Formula of leaching agent for preparing light calcium carbonate through indirect mineralization of carbide slag

Abstract

The invention discloses a formula of a leaching agent in preparation of light calcium carbonate by indirect mineralization of carbide slag, belongs to the technical field of production of light calcium carbonate, and aims to solve the problems of large reagent loss, low selectivity and the like of an ammonium salt leaching agent in the prior art. According to the technical scheme, the formula of the leaching agent comprises glycine, cane sugar, sodium citrate, tert-butyl alcohol and water. A two-stage leaching process is adopted, and in the first-stage leaching process, a glycine solution is adopted for leaching carbide slag; in the second-stage leaching, a mixed solution of cane sugar, sodium citrate and tert-butyl alcohol is adopted to leach the first-stage filter residues. According to the method, the total leaching efficiency of calcium is improved through two-stage leaching, a leaching agent is not prone to volatilization, small in loss, recyclable and high in calcium ion leaching selectivity, and high-purity light calcium carbonate can be prepared.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of light calcium carbonate production, and particularly relates to a leaching agent formula for preparing light calcium carbonate through indirect mineralization of carbide slag. BACKGROUND

[0002] Excessive emission of CO2 is one of the key factors leading to global climate change, causing global warming, sea level rise, and frequent occurrence of extreme natural disasters, which seriously threatens the sustainable development of human society. In the carbon capture, utilization and storage (CCUS) technology system, indirect mineralization technology, as an important component, can simultaneously achieve stable storage of CO2 and resource utilization of calcium-containing industrial solid waste, and is considered as a low-carbon technology with broad application prospects.

[0003] Currently, ammonium salt is mostly used as a leaching agent for preparing light calcium carbonate through indirect mineralization of CO2 using carbide slag. Although ammonium salt has the advantages of high leaching efficiency and recyclable reagent, etc., researchers are committed to developing a recyclable leaching system to reduce the overall cost. For example, patent CN115650274B proposes a solid waste gypsum liquid-phase indirect mineralization method using tyrosine as an additive: potassium hydroxide is used to deprotonate tyrosine to form an alkaline solution for leaching calcium ions in waste gypsum; then CO2 is introduced into the calcium-rich solution to promote the co-precipitation of calcium ions and tyrosine; finally, potassium hydroxide is added again to dissolve tyrosine, realizing the recycling of the reagent and obtaining high-purity calcium carbonate. Patent CN117361598A proposes a method for preparing vaterite-type calcium carbonate through one-step mineralization using carbide slag and CO2 as raw materials. The process uses ammonia medium as a multifunctional reaction platform to simultaneously achieve the leaching of calcium ions in carbide slag, efficient solidification of CO2, and directional regulation and stabilization of vaterite crystal form. The carbide slag sieved to 200 mesh is placed in a high-shear device with an ammonium salt solution containing NH4Cl, CH3COONH4, C2H7NO, and (NH4)2S2O4, and CO2 gas is directly introduced for one-step reaction at a reaction temperature of 15-30°C. The ammonia medium promotes the solidification of CO2 by regulating the release rate of calcium ions, and under the synergistic effect of high shear force, calcium carbonate products with a vaterite phase content of more than 95% and controllable morphology are successfully prepared.

[0004] Although ammonium salt has good performance in the application of indirect mineralization technology of carbide slag, there are still some problems that are difficult to solve, such as: (1) a large amount of ammonia gas is generated during the leaching stage of ammonium salt leaching agent, leading to a decrease in the effective concentration of the leaching agent, and the leaching efficiency of ammonium chloride leaching agent decreases by 60% after five cycles, requiring frequent replenishment of chemical reagents and increasing the process cost; (2) the main byproduct of ammonium salt leaching agent is NH4Cl, which is difficult to be recycled and reused, and the recycling of NH4Cl requires a large amount of energy and high cost. + Promoting Ca 2+However, it is found that Fe and Al and other metal impurities exist in the leaching solution in the actual application process, and further purification is still needed for mineralization and utilization.

