KR101282919B1 - Manufacturing of Silica particle from slag - Google Patents

Abstract

The present invention relates to a method for producing silica particles from slag, comprising the steps of adding a strong acid to the slag, stirring the slag to which the strong acid is added to dissolve and extract the intermetallic compound in the slag particles, and the intermetallic compound is It is composed of the step of removing the fluorspar by adding ammonium chloride solution to the dissolved extract residue, and by producing high-purity silica particles from a large amount of slag generated in steel mills, it is possible to create a high value-added by-products, The present invention relates to a method for producing silica particles from slag that can be used as a raw material.

Silica particles, slag, leaching, dusting slag, steel making slag

Description

Manufacturing method of silica particles from slag {Manufacturing of Silica particle from slag}

1 is a silica particle crystal phase photograph according to the present invention,

Figure 2 is a conventional mixture particle crystal phase photograph.

The present invention relates to a method for producing silica particles from slag, and more particularly, adding a strong acid to the slag, stirring the slag to which the strong acid is added, dissolving and extracting an intermetallic compound in the slag particle, and the metal It is composed of the step of removing the fluorspar by adding ammonium chloride solution to the residue extracted by dissolving the liver compound, and by producing a high-purity silica particles from a large amount of slag generated in the steel mill, it is possible to create a high value added by-products, The present invention relates to a method for producing silica particles from slag that can be used as a raw material for the field.

In general, slag generated in steel mill is mainly composed of blast furnace slag of blast furnace process, steel slag of steelmaking process, pretreatment slag generated in pretreatment process of steelmaking, oxidation and reduction slag of electric furnace, slag of stainless steelmaking process, etc. Depending on the particle properties and characteristics of slag, it is widely recycled as cement raw materials, fertilizer raw materials, concrete product raw materials, road furnace materials, landfill materials, and loading materials. The main components of these slag is composed of CaO and SiO ₂ , the chemical composition of the representative slag is shown in Table 1.

Slag CaO SiO ₂ Al ₂ O ₃ MgO MnO TiO ₂ blast furnace 41.8 33.5 13.6 6.4 0.5 1.3 Steelmaking 46.1 14.8 1.5 6.3 5.4 1.5 STS Steel Making 55.16 30.37 1.86 8.03 0.14 0.26

(unit : %)

As shown in Table 1, various slags vary depending on the generation process, but are mainly composed of about 40-55% CaO and about 15-34% SiO ₂ . As such, slag containing a large amount of CaO component is currently recycled only as a raw material for various civil works in the concept of simple processing by physical processing, which is a very simple crushing and classification adjustment means.

Therefore, in Korea, where there is a lack of existing resources, it is very urgent to develop new technologies that can create high value-added products for more efficient recycling of by-products.

In general, fine silica powder is manufactured by crushing and classifying high-purity SiO ₂ ore, and is a basic raw material of major inorganic materials widely used as fillers for various powder coatings, abrasives, and paper according to purity and particle size.

As a method of preparing ultrafine silica powder, a method of preparing silica powder from a silicon body contained in chaff (powder metallurgy journal, vol.2, No.2, 1995), nanometer particle size silica by liquid phase reaction The method of manufacturing a powder, etc. are proposed.

The present invention is to overcome the above-mentioned problems, the object of the present invention is to add a strong acid of 6N concentration or more to the slag of iron by-product 1mm or less, stirred and reacted for 30 minutes or more to completely dissolve and extract the intermetallic compound remaining The present invention provides a method for producing silica particles from slag in which water is treated with a NH ₄ Cl solution of 0.5 M or more.

According to an aspect of the present invention, there is provided a method for preparing silica particles from slag, the method comprising: adding a strong acid to slag, stirring the slag to which the strong acid is added, and dissolving and extracting the intermetallic compound in the slag particle; In addition, ammonium chloride (NH ₄ Cl) solution is added to the residue from which the intermetallic compound is dissolved and extracted to remove fluorspar.

In addition, the particle size of the slag is characterized in that less than 1mm, the strong acid is characterized in that the hydrochloric acid or nitric acid, the slag added with the strong acid is characterized in that the stirring for 30 minutes or more, the concentration of the ammonium chloride solution is 0.5 Characterized in that the M concentration (Mole concentration) or more, the hydrochloric acid or nitric acid is characterized in that the concentration is 6N concentration (Normal concentration) or more.

The present inventors have conducted various basic experiments for expanding the field of effective use of slag and creating high added value. As a result, the present inventors have confirmed the possibility of high value added by recovering SiO ₂ component containing a large amount of slag and based on the result, Proposed.

