KR-20260062379-A - METHOD FOR PRODUCING CALCITE-TYPE CALCIUM CARBONATE AND NESQUEHONITE-TYPE MAGNESIUM CARBONATE MIXTURE USING OYSTER SHELLS AND SEAWATER

Abstract

The present invention relates to a method for producing calcium carbonate using oyster shells and seawater. More specifically, the invention relates to a method for producing vaterite-type calcium carbonate using an indirect carbonation reaction, characterized by mixing calcined oyster shells and seawater and injecting carbon dioxide into a calcium filtrate prepared by filtering the mixture. Furthermore, the present invention relates to a method for producing a calcite-nesquehonite mixture using a direct carbonation reaction, characterized by mixing calcined oyster shells and seawater and injecting carbon dioxide into a residual byproduct prepared by filtering the mixture. The present invention produces calcium carbonate using oyster shells and seawater, thereby sequestering CO2 while directly carbonating residual by-products, and can produce high-value materials such as vaterite, calcite, and nessernite without waste.

Inventors

• 김명진
• 고은빛
• 김세훈

Assignees

• 국립한국해양대학교산학협력단

Dates

Publication Date

20260507

Application Date

20241029

Claims (6)

1. (S1) Step of calcining oyster shells; (S2) A step of preparing a first stirred product by mixing and stirring the above-mentioned calcined oyster shells with a first mixture of seawater and sucrose; (S3) A step of filtering the first stirred mixture to produce residual by-products (RBIC); (S4) A step of preparing a second mixture by mixing the above residual byproduct with distilled water; (S5) A step of producing a second mixture injected with carbon dioxide ( CO₂ ) by injecting carbon dioxide into the second mixture; and (S6) A step of filtering and drying the second mixture into which carbon dioxide has been injected to produce a calcite-nesquehonite mixture; comprising, Method for producing calcite and Nesquehonite using oyster shells and seawater.
2. In paragraph 1, The above (S4) step Characterized by preparing a second mixture by mixing the above residual byproduct and distilled water in a ratio of 1:8 to 12 (kg:L). Method for manufacturing calcite and Nesquehonite using oyster shells and seawater.
3. In paragraph 1, The above (S5) step Characterized by injecting carbon dioxide ( CO₂ ) into the second mixture at a flow rate of 8 to 12 L/min to produce a second mixture injected with carbon dioxide. Method for manufacturing calcite and Nesquehonite using oyster shells and seawater.
4. In paragraph 1, The above (S5) step Characterized by further including the step of aging the second mixture injected with carbon dioxide at 22 to 28°C for 12 to 36 hours. Method for manufacturing calcite and Nesquehonite using oyster shells and seawater.
5. In paragraph 1, The above (S6) step Characterized by drying the filtered second mixture at 50 to 70°C. Method for manufacturing calcite and Nesquehonite using oyster shells and seawater.
6. A calcite-neshwonite mixture prepared by a method according to any one of claims 1 to 5.

Description

Method for producing a mixture of calcite-type calcium carbonate and nesquehonite-type magnesium carbonate using oyster shells and seawater The present invention relates to a method for producing calcium carbonate using oyster shells and seawater. More specifically, it relates to a method for producing vaterite-type calcium carbonate using an indirect carbonation reaction, characterized by mixing calcined oyster shells and seawater and injecting carbon dioxide into a calcium filtrate prepared by filtering the mixture. Furthermore, the present invention relates to a method for producing a mixture of calcite-type calcium carbonate and Nesquehonite-type magnesium carbonate using a direct carbonation reaction, characterized by mixing calcined oyster shells and seawater and injecting carbon dioxide into a residual byproduct prepared by filtering the mixture. Carbon Capture, Utilization, and Storage (CCUS) technology refers to the capture of carbon dioxide for industrial or permanent storage. Among these, mineral carbonation is a promising CCUS technology that safely sequesters CO2 by reacting metals such as Ca and Mg with CO2 to convert them into stable, insoluble carbonates. This mineral carbonation can be classified into indirect carbonation and direct carbonation methods. Indirect carbonation is a method in which Ca and Mg are extracted from natural minerals or industrial byproducts, and then CO2 is injected into the leachate to induce carbonation. On the other hand, direct carbonation is a method characterized by directly reacting CO2 with materials containing Ca and Mg, without the need for a separate extraction process. Representative carbonates produced by mineral carbonation include calcium carbonate and magnesium carbonate compounds. Calcium carbonate exists in polymorphs such as calcite, vaterite, and aragonite; these possess distinct physicochemical properties, making them suitable for various industrial applications. The chemical composition of magnesium carbonate compounds varies depending on formation conditions. Nesquehonite ( MgCO₃ · 3H₂O ), a magnesium carbonate with a rod-like structure, is generally synthesized at room temperature and atmospheric pressure. This Nesquehonite is used as a precursor for flame retardants, pharmaceutical manufacturing, and other magnesium-based chemicals. Global oyster production has steadily increased, reaching 6 million tons in 2018. Oyster shells account for approximately 90% of the total weight of oysters; these shells decompose very slowly and are frequently stockpiled and discarded along coastlines, causing problems such as damaging natural landscapes and polluting soil and water. Therefore, there is a growing need for more efficient and eco-friendly methods to recycle oyster shells. Conventional mineral carbonation methods using oyster shells cause several problems. For example, a significant amount of CO2 is generated during the calcination step required for carbonation, but conventional mineral carbonation methods have not solved the problem of storing the excessively generated CO2 and have not solved the problem of treating residual by-products generated during the indirect carbonation process. Figure 1 is a schematic diagram showing the process of the method for manufacturing calcium carbonate and magnesium carbonate using oyster shells and seawater according to the present invention. Figure 2 shows the results of analyzing calcined oyster shells using XRD. Figure 3 shows the XRD, FT-IR, particle size, SEM, and TGA analysis results of vaterite-type calcium carbonate. Figure 4 shows the results of analyzing residual byproduct (RBIC) by XRD. Figure 5 shows the results of analyzing calcite and Nesquehonite by XRD. Figure 6 shows the results of TGA analysis of calcite and Nesquehonite. Figure 7 shows the results of observing the morphology of calcite and Nesquehonite according to aging time using SEM. The terms used in this specification have been selected based on currently widely used general terms whenever possible, taking into account their functions in the present invention; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant description of the invention. Therefore, the terms used in this invention should be defined not merely by their names, but based on their meanings and the overall content of the invention. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted