Apparatus and method for making nanocarbonates and for capturing escape gases

Abstract

The application discloses a device and method for preparing nanometer carbonate and capturing escaped gas, and belongs to the technical field of CO2 emission reduction and solid waste resource utilization. The device comprises a system for leaching alkali metal ions from solid waste, a system for preparing nanometer carbonate by CO2 mineralization, and a system for capturing escaped gas; specifically, the device comprises a circulating leaching liquid storage tank, a high-shear leaching kettle, a high-shear mineralization kettle, an external circulation ammonia capture tank of the mineralization kettle, a leaching liquid centrifuge, a circulating leaching liquid centrifuge, a CO2 microporous gas distributor and an external circulation slurry pump. In the leaching process, high shear is used to achieve high alkali metal ion leaching rate; in the mineralization process, high shear and a ceramic membrane microporous gas distributor are used to strengthen the CO2 mineralization process, improve the reaction efficiency, abandon the general filtration method, adopt a centrifuge solid-liquid separation, adopt an external circulation process and additionally arrange an ammonia capture tank, effectively solve the ammonia escape problem, capture and utilize all the gaseous phase escaped ammonia, and the external circulation strengthens the CO2 mineralization process.

Description

Technical Field

[0001] This invention belongs to the technical field of CO2 emission reduction and solid waste resource utilization, specifically relating to an apparatus and method for preparing nano-carbonates and capturing escaped gases. Background Technology

[0002] With industrial development and the use of fossil fuels, CO2 emissions have increased year by year. This has led to a series of problems, including global warming, melting icebergs, and sharp declines in species numbers. Solid waste, containing large amounts of alkaline metal oxides such as calcium and magnesium, is an effective way to permanently store CO2 with low energy consumption.

[0003] Industrial solid waste mainly includes: tailings, coal gangue, fly ash, steel slag, industrial by-product gypsum, red mud, etc. In recent years, the main areas of solid waste resource utilization in my country include: recycling of various metals, use as building material raw materials, agricultural production applications, tailings backfilling, and production of light calcium carbonate, etc.

[0004] CO2 mineralization of solid waste to produce carbonates involves selectively leaching calcium ions from the solid waste using water, acidic, or alkaline leaching media. CO2 is then introduced for further mineralization to produce calcium carbonate, with the remaining tailings used as raw materials for building materials. Nano-calcium carbonate possesses many excellent properties and is widely used in industries such as rubber and plastics, coatings, papermaking, inks, food, pharmaceuticals, and animal feed. Demand is projected to exceed 40 million tons by 2024, indicating a very promising market prospect and a wide range of applications.

[0005] Currently reported leaching media include water, hydrochloric acid, sodium hydroxide, acetic acid, and ammonium salts. Ammonium salts are widely used due to their recycling and cost reduction, but they also suffer from problems such as significant ammonia loss due to ammonia escape and low alkali metal ion leaching rates. Furthermore, indirect carbonation involves slow mineralization reactions and low efficiency. Patent CN 100571847 C discloses a mineral carbonation process for fixing CO2 and co-producing calcium carbonate, using an acidic medium to leach calcium ions from steel slag and then converting them into high-value-added carbonate products through carbonation. This process is lengthy, has a low leaching rate, and produces calcium carbonate products with large particle sizes. Patent CN110577232 A discloses a method for preparing nano-calcium carbonate, based on obtaining a CaCl2-NH4Cl-NH3-H2O system leaching solution from steel slag, and then preparing nano-calcium carbonate by adding sucrose, CO2, and ultrasound. This process does not effectively capture the ammonia generated after the leaching reaction, still resulting in ammonia escape problems. Patent CN 103111186B utilizes steel slag as raw material and enhances the reaction between CaO and CO2 in the slag by adding a catalyst containing alkali metal salts, thereby improving the conversion rate of CaO and the carbon fixation efficiency of the steel slag. The reported carbon fixation rate of the steel slag is 90-150 g. CO2 / kg钢渣 The carbon fixation rate has improved, but the problem of low carbon fixation rate still exists. Summary of the Invention

[0006] To address the problems of ammonia loss due to ammonia escape during the production of carbonates from CO2 mineralized solid waste, as well as the low leaching rate of alkali metal ions and low reaction efficiency of the leaching kettle, this invention provides an apparatus and method for preparing nano-carbonates and capturing escaped gases. This not only effectively solves the ammonia escape problem and improves the leaching rate of alkali metal ions, but also enhances the CO2 mineralization process, improving reaction efficiency and carbon fixation rate.

[0007] To achieve the above objectives, the present invention employs the following technical solutions:

[0008] An apparatus for preparing nano-carbonates and capturing escaped gases includes an alkali metal ion leaching system for solid waste, a CO2 mineralization system for preparing nano-carbonates, and a gas escape capture system.

[0009] The solid waste alkali metal ion leaching system includes a circulating leachate storage tank, a high-shear leaching kettle, a leachate centrifuge, a leachate transfer pump, and a solid waste residue inlet; the CO2 mineralization system for preparing nano-carbonates includes a high-shear mineralization kettle, a ceramic membrane microporous gas distributor, a circulating leachate centrifuge, and a leachate circulation pump; the gas escape capture system includes an ammonia induced draft fan, an external circulation slurry pump, an external circulation ammonia capture tank for the mineralization kettle, and a CO2 induced draft fan;

[0010] The circulating leachate storage tank has two inlets and one outlet. The first inlet of the circulating leachate storage tank is connected to the inlet for the flow of fresh leachate. The second inlet of the circulating leachate storage tank is connected to one of the outlets of the leachate centrifuge. The outlet of the circulating leachate storage tank is connected to the leachate inlet of the high-shear leachate vessel through a pipeline. A leachate circulation pump is installed on the pipeline between the circulating leachate storage tank and the high-shear leachate vessel for pumping the circulating leachate.

