KR101773132B1 - Manufacturing method of ferrosilicon from silicon sludge and millscale and ferrosilicon manufactured thereby - Google Patents

Abstract

According to an embodiment of the present invention, a manufacturing method of ferrosilicon from silicon sludge and mill scale comprises the following steps: producing a mixture by mixing silicon sludge and mill scale which contains iron oxide (step 1); heat-processing the obtained mixture in an inert gas atmosphere (step 2); and cooling the heat-processed mixture into a predetermined temperature, and separating slag (step 3). Silicon and iron can be used as resources again through the method of the present invention.

Description

FIELD OF THE INVENTION The present invention relates to a method for producing ferro silicon from silicon sludge and wheat scale, and to a ferro-

The present invention relates to a process for the production of ferrosilicon from silicon sludge and mill scale and to ferrosilicon produced thereby, and more particularly to a process for producing ferrosilicon from a silicon sludge and mill scale comprising melt heat treatment step and slag separation step using only dried silicon sludge and mill scale without further additives And a ferrosilicon produced in accordance with the method.

Generally, silicon sludge includes materials such as silicon (Si), silica (SiO ₂ ), and silicon carbide (SiC). The amount of silicon contained in the silicon sludge varies depending on the manufacturing process of semiconductor and photovoltaic plate, but it is known that silicon sludge contains approximately 93 wt% or more of silicon and approximately 7 wt% or less of oxygen and carbon. In addition, the mill scale includes materials of the form of metallic iron (Fe) and iron oxide (FeO, Fe ₃ O ₄ , Fe ₂ O ₃ ). The content of iron in the mill scale varies depending on the rolling process in the production of steel, but it is known that it contains approximately 70 wt% or more.

Since the silicon sludge and the silicon and iron contained in the mill scale can be used as a raw material for ferro silicon used as an alloy raw material for special steels, an alloy raw material for aluminum, and a deoxidizing raw material for producing steel, It is a very bad resource. Therefore, in order to maximize resource utilization, reuse as an industrial raw material may be required for the national economy, and recycling the industrial raw materials with high added value may be very useful in terms of effective use of resources.

At present, there are a carbon thermal reduction method and a compression molding method for producing ferrosilicon. Among them, the carbon thermal reduction method is a method of producing silica (SiO ₂ ) ore as a raw material of silicon by using iron ore or mill scale, and reducing silica, iron ore or mill scale with carbon at a high temperature of 1600 ° C. or higher, Silicon is produced because it requires a lot of energy. Especially when iron ore with low grade is used, it disadvantageously discharges a large amount of slag which is industrial waste.

As one of the methods for molding ferro silicon, Korean Patent Laid-Open Publication No. 10-2012-0043216 discloses a method of manufacturing molded ferro silicon using silicon sludge. Specifically, a method of mixing a paper sludge incineration ash, slaked lime, Thereby producing a mixed sludge; Drying the mixed sludge in a dryer filled with a vacuum or an inert gas to prepare a dried sludge; Mixing the dry sludge with polysilicon powder to produce a raw sludge; Mixing the raw sludge with water glass, stirring the raw sludge, and compressing the mixture; The present invention provides a method of manufacturing molded ferrosilicon using a silicon sludge.

Generally, the ferro-silicon compression molding method is manufactured by physically mixing silicon sludge with iron powder and calcium hydroxide (Ca (OH) ₂ ) as a binder, and then further compressing the mixture by addition of a binder such as water glass. The characteristics of the ferrosilicon produced by this method are that the silicon and the iron are not chemically bonded and are physically bonded, and the ferrosilicon produced by the above method exhibits a reduced fracture strength. Accordingly, undifferentiation occurs in the transportation and transportation process, which causes the loss of silicon. In addition, when the ferrosilicon produced by the above method is used as an alloy raw material in a molten special steel and a molten aluminum, the ferrosilicon prepared by the above method, which is put into the molten metal, is chemically bonded without being chemically bonded to silicon, And silicone is separated from the surface of the molten silicon so that the silicon having a low density floats rapidly to the surface of the molten metal and the yield of the silicon alloy is lowered. The ferrosilicon produced by the above method is used as a deoxidizer for oxygen- The ferrosilicon manufactured by the above method is chemically bonded to the molten metal without being chemically bonded to the molten metal. Therefore, iron and silicon are easily separated from each other. As a result, silicon with low density floats rapidly to the surface of the molten metal, There is a drawback that it is lowered.

