KR101315350B1 - Treating method of byproduct - Google Patents

Abstract

The present invention relates to a by-product treatment method, the process of grinding the slag generated in the steelmaking process; and the process of eluting magnesium by treating the milled slag with a solution containing acid; and separating the magnesium eluate from which magnesium is eluted Process of doing; And hydrolyzing by applying an alkali component to the magnesium eluate. Accordingly, high purity silicon dioxide (SiO ₂ ) may be separated, and magnesium compounds such as magnesium hydroxide (Mg (OH) ₂ ), magnesium oxide (MgO), and magnesium carbonate (MgCO ₃ ) may be produced and recycled in a steelmaking process. . Through this, it is possible to generate additional profits, resulting in cost savings, and creating new uses of slag. In addition, by recycling the carbon dioxide-containing gas generated in the steel mill can minimize environmental pollution and achieve an environmentally friendly steelmaking process.

Description

Treating method of byproduct

The present invention relates to a by-product treatment method, and more particularly to a by-product treatment method for treating the slag more effectively.

In general, serpentine (Mg ₃ Si ₂ O ₅ (OH) ₄ ) is one of the rocks containing a large amount of magnesium, and exists in nature in the form of magnesium silicate. These serpentine is mainly used as a raw material for the melt in the steel and steel industry, soluble impression fertilizer, building materials and decorative stone. Serpentine has sufficient potential as a raw material for carbonate mineralization and much research is being conducted. This is due to the high content of magnesium in the serpentine. However, since the carbon dioxide absorption reaction proceeds very slowly, there is a problem in that the serpentine needs to be pulverized very finely or heated to a high temperature in order to accelerate it.

Moreover, when serpentine is used in the related art, since the crushing is required several times by mining from the mine, there is a problem that a lot of energy loss occurs. In addition, since there is a risk of exposure to asbestos, a natural resource depletion and carcinogen, there is a problem that must be handled with great care.

Meanwhile, ferronickel is used as a raw material when manufacturing stainless steel, one of steel products. Nickel ore is reduced by coke in an electric furnace type furnace using nickel ore, where ferronickel is produced. The slag generated at this time is ferronickel slag.

In general, conventional steel slag, that is, blast furnace slag and steelmaking slag is composed of calcium oxide (CaO) and silicon dioxide (SiO ₂ ) components. On the other hand, ferronickel slag is a magnesium silicate slag containing silicon dioxide (SiO ₂ ) and magnesium oxide (MgO) as main components. Therefore, it can be supplied to a steel mill as a magnesium oxide source which is a slag forming agent for steelmaking. Ferronickel slag is recycled in advanced countries such as Japan and Canada as raw materials for cement manufacturing, civil engineering materials, concrete aggregates, runway aggregates, serpentine substitutes, etc. . In addition, ferronickel (Fe-Ni) slag, which is discharged at 1 million tons per year, will generate more than 2 million tons of waste slag a year due to further increase in facilities, and it is very urgent to find new uses such as recycling ferronickel slag.

Korean Patent Publication No. 2009-0083541

The present invention provides a by-product treatment method for efficiently utilizing the slag generated in the steelmaking process.

The present invention provides a by-product treatment method for producing magnesium compounds such as silicon dioxide (SiO ₂ ) and magnesium hydroxide (Mg (OH) ₂ ), magnesium oxide (MgO), and magnesium carbonate (MgCO ₃ ) from slag.

The by-product treatment method according to the present invention is a process of grinding the slag generated in the steelmaking process, the process of eluting magnesium by treating the milled slag with a solution containing acid, the process of separating the magnesium eluate eluted with magnesium, Applying an alkali component to the magnesium eluate to hydrolyze and prepare a magnesium compound through the above process.

The slag is a slag generated while refining ferronickel, and includes heat treatment after hydrolysis, and extracts magnesium hydroxide through the heat treatment. In addition, after the hydrolysis process, including the step of heat treatment, the heat treatment is carried out in the range of 350 to 600 to prepare magnesium oxide.

