Method for preparing calcium carbonate by low-temperature temperature control and biobased dispersant in cooperation

Abstract

This invention relates to the field of inorganic material preparation technology, specifically a method for the synergistic preparation of calcium carbonate using low-temperature temperature control and a bio-based dispersant. The method involves adding a bio-based dispersant and an auxiliary dispersant to a reaction vessel containing a calcium nitrate solution, adding ammonium bicarbonate to the reaction vessel, adjusting the pH of the solution to 7.5-8.5 with ammonia, and continuing stirring until the reaction is complete. The mixture is then allowed to stand and age to promote crystal growth and precipitate calcium carbonate. The calcium carbonate formed in the reaction vessel is separated by centrifugation, followed by alternating washing with deionized water and anhydrous ethanol to remove residual NH4+. 4+ NO 3‑ Impurities are removed, and then the mixture is dried to obtain calcium carbonate powder. This invention achieves the green preparation of calcium carbonate by utilizing the synergistic effect of dispersants under low-temperature controlled conditions (5~15℃). The low-temperature environment effectively inhibits molecular thermal motion, reduces particle collision frequency, and blocks agglomeration pathways from a kinetic perspective.

Description

Technical Field

[0001] This invention relates to the field of inorganic material preparation technology, specifically to a method for preparing calcium carbonate through the synergistic effect of low-temperature temperature control and bio-based dispersants. Background Technology

[0002] Calcium carbonate, as a novel functional material, has demonstrated its enormous potential as a highly efficient calcium fertilizer in agriculture. Its abundant surface active sites endow it with the ability to rapidly release calcium ions, enabling crops to efficiently absorb and utilize calcium, significantly improving the utilization rate of calcium fertilizer. Simultaneously, the application of calcium carbonate can effectively improve soil structure, enhance soil water and fertilizer retention capacity, create a more favorable environment for crop growth, and its weakly alkaline properties can neutralize acidic soils, adjusting the soil pH to a suitable range for crop growth, thereby further promoting healthy crop growth and high yields.

[0003] Traditional preparation methods, such as limestone calcination, suffer from high energy consumption and large carbon emissions. While metathesis methods offer milder conditions, they are prone to particle agglomeration, leading to poor product dispersibility. Existing chemical dispersants, such as polyacrylic acid and sodium hexametaphosphate, effectively inhibit agglomeration, but suffer from poor biodegradability and potential for harmful residues. Furthermore, high-temperature reaction environments accelerate particle collisions, further exacerbating agglomeration.

[0004] Chinese patent CN119976917A discloses a method for preparing calcium carbonate by encapsulating carbon dioxide using phosphogypsum. The advantages are that calcium ions are efficiently purified through water leaching and ammonium leaching with ultra-low solid-liquid ratio, and high-purity calcium carbonate is prepared by combining carbonation reaction and carbon dioxide fixation. Filtrate recycling and impurity recovery reduce costs, increase profits, and reduce phosphogypsum pollution. The disadvantages are that long-term sulfate accumulation affects calcium leaching efficiency, the multi-step operation requires high control of conditions and has a long cycle, and the fluctuation of raw material composition requires parameter adjustment, which increases the difficulty of large-scale production.

[0005] Chinese patent CN119898808A discloses a method for preparing calcium carbonate from carbide slag. Its advantages are that hydrolysis replaces chemical leaching, resulting in the low-cost preparation of high-purity (>98%) calcium carbonate. At the same time, it recycles the filtrate, recovers industrial salt, and fixes carbon dioxide, reducing carbide slag pollution. Its disadvantages are that raw material fluctuations require parameter adjustments, the operation involves many steps and a long cycle (2-3 hours), long-term circulation may affect efficiency due to ion accumulation, and large-scale production requires solving the problems of carbon dioxide supply and equipment investment.

[0006] Chinese patent CN114293035A discloses a method for the combined preparation of calcium carbonate by enriching vanadium in vanadium-containing steel slag. The advantages are that it achieves high-purity fine calcium carbonate through selective leaching of calcium under negative pressure and recycling of ammonia gas, with no waste gas or wastewater discharge and a cost reduction of 40% to 60%. The disadvantages are that the steel slag composition fluctuates and the process parameters need to be adjusted, there are many operation steps and high requirements for condition control, long-term circulation may affect efficiency due to ion accumulation, and the initial equipment investment is relatively large.

[0007] Although patents such as CN119976917A, CN119898808A and CN114293035A have proposed different methods for preparing calcium carbonate, there are still problems such as complex processes, high costs, high equipment requirements, and the impact of raw material fluctuations on performance. Summary of the Invention

[0008] The technical problem to be solved by this invention is: how to provide a method for preparing calcium carbonate that is simple in process, low in cost, and requires little equipment.

[0009] The technical solution adopted in this invention is: a method for the synergistic preparation of calcium carbonate using low-temperature temperature control and a bio-based dispersant, which is carried out according to the following steps: Step 1: Add the bio-based dispersant and auxiliary dispersant to a reaction vessel containing a calcium nitrate solution. Under stirring conditions, a reaction occurs to form a complex (the dispersant is uniformly adsorbed onto the calcium ion surface through mechanical stirring, forming a stable complex). The electrostatic repulsion and steric hindrance effect of the dispersant (bio-based dispersant and auxiliary dispersant) can form a synergistic dispersion network, effectively blocking the aggregation path of calcium carbonate particles. The mass ratio of the auxiliary dispersant to the bio-based dispersant is 2-3, and the concentration of the calcium nitrate solution is 1.0-4.0 mol / L.

[0010] Step 2: At 5-15℃, under continuous stirring, add 1.0-1.7 mol / L ammonium bicarbonate dropwise into the reaction vessel. The molar ratio of ammonium bicarbonate to calcium nitrate is 2.0-2.4. The low-temperature environment (5-15℃) reduces molecular thermal motion, thereby decreasing particle collision frequency and kinetically blocking aggregation pathways. Simultaneously, it slows the reaction rate, separating nucleation from growth, thus promoting uniform nucleation and inhibiting aggregation. After the addition is complete, add ammonia to adjust the pH to 7.5-8.5, continue stirring until the reaction is complete, and then allow the mixture to stand and age to promote perfect crystal growth and the formation of calcium carbonate precipitate.

[0011] Step 3: Separate the calcium carbonate generated in the reaction vessel by centrifugation, and then wash it alternately with deionized water and anhydrous ethanol to remove residual NH4+. 4+ NO3 - Remove impurities, then dry to obtain calcium carbonate powder.

[0012] The bio-based dispersant is one or more of the following: polyglutamic acid, lignin sulfonate, starch and its derivatives, cellulose derivatives (such as sodium carboxymethyl cellulose), chitosan and its derivatives (such as carboxymethyl chitosan), protein-based bio-based dispersants, or microbial metabolite dispersants (such as xanthan gum and pullulan); the auxiliary dispersant is one or more of the following: polyvinylpyrrolidone (PVP), sodium polyacrylate, sodium tripolyphosphate, SP-830 superdispersant, polyepoxysuccinic acid (sodium) (PESA), sodium oleate, and sodium dodecyl sulfate (SDS).

[0013] The bio-based dispersant is polyglutamic acid, and the auxiliary dispersant is polyvinylpyrrolidone.

[0014] In step one, when the reaction occurs under stirring conditions, the rotation speed is 300-500 rpm and the stirring time is 10-60 min. The total mass of the bio-based dispersant and auxiliary dispersant is 8.0%-15.0% of the total mass of the calcium nitrate solution and the ammonium bicarbonate solution.

[0015] In step two, the stirring speed is 1000-1500 rpm under continuous stirring, and stirring continues until the reaction is complete. The stirring time is 30-60 min; the standing and aging time is 8.0-15.0 h.

[0016] In step three, the centrifugation method involves a centrifugation speed of 1000-3000 rpm and a centrifugation time of 5-15 min. The centrifuge is then washed 3-5 times alternately with deionized water and anhydrous ethanol. During drying, the product is dried at 40-80℃ for 12-48 h.

[0017] The beneficial effects of this invention are: by utilizing the synergistic effect of dispersants under low temperature control (5-15℃), this invention achieves the green preparation of calcium carbonate. The low temperature environment effectively inhibits molecular thermal motion, reduces particle collision frequency, and blocks agglomeration pathways from a kinetic perspective.

[0018] Bio-based dispersants can chelate calcium ions to delay precipitation, control particle size, prevent particle agglomeration through electrostatic repulsion, and their long-chain structure forms a physical barrier on the particle surface, further inhibiting direct contact between particles; while auxiliary dispersants enhance dispersion stability through steric hindrance effects.

[0019] Polyglutamic acid, as an environmentally friendly dispersant, has a biodegradation cycle of less than 30 days, is non-toxic and harmless, and its dispersion efficiency far exceeds that of traditional chemical agents, thus solving the problem of potentially harmful residues in traditional dispersants.

[0020] This invention avoids the high energy consumption and high carbon emissions of high-temperature calcination, and conforms to the concept of low-carbon green manufacturing.

[0021] The preparation process of this invention is simple, requires no special equipment or complex condition control, has low cost, and is suitable for industrial continuous production. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. The described embodiments are some, but not all, of the embodiments of the present invention.

[0023] Example 1: Preparation stage: Prepare 2.5 mol / L calcium nitrate solution, 1.5 mol / L ammonium bicarbonate solution, 40 g / L sodium carboxymethyl cellulose solution, and 40 g / L sodium polyacrylate solution.