[0011] The high-shear leaching kettle is provided with a leaching liquid inlet and a solid waste residue inlet at the top; a process return water outlet is provided on the side wall; a process water temperature measuring point, a kettle bottom temperature measuring point, a mixture a discharge outlet, and a process water inlet are provided at the bottom; a high-shear homogenizing emulsifier is provided inside the leaching kettle; the solid waste residue is connected to the solid waste residue inlet on the high-shear leaching kettle through a pipeline;

[0012] The leaching centrifuge has one inlet and three outlets. The inlet of the leaching centrifuge is connected to the discharge port of the mixture a at the bottom of the high-shear leaching reactor via a pipeline. The first outlet of the leaching centrifuge is connected to one of the inlets of the external circulation ammonia collection tank of the mineralization reactor via a pipeline, and an ammonia induced draft fan is installed on the pipeline between the leaching centrifuge and the external circulation ammonia collection tank of the mineralization reactor to collect escaped ammonia. The second outlet of the leaching centrifuge is connected to the alkali metal ion leaching liquid inlet on the high-shear mineralization reactor, and a leaching liquid transfer pump is installed on the pipeline between the leaching centrifuge and the high-shear mineralization reactor to pump the alkali metal ion leaching liquid. The third outlet of the leaching centrifuge is a tailings discharge pipe.

[0013] The high-shear mineralization reactor is equipped with an alkali metal ion leaching liquid inlet and an external circulating liquid inlet at the top; a process return water outlet is located on the upper part of the side wall, and a CO2 gas inlet is located on the lower part of the side wall; a process water temperature measuring point, a reactor bottom temperature measuring point, a mixed material b outlet, and a process water inlet are located at the bottom; a high-shear homogenizing emulsifier and a ceramic membrane microporous gas distributor are installed inside the reactor.

[0014] The external circulation ammonia capture tank of the mineralization reactor has three inlets and one outlet. The first inlet of the external circulation ammonia capture tank is connected to one of the outlets of the leachate centrifuge. The second inlet of the external circulation ammonia capture tank is connected to the external circulation ammonia capture tank of the mineralization reactor via a pipeline. The third inlet of the external circulation ammonia capture tank is connected to the discharge port of the mixture b at the bottom of the high-shear mineralization reactor. An external circulation slurry pump is installed on the pipeline connecting the external circulation ammonia capture tank and the high-shear mineralization reactor to capture the escaped ammonia. The outlet of the external circulation ammonia capture tank is connected to the external circulation liquid inlet at the top of the high-shear mineralization reactor to input external circulation liquid into the high-shear mineralization reactor.

[0015] The inlet of the leaching centrifuge is connected to the discharge port of the mixture b at the bottom of the high-shear mineralization vessel via a pipeline, for conveying the solid-liquid mixture a; the leaching centrifuge has three outlets, the first outlet is connected to one of the inlets on the circulating leaching liquid storage tank via a pipeline; the second outlet is connected to the pipeline between CO2 gas and the high-shear mineralization vessel, and a CO2 induced draft fan is installed on the pipeline between the leaching centrifuge and the CO2 gas and the high-shear mineralization vessel to capture the escaped gaseous CO2; the third outlet is a light calcium carbonate discharge pipe;

[0016] CO2 gas is fed into the CO2 inlet on the side wall of the high-shear mineralization reactor through a pipeline, and a CO2 flow meter is installed on the pipeline between the CO2 gas and the high-shear mineralization reactor to record the amount of CO2 used.

[0017] Furthermore, both the high-shear leaching reactor and the high-shear mineralization reactor are jacketed reactors, heated by process hot water, and consist of an upper head and a lower volume. The upper head supports the emulsifier and drive unit and provides a seal. The lower volume contains the liquid and packing material. Baffles are installed on the side walls of the volume to block the liquid flow and create turbulence. For liquids that generate heat during stirring, a jacket is added to the volume to remove the heat from the liquid with cooling water.

[0018] Furthermore, the temperature range of the high-shear leaching reactor is 20℃~120℃ and 0.05~0.3 MPa; the temperature range of the high-shear mineralization reactor is 20℃~120℃ and 0.05~0.8 MPa.

[0019] Furthermore, the ceramic membrane microporous gas distributor consists of an inlet pipe and several outlet pipes. The inlet pipe is a CO2 inlet, and the several outlet pipes are evenly and vertically distributed inside the high-shear mineralization reactor. The sidewalls of the outlet pipes are provided with multiple micropores with a diameter of 50 nm to 400 nm. Gas enters the ceramic membrane microporous gas distributor from the CO2 inlet and is then released from the micropores on the outlet pipes.

[0020] Furthermore, the centrifuge for the leachate and the centrifuge for the circulating leachate have a rotation speed of 0 r / min to 1450 r / min.

[0021] Furthermore, the high-shear homogenizing emulsifier is installed at a position offset from the axis of the high-shear leaching kettle, with a rotation speed of 3000 rpm to 5000 rpm; the high-shear homogenizing emulsifier is installed at the axis of the high-shear mineralization kettle, with a rotation speed of 5000 rpm to 10000 rpm.

[0022] A method for preparing nano-carbonates and capturing escaped gases includes the following steps:

[0023] Step 1: The solid waste residue and leachate are transported to a high-shear leaching kettle and leached for 0.5 h at 20℃~120℃, 0.05~0.3 MPa, 3000 rmp~5000 rmp and high shear. The reacted material is then transported to a leachate centrifuge.