During the hydrolysis process or after the hydrolysis process, carbon dioxide-containing gas is added to form magnesium carbonate. Here, in the process of adding the gas containing carbon dioxide, the gas containing carbon dioxide is injected at ¹ Nm ³ / min · ton or more, and after adding the gas containing carbon dioxide, dry refinement is performed to prepare magnesium oxide. In this case, by-product gas generated in the steelmaking process is recycled as a gas containing carbon dioxide.

In the process of crushing the slag slag is crushed to 75㎛ or less. In addition, at least one of sulfuric acid, hydrochloric acid, and nitric acid may be used to elute the magnesium. Sulfuric acid solutions having a concentration of 1.0 to 5.0 M are prepared using sulfuric acid, and the slag is added to the solution at a concentration of 100 g / L to 300 g / L. At this time, the solution is maintained at 50 to 100 degrees and stirred in the range of 200 to 500 rpm.

In the process of separating the magnesium eluate, the magnesium eluate and the silicon dioxide remaining as a residue are separated through solid-liquid separation.

At this time, further comprising the step of removing impurities before the hydrolysis process, the H ₂ O ₂ solution is added to the magnesium eluate and the equivalent ratio of the H ₂ O ₂ has a range of 0.8 to 1.2. The hydrolysis process adds an alkaline hydroxide to the magnesium eluate and adjusts the pH to a range of 8 to 12. Here, the hydroxide is at least one of sodium hydroxide and potassium hydroxide, and adjusts the pH range to 10 to 12 range.

In the by-product treatment method according to the embodiment of the present invention, high-purity silicon dioxide (SiO ₂ ) is separated from slag, and magnesium, such as magnesium hydroxide (Mg (OH) ₂ ), magnesium oxide (MgO), and magnesium carbonate (MgCO ₃ ) The compound can be produced and recycled in the steelmaking process. From this, it is possible to improve the utilization of the slag that was entirely embedded. As the amount of slag generated during the steelmaking process increases, this effect can be further increased.

In addition, through the recycling of magnesium compounds, it has an additional revenue generation and cost reduction effect, there is an effect that a new use of slag is created.

In addition, by recycling the gas containing carbon dioxide generated in the steel mill it has the effect of minimizing environmental pollution and achieving environmentally friendly steelmaking process.

1 is a flowchart illustrating a method of treating a byproduct according to an exemplary embodiment of the present invention.
Figure 2 is a view showing in detail the by-product treatment method and the resulting product according to an embodiment of the present invention.
3 is a graph showing a change in the content of silicon dioxide (SiO ₂ ) in the slag treated by the by-product treatment method according to the experimental example of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know. Wherein like reference numerals refer to like elements throughout. In addition, in describing the present invention, a detailed description of related known functions or configurations will be omitted in order not to obscure the subject matter of the present invention.

1 is a flowchart illustrating a method of treating a byproduct according to an exemplary embodiment of the present invention.

Referring to Figure 1, the treatment method according to an embodiment of the present invention, the process of grinding the slag generated in the steelmaking process (S1); Separating magnesium ion eluate and silicon dioxide from the ground slag (S2); Hydrolysis of the magnesium ion eluate includes a step (S3). After hydrolyzing the eluate, two treatments may be performed.

That is, after the step of hydrolyzing the magnesium ion eluate (S3), it may include a carbonation reaction process (S4) and dry refining process (S5) of adding a gas containing carbon dioxide to the eluent.

Alternatively, the method may include a step (S6) of heat-treating the magnesium ion eluate having undergone the hydrolysis (S3) without a separate gas treatment.

Figure 2 is a view showing in detail the by-product treatment method and the resulting product according to an embodiment of the present invention. Hereinafter, each process will be described in detail with reference to FIG. 2.

Referring to FIG. 2, first, the slag which is a by-product of the steelmaking process is pulverized and classified (S1). This is a process of increasing the reaction surface area in order to improve the reactivity in the step of eluting magnesium (S21) to be described later.