[0024] In the preparation stage, calcium nitrate solution was placed in a reaction vessel (reactor), and sodium polyacrylate solution and polyglutamic acid solution were mixed evenly at a mass ratio of 2.5. The evenly mixed sodium polyacrylate and sodium carboxymethyl cellulose solution was placed in the reaction vessel and stirred at 400 rpm for 45 min. The total mass of sodium polyacrylate and sodium carboxymethyl cellulose solution was 12.0% of the total mass of calcium nitrate solution and ammonium bicarbonate solution.

[0025] At low temperature (5-15℃) and with a stirring speed of 1200 rpm, ammonium bicarbonate solution was added dropwise into the reaction vessel, with a molar ratio of ammonium bicarbonate to calcium nitrate of 2. After the addition was complete, ammonia water was added to adjust the pH of the solution to 8.0, and the stirring was maintained at 1200 rpm for 45 min, followed by aging for 12 h. The aged liquid was centrifuged at 2000 rpm for 10 min, then washed four times alternately with deionized water and anhydrous ethanol, and dried at 60℃ for 24 h to obtain calcium carbonate.

[0026] Example 2: Preparation stage: Prepare 1.0 mol / L calcium nitrate solution, 1.5 mol / L ammonium bicarbonate solution, 35 g / L carboxymethyl chitosan solution, and 35 g / L polyvinylpyrrolidone (PVP) solution.

[0027] In the preparation stage, calcium nitrate solution was placed in a reaction vessel (reactor), and polyvinylpyrrolidone (PVP) solution and carboxymethyl chitosan solution were mixed evenly at a mass ratio of 2. The evenly mixed PVP and carboxymethyl chitosan solution was placed in the reaction vessel and stirred at 300 rpm for 40 min. The total mass of PVP and carboxymethyl chitosan solution was 10.0% of the total mass of calcium nitrate solution and ammonium bicarbonate solution.

[0028] At low temperature (5-15℃) and with a stirring speed of 1500 rpm, ammonium bicarbonate solution was added dropwise into the reaction vessel, with a molar ratio of ammonium bicarbonate to calcium nitrate of 2.1. After the addition was complete, ammonia water was added to adjust the pH of the solution to 7.5, and stirring was maintained at 1500 rpm for 30 minutes, followed by aging for 15 hours. The aged liquid was then centrifuged at 1000 rpm for 15 minutes, followed by washing three times alternately with deionized water and anhydrous ethanol, and dried at 50℃ for 30 hours to obtain calcium carbonate.

[0029] Example 3: Preparation stage: Prepare 4.0 mol / L calcium nitrate solution, 1.5 mol / L ammonium bicarbonate solution, 35 g / L lignin sulfonate solution, and 35 g / L sodium tripolyphosphate solution.

[0030] In the preparation stage, calcium nitrate solution was placed in a reaction vessel (reactor), and sodium tripolyphosphate solution and lignin sulfonate solution were mixed evenly at a mass ratio of 3. The evenly mixed sodium tripolyphosphate and lignin sulfonate solution were placed in the reaction vessel and stirred at 500 rpm for 10 min. The total mass of sodium tripolyphosphate and lignin sulfonate solution was 8.0% of the total mass of calcium nitrate solution and ammonium bicarbonate solution.

[0031] At low temperature (5-15℃) and with a stirring speed of 1500 rpm, ammonium bicarbonate solution was added dropwise into the reaction vessel, with a molar ratio of ammonium bicarbonate to calcium nitrate of 2.2. After the addition was complete, ammonia water was added to adjust the pH of the solution to 8.5, and the stirring was maintained at 1500 rpm for 40 min, followed by aging for 15 h. The aged liquid was then centrifuged at 3000 rpm for 5 min, followed by washing three times alternately with deionized water and anhydrous ethanol, and dried at 80℃ for 12 h to obtain calcium carbonate.

[0032] Example 4: Preparation stage: Prepare 1.0 mol / L calcium nitrate solution, 1.7 mol / L ammonium bicarbonate solution, 35 g / L polyglutamic acid solution, and 35 g / L polyvinylpyrrolidone (PVP) solution.

[0033] In the preparation stage, calcium nitrate solution was placed in a reaction vessel (reactor), and polyvinylpyrrolidone (PVP) solution and polyglutamic acid solution were mixed evenly at a mass ratio of 2.3. The evenly mixed PVP and polyglutamic acid solutions were placed in the reaction vessel and stirred at 300 rpm for 30 min. The total mass of PVP and polyglutamic acid solutions was 13.0% of the total mass of calcium nitrate solution and ammonium bicarbonate solution.

