Method and system for mineralization and utilization of carbon dioxide

Abstract

The present invention discloses a method and system for the mineralization and utilization of carbon dioxide. The method for the mineralization and utilization of carbon dioxide provided by the present invention mainly involves directly contacting flue gas containing carbon dioxide with a sprayed calcium carbide slag slurry, thereby achieving the effective capture and solidification of low-concentration carbon dioxide without the need for enrichment, and ultimately converting it into a light calcium carbonate product with economic value. The method for the mineralization and utilization of carbon dioxide of the present invention can not only effectively achieve the resource regeneration of relatively low-concentration carbon dioxide and calcium carbide slag under conditions of low pollution and low energy consumption, but also obtain a calcium carbonate product with high purity and good quality, which is suitable for large-scale resource regeneration and has good application prospects. At the same time, the reasonable design of the equipment and connection method of the system provided by the present invention can also improve the utilization rate of raw materials and energy, and achieve low-cost, low-energy consumption, large-scale recovery and regeneration of flue gas and calcium carbide slag.

Description

Technical Field

[0001] The present invention relates to the technical field of resource recovery and comprehensive utilization, and in particular to a method and system for mineralization and utilization of carbon dioxide. Background Art

[0002] With the deepening of industrialization, carbon dioxide capture, utilization, and storage technologies are attracting significant attention because they can directly reduce carbon emissions and are a key approach to building a clean, low-carbon, safe, and efficient energy system. Among carbon dioxide utilization technologies, mineralization technology can carbonate carbon dioxide with alkaline metals such as calcium and magnesium found in industrial solid waste and natural minerals, generating high-value-added products. This simultaneously realizes the resourceful treatment of both carbon dioxide and industrial solid waste, making it a promising approach to carbon dioxide utilization.

[0003] Calcium carbide is a crucial component of the coal chemical industry. The calcium carbide acetylene process is the primary production process for key chemical materials in my country, including polyvinyl alcohol (PVA) and polyvinyl chloride (PVC). The calcium carbide industry is a typical high-coal-consuming industry. The reaction of calcium carbide with water to produce acetylene produces a large amount of calcium carbide slag as a byproduct. As living standards improve, calcium carbide slag not only consumes land resources and pollutes the surrounding environment, but also increases production costs and environmental pressures.

[0004] The main component of carbide slag is calcium hydroxide, and it also contains inorganic substances such as a small amount of metal oxides and organic impurities. The calcium-containing substances contained in the slag are good raw materials for carbon dioxide mineralization. Therefore, some researchers have proposed a process for preparing calcium carbonate products by mineralizing with carbide slag as a calcium source and adopting flue gas carbon dioxide, which can realize the reasonable disposal of industrial solid waste and carbon dioxide at the same time, and produce high value-added calcium carbonate products at the same time. For example, patent CN 102527225A proposes a method for capturing carbon dioxide in flue gas using carbide slag, wherein carbide slag is first calcined to obtain calcium oxide, and then the carbon dioxide in the flue gas is absorbed to obtain calcium carbonate and clean flue gas. However, the method has the problem that the calcination process consumes a lot of energy and the running cost is high. Other prior arts propose the process of leaching carbide slag with ammonium chloride, and then preparing calcium carbonate by carbon dioxide mineralization. The method can effectively separate the impurities in the carbide slag, but these processes have the problems of generating chlorine-containing wastewater and ammonia escape, low-concentration carbon dioxide being difficult to effectively utilize, and the low calcium ion leaching rate of carbide slag.

[0005] Therefore, there is an urgent need to develop a system for the mineralization and utilization of carbon dioxide that is low-pollution, low-energy consumption, and suitable for large-scale resource recovery. Summary of the Invention

[0006] In view of the problems of high energy consumption and pollution in the current carbon dioxide mineralization carbide slag process, the purpose of the present invention is to provide a method and system for the mineralization and utilization of carbon dioxide.

[0007] Specifically, the method developed by the present invention is to directly bring the flue gas containing carbon dioxide into full gas-liquid contact with the sprayed calcium carbide slag slurry, so that low-concentration carbon dioxide can be effectively captured and solidified without enrichment, and finally turned into a light calcium carbonate product with economic value.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] In a first aspect, the present invention provides a method for mineralization and utilization of carbon dioxide, comprising the following steps:

[0010] 1) adding ammonium chloride and water into an ammonium chloride dissolving tank to prepare an ammonium chloride absorption liquid, which is then passed into an ammonia absorption tower to obtain an ammonium chloride raw material liquid;

[0011] The flue gas is cooled by the heat exchanger to obtain low-temperature flue gas;

[0012] 2) adding the ammonium chloride raw material liquid and carbide slag into a leaching tank for mixing, subjecting the mixture to leaching reaction and filtering to obtain a calcium-containing solution;

[0013] 3) transporting the calcium-containing solution to a pre-cooling tank, cooling it to 35-60° C., adding ammonia water and a crystal directing agent, and adjusting the pH to 9.0-11.0 to obtain a slurry;

[0014] 4) The slurry is transported to the top feed of the continuous mineralization reactor, and low-temperature flue gas is introduced into the bottom of the continuous mineralization reactor. After mineralization reaction and solid-liquid separation, a crude product and ammonium chloride circulating liquid are obtained;

[0015] 5) mixing the crude product with an activator, subjecting the mixture to an activation reaction, filtering and drying to obtain a calcium carbonate product;

[0016] Wherein, the low-temperature flue gas in step 4) comprises 5% to 20% carbon dioxide by volume;

[0017] Step 4) The temperature of the low-temperature flue gas is 40-60° C.;

[0018] Step 4) The temperature of the mineralization reaction is 35°C to 65°C.

