KR102058713B1 - Manufacturing method for Fe-Si - Google Patents

Abstract

Ferrosilicon production method according to an embodiment of the present invention, a mixing step of preparing a mixture by mixing a silicon powder sludge, conidia lime, a carbon-based material and a binder; Agglomeration step of agglomerating the mixture; A melting step of charging the agglomerated mixture and an iron source into a melting furnace and melting the molten mixture; And an obtaining step of separating the ferrosilicon and the slag from the melt tapping from the melting furnace to obtain the ferrosilicon.

Description

Ferrosilicon manufacturing method {Manufacturing method for Fe-Si}

The present invention relates to a method for producing ferrosilicon, and more particularly, to a method for producing ferrosilicon that can effectively produce ferrosilicon using silicon powder sludge.

Ferro-silicon (Fe-Si) is a type of ferroalloy mainly used as an additive for steelmaking deoxidizer or silicon steel.

Ferrosilicon is generally produced by melting and reducing the raw material of silica and iron scrap and reducing agent coke in an electric furnace. Since the melt reduction method requires a high reduction temperature, a large amount of power is consumed, and since the relatively expensive coke is used as a reducing agent, an increase in manufacturing cost of ferrosilicon is inevitable. Therefore, there is a need for a more economical and efficient method for producing ferrosilicon.

Republic of Korea Patent Publication No. 10-2015-0076424 (published Jul. 7, 2015)

According to one aspect of the present invention can be provided a ferrosilicon manufacturing method capable of producing ferrosilicone effectively using silicon sludge powder.

The subject of this invention is not limited to what was mentioned above. Those skilled in the art will have no difficulty understanding the additional subject matter of the present invention from the general contents of this specification.

Ferrosilicon manufacturing method according to an embodiment of the present invention, a mixing step of preparing a mixture by mixing the silicon powder sludge, conidia lime, carbon-based material and binder; Agglomeration step of agglomerating the mixture; A melting step of charging the agglomerated mixture and an iron source into a melting furnace and melting the molten mixture; And an obtaining step of separating the ferrosilicon and the slag from the melt tapping from the melting furnace to obtain the ferrosilicon.

Means for solving the above problems are not listed all of the features of the present invention, various features of the present invention and its advantages and effects will be understood in more detail with reference to the following specific embodiments.

Ferrosilicon manufacturing method according to an embodiment of the present invention is to provide a silicon source by mixing condensed lime in silicon powder sludge and then agglomerated to provide a silicon source, it can effectively reduce the time and cost required for the production of ferrosilicon, silicon The recovery rate of can be effectively increased.

1 is a flow chart schematically showing a method for producing ferrosilicon according to an embodiment of the present invention.

The present invention relates to a ferrosilicon manufacturing method, it will be described below in the preferred embodiments of the present invention. Embodiments of the invention may be modified in various forms, the scope of the invention should not be construed as limited to the embodiments described below. These embodiments are provided to further illustrate the present invention to those skilled in the art.

The present inventors have found that when alloying with iron using silicon powder sludge as a raw material of ferrosilicon, it is possible to obtain ferrosilicon with high purity while significantly reducing power consumption.

As described above, the present invention uses silicon powder sludge as a raw material of ferrosilicon. In manufacturing solar cells or semiconductors, silicon is cut into wafers, and a large amount of silicon powder is discharged in the form of sludge during the cutting process. As such, silicon powder sludge generated as a by-product in the process of manufacturing a silicon wafer contains impurities and thus cannot be reused as a raw material of poly silicon for manufacturing a silicon wafer. Silicon powder sludge has a particle size of 8 ~ 100㎛, because there is a problem that is easily reacted with the air and oxidized when dissolved. In addition, there is a problem that impurities remain even when dissolved in a vacuum or dissolved using a reducing gas or a reducing agent to suppress the oxidation reaction of the silicon powder sludge.

Accordingly, the present inventors have conducted a study on a method for reusing the silicon powder sludge, and have derived a method of manufacturing ferrosilicon using the silicon powder sludge as follows.

Hereinafter, a method for manufacturing ferrosilicon of the present invention will be described in more detail.

1 is a flow chart schematically showing a method for producing ferrosilicon according to an embodiment of the present invention.