[0005] In view of the above problems, the present application provides a method for synthesizing light calcium carbonate from carbide slag and a leaching agent formula, the method has the advantages of reagent recycling, high selectivity of leaching, controllable calcium carbonate crystal form, and low loss of leaching agent, and the light calcium carbonate can be directly prepared by the simple indirect mineralization method using the method and the leaching agent formula. 2+ SUMMARY

[0006] The present application aims to provide a leaching agent formula for preparing light calcium carbonate from carbide slag by indirect mineralization, to solve the technical problems of large chemical reagent loss and low selectivity in the existing indirect mineralization using ammonium salt as a leaching agent.

[0007] The object of the present application can be achieved by the following technical solutions: A leaching agent formula for preparing light calcium carbonate from carbide slag by indirect mineralization, the formula comprising: glycine, sucrose, sodium citrate, tert-butyl alcohol and water.

[0008] In some embodiments, the preparation of light calcium carbonate from carbide slag by indirect mineralization includes one-stage leaching and two-stage leaching, the one-stage leaching uses a 5% glycine solution, the two-stage leaching uses 3% sucrose + 5% sodium citrate + 2% tert-butyl alcohol, and the solvents of the one-stage leaching and the two-stage leaching are both water.

[0009] In some embodiments, the preparation of light calcium carbonate from carbide slag by indirect mineralization includes one-stage leaching and two-stage leaching, the one-stage leaching uses a 5% glycine solution, the two-stage leaching uses 3% sucrose + 10% sodium citrate + 2% tert-butyl alcohol, and the solvents of the one-stage leaching and the two-stage leaching are both water.

[0010] In some embodiments, the preparation of light calcium carbonate from carbide slag by indirect mineralization includes one-stage leaching and two-stage leaching, the one-stage leaching uses a 10% glycine solution, the two-stage leaching uses 3% sucrose + 5% sodium citrate + 2% tert-butyl alcohol, and the solvents of the one-stage leaching and the two-stage leaching are both water.

[0011] In some embodiments, the preparation of light calcium carbonate from carbide slag by indirect mineralization includes one-stage leaching and two-stage leaching, the one-stage leaching uses a 10% glycine solution, the two-stage leaching uses 5% sucrose + 8% sodium citrate + 2% tert-butyl alcohol, and the solvents of the one-stage leaching and the two-stage leaching are both water.

[0012] ​In some embodiments, the indirect mineralization of calcium carbide slag to prepare light calcium carbonate includes a first-stage leaching and a second-stage leaching. The first-stage leaching uses a 15% glycine solution; the second-stage leaching uses 3% sucrose + 5% sodium citrate + 2% tert-butanol; and the solvent for both the first-stage and second-stage leaching is water.

[0013] In some embodiments, the indirect mineralization of calcium carbide slag to prepare light calcium carbonate includes a first-stage leaching and a second-stage leaching. The first-stage leaching uses a 20% glycine solution; the second-stage leaching uses 3% sucrose + 5% sodium citrate + 2% tert-butanol; and the solvent for both the first-stage and second-stage leaching is water.

[0014] In some embodiments, the indirect mineralization of calcium carbide slag to prepare light calcium carbonate includes a first-stage leaching and a second-stage leaching. The first-stage leaching uses a 20% glycine solution; the second-stage leaching uses 3% sucrose + 5% sodium citrate + 7% tert-butanol; and the solvent for both the first-stage and second-stage leaching is water.