In general, the slag which is a by-product of the steelmaking process includes blast furnace slag and steelmaking slag. It is composed of calcium oxide (CaO) and silicon dioxide (SiO ₂ ) components. In addition, ferronickel slag, another by-product of the steelmaking process, is a slag generated by refining ferronickel, and is a magnesium silicate slag composed of silicon dioxide (SiO ₂ ) and magnesium oxide (MgO) as main components. Therefore, it can be supplied to a steel mill as a magnesium oxide source which is a slag forming agent for steelmaking.

In the following, a method of treating by-products using ferronickel slag among various slags will be described.

In general, the particle size of ferronickel slag is discharged smaller (eg, 1 to 10 mm) than that of serpentine (Mg ₃ Si ₂ O ₅ (OH) ₄ ). Therefore, it can be used for the separation process of the silicon dioxide and magnesium ion eluate by acid leaching method only through the grinding process. This has the advantage of low energy dependence compared to serpentine (Mg ₃ Si ₂ O ₅ (OH) ₄ ). In addition, it is preferable that the ferronickel slag is pulverized to 75 μm or less in the process of grinding the slag (S1). This is to widen the specific surface area to maximize the reaction efficiency with acid in the process by acid leaching method.

A classification process may be performed after the grinding process, and the classification process is a process of classifying the crushed ferronickel slag by a certain particle size. This is to select the ferronickel slag pulverized to 75㎛ or less.

The ferronickel slag can be used in place of the serpentine because the chemical composition is similar, and in the following, the chemical composition of the serpentine and ferronickel slag is compared.

Table 1.

As shown in Table 1, the ferronickel slag is about 20% higher than the silicon serpentine, the magnesium oxide shows a similar component distribution. In addition, other components, such as calcium oxide (CaO), are contained less than serpentine.

S21 process shown in FIG. 2 is a process of eluting magnesium from crushed and classified ferronickel slag. At this time, an acid leaching method may be used, and the acid leaching method is treated with a solution containing acid to elute magnesium. That is, when slag is added to the acid-containing solution, magnesium is dissolved in the slag and is present in the solution as magnesium ions.

As the acid used in the acid-containing solution, sulfuric acid (H ₂ SO ₄ ), hydrochloric acid (HCl), nitric acid (HNO ₃ ) and the like may be used. Here, hydrochloric acid (HCl) and nitric acid (HNO ₃ ) is an efficient acid, but very expensive compared to sulfuric acid (H ₂ SO ₄ ), hydrochloric acid (HCl) has a problem that can corrode the facility because it is strong corrosive. Therefore, it is preferable to use sulfuric acid (H ₂ SO ₄ ) which is inexpensive and advantageous in terms of economics.

The sulfuric acid (H ₂ SO ₄ ) solution used in the step of treating the ground slag with an acid-containing solution to elute magnesium (S21) is maintained at a high concentration of 1.0M to 5.0M. This is in order to shorten the reaction time, the concentration of sulfuric acid (H ₂ SO ₄₎ solution of 1.0M or less Mg leach rate is very low, the processing solution used in a concentration of more sulfuric acid (H ₂ SO ₄₎ solution of 5.0M This is because there is a problem.

In addition, the ratio of ferronickel slag and sulfuric acid (H ₂ SO ₄ ) solution is maintained at 100 to 300g / L to proceed with the reaction. This is because the productivity decreases when the ratio of ferronickel slag and sulfuric acid (H ₂ SO ₄ ) solution is less than 100g / L, and the process is inefficient if more than 300g / L. Therefore, when the process is made within the above range can be processed efficiently.

In the step (S21) of eluting magnesium, the reaction is performed at 50 degrees to 100 degrees Celsius, and the stirring speed is preferably maintained at 200 to 500 rpm. This is because the leaching rate of magnesium ions increases as the leaching temperature increases, and is intended to increase the reaction efficiency through stirring.