Korean Patent Publication No. 10-2012-0043216

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the prior art, and it is an object of the present invention to provide a method of manufacturing a semiconductor device, a method of manufacturing the same, The ferrous silicon is produced by converting the silicon component contained in the silicon sludge and the iron component contained in the mill scale into the metal bond form by mixing with no additional additives and then reducing and melting. Of the present invention.

It is also an object of the present invention to provide a method for making slag generated less environmental problems and enabling recycling of silicon and iron.

According to an aspect of the present invention, there is provided a method of manufacturing a sludge slurry, comprising: (1) preparing a mixture of a silicon sludge and a mill scale containing iron oxide; Heat treating the prepared mixture in an inert gas atmosphere (step 2); And separating the slag after cooling the heat-treated mixture to a predetermined temperature (step 3). The present invention also provides a method for producing ferrosilicon from a silicon sludge and a mill scale.

In one embodiment, the silicon sludge of step 1 may be dehydrated and then dried.

In one embodiment, the drying may be carried out in an inert gas atmosphere at a temperature of 150 ° C to 450 ° C for 20 minutes to 100 minutes.

In one embodiment, the inert gas may include at least one selected from the group consisting of nitrogen, argon, helium, and neon.

In one embodiment, the mixing of step 1 comprises mixing the mixture with 70 wt% to 90 wt% silicon sludge; And a mill scale residual amount.

In one embodiment, the inert gas in step 2 may include at least one selected from the group consisting of nitrogen, argon, helium, and neon.

In one embodiment, the heat treatment of step 2 may be performed at a temperature of 1250 ° C to 1500 ° C for 10 minutes to 100 minutes.

In one embodiment, the temperature of step 3 may be between 1100 ° C and 1250 ° C.

In one embodiment, the cooling of step 3 may be performed with natural cooling.

In order to achieve the above object, another aspect of the present invention provides a ferrosilicon manufactured by the above method, wherein the silicon content is 75 wt% to 90 wt%.

In one embodiment, the ferrosilicon may comprise 90 wt% to 98 wt% silicon relative to the silicon content of the starting silicon sludge.

In one embodiment, the ferrosilicon may comprise from 95 wt% to 99.0 wt% of iron relative to the iron content of the mill scale, which is the starting material.

According to an aspect of the present invention, silicon sludge discharged from a semiconductor or a photovoltaic plate is used as a silicon component in ferrosilicon, and iron oxide (FeO, Fe ₃ O ₄ , Fe ₂ O ₃ ) is used as a reducing agent, so that it is advantageous not to use carbon, which is a reducing agent that causes an increase in the process cost.

In addition, the iron contained in the mill scale discharged from the steel rolling process is used as an iron component in the ferrosilicone, thereby not using the iron scrap or iron powder which causes the increase in the process cost, and further, It is possible to produce ferro-silicon in a metal-bonded form excellent in the effect of silicon when it is used as an alloy raw material for special steels, an alloy raw material for aluminum, and a deoxidizing agent in the production of steel, without using the slaked lime and water glass used.

Furthermore, carbon dioxide (CO ₂ ), which is a global warming gas, is not produced during the production of ferrosilicon, and an additive is not used, and the generated slag has the advantage of being recyclable because there is no environmental problem.

Therefore, the present invention discloses an energy-saving environment-friendly technology that does not use carbon dioxide (CO ₂ ), which is a global warming gas, and does not use any subsidiary material, and simultaneously makes different industrial by- .