As shown in Figure 1, the ferrosilicon manufacturing method according to an embodiment of the present invention, a mixing step (S100) for preparing a mixture by mixing a silicon powder sludge, conidia lime (CaO), a carbon-based material and a binder; An agglomeration step of agglomerating the mixture (S200); A melting step (S300) of charging the melted mixture and the iron source in a melting furnace; And an obtaining step (S400) of separating the ferrosilicon and the slag from the molten metal from the melting furnace to obtain the ferrosilicon.

In the mixing step (S100) of the present invention, the prepared silicon powder sludge, conidia, a carbon-based material and a binder may be combined to prepare a mixture, and preferably, the mixture may be kneaded to prepare a mixture. In addition, the silicon powder sludge, powdery lime, carbonaceous material and binder may be provided in a powder state, but may be subjected to separate grinding steps for each of them or a mixture thereof in order to control the particle size. In the present invention, the particle size of the mixture is not particularly limited, but it is more preferable to adjust the particle size of the mixture to have a particle size similar to that of the silicon powder sludge supplied to the mixture. .

The silicon powder sludge of the present invention may mean any kind of silicon source whose main component is silicon and is provided in a powder state, but preferably, silicon powder sludge generated in a semiconductor, a solar panel manufacturing process, or the like. In addition, the particle size of the silicon powder sludge is not particularly limited, but the particle size of the preferred silicon powder sludge may be 8 ~ 100㎛.

The conidia of the present invention may be pulverized or differentiated calcium oxide (CaO, burnt lime). That is, the powder quicklime of the present invention may mean pulverized lime or dust collected in the manufacturing process of quicklime.

The mixture of the present invention includes condensed lime, which can effectively lower the slag formed in the melting step (S300) to be described later.

In the melting step (S300) to be described later, iron oxide is present on the surface of the iron source charged into the melting furnace, the silicon of the silicon powder sludge charged with the iron source reacts directly with the iron oxide to form a SiO ₂ film on the surface of the iron source Done. Since the SiO ₂ film has a high melting point (about 1725 ° C.), excessive energy is consumed in melting the SiO ₂ film, or a long reaction time is required to diffuse silicon particles from a solid SiO ₂ to an iron source. do.

CaO reacts with SiO ₂ to lower the melting point of the slag formed during melting.The liquid iron (Fe) and the liquid silicon (Si) are reacted at a relatively low melting temperature (temperature below the SiO ₂ melting point). The reaction time can be shortened effectively. In addition, the slag generated during melting can be more easily liquefied by the low melting point of the slag, thereby allowing the slag to be more effectively separated from the ferrosilicon.

If the slag basicity (% CaO /% SiO ₂ ) is in the range of 0.4 to 1.5, the melting point of the slag may be low melting point to a level of 1435 ~ 1650 ℃. In order to satisfy the basicity (% CaO /% SiO ₂ ) of such slag, the mixture may include silicon powder sludge and condensed lime at a ratio of 83 to 95 wt% and 4 to 16 wt%, respectively.

The carbonaceous material of the present invention may be any one of powdered coal and powdered coke, or a mixture thereof. Since the mixture of the present invention includes a carbon-based material, it is possible to effectively prevent the oxidation of Si contained in the silicon powder sludge. For the antioxidant effect of Si, the mixture may contain 0.5 to 2 wt% carbonaceous material.

The binder of the present invention may be a hydrocarbon-based organic material, preferably may be any one of molasses and starch, or a mixture thereof. In addition, the binder of the present invention may further include water glass (silicate binder) as necessary.

In general, the silicon powder sludge is provided in a fine powder state, and the silicon particles in the silicon powder sludge may easily react with oxygen in the air or oxides present in the surroundings to form SiO ₂ . As described above, since SiO ₂ adversely affects the ferrosilicon production time and the silicon recovery rate, it is preferable to actively suppress the formation of SiO ₂ during the ferrosilicon production process.

Hydrocarbon-based organics and carbonaceous materials included in the mixture of the present invention remove oxygen in a powdered mixture or agglomerated mixture, as shown in Scheme 1 below, thereby actively reducing the oxygen provided in the formation of SiO ₂ . Can be.

