KR102642978B1 - Manufacturing method of precipitated calcium carbonate using blast furnace slag - Google Patents

Abstract

The disclosed content relates to a method for manufacturing precipitated calcium carbonate using blast furnace slag, which can reduce manufacturing costs while contributing to environmental protection by recycling blast furnace slag and carbon dioxide generated as by-products in the process of manufacturing pig iron.
The method for producing precipitated calcium carbonate using blast furnace slag includes (a) preparing blast furnace slag by pulverizing it, (b) dissolving the prepared blast furnace slag powder in hydrochloric acid to obtain an acid-dissolving mother liquor, and (c) the acid-dissolving mother liquor. Adding at least one selected from oxidizing agents, coagulants, and metal removers to the leaching mother liquor to precipitate impurities and extract the leaching mother liquor, (d) adding at least one pH adjuster selected from sodium hydrogen sulfide and sodium sulfide to the leaching mother liquor. and precipitating and separating impurities to obtain a calcium mother solution, (e) performing a multi-stage carbonation reaction of the calcium mother solution and carbon dioxide at least twice, and (f) filtering the calcium carbonate slurry produced by the carbonation reaction and and drying to obtain precipitated calcium carbonate.

Description

Method for producing precipitated calcium carbonate using blast furnace slag {MANUFACTURING METHOD OF PRECIPITATED CALCIUM CARBONATE USING BLAST FURNACE SLAG}

The information disclosed in this specification relates to a method for producing precipitated calcium carbonate using blast furnace slag.

Unless otherwise indicated herein, the material described in this section is not prior art to the claims of this application, and is not admitted to be prior art by inclusion in this section.

Generally, calcium carbonate is produced through the reaction of supernatant and carbon dioxide after calcium elution from blast furnace slag and solid-liquid separation. Carbon dioxide is a representative greenhouse gas, and its reduction is emerging as a global issue. However, practical greenhouse gas reduction technologies such as carbon dioxide capture and storage (CCS) are still difficult to commercialize in terms of economic feasibility. In other words, it is not realistically easy to secure economic feasibility through processing of captured carbon dioxide.

In Korea, the market for liquefied carbon dioxide for welding and beverage purposes in the shipbuilding industry, which accounts for most of the carbon dioxide market, is approximately 1 million tons/year, the supply price of liquid carbonate is 150,000 won/ton, and the market is known to be almost saturated. Therefore, even if carbon dioxide capture and sales projects are promoted only to power plants and steel mills, which are sources of large amounts of carbon dioxide emissions, the commercial market for captured carbon dioxide is quite limited. Nevertheless, many countries around the world are paying attention to reducing greenhouse gases caused by carbon dioxide as an essential element for sustainable development, and Korea also recognized the importance of this and declared a national greenhouse gas reduction goal. In addition, we introduced reduction measures in the industry, power generation, transportation, and building sectors to reduce greenhouse gases, and focused on the commercialization of carbon dioxide capture and storage technology (CCS) as a major reduction method in the power generation sector.

Carbon dioxide capture and storage technology (CCS) is a technology that captures carbon dioxide from sources that emit large amounts of carbon dioxide, such as power plants and steel mills, and then stores the carbon dioxide in the ground or ocean for a long period of time. However, in the case of Korea, it is not easy to secure a carbon dioxide storage site due to geological conditions, and storage facilities also have the problem of requiring enormous investment and management costs. Accordingly, recently, carbon dioxide utilization and storage technology (CCUS), which seeks to reuse carbon dioxide as a useful resource beyond the concept of simply capturing and storing it, has been attracting attention.

Carbon dioxide utilization and storage technology (CCUS) is characterized by utilizing carbon dioxide and converting it into a material with high added value. It not only solves the storage problem through recycling of carbon dioxide, but also solves the storage problem generated by existing carbon dioxide capture and storage technology (CCS). It is expected to become a new alternative as it has the advantage of offsetting the cost of reducing carbon dioxide.

Among carbon dioxide utilization and storage technologies (CCUS), mineral carbonation or mineralization, a technology that converts various mineral resources into carbonate form by directly or indirectly reacting with carbon dioxide, is a technology that can safely isolate and store carbon dioxide. However, the processing capacity is currently small to medium-sized, and problems include energy-intensive pretreatment processes such as crushing of raw materials, overall slow reaction speed, location problems of mineral resources and carbon dioxide emission sources, and lack of large-scale transportation and storage facilities that can accommodate carbonate. Therefore, its effect is limited.