Hereinafter, the configuration of the present invention will be described in more detail.

First, strong acid is added to the slag.

The slag targeted in the present invention can be applied to all slags (blast furnace, steelmaking, electric furnace, preliminary treatment, etc.) generated in the steel mill, it is preferable to use a slag with a high SiO ₂ content.

It is preferable that the particle size of the target slag is 1 mm or less, and this means that the slag artificially ground by the crushing and classification process, and the differentiation slag that is naturally formed by the crystal transition during the cooling process, such as stainless slag, are particles. The finer the particle size, the higher the reactivity with acid, so that the reaction treatment time can be shortened. Therefore, the finer particles are preferable. When particles having a particle size of 1 mm or more are used, the reactivity with acid is drastically reduced, so that the reaction time is very long, which is not suitable for productivity, and unreacted slag particles are mixed in the product, so that single phase silica particles cannot be produced and have high purity. The production of silica powder is impossible.

The strong acid used for dissolving and extracting the intermetallic compound in the slag particles may be hydrochloric acid, nitric acid, or the like, and the acid concentration is preferably at least 6N (normal concentration). If the concentration of the acid is less than the concentration of 6N because the intermetallic compound in the slag can not be completely dissolved and extracted, it is not possible to produce a single-phase silica particles, because of this it is impossible to produce a high purity silica particles. If the concentration is increased under the condition of more than 6N concentration, the dissolution rate of the slag will be faster and the reaction completion time will be shortened, but care must be taken to handle high concentrations of acid. When sulfuric acid is used as a strong acid, calcium components contained in a large amount of the slag are eluted to react with sulfate ions to form gypsum (CaSO 4), which is a solid phase. Therefore, it is preferable to use hydrochloric acid, nitric acid, etc. as a strong acid to be used.

Slag components such as Al 2 O 3, MgO and MnO are eluted by a strong acid because they are present in the form of intermetallic compounds in the slag particles, not in a single phase, but SiO ₂ in the slag is eluted by the strong acid and is not eluted by the strong acid.

Next, the slag added with the strong acid is stirred to dissolve and extract the intermetallic compound in the slag particles.

It is preferable to maintain the reaction time at 30 minutes or more during the stirring reaction by the addition of slag and a strong acid of 6N concentration or more. When a strong acid of 6N concentration or more is used, when the reaction time is 30 minutes or less, single phase silica particles cannot be prepared because slag is not completely dissolved and some undissolved intermetallic compounds are present. As the concentration of acid increases above 6N concentration, the rate of dissolution of slag increases.

Finally, ammonium chloride solution is added to the residue from which the intermetallic compound is dissolved and extracted to remove fluorite.

After complete extraction of the intermetallic compound by reaction with a strong acid of 6N or higher concentration, it is preferable to treat the residue with a NH ₄ Cl solution of 0.5 M or higher concentration. Treatment of the residue with NH ₄ Cl solution is intended to remove fluorite (CaF ₂ ) which is not dissolved even by strong acid, and its concentration is preferably 0.5M (mole concentration) or more.

If NH ₄ Cl below 0.5M is used, it is difficult to completely remove the fluorspar and the reaction time is very long. Fluorite is a substance that is added to easily remove impurities in steel during steel mill operations, and is mainly used as a slag forming agent.

The experiment was conducted using materials other than NH ₄ Cl, but there was no effect of removing fluorite (CaF ₂ ).

Referring to FIG. 1, a crystalline photograph of silica particles according to the present invention is shown, and referring to FIG. 2, a mixture particle crystalline photograph according to a comparative example is shown.

As shown, it can be seen that the crystalline phase of the silica particles according to the present invention is produced as an amorphous silica single phase.

<Example 1>

Hereinafter, the present invention will be described in more detail with reference to Examples.

First, 18% HCl (6N concentration), 24.5% HCl (8N concentration), and 31% HCl (100g) of 100g of differentiated slag with an average particle size of 75 µm generated during the refining process of stainless steel according to the method for preparing silica particles from slag according to the present invention 10N concentration) and 500ml of 27% HNO ₃ (6N concentration) were added thereto, followed by stirring at 100 rpm for 30 minutes to complete the reaction. In addition, the steelmaking slag generated in the steelmaking process was separated by particle size, 18% HCl (6N concentration) was added to the particle size slag of 1mm or less, and stirred for 30 minutes to complete the reaction. After the reaction, the filtrate was removed by filtration, and the remaining residue was added to 500 ml of 0.5 M NH ₄ Cl solution, followed by stirring for 10 minutes. The reaction was washed with water to remove impurities and dried in a dryer to prepare an off-white product. The crystal phase of this product was analyzed by XRD, and the particle size was analyzed by particle size analyzer and the component content by fluorescence X-ray analyzer, and the results are shown in Table 2 below.