[0024] Step 2: After separation by a centrifuge at a rotation speed of 0 r / min to 1450 r / min, a high-purity calcium-containing leachate is obtained. The alkali metal ion leachate is then transported to the high-shear mineralization reactor by a leachate transfer pump. The escaped ammonia gas is captured in the external circulation ammonia capture tank of the mineralization reactor. The separated tailings are collected and used as building materials.

[0025] Step 3: In the high-shear mineralization reactor, the mineralization reaction is carried out under high shear conditions at 20℃~120℃, CO2 inlet pressure 0.05~0.8 MPa, and rotation speed 5000 rpm~10000 rpm. At the same time, the external circulation pump is turned on, and the reaction material circulates in the external circulation ammonia capture tank of the mineralization reactor to enhance the reaction process and capture the escaped ammonia. The reacted material is then transported to the circulating leachate centrifuge.

[0026] Step 4: After separation in a centrifuge with a rotation speed of 0 r / min to 1450 r / min, high-purity product carbonate is obtained; the separated leachate is recycled back to the leachate storage tank for reuse; and the gaseous CO2 is captured in a high-shear mineralization reactor for reuse.

[0027] Furthermore, the solid waste residue includes steel slag, carbide slag, wollastonite, and fly ash; the leachate includes an ammonium salt composite leachate, including ammonium chloride, ammonium acetate, and ammonium nitrate.

[0028] Furthermore, the liquid-to-solid ratio in step 1 is 5 to 7.

[0029] Furthermore, in step 3, the mineralization reaction ends when the pH value of the reactants in the high-shear mineralization reactor is neutral or slightly acidic.

[0030] The process of this invention is as follows: Solid waste residue and circulating leachate enter the high-shear leaching reactor through the solid waste residue inlet and the leachate inlet, respectively. Under high shear, a reaction occurs. The resulting solid-liquid mixture a is transported to a leachate centrifuge for separation, yielding an alkali metal ion leachate, which is then pumped to the high-shear mineralization reactor by a leachate transfer pump. Ammonia gas escaping from the leachate centrifuge is collected by an ammonia gas induced draft fan into the external circulating ammonia collection tank of the mineralization reactor. In the high-shear mineralization reactor, CO2 from the flue gas duct passes through microporous gas... The distributor releases the leaching solution from the micropores on the side wall, which then reacts with the alkali metal ion leachate under high shear. Simultaneously, the external circulation slurry pump is activated, and the reactants circulate in the external circulation ammonia collection tank of the mineralization reactor to collect any escaping ammonia. The resulting solid-liquid mixture b is transported to a circulating leachate centrifuge, where it is separated to obtain high-purity carbonate. The separated leachate is then recycled back to the circulating leachate storage tank for reuse. Gas-phase CO2 is captured and reused in the high-shear mineralization reactor.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) The leaching process of this invention utilizes high shear to achieve a high alkali metal ion leaching rate;

[0033] (2) The present invention utilizes a high shear and ceramic membrane microporous gas distributor in the mineralization process to enhance the CO2 mineralization process and improve the reaction efficiency.

[0034] (3) This invention abandons the common filtration method, adopts centrifuge solid-liquid separation and external circulation process and adds ammonia capture tank, effectively solves the ammonia escape problem, captures and utilizes all gas phase escaped ammonia, and the external circulation enhances the CO2 mineralization process. Attached Figure Description

[0035] Figure 1 This is a process flow diagram of the present invention;

[0036] Figure 2 This is a diagram of the high-shear leaching reactor equipment of the present invention;

[0037] Figure 3 This is a diagram of the high-shear mineralization reactor equipment of the present invention;

[0038] Figure 4 This is the XRD pattern of the nano-calcium carbonate of this invention;

[0039] Figure 5 This is a SEM image of nano-calcium carbonate.

[0040] Figure label:

[0041] Appendix Figure 1 Each marker represents:

[0042] CO1, Ammonia Exhaust Fan; CO2, CO2 Exhaust Fan; FT01, CO2 Flow Meter; H01, Leachate Centrifuge; H02, Circulating Leachate Centrifuge; P01, Leachate Circulating Pump; P02, Leachate Transfer Pump; P03, External Circulating Slurry Pump; R01, High Shear Leaching Reactor; R02, High Shear Mineralization Reactor; V01, Circulating Leachate Storage Tank; V02, Solid Waste Inlet; V03, External Circulating Ammonia Collection Tank of Mineralization Reactor; W01, CO2 Microporous Gas Distributor;

[0043] 1-1 Circulating leachate; 2-2 Solid waste residue; 3-3 Solid-liquid mixture a; 4-4 Alkali metal ion leachate; 5-5 Escaped ammonia; 6-6 Escaped CO2; 7-7 Solid-liquid mixture a; 8-8 External circulating liquid; 9-9 Solid-liquid mixture a; 10-10 Circulating leachate; 11-11 CO2.

[0044] Appendix Figure 2 Each marker represents:

[0045] aa, Solid waste residue inlet; ab, Leachate inlet; ac, Process return water outlet; ad, Process water temperature measuring point; ae, Bottom temperature measuring point; af, Mixed material a outlet; ag, Process water inlet; ah, High shear homogenizer emulsifier.