Scheme 1

C + 1/2 O2 = CO (g)

In the block forming step (S200) of the present invention, the mixture prepared in the mixing step (S100) may be pressurized to block. The agglomeration step (S200) of the present invention may include not only the case of pressing the mixture at room temperature, but also the case of heating and pressing the mixture. In addition, in the agglomeration step (S200) of the present invention, after supplying water to the mixture may be carried out at room temperature pressurization or heating pressurization.

According to the present invention, when the mixture containing silicon powder sludge is massified and introduced into the melting furnace, the recovery rate of silicon may be further increased as compared with the case where powdered silicon powder sludge is directly introduced into the melting furnace.

In addition, the mixture containing the silicon powder sludge is agglomerated and introduced into the melting furnace, and thus the probability of the silicon of the silicon powder sludge reacting with the oxygen in the air before the melting furnace is reduced, thus the formation of SiO ₂ can be effectively suppressed. have.

The particle size of the mixture agglomerated in the bulking step (S200) of the present invention may be 10 ~ 100mm. This is because when the size of the bulked mixture exceeds 100 mm, reactivity may cause a decrease in productivity due to a decrease, whereas when the size of the bulked mixture is less than 10 mm, it may cause a decrease in the real rate of Si due to dust.

In addition, in terms of productivity, the porosity of the massed mixture is preferably managed at a low level as much as possible, and the porosity of the most preferred massed mixture in terms of productivity may be 35% or less.

The ferrosilicon manufacturing method of the present invention may further include a drying step (S250) of drying the massed mixture after the bulking step (S200).

In the drying step (S250), in order to remove the water contained in the mass mixture, the mass mixture can be heated to a temperature of 350 ℃ or less. When the water mixture is excessively included in the bulked mixture, a problem occurs in that the concentration of hydrogen contained in the final ferrosilicon rises to a predetermined level or more, and the water included in the bulked mixture is dried through the drying step (S250). It is desirable to adjust it to about 10% or less.

In the melting step (S300) of the present invention, the iron source and agglomerated mixture may be charged together in a melting furnace to be heated to a temperature range of 1550 ~ 1700 ℃. The iron source of the present invention means an iron (Fe) source of ferrosilicon, but iron scrap or reduced iron, which minimizes the iron oxide type, is more preferable in terms of suppressing the formation of SiO ₂ .

The present invention actively suppresses the formation of high melting point SiO ₂ by adding condensed lime and bulking, so that the slag can be liquefied even at a melting temperature below the melting point of SiO ₂ . Therefore, it is possible to easily create a reaction environment of liquid silicon and liquid iron in the melting furnace, thereby effectively reducing the reaction time of iron and silicon and at the same time effectively preventing excessive energy consumption for their melting. Can be.

In addition, the present invention effectively lowers the melting point of the slag by the injection of condensed lime, it is possible to liquefy both ferrosilicon and slag at the melting temperature of less than the melting point of SiO ₂ . Therefore, in the melting step (S300) of the present invention, both the ferrosilicon and the slag is liquefied, the slag is located on top of the ferrosilicon due to their specific gravity difference.

The liquefied slag prevents the lower ferrosilicon from contacting the air in the atmosphere to prevent oxidation of the ferrosilicon, thereby effectively improving the recovery rate of Si. In addition, since the molten slag of the upper side physically blocks the contact between the molten ferrosilicon and the atmosphere, it is possible to effectively suppress the heat loss of the liquefied ferrosilicon to effectively improve the heat rate of the melting step (S300). This is because liquefied slag has a lower thermal conductivity than liquefied ferrosilicon.

In the obtaining step (S400) of the present invention, the molten molten metal in the melting furnace may be tapped out by ladle to separate the slag and the ferrosilicon to obtain ferrosilicon. As described above, in the melting step (S300) of the present invention, both the slag and the ferrosilicon are liquefied, and they are separated from each other by the difference in specific gravity, so that the ease of separation of the ferrosilicon and the slag during the tapping of the molten metal is effective. It can be ensured, thereby effectively preventing impurities from being contained in the ferrosilicon.

Hereinafter, the ferrosilicon manufacturing method of the present invention through a specific embodiment to be described in more detail.

