Supercritical carbon dioxide mineralization and storage method based on paste filling technology

Abstract

The invention discloses a supercritical carbon dioxide mineralization and storage method based on a paste filling technology. The supercritical carbon dioxide mineralization and storage method comprises the following steps: S1, preparing a paste filling material; s2, preparing supercritical carbon dioxide; s3, mineralization and storage: in order to realize large-scale mineralization and storage of CO2 in the mine, the mineralization and storage step comprises a mineralization filling slurry preparation process and a carbon injection mineralization process; according to the supercritical carbon dioxide mineralization and storage method based on the paste filling technology, the paste filling technology and supercritical carbon dioxide mineralization and storage are combined, mine solid waste with a large number of calcium and magnesium resources and supercritical carbon dioxide are fully mineralized, mineralization filling slurry is prepared and filled into an underground goaf, and the mining goaf is filled with the mineralization filling slurry. The mechanical property and the pore structure of the filling body are improved, the concept of treating waste with waste in a mine is met, and green mining of the metal mine is achieved.

Description

Technical Field

[0001] The invention relates to the field of engineering technology combining mine paste filling technology with supercritical carbon dioxide mineralization and storage, in particular to a supercritical carbon dioxide mineralization and storage method based on the paste filling technology. Background Art

[0003] After years of continuous exploration and practice, paste filling technology has been recognized and applied by many countries in the world. By making full tailings a resource for solid waste, preparing paste slurry and filling it underground, safe, environmentally friendly and efficient mining of metal mines can be achieved. The full tailings in the paste filling material is not only an important source of pollution, but also contains a large amount of calcium and magnesium-based resources that can be used for mineralization. By reacting with CO2 for carbonation, it can not only achieve permanent storage of CO2, but also improve the mechanical properties of the filling body and improve its pore structure. Underground goafs also provide a large number of storage sites for CO2 storage. Therefore, paste filling technology has great application prospects for the mineralization and storage of CO2.

[0004] However, CO2 mineralization storage technology is still in the basic research stage, and there are few related demonstration projects. For the direct mineralization and storage of CO2 by solid waste, the reaction process is too slow, and the reaction requires high temperature and high pressure operation, which is not suitable for large-scale industrial application. After the filling slurry is transported to the goaf for carbon injection mineralization, the CO2 dissolution rate is low and the escape rate is fast; and due to the closed characteristics of the mining area, the CO2 injection range cannot be expanded, and the mineralization efficiency is low.

[0005] When the temperature is higher than 31.1℃ and the pressure is higher than 7.38MPa, CO2 becomes a supercritical state. Supercritical carbon dioxide has the high density of liquid and the low viscosity of gas, with high solubility and strong diffusion ability.

[0006] In view of this, the present invention combines paste filling technology with supercritical carbon dioxide mineralization and storage, and proposes a supercritical carbon dioxide mineralization and storage method based on paste filling technology to achieve large-scale mineralization and storage of CO2 in mines. Summary of the invention

[0007] The purpose of the present invention is to provide a supercritical carbon dioxide mineralization and storage method based on paste filling technology in view of the above situation. This method is not only beneficial to improving the mechanical properties of the filling body and improving its pore structure, but also significantly improves the mineralization efficiency. It is of great significance for realizing green mining of metal mines and large-scale mineralization and storage of CO2 in mines.

[0008] The specific scheme of the present invention is: a supercritical carbon dioxide mineralization storage method based on paste filling technology, comprising the following steps: S1. Preparation of paste filling material: the paste filling material is made by a paste filling material preparation device, which is composed of a deep cone thickener, a flocculant adding device, a cement silo, a micro powder scale and a screw conveyor. The whole tailings from the concentrator are pumped to the deep cone thickener, and then a proper proportion of flocculants are added through the flocculant adding device to accelerate the sedimentation of the tailings. When the underflow mass fraction reaches the design requirement, it is transported to the mixing tank; at the same time, the cement silo is measured by the micro powder scale and then transported to the mixing tank by the screw conveyor; S2. Preparation of supercritical carbon dioxide: Supercritical carbon dioxide is produced by a supercritical carbon dioxide preparation device, which is composed of a CO2 gas tank, a gas booster pump, a heating device, a supercritical carbon dioxide gas tank and corresponding high-pressure pipelines. The CO2 inlet valve is opened, and the CO2 gas source is injected from the CO2 gas tank into the gas booster pump, wherein the CO2 gas flow rate is controlled by a CO2 flow controller; the CO2 gas is pressurized by the gas booster pump and then transported to the heating device to prepare the gaseous CO2 into a supercritical state, i.e., the temperature is higher than 31.1°C and the pressure is higher than 7.38MPa, and is stored in the supercritical carbon dioxide gas tank for subsequent mineralization and sealing; S3. Mineralization storage: To achieve large-scale mineralization storage of CO2 in mines, the mineralization storage steps include the mineralization filling slurry preparation process and the carbon injection mineralization process; Preparation process of mineralized filling slurry: open the water inlet valve to inject water into the stirring tank, and at the same time open the gas flow control valve a on the supercritical carbon dioxide gas storage tank to inject the supercritical carbon dioxide into the stirring tank, fully stir and mineralize with the thickened whole tailings and cementitious materials to prepare the mineralized filling slurry; Carbon injection mineralization process: After the mineralized filling slurry is prepared, open the gas flow control valve b on the supercritical carbon dioxide gas storage tank, continue to inject the supercritical carbon dioxide for mineralization, and transport the mineralized filling slurry and the supercritical carbon dioxide together to the underground goaf by gravity transportation or plunger pumping.

