KR102328965B1 - Method for recycling Mn dust - Google Patents

Abstract

The present invention relates to a method capable of reducing the processing cost of by-products generated in the ferromanganese manufacturing process by recycling the dust generated during the ferromanganese manufacturing process. Mn dust; Fe dust; reducing agent; and mixing a binder to prepare a dust mixture; manufacturing the dust pellets by molding the dust mixture; heat-treating the dust pellets; And it provides a recycling method of Mn dust, comprising the step of using the heat-treated dust pellets to manufacture ferromanganese.

Description

Method for recycling Mn dust

The present invention relates to a method of recycling Mn dust, and more particularly, to a method of recycling dust generated during ferromanganese production.

By-products generated during ferromanganese production are classified as slag and dust. Although the slag is recycled as a material for embankment and road slag, dust, which is a very small particle (fine particle) with a particle diameter of about 200 μm, requires a lot of investment to be commercially produced, and thus is mostly landfilled as industrial waste.

On the other hand, a method for reusing the dust in the ferromanganese manufacturing process is being studied, but it contains a lot of impurities such as Na, K and Cl to reuse the dust in the ferromanganese manufacturing process. The total content of Na, K and Cl of the dust is 20 wt% or more, and it is necessary to remove up to 5 wt% or less for process recycling.

In addition, the ferromanganese manufacturing process uses an electric furnace, and since the raw material is input from the upper part of the electric furnace, granulation is required to input fine dust.

To this end, as in Korean Patent Application Laid-Open No. 2010-0002046, a method of manufacturing manganese oxide by increasing the manganese metal concentration after removing impurities contained in the electric furnace dust is being studied. However, the method as described above has a problem in that it cannot be commercialized because of excessive investment cost and low commercial value, so an invention for recycling the dust generated during the manufacture of ferromanganese is still required.

The present invention provides a method capable of reducing the cost of processing by-products generated in the ferromanganese manufacturing process by recycling the dust generated during the ferromanganese manufacturing process.

In one aspect of the present invention, the present invention provides a Mn dust containing Na, K, Cl and Mn; Fe dust; reducing agent; and mixing a binder to prepare a dust mixture; manufacturing the dust pellets by molding the dust mixture; heat-treating the dust pellets; And it provides a recycling method of Mn dust, comprising the step of using the heat-treated dust pellets to manufacture ferromanganese.

The present invention provides a method of recycling dust generated during ferromanganese production, thereby reducing the processing cost of by-products, thereby providing a cost saving effect of operation, and further using Na, K and Cl in the dust as fertilizer raw materials Thus, it is possible to establish a resource cycle utilization process.

1 shows a schematic diagram of recycling dust generated during manufacturing ferromanganese, according to an embodiment of the present invention.
2 shows an experiment in which dust is fused to a mixer when manufacturing the dust pellets of the present invention.
Figure 3 shows an experiment simulating the RHF (Rotary Hearth Furnace) used in the heat treatment of the dust pellets of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

The dust generated during the manufacture of ferromanganese contains more than 25% by weight of manganese, so it is worth recycling for the manufacture of ferromanganese. However, since by-products such as Na, K and Cl are contained in an amount of 20% by weight or more, and such by-products can be volatilized at a temperature of 700° C. or higher, the by-products are volatilized in an electric furnace used for manufacturing ferromanganese. and may be fused to the refractory material, which may cause melting of the refractory material.

Therefore, in order to recycle the dust, it is necessary to minimize the fusion problem as described above.

In consideration of this point, the present invention provides a method of recycling dust among by-products generated during the production of ferromanganese.

Specifically, the present invention relates to a Mn dust containing Na, K, Cl and Mn; Fe dust; reducing agent; and mixing a binder to prepare a dust mixture; manufacturing the dust pellets by molding the dust mixture; heat-treating the dust pellets; And it provides a recycling method of Mn dust, comprising the step of using the heat-treated dust pellets to manufacture ferromanganese.