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a schematic view showing an example of a method for producing ferrosilicon from a silicon sludge and a mill scale according to an embodiment of the present invention.
2 and 3 are schematic views showing another example of a method for producing ferrosilicon from a silicon sludge and a mill scale according to an embodiment of the present invention.
4 is a graph showing the results of X-ray diffraction analysis performed in Experimental Example 2 of the present invention.
FIG. 5 is a graph showing the silicon and iron recovery rates and the silicon content of each of the examples and comparative examples in Experimental Example 1 of the present invention. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving it will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings.

It should be understood, however, that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. To fully inform the inventor of the category of invention. Further, the present invention is only defined by the scope of the claims.

Further, in the following description of the present invention, if it is determined that related arts or the like may obscure the gist of the present invention, detailed description thereof will be omitted.

As a result of intensive efforts to solve the problems of the prior art, the present inventors have found that the silicon sludge discharged from the process of manufacturing a semiconductor or a solar panel and the mill scale discharged from the steel rolling process are mixed without any additional additives, (FeO, Fe ₃ O ₄ , and Fe ₂ O ₃ ) contained in the mill scale is reduced to a part of silicon contained in the silicon sludge by heating at a high temperature under a reduced pressure, and iron oxide (FeO , Fe ₃ O ₄ , and Fe ₂ O ₃ ) in the silicon sludge are simultaneously melted to form the silicon component in the silicon sludge and the iron component in the mill scale in the metal bond form, Silicon, and completed the present invention.

According to an aspect of the present invention,

(Step 1) (S10) of preparing a mixture of a silicon sludge and a mill scale containing iron oxide;

Heat treating the prepared mixture in an inert gas atmosphere (step 2) (S20); And

And a step (S30) of separating the slag after cooling the heat-treated mixture to a predetermined temperature (step S30). The present invention also provides a method for producing ferrosilicon from a silicon sludge and a mill scale.

Hereinafter, the method for producing ferrosilicon from silicon sludge and mill scale according to one aspect of the present invention will be described in detail for each step.

In the method for producing ferrosilicon from silicon sludge and wheat scale according to an aspect of the present invention, the step 1 (S10) comprises mixing a mixture of silicon sludge and a mill scale comprising iron oxide.

The silicon sludge of step 1 is preferably subjected to dehydration and then dried. At this time, the dehydration may be dehydrated through centrifugation.

The drying treatment is preferably carried out in an inert gas atmosphere at a temperature of 150 ° C to 450 ° C for 20 minutes to 100 minutes. When the drying temperature is lower than 150 ° C, the drying time of the silicon sludge is increased. When the drying temperature is higher than 450 ° C, silicon contained in the silicon sludge is oxidized. If the drying time is less than 20 minutes, drying may be incomplete, and a large amount of moisture may remain in the silicon sludge. If the drying time is more than 100 minutes, drying may be sufficiently performed, There is a disadvantage in that energy loss and waste are increased as the length increases.

The inert gas in the drying treatment may include at least one kind selected from the group consisting of nitrogen, argon, helium and neon, and preferably nitrogen or argon.

Wherein the mixing of step 1 comprises mixing 70 wt% to 90 wt% of the silicon sludge; And a mill scale residual amount. If the amount of the silicon sludge of the mixture at the time of mixing is less than 70 wt%, the amount of slag generated in the following step increases and energy loss and loss of silicon may increase. When the silicon sludge of the mixture is 90 wt% It may cause a problem that the melting temperature is increased in the production of ferrosilicon in the following step and the energy loss is increased.

The silicon sludge of step 1 may include at least one selected from the group consisting of silicon, silica and silicon carbide.

The mill scale of step 1 may specifically include at least one iron oxide selected from the group consisting of FeO, Fe ₃ O _4, and Fe ₂ O ₃ .

In the method of manufacturing ferrosilicon from silicon sludge and mill scale according to one aspect of the present invention, the step 2 (S20) heat-treats the prepared mixture in an inert gas atmosphere.