[0015] The beneficial effects of this invention are: This invention relates to a synthesis method and leaching agent formulation for preparing light calcium carbonate from carbide slag mineralization. The calcium carbonate synthesis method is simple, achieving Ca synthesis through a two-stage leaching reaction. 2+ Maximum leaching efficiency. One stage of the leaching reaction uses glycine to dissolve the carbide slag; glycine promotes Ca2+ leaching by releasing H+. 2+ Leaching. The second leaching reaction utilizes sucrose and sodium citrate for a secondary leaching of the residue from the first leaching stage. The sucrose and sodium citrate react with Ca during the leaching process. 2+ The chelation effect reduces the free Ca in the solution 2+ Concentration, promotes Ca 2+ The leaching reaction proceeds in the forward direction and releases OH-. - Increasing the alkalinity of the leachate is beneficial for Ca. 2+ Precipitation reaction during the mineralization stage. The leachates obtained from the two leaching stages are mixed and a certain proportion of tert-butanol is added. CO2 is then introduced into the solution to initiate a mineralization reaction. Tert-butanol selectively adsorbs onto the surface of the generated calcium carbonate, reducing the particle size of the calcium carbonate. Furthermore, the glycine, sodium citrate, and sucrose in this leaching agent regulate the crystal form of calcium carbonate, achieving the directional synthesis of aragonite. All components of the leaching agent are not easily volatile, resulting in minimal reagent loss, and it offers multiple advantages over existing ammonium salt leaching agents for the indirect mineralization preparation of light calcium carbonate. Attached Figure Description

[0016] The present invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1 This is a flowchart of the process for preparing light calcium carbonate by two-stage leaching indirect mineralization of carbide slag according to the present invention.

[0018] Figure 2 This is a SEM microstructure image of calcium carbonate from the present invention.

[0019] Figure 3 This is the result of the EDS element distribution of calcium carbonate in this invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Furthermore, unless otherwise specified, the raw materials, reagents, or devices used in the following embodiments can be obtained from conventional commercial channels or by existing known methods.

[0021] This invention provides seven examples of preparing light calcium carbonate with different leaching agent ratios.

[0022] The test operating parameters and the raw material ratio of the leaching agent are shown in Tables 1 and 2: Table 1 Leaching and mineralization reaction parameters

[0023] Table 2 Leaching and mineralization reaction parameters

[0024] This invention provides seven embodiments according to the above-described invention. In some embodiments, glycine solution is added to calcium carbide slag in proportion and stirred for 30 minutes before the reaction is stopped. The mixture is then filtered to obtain a first-stage leaching solution rich in calcium and filter residue. A second-stage leaching agent is added to the filter residue, and after stirring for 30 minutes, the two-stage leachate is obtained. The two-stage leachate is then mixed to further carry out the CO2 mineralization reaction.

[0025] In this invention, glycine can absorb and release protons during leaching and mineralization, thereby achieving better recycling performance.

[0026] In this invention, leaching and mineralization both occur at lower temperatures, thus effectively reducing solvent loss due to volatilization.

[0027] The sucrose and sodium citrate of this invention can react with Ca during the two-stage leaching process. 2+ Chelation and release of OH - Mixing the two leachates can effectively improve mineralization efficiency.

[0028] The leaching agent of the present invention, comprising glycine, sodium citrate, sucrose and tert-butanol, can be adsorbed on the surface of calcium carbonate crystals during the mineralization stage, thereby regulating the crystal form and particle size of calcium carbonate.

[0029] The above-described process and experimental methods were used to test experimental schemes numbered 1 to 7 to demonstrate the effectiveness of the calcium carbonate preparation method and leaching agent formulation of the present invention. The test results of these methods and formulations are shown in Table 3. Table 3. Test results of preparing nano-calcium carbonate from carbide slag through two-stage leaching indirect mineralization.

[0030] The two-stage leaching test results of the calcium carbide slag of this invention show that the leaching efficiency of the first stage increases with the increase of glycine concentration. As shown in Table 3, the leaching efficiency of the first stage reaches its maximum of 79.65% when the glycine concentration is 20%. The data of the second stage leaching results show that some Ca2+ remains in the leached residue from the first stage. 2+ Ineffective leaching occurred; after adding a second-stage leaching agent, sucrose and sodium citrate could further remove residual calcium through chelation. 2+ Leaching efficiency increased with increasing sucrose and sodium citrate ratios, reaching a maximum of 26.79%. Mineralization experiments showed that mineralization efficiency increased with increasing sucrose and sodium citrate concentrations in the two-stage leaching agent, reaching a maximum of 98.78%. After five cycles, the leaching efficiency decreased by only about 5%, while the mineralization efficiency decreased by 1%–3%. These data demonstrate the effectiveness of this leaching agent in the leaching and mineralization of carbide slag.