As a comparative example, except that 12% HCl (4N concentration) and 18% HNO ₃ (4N concentration) were used as the concentrations of the acid added to the differentiating slag, the same method as in the invention was performed. In addition, the residue obtained after reacting with an acid of 18% HCl (6N concentration) concentration was carried out in the same manner as in the invention except that the residue was not treated with 0.5M NH ₄ Cl solution. In addition, steelmaking slag generated in the steelmaking process was separated, and 500ml of 31% HCl (10N concentration) was added to the slag of 1-2mm particle size, stirred for 30 minutes, and the residue was treated with 0.5M NH ₄ Cl solution. Was completed and the results are shown in Table 2.

Reaction condition Product property Slag granularity Acid concentration
(N) Reaction time
(min.) Crystalline phase Granularity Silica content (%) Example One 75 μm HCl 6N 30 Amorphous SiO ₂ 37 μm 96.5 2 75 μm HCl 8N 30 Amorphous SiO ₂ 37 μm 96.3 3 75 μm HCl 10N 30 Amorphous SiO ₂ 37 μm 98.2 4 75 μm HNO ₃ 6N 30 Amorphous SiO ₂ 37 μm 97.4 5 Less than 1mm HCl 6N 30 Amorphous SiO ₂ 37 μm 95.2 Comparative example One 75 μm HCl 4N 30 Amorphous SiO ₂
+ ₂ CaOSio ₂ 37-100㎛ 29.4 2 75 μm HNO ₃ 4N 30 Amorphous SiO ₂
+ ₂ CaOSio ₂ 37-100㎛ 30.7 3 75 μm HCl 6N 30 Amorphous SiO ₂
CaF ₂ 37-50㎛ 63.5 4 1-2mm HCl 10N 30 Amorphous SiO ₂
+ ₂ CaOSio ₂ 37-0.5㎛ 29.

As shown in Table 2, in the case of Inventive Example (1-5), in which the acid concentration conditions of the present invention, that is, conditions in which the reaction was completed using an acid of 6N concentration or more and a NH ₄ Cl solution of 0.5 M or more, were used, It was an amorphous silica particle single phase, had a particle size of about 37 μm, and a SiO ₂ content of about 95-98%. However, in the case of Comparative Example (1-2) using an acid concentration lower than the conditions of the present invention and Comparative Example (3) not treated with 0.5M NH ₄ Cl solution, C ₂ S (2CaO. It can be confirmed that SiO ₂ ), the partially dissolved amorphous silica phase, and the undissolved CaF ₂ phase coexist, and the particle size is about 37-100㎛, and the silica content is contained in the produced amorphous silica and slag. The silica was mixed to show a content of about 29% or about 64% due to the coexistence of CaF ₂ phase. C ₂ S is present in a crystalline form having a size of 20 ~ 40㎛ in the form of a spherical or hemispherical. In the case of slag particle size, in the case of Inventive Example (1-5) using a particle size of 1 mm or less, which is the condition of the present invention, especially in the case of Inventive Example (5) using a steelmaking slag of 1 mm or less as well as a very fine stainless steel differentiation slag It was confirmed that it was dissolved and produced as an amorphous silica single phase. On the contrary, in the case of Comparative Example (4) using steelmaking slag having a particle size larger than the conditions of the present invention, even when 10N concentration of strong acid was used, the slag was not completely dissolved and coexisted as an undissolved substance. can confirm.

From the above results, the particle size of 1mm or less is suitable for producing high purity silica particles from slag, and the concentration of strong acid used is more than 6N concentration, and NH ₄ Cl solution is used to remove fluorite that cannot be dissolved and removed by strong acid. It can be confirmed that the treatment is preferable.

<Example 2>

First, according to the method for producing silica particles from slag according to the present invention, 500 ml of 18% HCl (6N concentration) was added to 100 g of the differentiated slag of 75 µm by-product produced in the refining process of stainless steel, and then 60 minutes and 120 minutes at 100 rpm. The reaction was completed by stirring each minute and the residue was treated with 0.5M NH ₄ Cl and 1M NH ₄ Cl solution, respectively. The reaction was washed with water to remove impurities and dried in a dryer to prepare an off-white product. The crystal phase of this product was analyzed by XRD, and the particle size was analyzed by particle size analyzer and component content by fluorescence X-ray analyzer, and the results are shown in Table 3 below.

And as a comparative example, it carried out by the method similar to the said invention example except the completion | finish of reaction by advancing stirring and reaction time by addition of slag and an acid for 10 minutes and 20 minutes, respectively.

In addition and is carried out in the same manner as in Example except that the treatment with _{0.1M NH 4 Cl, 0.3M NH 4} Cl to the residue after reaction of the acid and the results are shown in Table 3 below.

Reaction condition Product property Slag granularity Acid concentration
(N) NH ₄ Cl
density reaction
time Crystalline phase Granularity
(탆) SiO ₂ content
(%) Example 6 75 μm HCl 6N 0.5M 60 Amorphous SiO ₂ 47 96.4 7 75 μm HCl 6N 1.0 M 120 Amorphous SiO ₂ 40 96.7 Comparative example 5 75 μm HCl 6N 0.5 M 10 Amorphous SiO ₂
+ ₂ CaOSio ₂ 40-100 28.9 6 75 μm HCl 6N 0.5 M 20 Amorphous SiO ₂
+ ₂ CaOSio ₂ 40-80 28.7 7 75 μm HCl 6N 0.1 M 60 Amorphous SiO ₂
CaF ₂ 40-50 64 8 75 μm HCl 6N 0.3 M 60 Amorphous SiO ₂
CaF ₂ 40-50 65

As shown in Table 3, in Example (6-7) which is the reaction time condition of the present invention, all the intermetallic compounds in the slag are completely dissolved under the reaction time of 30 minutes or more to prepare single-phase amorphous silica particles. There was no significant difference in the silica content with the increase of the reaction time under the reaction time of 30 minutes or more. On the other hand, in the case of carrying out under the conditions of Comparative Example (5-6) less than the reaction time condition of the present invention, the 2CaO · SiO ₂ phase caused by undissolved slag and the partially dissolved silica phase coexisted. The silica content in the slag itself was about the same as about 30%. In addition, in the case of Comparative Example (7-8) using 0.1 M and 0.3 M NH ₄ Cl solution to remove undissolved fluorspar material after reaction with strong acid, coexists without being completely removed in undissolved state even after completion of reaction. It could be confirmed. Therefore, in order to completely remove the fluorspar, it can be confirmed that the treatment with a NH ₄ Cl solution of 0.5M or more is preferable.

When strong acid was added to the slag and stirred, the temperature of the reaction solution increased to 90 ° C. due to a rapid exothermic reaction at the beginning of the reaction. As the reaction proceeded, the temperature of the reaction solution gradually decreased, and the reaction time was 30 minutes at the end of the reaction. In about 35-40 degreeC. It was confirmed that the initial exotherm rapidly increased as the concentration increased in the condition of the acid concentration above 6N concentration, and the end point of the reaction was shortened. From the exothermic reaction of the reaction solution and the temperature rise and fall of the reaction solution, the approximate timing of completion of the reaction can be determined.

In the above results, in order to prepare high purity silica particles from slag, it is confirmed that it is preferable to use a particle size of 1mm or less, react with a strong acid of 6N concentration or more for 30 minutes, and then treat with ammonium chloride solution of 0.5M concentration or higher. Can be.

Judging from the above results, in order to produce high purity silica particles from various slag by-products in steel mills, the particle size of 1mm or less is suitable and the concentration of strong acid used for melting slag is 30 After stirring and reacting for more than a minute, it can be determined that treatment with an ammonium chloride solution of 0.5 M or more is a very effective condition.

As described above, the silica particle production method from slag according to the present invention, by producing a high-purity silica particles from a large amount of slag generated in steel mills, it is possible to create a high value-added by-products, raw materials of various fields It can be used as.

Claims (6)

Adding a strong acid to the slag; Stirring the slag to which the strong acid is added to dissolve and extract the intermetallic compound in the slag particles; And adding ammonium chloride solution to the residue from which the intermetallic compound is dissolved and extracted to remove fluorite. The method of claim 1, The particle size of the slag is 1mm or less, the silica particle production method from the slag. The method of claim 1, Wherein said strong acid is hydrochloric acid or nitric acid. The method of claim 1, The slag to which the strong acid is added is stirred for 30 minutes or more. The method of claim 1, The method for producing silica particles from slag, characterized in that the concentration of the ammonium chloride solution is at least 0.5M concentration. The method of claim 3, The method of producing silica particles from slag, wherein the concentration of hydrochloric acid or silver nitrate is 6N or higher.

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