In addition, this is an area that requires technological development in that precipitated calcium carbonate can be used as a high value-added material rather than carbonate produced during the mineral carbonation process. A large amount of blast furnace slag is discharged during the steelmaking process, and is currently used as roadbed material and fill aggregate, but various efforts are being made to gradually increase the value of this blast furnace slag. In particular, blast furnace slag, which contains a large amount of alkaline components, generates precipitated calcium carbonate through a mineral carbonation reaction and can be used as a high value-added product in that it can be used in building materials such as lightweight blocks and ceiling materials, while also storing carbon dioxide. and has great significance in terms of immobilization.

Republic of Korea Patent No. 10-1181451 (2012.09.04) Republic of Korea Patent No. 10-2162695 (2020.09.28)

The aim is to provide a method for manufacturing precipitated calcium carbonate using blast furnace slag that can improve environmental problems caused by carbon dioxide while satisfying quality, economic efficiency, and productivity.

Additionally, it is not limited to the technical challenges described above, and it is obvious that other technical challenges may be derived from the description below.

According to one embodiment of the disclosed content, the method for producing precipitated calcium carbonate using blast furnace slag includes (a) preparing blast furnace slag by pulverizing it, (b) dissolving the prepared blast furnace slag powder in hydrochloric acid to obtain an acid-eluting mother liquor. (c) adding at least one selected from oxidizing agents, coagulants, and metal removers to the acid-dissolving mother liquor to precipitate impurities and extract the leaching mother liquor, (d) adding a pH adjuster, sodium hydrogen sulfide, and sulfide to the leaching mother liquor. Obtaining a calcium mother liquid by adding at least one selected from sodium and precipitating and separating impurities, (e) performing a multi-stage carbonation reaction of the calcium mother liquid and carbon dioxide at least twice, and (f) producing by the carbonation reaction. and filtering and drying the calcium carbonate slurry to obtain precipitated calcium carbonate.

Additionally, step (b) may be performed under conditions of pH 3 to 4.

Additionally, in step (c), the oxidizing agent may be one or more selected from sodium hypochlorite, hydrogen peroxide, and chloric acid.

Additionally, in step (c), the coagulant may be one or more selected from polyacrylamide, iron sulfate, and iron chloride.

Additionally, in step (c), the metal remover may be one or more selected from magnesium oxide, magnesium chloride, and magnesium hydroxide.

In addition, in step (d), the pH of the leaching mother liquor is adjusted to a pH range of 6.5 to 8.5 by the pH adjuster, and the pH adjuster may be one or more selected from ammonia water and sodium hydroxide.

According to an embodiment disclosed herein, the method for producing precipitated calcium carbonate using blast furnace slag can reduce manufacturing costs while contributing to environmental protection by recycling blast furnace slag and carbon dioxide generated as by-products in the process of manufacturing pig iron. It works.

1 is a process diagram illustrating a method for producing continuous precipitated calcium carbonate using blast furnace slag according to an embodiment of the disclosure disclosed herein.

Hereinafter, the configuration and operational effects of preferred embodiments of the disclosed content will be examined with reference to the attached drawings. For reference, in the drawings below, each component is omitted or schematically shown for convenience and clarity, and the size of each component does not reflect the actual size. In addition, the same reference numerals refer to the same components throughout the specification, and reference numerals for the same components in individual drawings will be omitted.

Hereinafter, a method for producing precipitated calcium carbonate using blast furnace slag according to an embodiment of the content disclosed in this specification will be described in detail with reference to the drawings.

1 is a process diagram illustrating a method for producing precipitated calcium carbonate using blast furnace slag according to an embodiment of the content disclosed herein.

Referring to Figure 1, first, blast furnace slag is prepared by grinding (S10).

Blast furnace slag, the main raw material of this embodiment, refers to a by-product generated when producing pig iron in a blast furnace, and its chemical components include calcium oxide (CaO), silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), and magnesium oxide (MgO). It accounts for 93-98% of the main ingredients, and small amounts of manganese oxide (MnO), iron oxide (FeO), titanium oxide (TiO ₂ ), and sulfur (S) are mixed in. Those with a weight ratio of calcium oxide/silicon dioxide (CaO/SiO ₂ ) of more than 1 are classified as basic slag, and those with a weight ratio of 1 or less are classified as acid slag. The blast furnace slag used in this example refers to crushed slag, which is sand-like glassy slag obtained by rapidly cooling molten slag with water in a blast furnace.