[0019] Specifically, the present invention first prepares an ammonium chloride raw material liquid, uses a leaching reaction to leach calcium-containing substances in carbide slag, and then uses a pump to pump it into a filter press to obtain a calcium-containing solution (mainly a calcium chloride solution); then, by cooling the liquid, adding ammonia water and a crystal directing agent, precipitation and adjustment of the particle size and crystal form of the precipitate are carried out to obtain a slurry; thereafter, the slurry is brought into full contact with low-temperature flue gas containing 5% to 20% carbon dioxide at normal pressure, using flue gas heat energy and controlling the pH value of the reaction liquid, to carry out a mineralization reaction and a clarification process through gas-liquid contact, thereby obtaining a crude calcium carbonate product and an ammonium chloride circulating liquid; finally, an activator is used to adjust the oil absorption value, specific surface area and other properties of the crude calcium carbonate product to obtain a crude calcium carbonate product.

[0020] At the same time, the ammonium chloride circulating liquid can be prepared into ammonium chloride absorption liquid by recycling and adding ammonium chloride and water, and is used for absorbing ammonia-containing tail gas generated by the mineralization reaction at a higher temperature.

[0021] In some embodiments of the present invention, the method for mineralization and utilization of carbon dioxide further comprises: step 5) the drying process is heated using the heat energy recovered by the heat exchanger in step 1).

[0022] Specifically, the present invention recovers waste heat from flue gas by setting a waste heat recovery heat exchanger, and the recovered heat is used as a heat source for drying the product calcium carbonate.

[0023] In some embodiments of the present invention, the method for mineralization and utilization of carbon dioxide further comprises: transporting the ammonium chloride circulating liquid in step 4) to an ammonium chloride dissolution tank for recovering ammonium chloride and preparing ammonium chloride absorption liquid.

[0024] In some embodiments of the present invention, the method for mineralization and utilization of carbon dioxide further comprises: step 4) the ammonia-containing tail gas generated by the mineralization reaction is absorbed by an ammonium chloride absorption liquid in an ammonia absorption tower to obtain purified gas.

[0025] Specifically, the ammonia content of the purified gas is ≤0.5% (volume fraction); the carbon dioxide content of the purified gas is ≤1% (volume fraction).

[0026] In some embodiments of the present invention, the ammonium chloride content of the ammonium chloride absorption solution is 100 to 300 g / L.

[0027] The ammonium chloride content of the ammonium chloride raw material solution in step 1) is 100-300 g / L.

[0028] In some preferred embodiments of the present invention, the method for mineralization and utilization of carbon dioxide further comprises: steps 1) to 5) can be cyclically operated, and the number of operations is ≥ 1.

[0029] In some more preferred embodiments of the present invention, the method for mineralization and utilization of carbon dioxide further comprises: steps 1) to 5) can be cyclically operated, and the number of operations is ≥ 1 to 5 times.

[0030] In some embodiments of the present invention, the source of the flue gas in step 1) is the flue gas after dust removal from the tail gas of the gas kiln in the chlor-alkali chemical plant.

[0031] In some embodiments of the present invention, the temperature of the flue gas in step 1) is 40-100°C.

[0032] In some embodiments of the present invention, the temperature of the flue gas in step 1) is 40-60°C.

[0033] In some preferred embodiments of the present invention, the temperature of the flue gas in step 1) is 50-80°C.

[0034] In some embodiments of the present invention, the temperature of the low-temperature flue gas in step 4) is 40-60°C.

[0035] In some preferred embodiments of the present invention, the low-temperature flue gas in step 4) comprises 8% to 18% carbon dioxide by volume.

[0036] In some preferred embodiments of the present invention, the low-temperature flue gas in step 4) comprises 10% to 16% carbon dioxide by volume.

[0037] In some embodiments of the present invention, the carbide slag in step 2) comprises 60% to 80% calcium hydroxide by mass.

[0038] In some embodiments of the present invention, the mass ratio of ammonium chloride to carbide slag in the ammonium chloride raw material solution in step 2) is (2-5):1.

[0039] In some preferred embodiments of the present invention, the mass ratio of ammonium chloride to carbide slag in the ammonium chloride raw material solution in step 2) is (2.5-3.5):1.

[0040] In some embodiments of the present invention, the temperature of the leaching reaction in step 2) is 20°C to 70°C.

[0041] In some preferred embodiments of the present invention, the temperature of the leaching reaction in step 2) is 25°C to 35°C.

[0042] Specifically, the leaching reaction involves an exothermic process, and the "temperature of the leaching reaction" refers to the temperature of the external environment, without considering the effect of the "exothermic reaction" on the leaching reaction temperature.

[0043] In some embodiments of the present invention, the leaching reaction time in step 2) is 0.5 h to 3 h.

[0044] In some preferred embodiments of the present invention, the leaching reaction time in step 2) is 1 h to 2 h.

[0045] In some embodiments of the present invention, the concentration of the ammonia water in step 3) is 20% to 28% by mass.

[0046] In some preferred embodiments of the present invention, the concentration of the ammonia water in step 3) is 25% by mass.

[0047] Specifically, adding 25% by mass of ammonia water to the pre-cooling tank in step 3) can enhance the absorption effect of the continuous mineralization reactor (ie, the continuous mineralization reaction tower, which is essentially an absorption tower).

[0048] In some embodiments of the present invention, the crystal directing agent in step 3) is one or more of sodium pyrophosphate, n-butanol, sodium polyphosphate, and sucrose.

[0049] In some embodiments of the present invention, the mass of the crystal directing agent in step 3) is 0.1% to 1% of the mass of the slurry based on the final concentration.

[0050] In some embodiments of the present invention, the temperature of the mineralization reaction in step 4) is 40°C to 50°C.

[0051] In some embodiments of the present invention, in step 4), the mineralization reaction is specifically carried out in a continuous mineralization reactor using a countercurrent spraying method, and the pH value of the liquid obtained after the mineralization reaction at the bottom of the continuous mineralization reactor is controlled to be ≤7.

[0052] In some embodiments of the present invention, the mineralization reaction in step 4) is carried out under normal pressure.

[0053] Specifically, the "normal pressure" refers to 99 kPa to 102 kPa.

[0054] In some embodiments of the present invention, the solid-liquid separation in step 4) includes the step of standing in a clarification tank for 1 to 2 hours.

[0055] In some embodiments of the present invention, the temperature of the activation reaction in step 5) is 30°C to 60°C.

[0056] In some embodiments of the present invention, the activation reaction time in step 5) is 0.5 h to 3 h.

[0057] In some embodiments of the present invention, the activator in step 5) is one or more of sodium citrate, sodium acrylate, and sodium stearate.

[0058] In a second aspect, the present invention provides a system for the mineralization and utilization of carbon dioxide, comprising a leaching tank, a first filter press, a pre-cooling water tank, a continuous mineralization reactor, an ammonia absorption tower, an ammonium chloride dissolution tank, a clarification tank, a washing tower, and a solidification tank;

[0059] The ammonium chloride dissolving tank is connected to the clarification tank and the top of the ammonia absorption tower through pipelines, and is used to recover ammonium chloride and ammonia and improve the utilization rate of the reaction raw materials;

[0060] The bottom of the ammonia absorption tower is connected to the leaching tank through a pipeline for transporting ammonium chloride raw material liquid;

[0061] The leaching tank is connected to the first filter press, the pre-cooling water tank, and the top of the continuous mineralization reactor in sequence through pipelines for transporting the mineralization reaction raw materials;

[0062] The continuous mineralization reactor is provided with a flue gas inlet for conducting a mineralization reaction;

[0063] The continuous mineralization reactor is also connected to the clarification tank and the solidification tank in sequence through pipelines to adjust the calcium carbonate product.

[0064] In some embodiments of the present invention, the system for mineralization and utilization of carbon dioxide further comprises a washing tower, a second filter press, a dryer, and a heat exchanger;

[0065] The bottom of the continuous mineralization reactor is connected to the clarification tank, the washing tower, the solidification tank, the second filter press and the drum dryer in sequence through pipelines;

[0066] The hot fluid outlet of the heat exchanger is connected to the continuous mineralization reactor through a pipeline to provide low-temperature flue gas; the cold fluid outlet of the heat exchanger is connected to the dryer through a pipeline to provide drying heat energy.

[0067] In some embodiments of the present invention, the leaching tank is further provided with a feeding port or an external feeding pipe for carbide slag.

[0068] In some embodiments of the present invention, the continuous mineralization reactor is selected from a spray tower, a plate tower, and a bubbling absorption tower.

[0069] In some preferred embodiments of the present invention, the continuous mineralization reactor is selected from a spray tower and a plate tower.

[0070] In some embodiments of the present invention, the first filter press and the second filter press are both selected from one or more of a plate and frame filter press, a chamber filter press, a vertical filter press, a belt filter press, and a diaphragm filter press.

[0071] In some embodiments of the present invention, the dryer is selected from a drum dryer, a spray dryer, a vacuum dryer, and a conveyor belt dryer.

[0072] In a third aspect, the present invention also provides the use of the above-mentioned method for mineralization and utilization of carbon dioxide in the preparation of calcium carbonate.

[0073] In particular, the application can produce a calcium carbonate product.

[0074] In some embodiments of the present invention, the average density of the calcium carbonate product is 2.5 to 3.0 g / cm 3 .

[0075] In some embodiments of the present invention, the average particle size of the calcium carbonate product is 1 to 10 μm.

[0076] In some preferred embodiments of the present invention, the average particle size of the calcium carbonate product is 2 to 5 μm.

[0077] In some embodiments of the present invention, the crystal form of the calcium carbonate product is selected from at least one of calcite and vaterite.

[0078] In some embodiments of the present invention, the oil absorption value of the calcium carbonate product is 20 to 30 mL / 100 g.

[0079] In some embodiments of the present invention, 3 to 4 m 2 / g.

[0080] In some embodiments of the present invention, the calcium carbonate content of the calcium carbonate product is ≥99% by mass.

[0081] In some preferred embodiments of the present invention, the calcium carbonate content of the calcium carbonate product is 99.1-99.9% by mass.

[0082] In some more preferred embodiments of the present invention, the calcium carbonate content of the calcium carbonate product is 99.7% by mass.

[0083] The beneficial effects of the present invention are as follows: the method for mineralizing and utilizing carbon dioxide of the present invention can not only effectively realize the resource regeneration of relatively low concentration carbon dioxide and carbide slag under conditions of low pollution and low energy consumption, but also obtain a calcium carbonate product with high purity and good quality, which is suitable for large-scale resource regeneration and has good application prospects.