[0034] At low temperature (5-15℃) and with a stirring speed of 1300 rpm, ammonium bicarbonate solution was added dropwise into the reaction vessel, with a molar ratio of ammonium bicarbonate to calcium nitrate of 2.3. After the addition was complete, ammonia water was added to adjust the pH of the solution to 8.5, and stirring was maintained at 1300 rpm for 60 min, followed by aging for 15 h. The aged liquid was then centrifuged at 1500 rpm for 12 min in a centrifuge, followed by washing three times alternately with deionized water and anhydrous ethanol, and then dried at 70℃ for 12 h to obtain calcium carbonate.

[0035] Example 5: Preparation stage: Prepare 2.0 mol / L calcium nitrate solution, 1.0 mol / L ammonium bicarbonate solution, 35 g / L polyglutamic acid solution, and 35 g / L sodium oleate solution.

[0036] In the preparation stage, calcium nitrate solution was placed in a reaction vessel (reactor), and sodium oleate solution and polyglutamic acid solution were mixed evenly at a mass ratio of 2. The evenly mixed sodium oleate and polyglutamic acid solution was placed in the reaction vessel and stirred at 300 rpm for 30 min. The total mass of sodium oleate and polyglutamic acid solution was 15.0% of the total mass of calcium nitrate solution and ammonium bicarbonate solution.

[0037] At low temperature (5-15℃) and with a stirring speed of 1100 rpm, ammonium bicarbonate solution was added dropwise into the reaction vessel, with a molar ratio of ammonium bicarbonate to calcium nitrate of 2.4. After the addition was complete, ammonia water was added to adjust the pH of the solution to 8.5, and stirring was maintained at 1100 rpm for 60 min, followed by aging for 12 h. The aged liquid was centrifuged at 2500 rpm for 12 min, then washed four times alternately with deionized water and anhydrous ethanol, and dried at 40℃ for 48 h to obtain calcium carbonate.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for the synergistic preparation of calcium carbonate using low-temperature temperature control and a bio-based dispersant, characterized in that, Follow these steps: Step 1: Add the bio-based dispersant and the auxiliary dispersant to a reaction vessel containing a calcium nitrate solution, and react under stirring conditions to form a complex. The mass ratio of the auxiliary dispersant to the bio-based dispersant is 2-3, and the concentration of the calcium nitrate solution is 1.0-4.0 mol / L. Step 2: At 5-15℃, under continuous stirring, add 1.0-1.7 mol / L ammonium bicarbonate to the reaction vessel dropwise. The molar ratio of ammonium bicarbonate to calcium nitrate is 2.0-2.

4. After the addition is complete, add ammonia water to adjust the pH of the solution to 7.5-8.

5. Continue stirring until the reaction is complete, and then let it stand to age, forming calcium carbonate precipitate. Step 3: Separate the calcium carbonate generated in the reaction vessel by centrifugation, then wash it alternately with deionized water and anhydrous ethanol, and then dry it to obtain calcium carbonate powder.

2. The method for preparing calcium carbonate by low-temperature control and synergistic use of bio-based dispersants according to claim 1, characterized in that: The bio-based dispersant is one or more of the following: polyglutamic acid, lignin sulfonate, starch and its derivatives, cellulose derivatives, chitosan and its derivatives, protein-based bio-based dispersants, or microbial metabolite dispersants; the auxiliary dispersant is one or more of the following: polyvinylpyrrolidone, sodium polyacrylate, sodium tripolyphosphate, SP-830 superdispersant, polyepoxysuccinic acid (sodium), sodium oleate, and sodium dodecyl sulfate.

3. The method for preparing calcium carbonate by synergistic use of low-temperature temperature control and bio-based dispersants according to claim 2, characterized in that: The bio-based dispersant is polyglutamic acid, and the auxiliary dispersant is polyvinylpyrrolidone.

4. The method for preparing calcium carbonate by low-temperature control and synergistic use of bio-based dispersants according to claim 1, characterized in that: In step one, when the reaction occurs under stirring conditions, the rotation speed is 300-500 rpm and the stirring time is 10-60 min. The total mass of the bio-based dispersant and auxiliary dispersant is 8.0%-15.0% of the total mass of the calcium nitrate solution and the ammonium bicarbonate solution.

5. The method for preparing calcium carbonate by low-temperature temperature control and synergistic use of bio-based dispersants according to claim 1, characterized in that: In step two, the stirring speed is 1000-1500 rpm under continuous stirring, and stirring continues until the reaction is complete. The stirring time is 30-60 min; the standing and aging time is 8.0-15.0 h.

6. The method for preparing calcium carbonate by low-temperature control and synergistic use of bio-based dispersants according to claim 1, characterized in that: In step three, the centrifugation method involves a centrifugation speed of 1000-3000 rpm and a centrifugation time of 5-15 min. The centrifuge is then washed 3-5 times alternately with deionized water and anhydrous ethanol. During drying, the product is dried at 40-80℃ for 12-48 h.