Blast furnace slag can be easily dissolved in hydrochloric acid, which will be described later, in a ball mill, Raymond mill, hammer mill, attrition mill, or jet mill. ), it can be pulverized with one or more equipment selected from a rotary mill and a vibration mill. The blast furnace slag powder pulverized in this way may have an average particle diameter of 0.01 to 0.3 mm. If the average particle diameter of the blast furnace slag powder is less than 0.01 mm, it is difficult to handle and the amount of loss due to dispersion in the air may increase, and 0.3 mm If it exceeds, it is undesirable because the surface area of the blast furnace slag powder in contact with hydrochloric acid is small and the calcium dissolution rate may be low. Therefore, it is desirable to grind the blast furnace slag to have an average particle diameter of 0.01 to 0.3 mm so that the blast furnace slag powder can be more efficiently dissolved in hydrochloric acid.

After pulverizing the blast furnace slag, a step of selecting only the blast furnace slag powder having a particle size range of 0.01 to 0.3 mm may be further performed using a sieve, and the blast furnace slag powder exceeding the particle size range of 0.3 mm may be further carried out. Further pulverization can be performed to have a particle size range. As the selection step is further performed, the calcium elution rate can be further increased by easily dissolving the blast furnace slag powder in hydrochloric acid in the step of obtaining the acid-dissolving mother liquor.

Next, the blast furnace slag powder is dissolved in hydrochloric acid to obtain the acid-dissolving mother liquor (S20).

After putting the blast furnace slag powder prepared in step S10 into the dissolution tank, hydrochloric acid can be slowly added until the elution of calcium is completed, but dissolution can be performed under conditions of pH 3 to 4, and dissolution can be performed at least twice. When using hydrochloric acid rather than other acid solutions, the calcium dissolution rate is the highest and it can be more economical. In addition, ammonia water (NH ₄ OH) can be additionally added, and ammonium chloride (NH ₄ Cl) generated by ammonia water (NH ₄ OH) can be used as a leachate.

Meanwhile, the dissolution tank may be made of a wear-resistant and acid-resistant material, and considering the physical properties of blast furnace slag, it is preferable to use an interior treated with basalt. The first dissolution tank for directly eluting the blast furnace slag powder and the leached slag for which leaching has been completed are used. It may consist of a second dissolution tank for additional dissolution, but is not limited thereto.

Thereafter, at least one selected from oxidizing agents, coagulants, and metal removers is added to the acid-dissolving mother liquor to precipitate impurities and extract the leaching mother liquor (S30).

One or more selected from oxidizing agents, coagulants, and metal removers may be added to the acid-eluting mother liquor obtained in step S20 to precipitate impurities and extract the leaching mother liquor. It may contain unreleased residue.

The oxidizing agent may be one or more selected from sodium hypochlorite (NaOCl), hydrogen peroxide (H ₂ O ₂ ), and perchloric acid (HClO ₃ ), and the coagulant may be polyacrylamide, iron sulfate (FeSO _{4 )} . ) and iron chloride (FeCl ₂ ) can be used, and the metal remover is added to remove phosphorus (P), etc., and includes magnesium oxide (MgO), magnesium chloride (MgCl ₂ ), and magnesium hydroxide (Mg). (OH) ₂ ) can be used.

On the other hand, step S30 can be carried out by continuously circulating in a plurality of leaching tanks composed of multiple stages, and by adjusting the concentration of each stage, the leaching mother liquor and residue can be more efficiently separated, and the retention in the leaching tank at each stage is possible. The leaching rate can be increased by increasing the time. For example, one or more selected from oxidizing agents, coagulants, and metal removers can be supplied to the leaching tank located at the first stage to oxidize and precipitate iron salts contained in the mother acid solution, and washing water can be supplied to the leaching tank located at the end. By washing the residue, you can prevent any eluted mother liquor from sticking to the residue.

Then, one or more pH adjusters selected from sodium hydrogen sulfide (NaHS) and sodium sulfide (Na ₂ S) are added to the leaching mother liquor, and impurities are precipitated and separated to obtain calcium mother liquor (S40).

The pH of the leaching mother liquor obtained in step S30 is adjusted to a pH range of 6.5 to 8.5 by one or more pH adjusters selected from ammonia water and sodium hydroxide (NaOH), leaving only the calcium component and separating the remaining magnesium and iron components by precipitation. can do. If the above-mentioned pH range is satisfied, magnesium, iron, etc. can be more easily precipitated from the leaching mother liquor.