The inert gas in step 2 may include at least one kind selected from the group consisting of nitrogen, argon, helium, and neon, and is preferably nitrogen or argon gas.

The heat treatment in step 2 is preferably carried out at a temperature of 1250 ° C to 1500 ° C for 10 minutes to 100 minutes. If the heat treatment in step 2 is carried out at less than 1250 ° C, there is a risk that the mixture of silicon sludge and mill scale will not be completely melted, and if the heat treatment in step 2 is carried out above 1500 ° C, The melt can be completely melted, but the energy loss due to the increase of the melt temperature may be significantly increased. If the heat treatment in step 2 is carried out for less than 10 minutes, the reduction of iron oxide contained in the mill scale may not be completed and ferrosilicon may not be easily formed. If the heat treatment in step 2 is performed for more than 100 minutes The iron oxide contained in the mill scale can be easily reduced, but the energy loss may increase as the holding time becomes longer.

Step 2 may be performed in an electric furnace.

The step 2 may be carried out by raising the temperature of the electric furnace charged with the mixture to the above-mentioned temperature, and maintaining the temperature for the above-mentioned time.

That is, in the step 2, iron oxide (FeO, Fe ₃ O ₄ , Fe ₂ O ₃ ) which can be contained in the mill scale can be reduced by heat-treating the mixture of the silicon sludge and the mill scale uniformly in an inert gas atmosphere At the same time, silicon contained in the remaining silicon sludge not used for the reduction of reduced iron and iron oxide can be melted together to synthesize ferrosilicon in one step.

In the method for producing ferrosilicon from silicon sludge and mill scale according to one aspect of the present invention, the step 3 (S30) separates the slag after cooling the heat-treated mixture to a predetermined temperature.

It is preferable that the cooling to the predetermined temperature of step 3 is carried out through natural cooling.

Cooling to the predetermined temperature of step 3 may be performed in an electric furnace as in step 2 above.

The cooling to the predetermined temperature of step 3 may be performed in an inert gas atmosphere as in step 2 above. The inert gas may include at least one kind selected from the group consisting of nitrogen, argon, helium and neon, and is preferably nitrogen or argon gas.

The predetermined temperature in step 3 is preferably 1100 ° C to 1250 ° C. If the temperature of step 3 is higher than 1250 DEG C, the amount of silicon and iron oxidized increases and the silicon and iron content in the finally produced ferrosilicon may decrease, and the amount of slag produced may increase.

The slag separation of step 3 can be carried out by taking out from the furnace and cooling the furnace to a predetermined temperature of the step 2 and the step 3 when the cooling is carried out in a furnace and separating the ferrosilicon phase and the slag phase have.

Secondary waste, which is a silica (SiO ₂ ) component that can be included in the slag in the step 3, has no environmental problems and can be recycled.

The slag separated in step 3 can be used as a raw material for cement.

As a result, the method of manufacturing ferrosilicon from silicon sludge and mill scale according to one aspect of the present invention is capable of manufacturing ferrosilicon using silicon sludge and mill scale, which are industrial byproducts, without using carbon and other solvents as reductant And the resulting slag provides a way to make it possible to recycle without environmental problems. Therefore, it is meaningful in that it is an energy-saving environment-friendly technology that does not emit carbon dioxide (CO ₂ ), a global warming gas, and a technology that maximizes the utilization rate of resources.

According to another aspect of the present invention,

The ferro silicon is produced by the above method (step 1 to step 3) and has a silicon content of 75 wt% to 90 wt%.

The ferrosilicon may comprise 90 wt% to 98 wt% silicon relative to the silicon content of the starting silicon sludge, and may include 95 wt% to 99.0 wt% iron relative to the iron content of the other starting material mill scale .

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. However, the following examples and experimental examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

In the following Examples and Experimental Examples, a mill scale containing silicon sludge containing 93 wt% of silicon and iron of 73 wt% was used.