[0009] Furthermore, the stirring tank in the present invention is sealed by a sealing cover plate and is provided with a pressure safety valve to ensure that no accidents occur during the supercritical carbon dioxide mineralization process due to excessive pressure.

[0010] Furthermore, the tops of the CO2 gas storage tank in step S2 and the supercritical carbon dioxide gas storage tank are both sealed with a sealing cover plate.

[0011] Furthermore, in the step S2 of the present invention, the outer wall of the high-pressure pipeline is wrapped with a layer of rubber-plastic insulation material to perform insulation treatment on the pipeline.

[0012] Furthermore, in the step S3 of the present invention, the slurry undergoes a mineralization reaction with the supercritical carbon dioxide to generate the mineralized filling slurry: CaO+H2O→Ca(OH)2(aq), Ca(OH)2(aq) + CO2→CaCO3+ H2O.

[0013] Furthermore, the injection amount of the supercritical carbon dioxide in the mineralization and storage process of the present invention is determined by the content and amount of CaO in the whole tailings and cementitious materials.

[0014] Furthermore, after the mineralization and filling process in the present invention is completed, the CO2 intake valve is closed, the air intake valve is opened, and after pressurization by the gas booster pump, the high-pressure gas is used to push clean water to clean the filling pipeline.

[0015] Compared with the prior art, the present invention has achieved the following beneficial technical effects: 1. The present invention provides a supercritical carbon dioxide mineralization and storage method based on paste filling technology, which combines paste filling technology with supercritical carbon dioxide mineralization and storage, so that mine solid waste containing a large amount of calcium and magnesium resources is fully mineralized with supercritical carbon dioxide, and prepared into mineralized filling slurry, which is filled into underground goaf, which is not only beneficial to improving the mechanical properties of the filling body and improving its pore structure, but also conforms to the concept of "treating waste with waste" in mines, and realizes green mining of metal mines.

[0016] 2. Compared with the current method of injecting gas CO2 for mineralization and storage in mines, supercritical carbon dioxide has the characteristics of high solubility and strong diffusion capacity, which reduces the mineralization reaction time and slows down the CO2 escape rate, significantly improving the mineralization efficiency; after the mineralization filling slurry is prepared, supercritical carbon dioxide is injected again and filled into the underground goaf together with the mineralization filling slurry to make the mineralization reaction more complete; this method has a large CO2 mineralization storage capacity and can realize large-scale mineralization and storage of CO2 in mines.

[0017] 3. After the mineralization and filling process is completed, a gas booster pump is used to prepare high-pressure gas to push clean water to clean the filling pipe, which can reduce the use of clean water and prevent excessive water in the filling operation area. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall device process of the present invention.