[0084] Specifically:

[0085] (1) The carbon dioxide mineralization and utilization process provided by the present invention can utilize carbide slag as a raw material for producing light calcium carbonate, thereby achieving harmless treatment of solid waste and preparing high value-added products. At the same time, it avoids the energy consumption input of calcining limestone to prepare quicklime in the traditional light calcium carbonate preparation process.

[0086] (2) The process of the present invention utilizes low-concentration flue gas carbon dioxide to directly mineralize carbide slag to prepare light calcium carbonate, thereby achieving carbon dioxide emission reduction and avoiding the capture and concentration of flue gas carbon dioxide, simplifying the system flow, reducing process energy consumption, and improving process energy utilization efficiency, thereby solving the problems of high energy consumption and low efficiency of existing mineralization and storage.

[0087] (3) The process of the present invention uses the ammonium chloride solution filtered from the clarifier to capture escaping ammonia gas. The captured absorption liquid is then circulated to the carbide slag leaching tank to further leach the carbide slag, achieving the recycling of ammonia gas and ammonium chloride solution and reducing pollution. Finally, the waste heat of the flue gas is used as a heat source for drying the product calcium carbonate, further reducing process energy consumption.

[0088] (4) The key technical points of the process of the present invention are: using low-concentration flue gas carbon dioxide to directly mineralize carbide slag to prepare light calcium carbonate, avoiding the capture and concentration of flue gas carbon dioxide; recovering the ammonium chloride solution filtered out of the clarifier, and using it to capture escaped ammonia after regeneration, and the captured absorption liquid is circulated to the carbide slag leaching tank to continue leaching the carbide slag, thereby realizing the recycling of ammonia and ammonium chloride solution and reducing pollution; recovering the waste heat of the flue gas as a heat source for drying the product calcium carbonate, thereby reducing the energy consumption of the process.

[0089] (5) The reasonable design of the equipment and connection method of the system provided by the present invention can not only improve the utilization rate of raw materials and energy, and realize low-cost, low-energy consumption, large-scale recovery and regeneration of flue gas and calcium carbide slag, but also has a high degree of compatibility with the above-mentioned method, and can also realize the batch production of high-quality, micron-level, high-calcium carbonate content calcium carbonate products, which has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Figure 1 This is a schematic diagram of the operation flow of the system for mineralization and utilization of carbon dioxide in the present invention. DETAILED DESCRIPTION

[0091] The present invention is further described in detail below through specific examples.

[0092] Unless otherwise specified, the composition of the carbide slag used in the embodiments of the present invention is as follows: the content of calcium hydroxide is 60% to 80% (mass fraction);

[0093] The characteristics of the flue gas used in the embodiments of the present invention are as follows: the source is the tail gas after dust removal from the gas kiln of the chlor-alkali chemical plant, the temperature is 45-100°C, and its composition is basically the same as that of the low-temperature flue gas; the characteristics of the low-temperature flue gas are as follows: the temperature is 40-60°C; the carbon dioxide content is 5%-20% (volume fraction); NO x Content less than 150mg / m 3 ; Sulfur dioxide and sulfur trioxide content is less than 0.5 mg / m 3 ;

[0094] The ammonia content of the purified gas in the embodiment of the present invention is ≤0.5%;

[0095] The ammonium chloride absorption liquid used in the embodiment of the present invention has an ammonium chloride content of 100-300 g / L, and the device in which the absorption liquid works is a water scrubber, which mainly relies on the water in the dilute solution (i.e., the absorption liquid) for absorption, and has a good effect of absorbing ammonia;

[0096] The ammonium chloride content of the ammonium chloride raw material solution is 100-300 g / L;

[0097] The systems used in the embodiments of the present invention are all connected through pipelines, and directional transportation of materials can be achieved by arranging valves and pumps on the pipelines.

[0098] Example 1

[0099] This embodiment provides a system for the mineralization and utilization of carbon dioxide (see Figure 1 ), including an extraction tank, a first filter press, a pre-cooling water tank, a continuous mineralization reactor, an ammonia absorption tower, an ammonium chloride dissolution tank, a clarification tank, a washing tower, a solidification tank, a second filter press, a drum dryer and a heat exchanger;

[0100] The ammonium chloride dissolving tank is connected to the clarification tank and the ammonium chloride absorption liquid feed port at the top of the ammonia absorption tower through pipelines, while the absorption liquid outlet at the bottom of the ammonia absorption tower is connected to the leaching tank through pipelines to improve the utilization rate of ammonium chloride, ammonia water and water;

[0101] The leaching tank is provided with a feeding port and a discharging port. The discharging port of the leaching tank is connected to the first filter press, the pre-cooling water tank, and the top feeding port of the continuous mineralization reactor in sequence through pipelines, so as to transport the calcium chloride-containing leachate to the top of the continuous mineralization reactor;

[0102] An external low-temperature flue gas access pipe is provided on the side wall near the bottom of the continuous mineralization reactor to provide low-temperature flue gas containing carbon dioxide, so that the calcium chloride-containing leachate added to the top of the reactor and the low-temperature flue gas containing carbon dioxide can fully contact with each other and undergo mineralization reaction;

[0103] The continuous mineralization reactor is also provided with an ammonia-containing tail gas outlet, which is connected to the air inlet at the bottom of the ammonia absorption tower through a pipeline for absorbing and recovering ammonia generated by the mineralization reaction;

[0104] The bottom of the continuous mineralization reactor is also connected to the clarifier, washing tower, solidification tank, second filter press and drum dryer in sequence through pipelines for precipitation, washing precipitation, solidification, filtering and drying to obtain light calcium carbonate product;

[0105] The outlet of the heat exchanger's hot fluid is connected to the external low-temperature flue gas access pipeline for providing low-temperature flue gas; the outlet of the heat exchanger's cold fluid is connected to the drum dryer for using the recovered heat as a heat source for drying the product calcium carbonate.