After eluting the magnesium through the S21 process, the process of separating the magnesium eluted solution from which the magnesium is eluted (S22). The S22 process separates the magnesium eluate and the remaining silicon dioxide through the solid-liquid separation process. Here, the magnesium eluate refers to a solution from which magnesium is eluted, and more specifically, a solution from which magnesium ions are eluted.

On the other hand, the following formula is a reaction formula in the case of extracting a magnesium compound from the conventional serpentine (Mg ₃ Si ₂ O ₅ (OH) ₄ ).

 Reaction 1.

_{Mg 3 Si 2 O 5 (OH} ) 4 + 3H 2 SO 4 → 3Mg 2 + + 3SO 4 2 - + 2SiO 2 + 5H 2 O

As can be seen in Scheme 1, the magnesium eluate in which silicon dioxide (SiO ₂ ) and magnesium (Mg) ions are eluted is separated by an acid leaching method using sulfuric acid (H ₂ SO ₄ ).

When slag containing magnesium is treated with an acid, a reaction similar to that of the serpentine (Mg ₃ Si ₂ O ₅ (OH) ₄ ) is generated. In particular, ferronickel slag having a composition similar to serpentine can be used to replace serpentine, and even when ferronickel slag is used, a magnesium eluate, in which silicon dioxide (SiO ₂ ) and magnesium (Mg) ions are eluted by acid leaching, Are separated.

The high purity silicon dioxide (SiO ₂ ) separated in the solid-liquid separation process (S22) for separating the magnesium eluate may be formed into a powder through washing with two to four times neutral water, followed by filtration and drying.

Using the magnesium eluate obtained in the above manner, the magnesium compound is prepared through S3, S4, and S5 which will be described later, or through the S3, S61, and S62 processes. In each case, the magnesium compound produced may be different.

S3 process shown in Figure 2 is a process of hydrolysis by applying an alkali component to the separated magnesium eluate. In the hydrolysis process (S3), an alkali component is applied to the magnesium eluate. This produces a magnesium compound, the alkaline component may be an alkaline hydroxide. At least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH) may be used for the alkaline hydroxide. In the S3 process of the present invention, sodium hydroxide (NaOH) is used, and adjusts the pH range of the eluate. The pH range is preferably 8 to 12. More preferably, the pH range is adjusted to 10-12. This is because the higher the pH value, the better the reactivity of magnesium and the more efficiently magnesium hydroxide can be obtained.

Meanwhile, the method may further include removing impurities before the hydrolysis process S3. The process of removing impurities is a process of purification using H ₂ O ₂ solution. Purifying is a process of removing impurities present in the magnesium eluate formed after S22. At this time, H ₂ O ₂ Preference is given to using H ₂ O ₂ solutions having an equivalence ratio of 0.8 to 1.2.

After the hydrolysis process S3, a first treatment process through a heat treatment process or a second treatment process through a carbonation reaction may be performed. That is, in the first treatment process, the magnesium eluate obtained is subjected to low temperature heat treatment without additional treatment to extract magnesium hydroxide or high temperature heat treatment to prepare magnesium oxide. In the second process, carbon dioxide gas is added to the magnesium eluate to produce magnesium carbonate through a carbonation reaction.

First, the first treatment is a process of extracting magnesium hydroxide ((Mg (OH) ₂ ) by heat-treating the magnesium eluate having undergone the process of S1 to S3 at low temperature (first heat treatment) and the extracted magnesium hydroxide ((Mg ( OH) ₂ ) is heat-treated at a high temperature (second heat treatment process) to produce magnesium oxide (MgO)

The first heat treatment process S61 is a low temperature heat treatment process performed at 100 degrees to 350 degrees Celsius. This, Mg (OH) _2, or a magnesium ion, and OH bonds present in the solution was extracted with magnesium hydroxide _{((Mg (OH) 2)} . Magnesium hydroxide ((Mg (OH) ₂₎ are Celsius 370 also near the Since the decomposition process occurs in the magnesium oxide (MgO) at the heat treatment in the temperature range lower than this to obtain a hydroxide.