[0019] In the figure: A-paste filling material preparation, B-supercritical carbon dioxide preparation, C-mineralization and sealing, 1-deep cone thickener, 2-flocculant adding device, 3-cement silo, 4-micro powder scale, 5-screw conveyor, 6-mixing tank, 7-CO2 gas storage tank, 8-gas booster pump, 9-heating device, 10-supercritical carbon dioxide gas storage tank, 11-CO2 air intake valve, 12-air air intake valve, 13-CO2 flow controller, 14-water inlet valve, 15-gas flow control valve a, 16-gas flow control valve b, 17-sealing cover plate, 18-pressure safety valve, 19-plunger pump. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. It is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention. In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the invented product is usually placed when used, which are only for the convenience of describing the present invention or simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] See also Figure 1 The present invention is a supercritical carbon dioxide mineralization storage method based on paste filling technology, which comprises paste filling material preparation A, supercritical carbon dioxide preparation B and mineralization storage C, and specifically includes the following steps: S1. Preparation of paste filling material: the paste filling material is made by a paste filling material preparation device, which consists of a deep cone thickener 1, a flocculant adding device 2, a cement silo 3, a micro powder scale 4 and a screw conveyor 5. After the whole tailings from the concentrator are pumped to the deep cone thickener, a proper proportion of flocculants are added through the flocculant adding device to accelerate the sedimentation of the tailings. When the underflow mass fraction reaches the design requirement, it is transported to the mixing tank 6; at the same time, the cement silo is measured by the micro powder scale and then transported to the mixing tank by the screw conveyor; S2. Preparation of supercritical carbon dioxide: Supercritical carbon dioxide is produced by a supercritical carbon dioxide preparation device, which is composed of a CO2 gas tank 7, a gas booster pump 8, a heating device 9, a supercritical carbon dioxide gas tank 10 and corresponding high-pressure pipelines. The CO2 inlet valve 11 is opened, and the CO2 gas source is injected from the CO2 gas tank into the gas booster pump, wherein the CO2 gas flow rate is controlled by a CO2 flow controller 13; the CO2 gas is pressurized by the gas booster pump and then transported to the heating device to prepare the gaseous CO2 into a supercritical state, i.e., the temperature is higher than 31.1°C and the pressure is higher than 7.38MPa, and is stored in the supercritical carbon dioxide gas tank for subsequent mineralization and sealing; S3. Mineralization storage: To achieve large-scale mineralization storage of CO2 in mines, the mineralization storage steps include the mineralization filling slurry preparation process and the carbon injection mineralization process; Preparation process of mineralized filling slurry: open the water inlet valve 14 to inject water into the stirring tank, and at the same time open the gas flow control valve a15 on the supercritical carbon dioxide gas storage tank to inject the supercritical carbon dioxide into the stirring tank, fully mix and mineralize with the thickened whole tailings and cementitious materials to prepare the mineralized filling slurry; Carbon injection mineralization process: After the mineralized filling slurry is prepared, open the gas flow control valve b16 on the supercritical carbon dioxide gas storage tank, continue to inject the supercritical carbon dioxide for mineralization, and transport the mineralized filling slurry and the supercritical carbon dioxide to the underground goaf through gravity transportation or plunger pumping.

[0023] Furthermore, the stirring tank described in the present invention is sealed by a sealing cover plate and is provided with a pressure safety valve to ensure that the supercritical carbon dioxide mineralization process does not cause an accident due to excessive pressure. Furthermore, the CO2 gas storage tank in step S2 described in the present invention and the top of the supercritical carbon dioxide gas storage tank are both sealed with a sealing cover plate.

[0024] Furthermore, the outer wall of the high-pressure pipeline in step S2 described in the present invention is wrapped with a layer of rubber-plastic insulation material to insulate the pipeline. Furthermore, the slurry in step S3 described in the present invention undergoes a mineralization reaction with the supercritical carbon dioxide to generate the mineralized filling slurry: CaO+H2O→Ca(OH)2(aq), Ca(OH)2(aq) + CO2→CaCO3+ H2O. Furthermore, the injection amount of the supercritical carbon dioxide in the mineralization and sealing process of the present invention is determined by the content and amount of CaO in the whole tailings and cementitious materials. Furthermore, after the mineralization and filling process of the present invention is completed, the CO2 intake valve is closed, the air intake valve 12 is opened, and after pressurization by the gas booster pump, the high-pressure gas is used to push clean water to clean the filling pipeline.