[0106] It should be noted that the system of this embodiment is provided with a pre-cooling tank between the first filter press and the mineralization reactor, which can effectively improve the utilization rate of ammonia and crystal directing agent. Since the pre-cooling tank and the continuous mineralization reactor are two spaces and equipment, different temperatures can be controlled, creating conditions for batch and continuous production and subsequent recovery of ammonia-containing tail gas.

[0107] The system of this embodiment connects the continuous mineralization reactor, the ammonia absorption tower, the ammonium chloride dissolution tank, and the clarification tank through pipelines, and also connects the liquid outlet of the ammonia absorption tower to the leaching tank, thereby effectively improving the utilization rate of ammonium chloride, ammonia water, and water, and realizing the comprehensive utilization of carbide slag and flue gas containing carbon dioxide.

[0108] In the system of this embodiment, low-temperature flue gas can directly undergo mineralization reaction under low-temperature conditions without the need for external heating, thus achieving low energy consumption.

[0109] The continuous mineralization reactor in the system of this embodiment is similar in structure to the optimized spray tower;

[0110] The heat exchanger in the system of this embodiment is used to recover the thermal energy of the flue gas, and the recovered heat is used as a heat source for drying the product calcium carbonate.

[0111] It should be noted that in the leaching tank, carbide slag and ammonium chloride will react as follows:

[0112] Ca(OH)2+2NH4Cl=CaCl2+2H2O+2NH3;

[0113] In the continuous mineralization reactor, the filtrate, ammonia and low-temperature flue gas will undergo the following reactions:

[0114] CaCl2+2NH3·H2O+CO2=CaCO3+2NH4Cl+H2O.

[0115] This embodiment provides a method for mineralization and utilization of carbon dioxide, comprising the following steps:

[0116] 1) adding ammonium chloride into an ammonium chloride dissolving tank to dissolve and prepare an ammonium chloride aqueous solution, and passing the ammonium chloride aqueous solution into an ammonia absorption tower as an absorption liquid to obtain an ammonium chloride raw material liquid; the flue gas is cooled by a heat exchanger to obtain low-temperature flue gas and recovered heat energy;

[0117] The carbide slag and the ammonium chloride raw material liquid are added to a leaching tank at a mass ratio of ammonium chloride to carbide slag of 3.5:1, mixed evenly, reacted at a temperature of 35° C. for 2 h, and filtered using a first filter press to obtain a carbide slag residue and a filtrate (the filtrate contains calcium chloride);

[0118] 2) transferring the filtrate from step 1) to a pre-cooling tank, and when the temperature drops to 35-60° C., adding 25% by mass of ammonia water and 1% by mass of sodium pyrophosphate of the slurry, and adjusting the pH value to 9.0-11.0 to obtain a slurry;

[0119] The slurry is transported to the top of a continuous mineralization reactor for feeding, and low-temperature flue gas containing 16% (volume fraction) CO2 is continuously introduced into the continuous mineralization reactor for a mineralization reaction. The temperature of the mineralization reaction is 50° C., the pressure of the mineralization reaction is normal pressure (i.e., 101±2 kPa), and the pH value of the liquid at the bottom of the continuous mineralization reactor is controlled to be ≤7, thereby obtaining a slurry after the mineralization reaction;

[0120] 3) transporting the slurry in step 2) to a clarification tank and allowing it to stand for 1 hour to obtain a crude product and an ammonium chloride circulating liquid;

[0121] The ammonium chloride circulating liquid is transported to the ammonium chloride dissolution tank to realize the reuse of the ammonium chloride raw material;

[0122] 4) The crude product is transferred to a washing tower for washing, and then transferred to a solidification tank, where sodium citrate (1% by weight of the crude product) and water are added for activation at 60° C. for 3 hours to obtain an activated slurry;

[0123] 5) filtering the activated slurry with a second filter press and drying it with a drum dryer using recovered heat to obtain a light calcium carbonate product;

[0124] Wherein, in step 2), since the temperature of the mineralization reaction is 50° C., the mineralization reaction process is accompanied by the generation of ammonia-containing tail gas; step 2) further comprises the following steps:

[0125] The ammonia-containing tail gas is passed into the absorption tower and fully contacted with the ammonium chloride absorption liquid from the ammonium chloride dissolution tank to obtain purified gas;

[0126] Process for monitoring ammonia content in ammonia-containing tail gas and purge gas;

[0127] Monitor the CO2 content in low-temperature flue gas and ammonia-containing tail gas to analyze the CO2 absorption conversion rate.

[0128] The method for mineralization and utilization of carbon dioxide in this embodiment further includes: steps 1) to 5) are performed multiple times; the ammonia in the ammonium chloride circulating liquid in step 3) and the ammonia-containing tail gas in step 2) can be used for the next mineralization reaction, and ammonium chloride solid can be appropriately added according to the ammonium chloride content in the ammonium chloride circulating liquid.