[0046] Appendix Figure 3 Each marker represents:

[0047] ba, alkali metal ion leaching solution inlet; bb, process return water outlet; bc, process water temperature measuring point; bd, bottom temperature measuring point; be, mixed material b outlet; bf, process water inlet; bg, CO2 inlet; bh, external circulating liquid inlet; bi, high shear homogenizing emulsifier; bj, ceramic membrane microporous gas distributor. Detailed Implementation

[0048] Example 1

[0049] An apparatus for preparing nano-carbonates and capturing escaped gases includes an alkali metal ion leaching system for solid waste, a CO2 mineralization system for preparing nano-carbonates, and a gas escape capture system.

[0050] The solid waste alkali metal ion leaching system includes a circulating leachate storage tank V01, a high-shear leaching kettle R01, a leachate centrifuge H01, a leachate transfer pump P02, and a solid waste residue inlet V02; the CO2 mineralization system for preparing nano-carbonates includes a high-shear mineralization kettle R02, a ceramic membrane microporous gas distributor bj, a circulating leachate centrifuge H02, and a leachate circulation pump P01; the gas escape capture system includes an ammonia induced draft fan CO1, an external circulation slurry pump P03, an external circulation ammonia capture tank V03 for the mineralization kettle, and a CO2 induced draft fan CO2;

[0051] The circulating leachate storage tank V01 has two inlets and one outlet. The first inlet of the circulating leachate storage tank V01 is connected to the inlet for fresh leachate to flow in. The second inlet of the circulating leachate storage tank V01 is connected to one of the outlets of the leachate centrifuge H02. The outlet of the circulating leachate storage tank V01 is connected to the leachate inlet ab of the high-shear leaching vessel R01 through a pipeline. A leachate circulation pump P01 is installed on the pipeline between the circulating leachate storage tank V01 and the high-shear leaching vessel R01 for pumping the circulating leachate 1-1.

[0052] The high-shear leaching reactor R01 is provided with a leachate inlet ab and a solid waste residue inlet aa at the top; a process return water outlet ac is provided on the side wall; a process water temperature measuring point ad, a bottom temperature measuring point ae, a mixed material outlet af, and a process water inlet ag are provided at the bottom; a high-shear homogenizing emulsifier ah is provided inside the leaching reactor; solid waste residue 2-2 is connected to the solid waste residue inlet aa on the high-shear leaching reactor R01 through a pipeline;

[0053] The leaching centrifuge H01 has one inlet and three outlets. The inlet of the leaching centrifuge H01 is connected to the discharge port af of the mixture a at the bottom of the high-shear leaching kettle R01 via a pipeline. The first outlet of the leaching centrifuge H01 is connected to one of the inlets of the external circulation ammonia collection tank V03 of the mineralization kettle via a pipeline, and an ammonia induced draft fan C01 is installed on the pipeline between the leaching centrifuge H01 and the external circulation ammonia collection tank V03 of the mineralization kettle to collect escaped ammonia. The second outlet of the leaching centrifuge H01 is connected to the alkali metal ion leaching liquid inlet ba on the high-shear mineralization kettle R02, and a leaching liquid transfer pump P02 is installed on the pipeline between the leaching centrifuge H01 and the high-shear mineralization kettle R02 to pump the alkali metal ion leaching liquid 4-4. The third outlet of the leaching centrifuge H01 is a tailings discharge pipe.

[0054] The high-shear mineralization reactor R02 is equipped with an alkali metal ion leaching liquid inlet ba and an external circulating liquid inlet bh at the top; a process return water outlet bb is located on the upper side wall, and a CO2 inlet bg is located on the lower side wall; a process water temperature measuring point bc, a reactor bottom temperature measuring point bd, a mixed material outlet be, and a process water inlet bf are located at the bottom; and a high-shear homogenizing emulsifier bi and a ceramic membrane microporous gas distributor bj are located inside the reactor.

[0055] The external circulation ammonia collection tank V03 of the mineralization reactor has three inlets and one outlet. The first inlet of the external circulation ammonia collection tank V03 is connected to one of the outlets of the leachate centrifuge H01. The second inlet of the external circulation ammonia collection tank V03 is connected to the external circulation ammonia collection tank V03 through a pipeline. The third inlet of the external circulation ammonia collection tank V03 is connected to the discharge port be of the mixture b at the bottom of the high-shear mineralization reactor R02. An external circulation slurry pump P03 is installed on the pipeline connecting the external circulation ammonia collection tank V03 and the high-shear mineralization reactor R02 for capturing escaped ammonia. The outlet of the external circulation ammonia collection tank V03 is connected to the external circulation liquid inlet bh at the top of the high-shear mineralization reactor R02 for inputting external circulation liquid 8-8 into the high-shear mineralization reactor R02.

[0056] The inlet of the leachate centrifuge H02 is connected to the discharge port be of the mixture b at the bottom of the high-shear mineralization vessel R02 via a pipeline, for conveying the solid-liquid mixture a9-9; the leachate centrifuge H02 has three outlets. The first outlet is connected to one of the inlets on the circulating leachate storage tank V01 via a pipeline; the second outlet is connected to the pipeline between CO2 gas and the high-shear mineralization vessel R02, and a CO2 induced draft fan C02 is installed on the pipeline between the leachate centrifuge H02 and the CO2 gas and the high-shear mineralization vessel R02 to capture the escaped gaseous CO26-6; the third outlet is a light calcium carbonate discharge pipe;

[0057] CO2 gas is fed into the CO2 inlet bg on the side wall of the high-shear mineralization reactor R02 through a pipeline, and a CO2 flow meter FT01 is installed on the pipeline between the CO2 gas and the high-shear mineralization reactor R02 to record the amount of CO2 used.