< Example  1> Ferro silicon  Manufacturing 1

Step 1: In producing a mixture of silicon sludge and a mill scale comprising iron oxide (FeO, Fe ₃ O ₄ , Fe ₂ O ₃ ), the silicon sludge is heated in a nitrogen gas atmosphere at 60 ° C Min, and then the mixture was mixed so as to contain 29.2 wt% (100 g) of the mill scale and 70.6 wt% (243 g) of the silicon sludge, and then the mixture was uniformly stirred through a V-mixer (Hanyang Scientific, Korea) .

Step 2: The mixture thus prepared was put into an electric furnace in a nitrogen gas atmosphere and heat-treated at a temperature of 1300 캜 for 40 minutes.

Step 3: The heat-treated mixture (molten metal) was cooled to 1200 DEG C in a nitrogen gas atmosphere, and the ferrosilicon was taken out from the furnace and separated and recovered from the slag phase.

< Example  2> Ferro silicon  Manufacturing 2

Step 1: In preparing a mixture of a silicon sludge and a mill scale containing iron oxide, the silicon sludge is dried in an argon gas atmosphere at a temperature of 400 DEG C for 30 minutes, 100 g) and silicone sludge (76.0 wt%, 316 g) were mixed to prepare a uniformly stirred mixture through a V-mixer (Hanyang Scientific, Korea).

Step 2: The mixture thus prepared was put into an electric furnace in an argon gas atmosphere and heat-treated at a temperature of 1350 DEG C for 30 minutes.

Step 3: The heat-treated mixture (molten metal) was cooled to 1200 DEG C in an argon gas atmosphere, and the ferrosilicon was taken out from the furnace and separated and recovered from the slag phase.

< Example  3> Ferro silicon  Manufacturing 3

Step 1: In the preparation of the mixture of the silicon sludge and the mill scale containing iron oxide, the silicon sludge is dried in a nitrogen gas atmosphere at a temperature of 350 DEG C for 40 minutes, and then the mill scale is added to 12.8 wt% 100 g) and silicone sludge (87.2 wt%) were mixed to prepare a homogeneously stirred mixture through a V-mixer (Hanyang Scientific, Korea).

Step 2: The mixture thus prepared was put into an electric furnace in a nitrogen gas atmosphere and heat-treated at a temperature of 1450 DEG C for 20 minutes.

Step 3: The heat-treated mixture (molten metal) was cooled to 1200 DEG C in a nitrogen gas atmosphere, and the ferrosilicon was taken out from the furnace and separated and recovered from the slag phase.

< Comparative Example  1> Ferro silicon  Manufacturing 4

The procedure of Example 1 was repeated except that the mill scale was mixed so as to include 5.0 wt% (100 g) and silicon sludge 95.0 wt% (1900 g) in the mixing of Step 1 in Example 1 The ferrosilicon was separated and recovered from the slag phase.

< Comparative Example  2> Ferro silicon  Manufacturing 5

The procedure of Example 1 was repeated except that the mixing ratio of the mill scale and the silicon sludge was changed to 40.0 wt% (100 g) and 60.0 wt% (150 g) The ferrosilicon was separated and recovered from the slag phase.

The conditions of the above embodiments and comparative examples are schematically shown in Table 1.

division Step 1 Step 2 Example 1 Drying: N _2/200 ℃ / 60 bun
Addition: Si sludge 70.8 wt% Heat treatment: N _2/1300 ℃ Example 2 Drying: Ar / 200 캜 / 30 min
Addition: Si sludge 76 wt% Heat treatment: Ar / 1300 ℃ Example 3 Drying: N _2/200 ℃ / 40 bun
Addition: Si sludge 87.2 wt% Heat treatment: N _2/1300 ℃ Comparative Example 1 Drying: Same as in Example 1
Addition: Si sludge 60.0 wt% Same as Example 1 Comparative Example 2 Drying: Same as in Example 1
Addition: Si sludge 95.0 wt% Same as Example 1

< Experimental Example  1> Evaluation of silicon and iron recovery

The iron and silicon recovery rates of the above examples and comparative examples were measured by ICP analysis, and the results are shown in Table 2 and FIG.

