KR20130032093A - Method for carbon dioxide solidification - Google Patents

Abstract

PURPOSE: An immobilization method of carbon dioxide carbonate is provided to fix carbon dioxide by reacting calcium with gas carbon dioxide, thereby effectively generating calcium carbonate. CONSTITUTION: An immobilization method of carbon dioxide carbonate comprises a step of adding 8-9 wt% of ammonium salt into slag of 100g, as an extraction solvent to extract calcium from the slag; a step of adding NaOH which is pH controller to raise pH of the solution to 12 from 8-9; a step of supplying the solution into a carbonization reactor, injecting carbon dioxide to the solution, and obtaining calcium carbonate with high purity; and a step of forming calcium carbonate from carbon dioxide by the reaction of carbon dioxide and calcium ions. [Reference numerals] (10) Slag/mineral extracting device; (20) Carbonization reactor, pH 12 -> 7; (AA) Extracted solution after reaction, pH 8 -> 9; (BB) Separating slag/extracted solution(Filtering); (CC) Ammonium salt solvent(pH 6); (DD) Slag/mineral; (EE) PH adjustment(NaOH addition) pH 8-9 -> 12; (FF) CO_2 injection; (GG) Separating/refining precipitate; (HH) Calcium carbonate(solid); (II) Extracted solution pH 6-7;

Description

Method for carbon dioxide solidification

The present invention relates to a method of immobilizing carbon dioxide carbonate, and more particularly, to a method of extracting only calcium from steel slag in solution and reacting with gaseous carbon dioxide to fix the carbonate precipitate.

Due to the recent global warming, the trading price of carbon dioxide emission rights continues to rise, and many countries are making efforts to reduce carbon dioxide. Therefore, reducing carbon dioxide emissions and fixing them with carbonates is very important in terms of resource efficiency. would.

In the conventional method of fixing carbon dioxide carbonate using steel slag or natural mineral, acetic acid was used as an extraction solvent to extract alkali metal components such as calcium (Ca). Since the Ca extraction rate of acetic acid is about 99% higher than that of other solvents, Although it has the advantage of maximizing the total amount of carbon dioxide fixed, it is difficult to handle due to strong olfactory irritation in large quantities, eluting not only Ca component but other components of slag, and also causing many impurities to precipitate together in the carbonate conversion reaction. In addition, additional cost is required to increase the pH from pH 4 to pH 12 for the carbonate conversion reaction, since NaOH must be added in a large amount, and the use of NaOH results in excessive generation of hydrated lime (Ca (OH) ₂ ). the disturbance of the Ca conversion to CaCO ₃ in and switch as an additional purification operations require a lot of carbonated knife There is also the disadvantage that pure economics are less low.

That is, in the related art, calcium and magnesium are extracted from a steel slag containing alkali components such as calcium and magnesium in a solution state and reacted with gaseous carbon dioxide and fixed with carbonates such as calcium carbonate (CaCO ₃ ) and magnesium carbonate (MgCO ₃ ). In the process, a very large amount of NaOH is added to adjust the pH of the extraction solution to pH 12 required for the conversion of carbonate using acetic acid, which accounts for more than 50% of the total carbon dioxide fixed cost. There is a problem that cost is generated.

As an example of the prior art, US Patent Publication (20110139628A1) discloses a method for producing calcium carbonate using by-products and industrial wastes, and a method of sequentially extracting valuable components such as vanadium while preparing calcium carbonate using alkaline industrial waste or by-products. As described above, the slag is characterized by a process of dissolving and extracting calcium using an ammonium salt type and carbonizing to obtain calcium carbonate, or carbonizing reaction after re-extracting an element such as vanadium after calcium extraction. In general, there is no mention of pH change during the reaction, and there is no clear reaction section for calcium carbonate precipitation because there is no mention of pH change during the reaction.

As another example of the prior art, Japanese Laid-Open Patent Publication (20050097072) discloses a gas containing carbonic acid gas as water and an alkaline earth metal-containing material (natural mineral or steelmaking or steelmaking steel slag) with a weak base and a salt of strong acid (ammonium chloride or nitric acid). Ammonium) is a method of immobilization of carbonic acid gas to produce carbonates of alkaline earth metals, which is not a process at room temperature and pressure, and likewise there is no mention of pH and pH adjustment during the process. There is an unclear problem in the reaction section for the recovery of calcium carbonate.

As another example of the prior art, Korean Patent Publication (10-2009-0033353) discloses a method for producing calcium carbonate using lime-based by-products, that is, high-quality sedimentation, which enables commercialization and production at a low cost using a lime-based by-product generated in a steelmaking process. The present invention relates to a method for preparing calcium carbonate, wherein a carbonation process of selecting 0.01 to 10.0 parts by weight of calcium ion elution additive and 0.01 to 3.0 parts by weight of a precipitation agent based on 100 parts by weight of lime-based byproducts and reacting it to pH 9 and Although the process of collecting precipitated calcium carbonate after the completion of the process has been proposed, since the concentration of ammonium chloride used as an additive is relatively low at 0.014 mol%, compared to the lime-based by-product used as a raw material, the Ca extraction rate is low due to the low Ca extraction rate. There is a disadvantage in that the amount of is relatively small, and when the pH is dropped from pH 12 to 13 to 9, the reaction must be terminated to maintain the pH. There is a problem that the amount of calcium carbonate is limited.