The second heat treatment process S62 is a high temperature heat treatment process processed at a higher temperature than the first heat treatment process S61. Through this, magnesium oxide (MgO) is produced. Preferably, the second heat treatment process S62 is performed at 350 to 600 degrees. This is because magnesium hydroxide ((Mg (OH) ₂ ) is decomposed to magnesium oxide (MgO) at about 370 degrees Celsius similarly to the case of the first heat treatment process S61 having the above temperature range.

Here, although the first heat treatment and the second heat treatment have been exemplarily performed, only the first heat treatment may be performed or only the second heat treatment may be performed. In addition, when used in the steelmaking process without a separate heat treatment may be performed automatically by the heat applied during the steelmaking process.

The second treatment process is a process of undergoing a carbonation reaction process (S4) and dry refining process (S5).

Carbonation reaction process (S4) is a process of producing magnesium carbonate (MgCO ₃ ) by adding a gas containing carbon dioxide after the hydrolysis process (S3) or after the hydrolysis process (S3). That is, when carbon dioxide-containing gas is introduced into the eluate, magnesium ions present in the solution react with the CO-containing component supplied from the gas. Magnesium is produced as magnesium carbonate (MgCO ₃ ) because it reacts more easily with CO-containing components than with OH. Here, the gas containing carbon dioxide refers to by-product gases (eg, LDG and BFG) generated in steel mill processes. In the treatment process of the present invention, by recycling the gas, LDG gas may be used. LDG gas is a gas produced from melting iron and is composed of carbon dioxide and carbon monoxide. The addition flow rate of the gas is preferably added at ¹ Nm ³ / min · ton or more in consideration of the reaction time and the reaction efficiency. Through this, it is possible to reduce the harmful carbon dioxide emitted to the atmosphere by using a gas containing carbon dioxide generated in the steel mill. In addition, it can be used without separating the carbon dioxide in the flue-gas generated in the steel mill.

Dry refining process (S5) is a process of producing magnesium carbonate (MgCO ₃ ) produced through the carbonation reaction process (S4) to magnesium oxide (MgO). In the dry refining process (S5), it is preferable to heat-treat the magnesium carbonate (MgCO ₃ ) at a temperature of 1000 degrees or more. This is because the temperature at which carbon dioxide is dissociated is about 950 degrees, and accordingly, the dry refining process (S5) must be performed at 1000 degrees or more.

Through the above process, magnesium compounds (Mg (OH) _2, MgCO _3, MgO) can be prepared from ferronickel slag. Of course, silicon dioxide can also be prepared at this time. As such, various magnesium compounds prepared from ferronickel slag can be used again in the steelmaking process.

Hereinafter, the present invention will be described in more detail in Experimental Examples.

Experimental Example

Ferronickel slag is prepared, and the ferronickel slag is pulverized and classified to 75 μm or less. Then, the magnesium eluate and silicon dioxide are separated by acid leaching using sulfuric acid. Here, a sulfuric acid solution of 5M concentration is prepared, slag is added to 1 L of sulfuric acid solution, and the concentration of the mineral solution is adjusted to 200 g / L. Thereafter, an alkali component is applied to the magnesium eluate to undergo hydrolysis. In the hydrolysis process, sodium hydroxide (NaOH) is added, followed by a carbonation reaction process in which a gas containing carbon dioxide is added, thereby preparing a magnesium compound (Mg (OH) ₂ ).

3 is a graph showing a change in content of silicon dioxide (SiO ₂ ) in the slag (specifically, ferronickel slag) by the by-product treatment method according to the experimental example of the present invention.

Referring to FIG. 3, it can be seen that the content of silicon dioxide (SiO ₂ ) in the ferronickel slag increases from 55.5% to 80.5%. That is, before the treatment of the experimental example, the content of silicon dioxide (SiO ₂ ) in the slag was 55.5%, and after the treatment of the experimental example, the content of silicon dioxide (SiO ₂ ) was increased to 80.5%. This is a magnesium compound is produced during the treatment of the experimental example, the content of silicon dioxide (SiO ₂ ) in the ferronickel slag is relatively increased by the extraction of magnesium in the slag. Through this, it can be seen that the magnesium compound is effectively produced.

