of aluminum oxide (Al ₂ O ₃ ) by setting the ratio of metal aluminum within this range. That is, in Examples 1 to 4, since it was possible to optimize both the conditions for sufficiently carrying out the reduction reaction and the conditions for separating the produced silicomanganese from the reaction slag, it was possible to improve the Mn recovery rate. It is considered a thing.

  In Examples 1 to 4 in which stirring was performed using nitrogen gas, the Mn recovery rate was improved as compared with Example 8 in which stirring blades were used. This is considered to be because the molten slag and the reducing material could be more uniformly stirred by using nitrogen gas, and the reaction between the manganese oxide in the molten slag, metal silicon, and metal aluminum could be promoted.

  In Example 5, the mass of molten slag was as small as 10,090 kg, and the temperature was 1308 ° C., which was nearly 50 ° C. lower than the molten slag of Examples 1 to 4. Manganese could be manufactured. This is because the ratio of metallic aluminum in the reducing material was made higher than in Examples 1 to 4, so that the temperature could be sufficiently raised to maintain the temperature, and the reduction reaction could be promoted. It is thought that improvement and stable production were possible.

  On the other hand, in the method of Comparative Example 1, the slag temperature after the reaction was lower than that of Examples 1 to 8, and the Mn recovery rate was lowered. In particular, in Comparative Example 1, although the temperature of about 1300 ° C. is about 10 tons, the temperature rise is smaller than that in Comparative Example 5 even though the manufacturing conditions are the same as in Example 5. The Mn recovery rate was greatly reduced. This is because, in Comparative Example 1, the total amount of heat in the reaction vessel was small, so by introducing cold metallic silicon, the slag temperature further decreased and the reduction reaction did not proceed sufficiently. It is considered that the Mn recovery rate was lowered due to insufficient temperature increase. In the case of Comparative Example 1, since the reaction does not proceed easily even if the metal silicon is further increased, the temperature of the reaction slag may further decrease and solidify in the reaction vessel. Moreover, also when stirring is continued in a state where the reduction reaction is stagnant as in Comparative Example 1, the temperature decrease is promoted and the above problem may occur.

  According to the present invention, when producing manganese-based alloy iron from molten slag by-produced during the production of ferromanganese, stable operation is possible by using metallic aluminum together with iron-containing alloy iron as a reducing material. At the same time, since manganese in the molten slag can be efficiently recovered, energy and resources can be effectively utilized, and high-quality manganese-based alloy iron can be provided at a low cost.

The figure which shows an example of the manganese alloy iron manufacturing apparatus used in order to manufacture manganese alloy iron from byproduct slag according to this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Storage tank of alloy iron containing silicon, 11 ... Storage tank of metal aluminum, 12 ... Loading conveyor, 13 ... Loading hopper, 14 ... Reaction vessel, 15 ... Manganese alloy iron discharge port, 16 ... Reaction slag discharge port, 17 DESCRIPTION OF SYMBOLS ... Lid, 18 ... Nitrogen gas supply apparatus, 18a ... Nitrogen gas ejection nozzle, 19 ... Manganese alloy iron layer, 20 ... Reaction slag layer, 21 ... Nitrogen gas foam, 22 ... Exhaust port.

Claims (4)

  Molten slag produced as a by-product during the production of ferromanganese is stored in a reaction vessel, and a reducing material containing silicon-containing alloy iron and metallic aluminum is added to the molten slag and stirred, and contained in the molten slag. A method for producing manganese-based alloy iron from by-product slag, wherein at least a part of the manganese oxide is reduced.   2. The production method according to claim 1, wherein the metal aluminum is added at a ratio of 5 mass% to 25 mass% with respect to the total amount of the reducing material.   The manufacturing method according to claim 1, wherein the metallic aluminum is regenerated from waste and is in a particulate form.   The molten slag and the reducing material are agitated by jetting an inert gas at high speed from a nozzle provided in the charge in the reaction vessel. The manufacturing method of any one of Claims.

Images