The present invention has been made in view of the above, in a method for stably fixing / converting carbon dioxide to mineral carbonate using steel slag or natural mineral, selectively extracting only calcium from the steel slag in solution The present invention aims to provide a carbon dioxide carbonate immobilization method that can react with gaseous carbon dioxide and fix the carbonate precipitate, thereby effectively reducing the carbon dioxide by using seasonal by-products and natural minerals, and at the same time producing calcium carbonate as a precipitate.

In order to achieve the above object, the present invention supplies an ammonium salt solvent as an extraction solvent to raw material slag, and adds a high concentration of ammonium salt in a concentration of 8-9 wt% to 100 g of slag, and extracts an alkaline calcium component from slag. A first step of doing; Due to the addition of ammonium salts, the pH of the solution from which the calcium (Ca) component is extracted becomes 8-9, and after the extraction, the pH 8-9 solution is used immediately, or the pH adjuster NaOH is added in an amount that can be raised to pH ~ 12. Adding a second step; The third step of supplying the calcium component extraction solution into the carbonation reactor 20 and simultaneously injecting carbon dioxide into the calcium component extraction solution to react carbon dioxide and calcium ions to dissolve the carbon dioxide to obtain high purity calcium carbonate (CaCO3). ; It provides a carbon dioxide carbonate immobilization method comprising a.

Preferably, the ammonium salt is characterized in that any one selected from ammonium chloride (Ammonium chloride), ammonium nitrate (Ammonium Nitrate), ammonium acetate (Ammonium Acetate).

Particularly, in the third step, when the pH of the extract solution from which the carbonate is separated is 6 to 7, after the injection of carbon dioxide is terminated, high purity calcium carbonate (CaCO ₃ ) is obtained through sediment / solution separation. do.

Through the above-mentioned means for solving the problems, the present invention provides the following effects.

According to the present invention, since the target slag type includes not only steel slag but also electric furnace slag, there is a resource recycling effect of all slag species to be disposed of, and if an ammonium salt is used as a solvent instead of the conventional acetic acid solvent, When the pH is 8 or more, the amount of NaOH is reduced by 50% or more in the pH adjustment process compared to the acetic acid process having pH 4, and the suspended solids generated by the production of slaked lime (Ca (OH) ₂ ), a byproduct of NaOH, is removed. Since high-purity calcium carbonate (CaCO ₃ ) is obtained, it is possible to easily commercialize CaCO _{3 in the} future without reducing the cost of using NaOH and further post-treatment and purification.

In addition, compared to the conventional process using ammonium salt, the higher concentration of solvent is used, the Ca extraction rate is higher than that of low concentration, and in some cases, the amount of calcium carbonate obtained during the carbonation reaction due to additional pH adjustment is high, so that the final amount of carbon dioxide fixed 40 With the effect of increasing more than%, Ca utilization efficiency is also improved, which can ultimately improve the economics of carbon dioxide carbonation fixing method.

1 is a process chart illustrating a carbon dioxide carbonate immobilization method according to the present invention.

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

The present invention relates to a method for fixing carbon dioxide carbonate using a high concentration of ammonium salt for the recovery of high quality calcium carbonate and maximizing the total amount of carbon dioxide by using slag which is a limited amount of steel by-products (the annual slag output from steel mill and Ca is fixed in the slag). According to the effect of increasing the pH of the extraction solution, the pH of the extraction solution after extraction of Ca is 8 ~ 9, compared to acetic acid, the addition of very small amount of NaOH added to adjust the pH to 12 or more by effective conversion of carbonate through the use of minimal NaOH Since the reaction can occur, it is to provide a process for reducing the cost and carbonate conversion method to obtain a large amount of high purity carbonate.

First, an ammonium salt solvent is supplied to the alkaline component extraction reactor 10 as an extraction solvent to the raw material slag, and a high concentration of ammonium salt having a concentration of 8 to 9 wt% is added to 100 g of slag, and calcium, which is an alkaline component, is extracted from the slag. The first step is to proceed.

To this end, first, 100 g of LF slag in an electric furnace slag is put in a reactor, and ammonium chloride (93.5 g / 1.74 mol% based on 100 g of LF slag) is dissolved in water as an extraction solvent, and a 1 L solution is added to the reactor.

At this time, the ammonium salt (ammonium chloride [Ammonium chloride], ammonium nitrate [Ammonium Nitrate], ammonium acetate [Ammonium Acetate]) has its own pH 6 level, so the pH of the solution is about 6.

Subsequently, after stirring for 30 minutes at 150 RPM using an impeller in a reactor, when the slag and the eluate are separated using a filter, the pH of the Ca extract solution is 8-9.