The Mn dust may be dust generated during manufacture of the aforementioned ferromanganese. Based on the weight of the Mn dust, the Mn dust may include Mn in an amount of 35 to 40% by weight. On the other hand, based on the weight of the Mn dust, the total content of Na, K and Cl may be 5 wt% or more, for example, 20 wt% or more, Na 1.9 wt%, K 19 wt%, and Cl 2.9 wt% Mn dust may be used, and the Mn dust varies depending on operating conditions, but the total amount of Na, K and Cl is 40 wt% or less.

Furthermore, the Fe dust may be generated during the steelmaking process, and may include Fe in an amount of 30 to 60% by weight. However, since Fe may exist in the form of an oxide, the Fe dust may include Fe oxide in an amount of 70 to 90 wt%. Because of the Fe component of the Fe dust, the present invention uses a mixture of Mn dust and Fe dust. Fe dust used therein is 70 to 90% by weight of Fe ₂ O ₃ , 0.5 to 1.5% by weight of SiO ₂ , 0.5 to 1.0% by weight of Al ₂ O ₃ , 1.5 to 2.5% by weight of MgO, 6.5 to 14.0% by weight of CaO, and 2.5 to 3.5% by weight of ZnO, and the balance may include Cl, Na ₂ O, K ₂ O, etc. as impurities.

Meanwhile, the dust mixture may be prepared by mixing Mn dust and Fe dust, and then adding a reducing agent and a binder to the mixture in which the Mn dust and Fe dust are mixed, but is not limited thereto, and Mn dust, Fe Dust, reducing agent and binder can be mixed at the same time.

In this case, the reducing agent may be one or more selected from a carbon-based reducing agent, a silicon-based reducing agent, and an aluminum-based reducing agent. For example, the carbon-based reducing agent may be one or more selected from coke, coal, and graphite, and the silicon-based reducing agent may be one or more selected from ferro-silicon (Ferro-Si) powder and silicon (Si) powder. In addition, the aluminum-based reducing agent may be one or more selected from an aluminum silicon (Al-Si) alloy powder and an aluminum powder, but is not limited thereto.

Furthermore, the binder may be used by selecting one or more selected from water glass, rosin powder, molasses, and bentonite.

On the other hand, based on the total weight of the dust mixture, 40 to 60% by weight of Mn dust, 30 to 50% by weight of Fe dust, 5 to 10% by weight of reducing agent, and 1 to 5% by weight of binder may be mixed and used, preferably 40 to 50% by weight of the Mn dust, 35 to 40% by weight of Fe dust, 7 to 9% by weight of a reducing agent, and 2 to 4% by weight of a binder may be mixed and used.

When the content of Mn dust is less than 40% by weight, the content of recycled Mn is relatively small, which is not economically desirable, and when it exceeds 60% by weight, dust pellets are manufactured by Na, Cl and K in Mn dust When fusion occurs in the forming device, there may be a problem in that the operation is impaired.

When the content of the Fe dust is less than 30% by weight, the Fe content is lowered, and a problem of pellet forming may occur. This relatively low problem can arise.

When the content of the reducing agent is less than 5% by weight, the reduction rate of oxygen is low, and when ferromanganese is prepared from the manufactured dust pellets, the content of Mn may be decreased, and when it exceeds 10% by weight, the solid phase due to the excess of the reducing agent A lot of energy is required during reduction, and there is a possibility that the reducing agents remaining after not participating in the reaction react with each other to interfere with the reduction of the metal oxide.

If the content of the binder is less than 1% by weight, the strength of the pellets may be lowered due to the lack of the binder, so that use may be limited in manufacturing ferromanganese, and if it exceeds 5% by weight, the bonding strength of the mixture increases when molding the dust mixture, The particle size of the pellets may be larger than 15 mm. For example, in order to apply the pellets to the RHF process, the particle size of the pellets may be between 8 and 15 mm, and when the size of the pellets exceeds 15 mm, it may be difficult to apply to the RHF process.

Furthermore, the raw materials may be mixed using a rotary type ball mill. Not only a ball mill, but also a V-type mixer and a cylindrical mixer can be used, and as long as the raw material can be mixed from the dust mixture, the present invention is not limited thereto.

The heat treatment is preferably performed using a rotary hearth furnace (RHF). The heat treatment is a step in which Na, K, and Cl in the dust pellets are volatilized so that Mn dust can be used for manufacturing ferromanganese. In this step, setting the temperature is important.