[0129] During a single operation, analysis showed that the calcium ion mass leaching rate of calcium hydroxide in the carbide slag in step 1) of the method for mineralization and utilization of carbon dioxide in this embodiment was 88%; the CO2 absorption conversion rate in the flue gas in step 2) was 79%; the light calcium carbonate product CaCO3 in step 5) was ≥99.1wt.% and had an average density of 2.5-3.0g / cm 3 , average particle size: 3.4μm, crystal form or morphology: calcite and vaterite, oil absorption value: 20.16mL / 100g, specific surface area: 3.2m 2 / g.

[0130] Example 2

[0131] The system used in this embodiment is the same as that in embodiment 1.

[0132] This embodiment provides a method for mineralization and utilization of carbon dioxide, comprising the following steps:

[0133] 1) adding ammonium chloride into an ammonium chloride dissolving tank to dissolve the ammonium chloride aqueous solution, and passing the ammonium chloride aqueous solution into an ammonia absorption tower as an absorption liquid to obtain an ammonium chloride raw material solution;

[0134] The carbide slag and the ammonium chloride raw material liquid are added to a leaching tank at a mass ratio of ammonium chloride to carbide slag of 3:1, mixed evenly, reacted at a temperature of 30°C for 1 hour, and filtered using a first filter press to obtain a carbide slag residue and a filtrate (the filtrate contains calcium chloride);

[0135] 2) transferring the filtrate from step 1) to a pre-cooling tank, and when the temperature drops to 35-50° C., adding 25% by mass of ammonia water and 0.5% by mass of sodium pyrophosphate of the slurry, and adjusting the pH value to 9.0-11.0 to obtain a slurry;

[0136] The slurry is transported to the top of the continuous mineralization reactor for feeding, and low-temperature flue gas containing 16% (volume fraction) CO2 is continuously introduced into the continuous mineralization reactor for mineralization reaction. The mineralization reaction temperature is 50°C, and the pH value of the liquid at the bottom of the continuous mineralization reactor is controlled to be ≤7, to obtain a slurry after the mineralization reaction;

[0137] 3) transporting the slurry in step 2) to a clarifier tank and allowing it to stand for 1.5 hours to obtain a crude product and an ammonium chloride circulating liquid;

[0138] The ammonium chloride circulating liquid is transported to the ammonium chloride dissolution tank to realize the reuse of the ammonium chloride raw material;

[0139] 4) The crude product is transferred to a washing tower for washing, and then transferred to a solidification tank, and activated by adding 0.5% of the crude product weight of an activator sodium citrate and water at a temperature of 40° C. for 2 hours to obtain an activated slurry;

[0140] 5) filtering the activated slurry with a second filter press and drying it with a drum dryer to obtain a light calcium carbonate product;

[0141] Wherein, in step 2), since the temperature of the mineralization reaction is 50° C., the mineralization reaction process is accompanied by the generation of ammonia-containing tail gas; step 2) further comprises the following steps:

[0142] The ammonia-containing tail gas is passed into the absorption tower and fully contacted with the ammonium chloride absorption liquid from the ammonium chloride dissolution tank to obtain purified gas;

[0143] Process for monitoring ammonia content in ammonia-containing tail gas and purge gas;

[0144] Monitor the CO2 content in low-temperature flue gas and ammonia-containing tail gas to analyze the CO2 absorption conversion rate.

[0145] The method for mineralization and utilization of carbon dioxide in this embodiment further includes: steps 1) to 5) are performed multiple times; the ammonia in the ammonium chloride circulating liquid in step 3) and the ammonia-containing tail gas in step 2) can be used for the next mineralization reaction, and ammonium chloride solid can be appropriately added according to the ammonium chloride content in the ammonium chloride circulating liquid.

[0146] During a single operation, analysis showed that the calcium ion mass leaching rate of calcium hydroxide in the carbide slag in step 1) of the method for carbon dioxide mineralization and utilization of this embodiment was 81%; the CO2 absorption conversion rate in step 2) was 91%; the light calcium carbonate product CaCO3 in step 5) was ≥99.9wt% and had an average density of 2.5-2.8g / cm 3 , average particle size: 3.3μm, crystal form or morphology: calcite and vaterite, oil absorption value: 21.49mL / 100g, specific surface area: 3.4m 2 / g.

[0147] Example 3

[0148] The system used in this embodiment is the same as that in embodiment 1.

[0149] This embodiment provides a method for mineralization and utilization of carbon dioxide, comprising the following steps:

[0150] 1) adding ammonium chloride into an ammonium chloride dissolving tank to dissolve the ammonium chloride aqueous solution, and passing the ammonium chloride aqueous solution into an ammonia absorption tower as an absorption liquid to obtain an ammonium chloride raw material solution;

[0151] The carbide slag and the ammonium chloride raw material liquid are added to a leaching tank at a mass ratio of ammonium chloride to carbide slag of 2.5:1, mixed evenly, reacted at a temperature of 25° C. for 1 h, and filtered using a first filter press to obtain a carbide slag residue and a filtrate (the filtrate contains calcium chloride);

[0152] 2) transferring the filtrate from step 1) to a pre-cooling tank, and when the temperature drops to 35-60° C., adding 25% by mass of ammonia water and 0.2% by mass of sodium pyrophosphate of the slurry, and adjusting the pH value to 9.0-11.0 to obtain a slurry;