The mixture was prepared by mixing silicon powder sludge, powdery lime and powdered coal under the conditions of Table 1 below. Each mixture and iron scrap were charged into a melting furnace and melted, and the basicity (% CaO /% SiO ₂ ) and melting point of the slag formed during the melting were measured, respectively. After melting, the ferrosilicon was separated from the molten metal, and the Si real rate was calculated based on the weight of Si contained in the obtained ferrosilicon relative to the weight of the injected silicon powder sludge. Molasses was used as the binder.

division Experimental Example
One Experimental Example
2 Experimental Example
3 Experimental Example
4 Experimental Example
5 Experimental Example
6 Experimental Example
7 Si powder
(wt%) 97.3 94.6 92.6 89.5 86.6 83.2 81.6 quicklime
(wt%) - 4.3 6.3 9.4 12.1 15.3 18.2 Carbonaceous material
(wt%) 0.3 1.0 1.0 1.0 1.0 1.0 basicity
(% CaO /% SiO ₂ ) - 0.4 0.6 0.9 1.2 1.5 1.7 Slag melting point
(℃) 1725 1650 1544 1470 1460 1440 2100 Si real rate
(%) 75 90 91 93 95 97 81

As shown in Table 1, in the case of Experimental Examples 2 to 6 satisfying the range of 83 to 95wt% of silicon powder sludge and 4 to 16wt% of condensed lime, the basicity of slag (% CaO /% SiO ₂ ) was 0.4 to You can see that the level is 1.5. At this time, the slag melting point of Experimental Examples 2 to 6 satisfies the range of 1435 ~ 1650 ℃, it was confirmed that the Si real ratio is secured at a level of 90% or more.

On the other hand, in the case of Experimental Examples 1 and 7, the content of the silicon powder sludge and conidia are beyond the scope of the present invention, it was confirmed that the basicity (% CaO /% SiO ₂ ) of the slag is outside the range of 0.4 ~ 1.5. At this time, the slag melting point of Experimental Examples 1 and 7 exceeds 1700 ℃, it was confirmed that the Si real rate is 81% or less.

Accordingly, the method for producing ferrosilicon according to an embodiment of the present invention provides a silicon source by mixing condensed lime with silicon powder sludge at an optimum ratio and then providing it as a silicon source, effectively reducing the time and cost required for producing ferrosilicon It can reduce and effectively increase the recovery rate of silicon.

Although the present invention has been described in detail through the embodiments, other forms of embodiments are also possible. Therefore, the spirit and scope of the claims set forth below are not limited to the embodiments.

Claims (9)

A mixing step of preparing a mixture by mixing silicon powder sludge, conidia, carbonaceous material and a binder;
Agglomeration step of agglomerating the mixture;
A melting step of charging the agglomerated mixture and an iron source into a melting furnace and melting the molten mixture; And
And a step of obtaining the ferrosilicone by separating the ferrosilicon and slag from the molten metal from the melting furnace,
The mixing step, by weight percent, 83 to 95% of the silicon powder sludge, 4 to 16% of the condensed lime and 0.5 to 2% of the carbon-based material to prepare the mixture, a ferrosilicon manufacturing method . delete The method of claim 1,
Basicity (% CaO /% SiO ₂ ) of the slag is 0.4 ~ 1.5, ferrosilicon manufacturing method. The method of claim 1,
Melting point of the slag is 1435 ~ 1650 ℃, ferrosilicon manufacturing method. The method of claim 1,
In the melting step, the melting furnace temperature is raised to a temperature range of 1550 ~ 1700 ℃ to melt the block and the iron source, ferrosilicon manufacturing method. The method of claim 1,
The binder is a hydrocarbon-based organic ferro silicon manufacturing method. The method of claim 6,
The hydrocarbon-based organic material is any one of molasses and starch, or a mixture thereof, ferrosilicon manufacturing method. The method of claim 1,
The carbonaceous material is any one of powdered coal and powdered coke, or a mixture thereof, ferrosilicon manufacturing method. The method of claim 1,
The ferrosilicon manufacturing method further comprises a drying step of heating the dried mixture to a temperature range of less than 350 ℃ dried.

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