In the recycling method of Mn dust of the present invention, the heat treatment may be performed at a temperature of 900 to 1100 °C. When the temperature is less than 900°C, the reduction rate of impurities such as Na, K and Cl is small, and there may be a problem that granulation is not achieved due to insufficient sintering of the particles constituting the dust pellet, and when it exceeds 1100°C, RHF Dust pellets may be melted inside a device that performs heat treatment, such as a device, and operation problems may occur.

The dust pellets prepared as described above may be used as direct reduced iron (DRI) or sponge iron, and may be used in the ferromanganese manufacturing process.

On the other hand, Na and K contained in trace amounts in manganese stone, coal and limestone used in the ferromanganese manufacturing process are concentrated in the dust through the steel process. Therefore, as described above, in the dust generated in the ferromanganese manufacturing process, components such as Na and K and metal components such as Mn coexist.

At this time, components such as Na and K are essential components for fertilizers necessary for growing crops, and most of the raw materials used for domestic fertilizer production are imported. Moreover, the use of fertilizers is increasing every year due to the degradation of domestic soil. For this reason, the price of imported raw materials containing Na and K continues to rise.

Accordingly, an object of the present invention is to provide a method of using Na and K generated during recycling of Mn dust as fertilizer raw materials.

In detail, the present invention provides a recycling method of Mn dust, further comprising the step of collecting the gas volatilized in the heat treatment step and using it as a fertilizer raw material.

In the heat treatment step, Na, K and Cl are volatilized, and as a result, the gas may contain 20 wt% or more of Na and 40 wt% or more of K.

However, in the gas form as described above, it is difficult to be used as a raw material for fertilizer, so the gas containing Na and K may be crystallized and used as a raw material for fertilizer. Therefore, the present invention can perform the crystallization step by rapidly cooling the captured gas as described above to 20 to 25 ℃ Na and K contained in the gas can be more easily used as a fertilizer raw material.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are merely examples to help the understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

Mn dust was recycled to prepare pellets that could be used for ferromanganese.

Example 1

Mn dust generated during ferromanganese production and containing the components shown in Table 1 below was generated during the steelmaking process, and mixed with Fe dust containing the components shown in Table 1 below, pulverized coal as a reducing agent, and bentonite as a binder was added to prepare a dust mixture.

(weight%) XRD ICP Fe ₂ O ₃ SiO ₂ Al ₂ O ₃ MgO CaO SO ₃ MnO ZnO Cl Na ₂ O K ₂ O K Cl Pb Mn dust 2.5 6.8 3.7 3.6 2.3 3.2 39.3 1.7 2.1 3.5 23.7 19.10 2.9 0.4 Fe dust 85.1 0.9 0.7 1.5 6.9 3.3 - - - - - 0.15 N.D. 0.03

In detail, 500 g of the Mn dust, 380 g of the Fe dust, 80 g of the reducing agent, and 40 g of the binder were mixed to prepare a dust mixture of 1 kg.

Comparative Example 1

In Example 1, a dust mixture was prepared in the same manner as in Example 1, except that Mn dust was used instead of Fe dust.

Comparative Example 2

In Example 1, a dust mixture was prepared in the same manner as in Example 1, except that Mn dust was not used and Fe dust was used instead of Mn dust.

Each composition of Example 1 and Comparative Examples 1 and 2 is summarized in Table 2.

Category (wt%) Mn dust Fe dust reducing agent bookbinder Average particle size 100㎛ Average particle size 150㎛ Example 1 50 16 22 8 4 Comparative Example 1 88 - - 8 4 Comparative Example 2 41 47 8 4

Experimental Example 1

In order to mix Example 1 and Comparative Examples 1 and 2, a mixer used in the field was simulated and the raw materials were mixed with a ball mill (see FIG. 2).

For ball mill conditions, 10 balls with a particle diameter of 30 mm were used, the mixing time was 3 hours, and the input amount of each raw material was 1 kg.

At this time, the thickness change of the 10 balls was measured to evaluate the degree of fusion according to the raw material. The results are summarized in Table 2.