[0153] The slurry is transported to the top of the continuous mineralization reactor for feeding, and low-temperature flue gas containing 16% (volume fraction) CO2 is continuously introduced into the continuous mineralization reactor for mineralization reaction. The mineralization reaction temperature is 50°C, and the pH value of the liquid at the bottom of the continuous mineralization reactor is controlled to be ≤7, to obtain a slurry after the mineralization reaction;

[0154] 3) transporting the slurry in step 2) to a clarification tank and allowing it to stand for 1 hour to obtain a crude product and an ammonium chloride circulating liquid;

[0155] The ammonium chloride circulating liquid is transported to the ammonium chloride dissolution tank to realize the reuse of the ammonium chloride raw material;

[0156] 4) The crude product is transferred to a washing tower for washing, and then transferred to a solidification tank, and activated by adding 0.2% of the crude product weight of an activator sodium citrate and water at a temperature of 30° C. for 1 hour to obtain an activated slurry;

[0157] 5) filtering the activated slurry with a second filter press and drying it with a drum dryer to obtain a light calcium carbonate product;

[0158] Wherein, in step 2), since the temperature of the mineralization reaction is 50° C., the mineralization reaction process is accompanied by the generation of ammonia-containing tail gas; step 2) further comprises the following steps:

[0159] The ammonia-containing tail gas is passed into the absorption tower and fully contacted with the ammonium chloride absorption liquid from the ammonium chloride dissolution tank to obtain purified gas;

[0160] Process for monitoring ammonia content in ammonia-containing tail gas and purge gas;

[0161] Monitor the CO2 content in low-temperature flue gas and ammonia-containing tail gas to analyze the CO2 absorption conversion rate.

[0162] The method for mineralization and utilization of carbon dioxide in this embodiment further includes: steps 1) to 5) are performed multiple times; the ammonia in the ammonium chloride circulating liquid in step 3) and the ammonia-containing tail gas in step 2) can be used for the next mineralization reaction, and ammonium chloride solid can be appropriately added according to the ammonium chloride content in the ammonium chloride circulating liquid.

[0163] During a single run, analysis showed that the calcium ion mass leaching rate of calcium hydroxide in the carbide slag in step 1) of the method for carbon dioxide mineralization and utilization of this embodiment was 75%; the CO2 absorption conversion rate in step 2) was 92%; the light calcium carbonate product CaCO3 in step 5) was ≥99.5wt% and had an average density of 2.6-3.0g / cm 3 , average particle size: 4.6μm, crystal form or morphology: calcite and vaterite, oil absorption value: 22.17mL / 100g, specific surface area: 3.7m 2 / g.

[0164] Example 4

[0165] The system used in this embodiment is the same as that in embodiment 1.

[0166] This embodiment provides a method for mineralization and utilization of carbon dioxide, comprising the following steps:

[0167] 1) adding ammonium chloride into an ammonium chloride dissolving tank to dissolve the ammonium chloride aqueous solution, and passing the ammonium chloride aqueous solution into an ammonia absorption tower as an absorption liquid to obtain an ammonium chloride raw material solution;

[0168] The carbide slag and the ammonium chloride raw material liquid are added to a leaching tank at a mass ratio of ammonium chloride to carbide slag of 3:1, mixed evenly, reacted at a temperature of 40° C. for 1.5 h, and filtered using a first filter press to obtain a carbide slag residue and a filtrate (the filtrate contains calcium chloride);

[0169] 2) transferring the filtrate from step 1) to a pre-cooling tank, and when the temperature drops to 35-50° C., adding 25% by mass of ammonia water and 0.5% by mass of sodium pyrophosphate of the slurry, and adjusting the pH value to 9.0-11.0 to obtain a slurry;

[0170] The slurry is transported to the top of the continuous mineralization reactor for feeding, and low-temperature flue gas containing 12% (volume fraction) CO2 is continuously introduced into the continuous mineralization reactor for mineralization reaction. The mineralization reaction temperature is 40°C, and the pH value of the liquid at the bottom of the continuous mineralization reactor is controlled to be ≤7, to obtain a slurry after the mineralization reaction;

[0171] 3) transporting the slurry after the mineralization reaction in step 2) to a clarification tank and allowing it to stand for 1.5 hours to obtain a crude product and an ammonium chloride circulating liquid;

[0172] The ammonium chloride circulating liquid is transported to the ammonium chloride dissolution tank to realize the reuse of the ammonium chloride raw material;

[0173] 4) The crude product is transferred to a washing tower for washing, and then transferred to a solidification tank, and activated by adding 0.5% of the crude product weight of an activator sodium citrate and water at a temperature of 40° C. for 2 hours to obtain an activated slurry;

[0174] 5) filtering the activated slurry with a second filter press and drying it with a drum dryer to obtain a light calcium carbonate product;

[0175] In step 2), since the temperature of the mineralization reaction is 40° C., ammonia-containing tail gas is generated during the mineralization reaction; step 2) further comprises the following steps:

[0176] The ammonia-containing tail gas is passed into the absorption tower and fully contacted with the ammonium chloride absorption liquid from the ammonium chloride dissolution tank to obtain purified gas;

[0177] Process for monitoring ammonia content in ammonia-containing tail gas and purge gas;

[0178] Monitor the CO2 content in low-temperature flue gas and ammonia-containing tail gas to analyze the CO2 absorption conversion rate.