[0031] In summary, through experimental optimization and screening, this invention provides a novel two-stage leaching method for the indirect mineralization of calcium carbide slag to prepare light calcium carbonate, along with a leaching agent formulation. This method successfully prepares light calcium carbonate, and the leaching agent used significantly enhances the extraction of calcium carbonate. 2+ The leaching efficiency and mineralization efficiency. For example... Figure 2 and Figure 3 As shown, through SEM microstructure characterization and EDS elemental distribution analysis, it can be found that the prepared calcium carbonate has a particle size of about 0.5 to 1 micrometer. There are almost no other elements in the calcium carbonate, only 0.05% Al, and the purity of the calcium carbonate is extremely high.

[0032] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A leaching agent formulation for the indirect mineralization of carbide slags for the production of light calcium carbonate, characterized by, The formula includes: glycine, sucrose, sodium citrate, t-butyl alcohol and water.

2. A leaching agent formulation for the preparation of light calcium carbonate by indirect carbide slag mineralization according to claim 1, characterized by, The indirect mineralization preparation of light calcium carbonate from carbide slag includes one-stage leaching and two-stage leaching, the one-stage leaching adopts 5% glycine solution; the two-stage leaching adopts 3% sucrose+5% sodium citrate+2% t-butyl alcohol; the solvents of the one-stage leaching and the two-stage leaching are both water.

3. A leaching agent formulation for the preparation of light calcium carbonate by indirect carbide slag mineralization according to claim 1, characterized by, The indirect mineralization preparation of light calcium carbonate from carbide slag includes one-stage leaching and two-stage leaching, the one-stage leaching adopts 5% glycine solution; the two-stage leaching adopts 3% sucrose+10% sodium citrate+2% t-butyl alcohol; the solvents of the one-stage leaching and the two-stage leaching are both water.

4. A leaching agent formulation for the preparation of light calcium carbonate by indirect carbide slag mineralization according to claim 1, characterized by, The indirect mineralization preparation of light calcium carbonate from carbide slag includes one-stage leaching and two-stage leaching, the one-stage leaching adopts 10% glycine solution; the two-stage leaching adopts 3% sucrose+5% sodium citrate+2% t-butyl alcohol; the solvents of the one-stage leaching and the two-stage leaching are both water.

5. A leaching agent formulation for the preparation of light calcium carbonate by indirect carbide slag mineralization according to claim 1, characterized by, The indirect mineralization preparation of light calcium carbonate from carbide slag includes one-stage leaching and two-stage leaching, the one-stage leaching adopts 10% glycine solution; the two-stage leaching adopts 5% sucrose+8% sodium citrate+2% t-butyl alcohol; the solvents of the one-stage leaching and the two-stage leaching are both water.

6. A leaching agent formulation for the preparation of light calcium carbonate by indirect carbide slag mineralization according to claim 1, characterized by, The indirect mineralization preparation of light calcium carbonate from carbide slag includes one-stage leaching and two-stage leaching, the one-stage leaching adopts 15% glycine solution; the two-stage leaching adopts 3% sucrose+5% sodium citrate+2% t-butyl alcohol; the solvents of the one-stage leaching and the two-stage leaching are both water.

7. A leaching agent formulation for the preparation of light calcium carbonate by indirect carbide slag mineralization according to claim 1, characterized by, The indirect mineralization preparation of light calcium carbonate from carbide slag includes one-stage leaching and two-stage leaching, the one-stage leaching adopts 20% glycine solution; the two-stage leaching adopts 3% sucrose+5% sodium citrate+2% t-butyl alcohol; the solvents of the one-stage leaching and the two-stage leaching are both water.

8. A leaching agent formulation for the preparation of light calcium carbonate by indirect carbide slag mineralization according to claim 1, characterized by, The indirect mineralization preparation of light calcium carbonate from carbide slag includes one-stage leaching and two-stage leaching, the one-stage leaching adopts 20% glycine solution; the two-stage leaching adopts 3% sucrose+5% sodium citrate+7% t-butyl alcohol; the solvents of the one-stage leaching and the two-stage leaching are both water.

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