In the above, the slag generated during ferronickel refining has been described by way of example, but the present invention is not limited thereto. That is, the present invention can be applied to various slags containing magnesium in addition to ferronickel slag.

As mentioned above, although this invention was demonstrated in detail through the preferable Example, the scope of the present invention is not limited to a specific Example, Comprising: It should be interpreted by the attached Claim. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the present invention.

Claims (16)

Grinding slag generated in the steelmaking process;
Treating the ground slag with a solution containing acid to elute magnesium;
Separating the magnesium eluate from which the magnesium is eluted;
Hydrolyzing by applying an alkali component to the magnesium eluate,
Through the above process to prepare a magnesium compound,
The by-product treatment method of producing magnesium carbonate by adding a gas containing carbon dioxide during the hydrolysis process or after the hydrolysis process.
Grinding slag generated in the steelmaking process;
Treating the ground slag with a solution containing acid to elute magnesium;
Separating the magnesium eluate from which the magnesium is eluted;
Hydrolyzing by applying an alkali component to the magnesium eluate,
The process of eluting the magnesium is used at least one of sulfuric acid, hydrochloric acid and nitric acid,
Using sulfuric acid to prepare a sulfuric acid solution with a concentration of 1.0 to 5.0M, the slag input ratio to the solution is treated with 100g / L to 300g / L,
The by-product treatment method for producing a magnesium compound through the above process.
The method according to claim 1 or 2,
The slag is slag generated by refining ferronickel by-product treatment method.
The method of claim 3,
And a heat treatment process after the hydrolysis process, and extracting magnesium hydroxide through the heat treatment.
The method of claim 3,
And a heat treatment process after the hydrolysis process, and the by-product treatment method for producing magnesium oxide by performing the heat treatment in the range of 350 to 600 degrees.
The method of claim 2,
The by-product treatment method of producing magnesium carbonate by adding a gas containing carbon dioxide during the hydrolysis process or after the hydrolysis process.
The method according to claim 1 or 6,
The by-product treatment method of injecting a gas containing carbon dioxide at 1Nm ³ / min · ton or more in the process of adding the gas containing carbon dioxide.
The method according to claim 1 or 6,
By-product after the addition of the gas containing the carbon dioxide, dry refining to produce magnesium oxide.
The method according to claim 2,
The process of grinding the slag is a by-product treatment method for grinding the slag to 75㎛ or less.
The method according to claim 1,
The process of eluting the magnesium is used at least one of sulfuric acid, hydrochloric acid and nitric acid,
A by-product treatment method for preparing a sulfuric acid solution having a concentration of 1.0 to 5.0M using the sulfuric acid, and the slag input ratio to the solution to 100g / L to 300g / L.
The method of claim 10,
Maintaining the solution 50 to 100 degrees and by-product method for stirring in the range of 200 to 500rpm.
The method according to claim 1 or 2,
The process of separating the magnesium eluate is a by-product treatment method of separating the magnesium eluate and the remaining silicon dioxide through the solid-liquid separation.
The method according to claim 1 or 2,
And a process of removing impurities before the hydrolysis process, and the process of removing impurities by adding H ₂ O ₂ solution to the magnesium eluate.
The method according to claim 1 or 2,
The hydrolysis process is a by-product treatment method for adding an alkaline hydroxide to the magnesium eluate, adjusting the pH range to 8 to 12.
The method according to claim 14,
The hydroxide is at least one of sodium hydroxide and potassium hydroxide, by-products treatment method for adjusting the pH range to 10 to 12.
The method according to claim 1 or 6,
The by-product treatment method using the by-product gas generated in the steelmaking process with the gas containing carbon dioxide.

Images