[0058] Furthermore, both the high-shear leaching reactor R01 and the high-shear mineralization reactor R02 are jacketed reactors, heated by process hot water, and consist of an upper head and a lower volume. The upper head supports the emulsifier and drive unit and provides a seal. The lower volume contains liquid and packing material. Baffles are installed on the side walls of the volume to block the liquid flow and create turbulence. For liquids that generate heat during stirring, a jacket is added to the volume to remove the heat from the liquid with cooling water.

[0059] Furthermore, the temperature range of the high-shear leaching reactor R01 is 20℃~120℃ and 0.05~0.3 MPa; the temperature range of the high-shear mineralization reactor R02 is 20℃~120℃ and 0.05~0.8 MPa.

[0060] Furthermore, the ceramic membrane microporous gas distributor bj consists of an inlet pipe and several outlet pipes. The inlet pipe is a CO2 inlet bg, and the several outlet pipes are evenly and vertically distributed inside the high-shear mineralization reactor R02. The sidewalls of the outlet pipes are provided with multiple micropores with a diameter of 50 nm to 400 nm. Gas enters the ceramic membrane microporous gas distributor bj from the CO2 inlet bg and is then released from the micropores on the several outlet pipes.

[0061] Furthermore, the centrifuge H01 for the leachate and the centrifuge H02 for the circulating leachate have a rotation speed of 0 r / min to 1450 r / min.

[0062] Furthermore, the high-shear homogenizing emulsifier ah is installed at a position offset from the axis of the high-shear leaching vessel R01, with a rotation speed of 3000 rpm to 5000 rpm; the high-shear homogenizing emulsifier bi is installed at the axis of the high-shear mineralization vessel R02, with a rotation speed of 5000 rpm to 10000 rpm.

[0063] The process of this invention is as follows: Solid waste residue 2-2 and circulating leachate 1-1 enter the high-shear leaching reactor R01 through the solid waste residue inlet aa and the leachate inlet ab, respectively. Under high shear, a reaction occurs. The resulting solid-liquid mixture a3-3 is then transported to the leachate centrifuge H01 for separation, yielding alkali metal ion leachate 4-4, which is then transported by the leachate transfer pump P02 to the high-shear mineralization reactor R02. Ammonia gas escaping from the leachate centrifuge H01... Ammonia gas is collected by the ammonia induced draft fan CO1 into the external circulation ammonia collection tank V03 of the mineralization reactor; CO211-11 from the flue gas in the high-shear mineralization reactor R02 is released from the micropores on the side wall through the microporous gas distributor bj, and undergoes a mineralization reaction with the alkali metal ion leaching solution 4-4 under high shear; at the same time, the external circulation slurry pump P03 is turned on, and the reaction material circulates in the external circulation ammonia collection tank V03 of the mineralization reactor to capture the escaped ammonia; the solid-liquid mixture b9-9 after the reaction is transported to the circulating leaching solution centrifuge H02, and after separation in the centrifuge, high-purity product carbonate is obtained, and the separated leaching solution is recycled back to the circulating leaching solution storage tank V01 for reuse; gaseous CO2 is captured in the high-shear mineralization reactor R02 for reuse.

[0064] Example 2

[0065] A method for preparing nano-carbonates and capturing escaped gases includes the following steps:

[0066] Step 1: The solid waste residue and leachate are transported to the high-shear leaching reactor R01 and subjected to a leaching reaction for 0.5 h at 20℃~120℃, 0.05~0.3MPa, 3000 rpm~5000 rpm and high shear. The reacted material is then transported to the leachate centrifuge H01. The liquid-to-solid ratio is 5~7. The solid waste residue includes steel slag, carbide slag, wollastonite, and fly ash. The leachate includes an ammonium salt composite leachate, including ammonium chloride, ammonium acetate, and ammonium nitrate.

[0067] Step 2: After separation in a centrifuge H01 with a rotation speed of 0 r / min to 1450 r / min, a high-purity calcium-containing leachate is obtained. The alkali metal ion leachate is then transported to the high-shear mineralization reactor R02 by the leachate transfer pump P02. The escaped ammonia gas is captured in the external circulation ammonia capture tank V03 of the mineralization reactor. The separated tailings are collected and used as building materials.

[0068] Step 3: In the high-shear mineralization reactor RO2, a mineralization reaction is carried out at 20℃~120℃, CO2 inlet pressure 0.05~0.8 MPa, rotation speed 5000 rpm~10000 rpm, under high shear conditions; at the same time, the external circulation pump PO3 is turned on, and the reactants circulate in the external circulation ammonia collection tank VO3 of the mineralization reactor to enhance the reaction process and collect the escaped ammonia; the reacted material is then transported to the circulating leachate centrifuge HO2.

[0069] Step 4: After separation in a centrifuge H02 with a rotation speed of 0 r / min to 1450 r / min, high-purity carbonate product is obtained; the separated leachate is recycled back to the circulating leachate storage tank V01 for reuse; gaseous CO2 is captured in the high-shear mineralization reactor RO2 for reuse. The mineralization reaction ends when the pH of the reactants in the high-shear mineralization reactor in Step 3 is neutral or slightly acidic.

[0070] Example 3

[0071] A method for preparing nano-carbonates and capturing escaped gases

[0072] Prepare a leachate containing 5 kg of industrial-grade ammonium chloride and 30 kg of water; simultaneously weigh 5.4 kg of steel slag (48.31% CaO, 30.18% SiO2, 6.44% MgO, 6.89% Al2O3, 2.40% Fe2O3 and other impurities) with a mesh size of less than 500.