As shown in Table 2 and FIG. 5, it was confirmed that the silicon content of the ferrosilicon prepared in Examples 1 to 3 contained 95 wt% or more of the silicon content of the silicon sludge, Of the total iron content.

On the contrary, in Comparative Example 1, the silicon recovery rate was reduced to 87%, and in Comparative Example 2, the silicon recovery rate was less than 95%, indicating that the recovery rate was lower than those of Examples.

division Si Recovery Rate (%) Fe recovery (%) Ferro Silicon Si content (wt%) Example 1 96 98 75 Example 2 95 97 80 Example 3 95 96 90 Comparative Example 1 87 90 55 Comparative Example 2 93 98 90

< Experimental Example  2> Ferro silicon  X-ray diffraction analysis

The ferrosilicon prepared in Example 1 was analyzed by X-ray diffractometry. The results are shown in FIG.

As shown in Fig. 4, it was confirmed that ferro silicon was easily formed in Example 1. [

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. This is obvious.

Therefore, the scope of the present invention should not be construed as limited to the embodiments described, but should be determined by the scope of the appended claims, as well as the claims.

It is to be understood that the foregoing embodiments are illustrative and not restrictive in all respects and that the scope of the present invention is indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

Silicon sludge produced in the process of manufacturing semiconductors or solar panels is used as a silicon component in ferrosilicon and at the same time, it is used as a reducing agent of iron oxide (FeO, Fe ₃ O ₄ , Fe ₂ O ₃ ) The use of iron scrap or iron powder, which is a raw material of iron that causes an increase in the process cost, is not used because it does not use carbon, which is a reducing agent that causes a rise in cost, and uses iron contained in a mill scale discharged from a steel rolling process as an iron component in ferrosilicon Do not.

Further, when the alloy raw material of special steel, the alloy raw material of aluminum, and the deagglomeration raw material of steel are used without the use of the slaked lime and water glass used for the point settlement which raises the process cost, the ferro silicon (CO ₂ ) as a global warming gas, and to treat different industrial byproducts in a single process so as to maximize utilization as high value-added industrial raw materials.

In other words, by using the manufactured ferro-silicon as a raw material for steel industry, it is possible to maximize utilization of silicon and iron resources, It will be widely used in the high value added of silicon sludge and mill scale in the field.

Claims (12)

Preparing a mixture of the silicon sludge and the mill scale comprising iron oxide (step 1);
Heat treating the prepared mixture in an inert gas atmosphere (step 2); And
And separating the slag after cooling the heat treated mixture to a predetermined temperature (step 3).
The method according to claim 1,
The silicon sludge of the step (1)
Wherein the sludge is dehydrated and then dried.
3. The method of claim 2,
The drying is carried out,
In an inert gas atmosphere at a temperature of 150 ° C to 450 ° C for 20 minutes to 100 minutes.
The method of claim 3,
The inert gas may include,
And at least one selected from the group consisting of nitrogen, argon, helium, and neon.
The method according to claim 1,
In the mixing of the step 1,
Said mixture comprising 70 wt% to 90 wt% of silicon sludge; And a mill scale remainder. The method of manufacturing ferrosilicon from a silicon sludge and mill scale.
The method according to claim 1,
The inert gas of the step 2,
And at least one selected from the group consisting of nitrogen, argon, helium, and neon.
The method according to claim 1,
The heat treatment in the step (2)
At a temperature of 1250 ° C to 1500 ° C for 10 minutes to 100 minutes.
The method according to claim 1,
The temperature of step 3 is,
Lt; RTI ID = 0.0 &gt; 1200 C &lt; / RTI &gt; to &lt; RTI ID = 0.0 &gt; 1250 C. &lt; / RTI &gt;
The method according to claim 1,
The cooling in step (3)
&Lt; / RTI &gt; characterized in that it is carried out with natural cooling.
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