Next, the pH of the solution from which the calcium (Ca) component is extracted is 8-9 due to the addition of ammonium salt, and the extraction proceeds to the step of injecting carbon dioxide to immediately use the solution of pH 8-9 As a result, a step of adding NaOH, which is a pH adjuster, in an amount capable of raising pH to 12 is performed.

In this case, when the ammonium salt is used as the solvent, the pH of the extraction solution during the process becomes 8 or more, so that the amount of NaOH used may be reduced by 50% or more in the pH adjustment process as compared to the process using acetic acid having a pH of 4.

Next, while supplying a calcium component extraction solution into the carbonation reactor 20 and simultaneously injecting carbon dioxide into the calcium component extraction solution to react carbon dioxide and calcium ions, carbon dioxide is dissolved into calcium carbonate to obtain high purity calcium carbonate (CaCO ₃ ). The obtaining step proceeds.

That is, after the process of raising the pH to 12 by the addition of NaOH, which is a pH adjuster, the gaseous carbon dioxide from the carbon dioxide supply means 30 is directly injected into the carbonation reactor 20 at a flow rate of 2 L / min, so that carbon dioxide and calcium ions are injected. By reacting to induce a carbonation reaction, calcium carbonate precipitates are formed in the reactor.

At this time, during the step of obtaining the high purity calcium carbonate (CaCO ₃ ) by dissolving carbon dioxide dissolved carbon dioxide, when the pH of the extract solution separated from the carbonate reaches 6-7, after the injection of carbon dioxide, the precipitate / solution High purity calcium carbonate (CaCO ₃ ) is obtained through separation.

According to the embodiment of the present invention, as shown in Table 1 below, after dissolving 93.5 g of ammonium chloride in water to 100 g of LF slag in the furnace slag, the solution / slag ratio is 10/1, and then pH 8 Method of obtaining calcium carbonate by directing the solution extracted with calcium component of ˜9 to carbonation reactor 20 to react with carbon dioxide or raising the pH of the solution from which calcium component is extracted from 8-9 to pH ˜12 After passing through, the carbon component extraction solution is supplied into the carbonation reactor 20 and carbon dioxide is injected into the calcium component extraction solution to obtain high purity calcium carbonate (CaCO 3) of ˜93%.

As described above, the present invention provides a method for immobilizing carbon dioxide using steelmaking slag containing an alkaline component such as calcium (Ca) and magnesium (Mg) and an electric furnace slag, wherein calcium ions are formed using a high concentration of ammonium salt. Selective extraction rate of Ca in slag according to the use of high concentration ammonium salts through the extraction process, the process of obtaining an extraction solution of pH 8 or more, the pH adjustment process by adding a small amount of pH adjuster, and the effective carbonate conversion process by injecting carbon dioxide into the extraction solution. Increasing the pH of the extract solution induces an efficient carbonate conversion reaction, thereby reducing carbon dioxide emissions from the steelmaking process and recycling resources through reusing slag that is disposed of, as well as recovering high-purity calcium carbonate. can do.

In addition, the present invention has a recycling effect of all the slag to be disposed of existing waste slag because the target slag includes not only steel slag but also electric furnace slag, is a process made at room temperature and atmospheric pressure, the concentration of ammonium salt is also high concentration of 80g / L Since the ammonium salt is used as the extraction solvent, the Ca extraction rate is higher than the conventional one, and after adding a small amount of the pH regulator to the pH 12, the carbon dioxide carbonation process is induced. The fixed amount increase can be maximized.

10: alkali component extraction reactor
20: carbonation reactor
30: carbon dioxide supply means

Claims (4)

Supplying an ammonium salt solvent to the raw material slag as an extraction solvent, and adding an ammonium salt having a concentration of 8 to 9 wt% to 100 g of the slag, and extracting an alkali component calcium from the slag;
The pH of the solution from which the calcium (Ca) component is extracted becomes 8-9 due to the addition of ammonium salt, and after the extraction, a second amount of NaOH, which is a pH adjuster, is added in an amount capable of raising the solution of pH 8-9 to pH ~ 12. Steps;
Supplying a calcium component extraction solution into the carbonation reactor 20 and simultaneously injecting carbon dioxide into the calcium component extraction solution to react carbon dioxide and calcium ions, thereby dissolving carbon dioxide to obtain high purity calcium carbonate (CaCO ₃ ). step;
Carbon dioxide carbonate immobilization method comprising a.
The method according to claim 1,
The ammonium salt is ammonium chloride (Ammonium chloride), ammonium nitrate (Ammonium Nitrate), ammonium acetate (Ammonium Acetate) characterized in that any one selected from carbon dioxide carbonate immobilization method.
The method according to claim 1,
In the second step, since the concentration of ammonium salt used as the solvent is about 9wt% with respect to 100g of slag, the pH adjustment process to raise the pH to 12 can be omitted in some cases, carbon dioxide carbonate immobilization method.
The method according to claim 1,
In the third step, when the pH of the carbonate separated extract solution is 6 ~ 7, carbon dioxide characterized in that after obtaining the carbon dioxide injection, high purity calcium carbonate (CaCO ₃ ) through the sediment / solution separation Carbonate Immobilization Method.

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