[0073] The leachate is pumped from the leachate circulation pump P01 to the high-shear leaching reactor R01 via the leachate inlet aa. The high-shear homogenizing emulsifier ah is turned on for high-speed stirring, and the process water valve is opened to heat the solution to approximately 70℃. When the temperature of the ammonium chloride composite leachate in the reactor reaches 60℃, solid waste steel slag is added through the solid waste inlet aa, and then the solid waste inlet aa is closed to prevent ammonia escape. The reaction is carried out at 4500 rpm for 0.5 h. The reaction equation is as follows:

[0074] CaO + 2NH4Cl → CaCl2 + 2NH3 + H2O

[0075] MgO + 2NH4Cl → MgCl2 + 2NH3 + H2O

[0076] After the steel slag reacts with the compound ammonium chloride leaching solution for 0.5 h, the agitator is turned off, and the outlet a of the mixture at the bottom of the leaching vessel is opened. The solid-liquid mixture is then placed into the leaching solution centrifuge H01 at the bottom, and the outlet at the bottom of the leaching vessel is closed. The power to the leaching solution centrifuge is turned on, and the speed is slowly increased from low to high. After centrifugation at a high speed of 1450 r / min for 5 min, the side liquid phase outlet valve and the leaching solution transfer pump P02 are opened first to transfer it to the high-shear mineralization vessel R02, and the external circulation slurry pump P03 is turned on. At this time, the top gas phase outlet valve of the leaching solution centrifuge H01 and the ammonia induced draft fan C01 are opened to transfer it to the external circulation ammonia collection tank V03 of the high-shear mineralization vessel for collection. Simultaneously, the motor of the high-shear homogenizing emulsifier bi is turned on at a speed of 9000 rmp. When the temperature inside the vessel reaches 60℃, the CO2 feed valve is opened, and the feed pressure is 0.7 MPa. The reaction equation is as follows:

[0077] CaCl2 + 2NH3 + H2O + CO2→ CaCO3 ↓ + 2NH4Cl

[0078] MgCl2 + 2NH3 + H2O + CO2→ MgCO3 ↓ + 2NH4Cl

[0079] When the pH of the solution in the mineralization reactor reaches approximately 7, the reaction is complete. Turn off the agitator and the external circulation pump P03. Open the bottom outlet af of the mixture b and transfer the mixture into the lower circulating leachate centrifuge H02. Close the mixture outlet af. Turn on the power to the circulating leachate centrifuge H02, gradually increasing the speed from low to high. After centrifuging at a high speed of 1450 r / min for 5 minutes, open the side liquid phase outlet valve to discharge the leachate and circulate it back to the leachate circulation storage tank for reuse. Simultaneously, open the top gas phase outlet valve of the circulating leachate centrifuge H02 and the CO2 induced draft fan C01 to capture the escaped CO2 and return it to the mineralization reactor for reuse.

[0080] Finally, the nano-calcium carbonate product was washed, centrifuged, and dried. 2.53 kg of nano-calcium carbonate was obtained, with a purity of 98.07% and a whiteness of 95.05. The carbon fixation rate of the steel slag was 206 g. CO2 / kg 钢渣 .

[0081] Example 4

[0082] Prepare a leachate containing 5 kg of industrial-grade ammonium chloride and 26 kg of water; simultaneously weigh 3.8 kg of carbide slag (90.214% CaO, 2.306% SiO2, 4.755% MgO, 1.266% Al2O3, 0.196% Fe2O3, 0.04% TiO2, 0.005% V2O5 and other impurities) with a mesh size of less than 200.

[0083] The leachate is pumped from the leachate circulation pump P01 through the leachate inlet aa to the high-shear leaching reactor R01. The high-shear homogenizing emulsifier ah is turned on for high-speed stirring, and the process water valve is opened to heat the solution to approximately 70℃. When the temperature of the ammonium chloride composite leachate in the reactor reaches 60℃, carbide slag is added through the solid waste inlet aa, and then the solid waste inlet aa is closed to prevent ammonia escape. The reaction is carried out at 4500 rpm for 0.25 h. The reaction equation is as follows:

[0084] Ca(OH)2 + 2NH4Cl → CaCl2 + 2NH3 + 2H2O

[0085] Mg(OH)2 + 2NH4Cl → MgCl2 + 2NH3 + 2H2O

[0086] After the carbide slag reacts with the compound ammonium chloride leachate for 0.25 h, the stirring is turned off, and the outlet a of the mixture at the bottom of the leaching kettle is opened. The solid-liquid mixture is then placed into the lower leaching centrifuge H01, and the outlet at the bottom of the leaching kettle is closed. The power to the leaching centrifuge is turned on, and the speed is slowly increased from low to high. After centrifugation at a high speed of 1450 r / min for 5 min, the side liquid phase outlet valve and the leaching liquid transfer pump P02 are opened first to transfer it to the high-shear mineralization kettle R02, and the external circulation slurry pump P03 is turned on. At this time, the top gas phase outlet valve of the leaching centrifuge H01 and the ammonia induced draft fan C01 are opened to transfer it to the external circulation ammonia collection tank V03 of the high-shear mineralization kettle for collection. Simultaneously, the motor of the high-shear homogenizing emulsifier bi is turned on at a speed of 9000 rmp. When the temperature inside the kettle reaches 60℃, the CO2 feed valve is opened, and the feed pressure is 0.7 MPa. The reaction equation is as follows:

[0087] CaCl2 + 2NH3 + H2O + CO2→ CaCO3 ↓ + 2NH4Cl

[0088] MgCl2 + 2NH3 + H2O + CO2→ MgCO3 ↓ + 2NH4Cl

[0089] When the pH of the solution in the mineralization reactor reaches approximately 7, the reaction is complete. Turn off the agitator and the external circulation pump P03. Open the bottom outlet af of the mixture b and place the mixture into the lower circulating leachate centrifuge H02. Close the mixture outlet af. Turn on the power to the circulating leachate centrifuge H02, gradually increasing the speed from low to high. After centrifuging at a high speed of 1450 r / min for 5 minutes, open the side liquid phase outlet valve to discharge the leachate and circulate it back to the leachate circulation storage tank for reuse. Simultaneously, open the top gas phase outlet valve of the circulating leachate centrifuge H02 and the CO2 induced draft fan C01 to capture the escaped CO2 and return it to the high-shear mineralization reactor for reuse.