In addition, trace amounts of dissolved metal salts can be removed by adding 0.1 to 1% by weight of one or more selected from sodium hydrogen sulfide (NaHS) and sodium sulfide (Na ₂ S) based on the total weight % and precipitating them as sulfide salts. If the added content exceeds 1% by weight, economic feasibility may be affected, so it is desirable to satisfy the above-mentioned range.

Next, the calcium mother liquor and carbon dioxide are subjected to a multi-stage carbonation reaction at least twice (S50).

Calcium carbonate slurry can be produced by performing a multi-stage carbonation reaction of the calcium mother liquid and carbon dioxide obtained in step S40 at least twice. In this case, the carbonation reaction can be performed by a carbonation reaction device. The carbon dioxide generated during the process of generating blast furnace slag and that generated from a household waste incinerator or sewage slurry treatment facility can be recovered and used. The recovered carbon dioxide is used to remove foreign substances in the carbon dioxide using a wet scrubber and cool it. After this, it can be collected and purified in a self-circulating manner and then used in a carbonation reaction. Therefore, by minimizing carbon dioxide emissions into the atmosphere, manufacturing costs can be reduced while preserving the environment.

The carbonation reaction device stores the calcium mother liquid, a reaction column in which the calcium mother liquid and carbon dioxide undergo a carbonation reaction, a plurality of reaction tanks connected to the reaction column and in which the unreacted calcium mother liquid and carbon dioxide in the reaction column continuously undergo a carbonation reaction, and It may be configured as a preliminary reaction tank for recovering unreacted carbon dioxide from the reaction column and separately processing excess carbon dioxide.

The carbon dioxide can be continuously added in the reverse order in which the reaction was completed, regardless of the unreacted concentration of the calcium mother liquor, thereby maximizing the completeness of the reaction of the precipitated calcium carbonate. In addition, since it is carried out in multiple stages, the carbonation reaction can be completed without separately supplying carbon dioxide from outside in addition to the recovered carbon dioxide, and carbon dioxide loss can be minimized.

Finally, the calcium carbonate slurry is filtered and dried (S60).

The calcium carbonate slurry produced by the carbonation reaction in step S50 was continuously filtered using a press filter and dried in a spin flesh dryer at a temperature of 105 to 120° C. to obtain precipitated calcium carbonate, and an ammonium chloride solution ( NH ₄ Cl) can be recovered. The recovered ammonium chloride solution can be used as a leachate, but is not limited thereto.

The precipitated calcium carbonate obtained by the above-described method can satisfy economic efficiency and productivity while ensuring high purity and quality.

The disclosed content is merely an example, and various modifications and implementations may be made by those skilled in the art without departing from the gist of the claims, so the scope of protection of the disclosed content is limited to the above-mentioned specific scope. It is not limited to the examples.

Claims (6)

(a) preparing blast furnace slag by pulverizing it;
(b) dissolving the prepared blast furnace slag powder in hydrochloric acid to obtain an acid-dissolving mother liquor;
(c) adding at least one selected from an oxidizing agent, a coagulant, and a metal remover to the acid-dissolving mother liquor to precipitate impurities and extract the leaching mother liquor;
(d) adding at least one selected from a pH adjuster, sodium hydrogen sulfide, and sodium sulfide to the leaching mother liquor and precipitating and separating impurities to obtain a calcium mother liquor;
(e) performing a multi-stage carbonation reaction of the calcium mother liquid and carbon dioxide at least twice; and
(f) filtering and drying the calcium carbonate slurry produced by the carbonation reaction to obtain precipitated calcium carbonate,
In step (c), the oxidizing agent is at least one selected from sodium hypochlorite, hydrogen peroxide, and chloric acid,
The coagulant is at least one selected from polyacrylamide, iron sulfate, and iron chloride,
A method for producing precipitated calcium carbonate using blast furnace slag, wherein the metal remover is at least one selected from magnesium oxide, magnesium chloride, and magnesium hydroxide.
According to paragraph 1,
Step (b) is a method of producing precipitated calcium carbonate using blast furnace slag, characterized in that it is carried out under conditions of pH 3 to 4.
delete delete delete According to paragraph 1,
In step (d), the pH of the leaching mother liquor is adjusted to a pH range of 6.5 to 8.5 by the pH adjuster, and the pH adjuster is at least one selected from ammonia water and sodium hydroxide. Precipitated calcium carbonate using blast furnace slag Manufacturing method.