[0179] The method for mineralization and utilization of carbon dioxide in this embodiment further includes: steps 1) to 5) are performed multiple times; the ammonia in the ammonium chloride circulating liquid in step 3) and the ammonia-containing tail gas in step 2) can be used for the next mineralization reaction, and ammonium chloride solid can be appropriately added according to the ammonium chloride content in the ammonium chloride circulating liquid.

[0180] During a single operation, analysis showed that the calcium ion mass leaching rate of calcium hydroxide in the carbide slag in step 1) of the method for mineralization and utilization of carbon dioxide in this embodiment was 83%; the CO2 absorption conversion rate in the flue gas in step 2) was 87%; the light calcium carbonate product CaCO3 in step 5) was ≥99.7wt% and had an average density of 2.5-3.0g / cm 3 , average particle size: 3.7μm, crystal form or morphology: calcite and vaterite, oil absorption value: 20.39mL / 100g, specific surface area: 3.3m 2 / g.

[0181] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for mineralization and utilization of carbon dioxide, characterized in that: The following steps are involved: 1) adding ammonium chloride and water into an ammonium chloride dissolving tank to prepare an ammonium chloride absorption liquid, which is passed into an ammonia absorption tower to obtain an ammonium chloride raw liquid; the flue gas is cooled by a heat exchanger to obtain low-temperature flue gas; 2) adding the ammonium chloride raw material liquid and carbide slag into a leaching tank for mixing, subjecting the mixture to leaching reaction and filtering to obtain a calcium-containing solution; 3) transporting the calcium-containing solution to a pre-cooling tank, cooling it to 35-60° C., adding ammonia water and a crystal directing agent, and adjusting the pH to 9.0-11.0 to obtain a slurry; 4) The slurry is transported to the top feed of the continuous mineralization reactor, and low-temperature flue gas is introduced into the bottom of the continuous mineralization reactor. After mineralization reaction and solid-liquid separation, a crude product and ammonium chloride circulating liquid are obtained; 5) mixing the crude product with an activator, subjecting the mixture to an activation reaction, filtering and drying to obtain a calcium carbonate product; Wherein, in terms of volume fraction, the low-temperature flue gas in step 4) comprises 5% to 20% carbon dioxide; the temperature of the low-temperature flue gas in step 4) is 40° C. to 60° C.; the temperature of the mineralization reaction in step 4) is 35° C. to 65° C.; Step 2) The mass ratio of ammonium chloride to carbide slag in the ammonium chloride raw material solution is (2.5-3.0):1; Step 2) the leaching reaction temperature is 25°C to 30°C, and the leaching reaction time is 0.5-1h; Step 5) The activation reaction temperature is 30° C. to 40° C., and the activation reaction time is 0.5 h to 3 h.

2. The method for mineralization and utilization of carbon dioxide according to claim 1, characterized in that: The drying process in step 5) is heated by heat energy recovered by the heat exchanger in step 1); the source of the flue gas in step 1) is the flue gas after dust removal from the gas-fired kiln tail gas of a chlor-alkali chemical plant; the temperature of the flue gas in step 1) is 40-100°C.

3. The method for mineralization and utilization of carbon dioxide according to claim 1 or 2, characterized in that: The ammonium chloride circulating liquid in step 4) is transported to the ammonium chloride dissolving tank for recovering ammonium chloride and preparing ammonium chloride absorption liquid.

4. The method for mineralization and utilization of carbon dioxide according to claim 3, characterized in that: The method for mineralization and utilization of carbon dioxide further includes: steps 1) to 5) can be cyclically operated, and the number of operations is ≥ 1 time.

5. The method for mineralization and utilization of carbon dioxide according to claim 1 or 2, characterized in that: In step 4), the mineralization reaction is specifically carried out in a continuous mineralization reactor by using a countercurrent spraying method, and the pH value of the liquid obtained after the mineralization reaction at the bottom of the continuous mineralization reactor is controlled to be ≤7.

6. The method for mineralization and utilization of carbon dioxide according to claim 1 or 2, characterized in that: Step 5) The activator is one or more of sodium citrate, sodium acrylate, and sodium stearate.

7. A system for implementing the method for mineralization and utilization of carbon dioxide according to any one of claims 1 to 6, characterized in that: It includes leaching tank, first filter press, pre-cooling water tank, continuous mineralization reactor, ammonia absorption tower, ammonium chloride dissolution tank, clarification tank, washing tower and solidification tank; The ammonium chloride dissolving tank is connected to the clarification tank and the top of the ammonia absorption tower through pipelines; the bottom of the ammonia absorption tower is connected to the leaching tank through a pipeline; The leaching tank is connected to the first filter press, the pre-cooling water tank, and the top of the continuous mineralization reactor in sequence through pipelines; The continuous mineralization reactor is also connected to the clarification tank and the solidification tank in sequence through pipelines.

8. The system according to claim 7, characterized in that: The carbon dioxide mineralization and utilization system further includes a washing tower, a second filter press, a dryer and a heat exchanger; The bottom of the continuous mineralization reactor is connected to the clarification tank, washing tower, solidification tank, second filter press and drum dryer in sequence through pipelines; the hot fluid outlet of the heat exchanger is connected to the continuous mineralization reactor through a pipeline; the cold fluid outlet of the heat exchanger is connected to the dryer through a pipeline.

9. Use of the method according to any one of claims 1 to 6 in the preparation of calcium carbonate.

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