[0090] Finally, the nano-calcium carbonate product was washed, centrifuged, and dried. 4.21 kg of nano-calcium carbonate was obtained, with a purity of 97.80% and a whiteness of 96.23. The maximum carbon fixation rate of the carbide slag was 487 g. CO2 / kg 电石渣 .

[0091] The escaped ammonia and CO2 gases are fed into the ammonia induced draft fan CO1 and the CO2 induced draft fan CO2, respectively, and then fed into the external circulation ammonia capture tank V03 and the high-shear mineralization reactor R02 for reuse. This effectively solves the ammonia escape problem, capturing and utilizing all the ammonia escaping in the gas phase.

[0092] An external circulation system is implemented, consisting of an external circulation slurry pump PO3 and an external circulation ammonia collection tank VO3 located outside the high-shear mineralization reactor RO2, to allow for the circulation of reactants outside the reactor. This enhances the CO2 mineralization process and improves reaction efficiency.

[0093] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.

Claims

1. A method for preparing nano-carbonates and capturing escaped gases, characterized in that: The method includes the following steps: Step 1: Solid waste residue (2-2) and circulating leachate (1-1) are transported to a high-shear leachate tank (R01) and leached for 0.5 h at 20℃~120℃, 0.05~0.3 MPa, 3000 rmp~5000 rmp and high shear. The reacted material is then transported to a leachate centrifuge (H01). Step 2: After separation in a leachate centrifuge (H01) at a speed of 0 r / min to 1450 r / min, a high-purity calcium-containing leachate is obtained. The alkali metal ion leachate is then transported to the high-shear mineralization reactor (R02) by the leachate transfer pump (PO2). The escaped ammonia gas is captured in the external circulation ammonia capture tank (V03) of the mineralization reactor. The separated tailings are collected and used as building materials. Step 3: In the high-shear mineralization reactor (RO2), the mineralization reaction is carried out at 20℃~120℃, CO2 inlet pressure 0.05~0.8 MPa, rotation speed 5000 rpm~10000 rpm, under high shear conditions; at the same time, the external circulation pump is turned on, and the reaction material circulates in the external circulation ammonia capture tank (VO3) of the mineralization reactor to enhance the reaction process and capture the escaped ammonia; the reacted material is then transported to the circulating leachate centrifuge (HO2); Step 4: After separation in a centrifuge (H02) with a rotation speed of 0 r / min to 1450 r / min, high-purity product carbonate is obtained; the separated leachate is recycled back to the circulating leachate storage tank (V01) for reuse; the gaseous CO2 is captured in the high-shear mineralization reactor (R02) for reuse. The solid waste residue includes steel slag, carbide slag, wollastonite, and fly ash; the leachate includes an ammonium salt composite leachate, including ammonium chloride, ammonium acetate, and ammonium nitrate. The method is accomplished using the following apparatus, specifically including an alkali metal ion leaching system for solid waste, a CO2 mineralization system for preparing nano-carbonates, and a gas escape capture system. The solid waste alkali metal ion leaching system includes a circulating leachate storage tank (V01), a high-shear leaching kettle (R01), a leachate centrifuge (H01), a leachate transfer pump (P02), and a solid waste residue inlet; the CO2 mineralization system for preparing nano-carbonates includes a high-shear mineralization kettle (R02), a ceramic membrane microporous gas distributor (bj), a circulating leachate centrifuge (H02), and a leachate circulation pump (P01); the gas escape capture system includes an ammonia induced draft fan (C01), an external circulation slurry pump (P03), an external circulation ammonia capture tank (V03) for the mineralization kettle, and a CO2 induced draft fan (C02). The circulating leachate storage tank (V01) has two inlets and one outlet. The first inlet of the circulating leachate storage tank (V01) is connected to the inlet for fresh leachate. The second inlet of the circulating leachate storage tank (V01) is connected to one of the outlets of the circulating leachate centrifuge (H02). The outlet of the circulating leachate storage tank (V01) is connected to the leachate inlet (ab) of the high-shear leaching vessel (R01) through a pipeline. A leachate circulation pump (P01) is installed on the pipeline between the circulating leachate storage tank (V01) and the high-shear leaching vessel (R01) for pumping the circulating leachate (1-1). The high-shear leaching reactor (R01) is equipped with a leachate inlet (ab) and a solid waste inlet at the top; a process return water outlet is provided on the side wall; a process water temperature measuring point, a reactor bottom temperature measuring point, a mixture a outlet (af), and a process water inlet are provided at the bottom; a high-shear homogenizing emulsifier is provided inside the leaching reactor; the solid waste (2-2) is connected to the solid waste inlet on the high-shear leaching reactor (R01) through a pipeline; The leachate centrifuge (H01) has one inlet and three outlets. The inlet of the leachate centrifuge (H01) is connected via a pipeline to the discharge port (af) of the mixture a at the bottom of the high-shear leaching vessel (R01). The first outlet of the leachate centrifuge (H01) is connected via a pipeline to one of the inlets of the external circulation ammonia collection tank (V03) of the mineralization vessel. A pipeline is installed between the leachate centrifuge (H01) and the external circulation ammonia collection tank (V03) of the mineralization vessel. An ammonia induced draft fan (C01) is used to capture escaped ammonia gas; the second outlet of the leachate centrifuge (H01) is connected to the alkali metal ion leachate inlet (ba) on the high-shear mineralization kettle (R02), and a leachate transfer pump (P02) is installed on the pipeline between the leachate centrifuge (H01) and the high-shear mineralization kettle (R02) to pump the alkali metal ion leachate (4-4); the third outlet of the leachate centrifuge (H01) is a tailings discharge pipe; The high-shear mineralization reactor (R02) is equipped with an alkali metal ion leaching solution inlet (ba) and an external circulating liquid inlet (bh) at the top; a process return water outlet is located on the upper part of the side wall, and a CO2 gas inlet (bg) is located on the lower part of the side wall; a process water temperature measuring point, a reactor bottom temperature measuring point, a mixed material outlet (be), and a process water inlet are located at the bottom; a high-shear homogenizing emulsifier and a ceramic membrane microporous gas distributor (bj) are installed inside the reactor. The external circulation ammonia collection tank (VO3) of the mineralization reactor has three inlets and one outlet. The first inlet of the external circulation ammonia collection tank (VO3) is connected to one of the outlets of the leachate centrifuge (H01); the second inlet of the external circulation ammonia collection tank (VO3) is connected to the external circulation ammonia collection tank (VO3) via a pipeline; and the third inlet of the external circulation ammonia collection tank (VO3) is connected to the high-shear mineralization reactor (RO2). The bottom of the mixture b outlet (be) is connected, and an external circulation slurry pump (P03) is installed on the pipeline connecting the external circulation ammonia collection tank (V03) of the mineralization reactor and the high shear mineralization reactor (R02) to collect the escaped ammonia; the outlet of the external circulation ammonia collection tank (V03) of the mineralization reactor is connected to the external circulation liquid inlet (bh) at the top of the high shear mineralization reactor (R02) to input external circulation liquid (8-8) into the high shear mineralization reactor (R02); The inlet of the circulating leachate centrifuge (H02) is connected via a pipeline to the discharge port (be) of the mixture b at the bottom of the high-shear mineralization vessel (R02) for conveying the solid-liquid mixture a (9-9); the circulating leachate centrifuge (H02) has three outlets. The first outlet is connected via a pipeline to one of the inlets on the circulating leachate storage tank (V01); the second outlet is connected to the pipeline between CO2 gas and the high-shear mineralization vessel (R02), and a CO2 induced draft fan (CO2) is installed on the pipeline between the circulating leachate centrifuge (H02) and the CO2 gas and the high-shear mineralization vessel (R02) to capture the escaped gaseous CO2 (6-6); the third outlet is a light calcium carbonate discharge pipe; CO2 gas is fed into the CO2 inlet (bg) on ​​the side wall of the high shear mineralization reactor (R02) through a pipeline, and a CO2 flow meter (FT01) is installed on the pipeline between the CO2 gas and the high shear mineralization reactor (R02) to record the amount of CO2 used. The ceramic membrane microporous gas distributor (bj) consists of an inlet pipe and several outlet pipes. The inlet pipe is a CO2 inlet (bg), and the several outlet pipes are evenly and vertically distributed inside the high-shear mineralization reactor (RO2). The sidewalls of the outlet pipes are provided with multiple micropores with a diameter of 50 nm to 400 nm. Gas enters the ceramic membrane microporous gas distributor (bj) from the CO2 inlet (bg) and is then released from the micropores on the outlet pipes.