Furthermore, in order to measure the compressive strength of the dust pellets manufactured through the ball mill as described above, the strength of the dust pellets was measured using a compressive strength machine. The results are summarized in Table 3.

division Example 1 Comparative Example 1 Comparative Example 2 Ball diameter measurement (mm) One 31.62 32.42 31.54 2 29.78 31.50 31.53 3 31.77 32.24 30.03 4 32.82 32.04 32.11 5 31.72 32.18 31.26 6 32.21 33.26 31.39 7 30.51 31.85 31.91 8 32.27 32.43 32.33 9 31.87 32.51 32.12 10 31.63 31.07 31.85 average 31.62 32.15 31.61 Average (excluding maximum and minimum) 31.70 32.24 31.70 Dust Pellets Average Strength (N) 980 720 915

As a result, as shown in Table 2, when manufacturing dust pellets with the dust mixture of Example 1, it can be confirmed that the degree of fusion of the mixture to the balls is significantly smaller than when using only Mn dust (Comparative Example 1). There was, and it was confirmed that the strength of the dust pellets was superior to the case of using only Mn dust (Comparative Example 1) and the case of using only Fe dust (Comparative Example 2).

Experimental Example 2

In order to recover Na and K from Mn dust, the dust pellets prepared from the dust mixture of Example 1 in Experimental Example 1 were heated (calcined at high temperature to reduce MnO and FeO metal oxides and volatilize harmful substances), and then in the pellets. The content of the components present was determined. Table 4 shows the results of measuring the content of the components remaining in the pellets for each heating temperature.

Category (wt%) before heating 700℃ 800℃ 900℃ 1000℃ 1100℃ Mn 20.5 21.2 22.6 24.7 26.8 27.0 K 19.0 13.0 8.2 5.3 2.8 2.1 Cl 2.90 1.3 0.82 0.21 0.04 0.04 Pb 0.71 0.32 0.17 0.12 0.05 0.05 Na 1.9 1.9 1.8 1.6 1.5 1.3 balance CaO, SiO ₂ , Al ₂ O ₃

As a result, as shown in Table 3, it was confirmed that the content of the components except for Mn decreased as the temperature increased, and it was confirmed that similar contents remained at 1000 °C and 1100 °C. Therefore, the heat treatment of the present invention is preferably performed up to 1100 ℃.

Furthermore, it was confirmed that the gas generated by the heat treatment contained 40 wt% of K and 20 wt% of Na, and thus, it was confirmed that the gas as described above can be used as a raw material for fertilizer.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible within the scope without departing from the technical spirit of the present invention described in the claims. It will be apparent to those of ordinary skill in the art.

Claims (12)

40 to 60% by weight of Mn dust containing Na, K, Cl and Mn; Fe dust 30 to 50% by weight; 5 to 10% by weight of a reducing agent; and mixing 1 to 5% by weight of a binder to prepare a dust mixture;
manufacturing the dust pellets by molding the dust mixture;
heat-treating the dust pellets; and
Comprising the step of using the heat-treated dust pellets to manufacture ferromanganese,
Based on the weight of the Mn dust, the Mn dust comprises 35 to 40% by weight of Mn, the recycling method of Mn dust.
According to claim 1,
The Mn dust is a recycling method of Mn dust that is generated during the production of ferromanganese.
delete According to claim 1,
Based on the weight of the Mn dust, the Mn dust comprises a total of 5% by weight or more of Na, K, and Cl, Mn dust recycling method.
According to claim 1,
The Fe dust is generated during the steelmaking process, Mn dust recycling method.
According to claim 1,
The dust mixture is to be prepared by mixing the reducing agent and the binder after mixing Mn dust and Fe dust, Mn dust recycling method.
delete According to claim 1,
The dust pellets are manufactured using a ball mill, Mn dust recycling method.
According to claim 1,
The heat treatment is performed using a rotary reduction furnace (RHF), the recycling method of Mn dust.
According to claim 1,
The heat treatment is carried out at a temperature of 900 to 1100 ℃, Mn dust recycling method.
According to claim 1,
The recycling method of Mn dust further comprising the step of collecting the gas volatilized in the heat treatment and using it as a fertilizer raw material.
12. The method of claim 11,
The method of recycling Mn dust, further comprising the step of crystallizing by quenching the captured gas to 20 to 25 ℃.

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