2. The method for preparing nano-carbonates and capturing escaped gases according to claim 1, characterized in that: Both the high-shear leaching reactor (R01) and the high-shear mineralization reactor (R02) are jacketed reactors, heated by process hot water. They consist of an upper head and a lower volume. The upper head supports the emulsifier and drive unit and provides a seal. The lower volume contains the liquid and packing material. Baffles on the side walls of the volume block the liquid flow, creating turbulence. For liquids that generate heat during stirring, a jacket is added to the volume to remove the heat from the liquid with cooling water.

3. The method for preparing nano-carbonates and capturing escaped gases according to claim 1, characterized in that: The temperature range of the high-shear leaching vessel (R01) is 20℃~120℃ and 0.05~0.3 MPa; the temperature range of the high-shear mineralization vessel (R02) is 20℃~120℃ and 0.05~0.8 MPa.

4. The method for preparing nano-carbonates and capturing escaped gases according to claim 1, characterized in that: The leachate centrifuge (H01) and the circulating leachate centrifuge (H02) have a rotation speed of 0 r / min to 1450 r / min.

5. The method for preparing nano-carbonates and capturing escaped gases according to claim 1, characterized in that: The high-shear homogenizing emulsifier is installed at a position off-center from the axis of the high-shear leaching vessel (R01), with a rotation speed of 3000 rpm to 5000 rpm; the high-shear homogenizing emulsifier is installed at the axis of the high-shear mineralization vessel (R02), with a rotation speed of 5000 rpm to 10000 rpm.

6. The method for preparing nano-carbonates and capturing escaped gases according to claim 1, characterized in that: The liquid-to-solid ratio in step 1 is 5-7.

7. The method for preparing nano-carbonates and capturing escaped gases according to claim 1, characterized in that: In step 3, the mineralization reaction ends when the pH of the reactants in the high-shear mineralization reactor is neutral or slightly acidic.

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