[0025] The above method is carried out as follows during specific implementation: Step 1: Preparation of paste filling materials. The paste filling material preparation device consists of a deep cone thickener, a flocculant adding device, a cement silo, a micro powder scale, and a screw conveyor. The whole tailings from the concentrator are pumped to the deep cone thickener, and then a proper proportion of flocculants are added through the flocculant adding device to accelerate the sedimentation of the tailings. When the underflow mass fraction reaches the design requirement (usually higher than 60%), it is transported to the mixing tank; At the same time, the cement silo is measured by the micro powder scale and then transported to the mixing tank by the screw conveyor; Step 2: Preparation of supercritical carbon dioxide. The supercritical carbon dioxide preparation device consists of a CO2 gas tank, a gas booster pump, a heating device, a supercritical carbon dioxide gas tank and a corresponding high-pressure pipeline. The CO2 gas tank 7 and the top of the supercritical carbon dioxide gas tank are sealed with a sealing cover plate, and the high-pressure pipeline is wrapped with a layer of rubber and plastic insulation material to insulate the pipeline; Open the CO2 inlet valve, and inject the CO2 gas source from the CO2 gas storage tank into the gas booster pump, wherein the CO2 gas flow rate is controlled by a CO2 flow controller; After the CO2 gas is pressurized by the gas booster pump, it is transported to the bottom of the heating device and heated and output upward, so that the gaseous CO2 is prepared into a supercritical state (temperature higher than 31.1°C, pressure higher than 7.38MPa), and stored in the supercritical carbon dioxide gas storage tank for subsequent mineralization and sealing use; Step 3: Open the water inlet valve to inject water into the stirring tank, and at the same time open the gas flow control valve a to inject the supercritical carbon dioxide into the stirring tank, fully stir and mineralize with the concentrated whole tailings and cementitious materials, and prepare the mineralized filling slurry, wherein all materials should be strictly quantitatively controlled, and the material level of the stirring tank should exceed 1 / 2 of the stirring blade; The slurry undergoes a mineralization reaction with the supercritical carbon dioxide: CaO+H2O→Ca(OH)2(aq), Ca(OH)2(aq)+ CO2→CaCO3+ H2O. The amount of supercritical carbon dioxide injected during the mineralization and storage process is determined by the content of CaO in the whole tailings and cementitious materials and their dosage. The stirring tank is sealed by the sealing cover plate and is provided with a pressure safety valve. When the pressure in the stirring tank exceeds a specified value, the pressure safety valve automatically opens to discharge a portion of the gas, thereby ensuring that the stirring tank does not cause an accident due to excessive pressure; Step 4: After the mineralized filling slurry is prepared, open the gas flow control valve b, continue to inject the supercritical carbon dioxide for mineralization, and transport the mineralized filling slurry and the supercritical carbon dioxide to the underground goaf by gravity transportation or plunger pump 19. The pipeline transportation flow rate should be controlled at 1m / s to 2m / s, and the inner diameter of the filling pipeline should be controlled at 100mm to 200mm; Step 5: After the mineralization and filling process is completed, the CO2 intake valve is closed, and the air intake valve 12 is opened. After the gas booster pump is pressurized, the high-pressure gas is used to push clean water to clean the filling pipeline.

[0026] The present invention provides a supercritical carbon dioxide mineralization and storage method based on paste filling technology, which combines paste filling technology with supercritical carbon dioxide mineralization and storage, so that the solid waste of mines with a large amount of calcium and magnesium resources is fully mineralized with supercritical carbon dioxide, and prepared into mineralized filling slurry, which is filled into the underground goaf, which is not only conducive to improving the mechanical properties of the filling body and improving its pore structure, but also conforms to the concept of "waste treatment with waste" in mines, and realizes green mining of metal mines. Compared with the current mine gas CO2 mineralization and storage method, supercritical carbon dioxide has the characteristics of large solubility and strong diffusion capacity, which reduces its mineralization reaction time and slows down the CO2 escape rate, significantly improving the mineralization efficiency; after the preparation of the mineralized filling slurry is completed, supercritical carbon dioxide is continuously injected, and it is filled into the underground goaf together with the mineralized filling slurry to make the mineralization reaction more sufficient; this method has a large CO2 mineralization and storage capacity, and can realize large-scale mineralization and storage of CO2 in mines. After the mineralization and filling process is completed, a gas booster pump is used to prepare high-pressure gas to push clean water to clean the filling pipe, which can reduce the use of clean water and prevent excessive water in the filling operation area.

[0027] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A supercritical carbon dioxide mineralization storage method based on paste filling technology, characterized in that: The following steps are included: S1. Preparation of paste filling material: the paste filling material is made by a paste filling material preparation device, which is composed of a deep cone thickener, a flocculant adding device, a cement silo, a micro powder scale and a screw conveyor. The whole tailings from the concentrator are pumped to the deep cone thickener, and then a proper proportion of flocculants are added through the flocculant adding device to accelerate the sedimentation of the tailings. When the underflow mass fraction reaches the design requirement, it is transported to the mixing tank; at the same time, the cement silo is measured by the micro powder scale and then transported to the mixing tank by the screw conveyor; S2. Preparation of supercritical carbon dioxide: Supercritical carbon dioxide is produced by a supercritical carbon dioxide preparation device, which is composed of a CO2 gas tank, a gas booster pump, a heating device, a supercritical carbon dioxide gas tank and corresponding high-pressure pipelines. The CO2 inlet valve is opened, and the CO2 gas source is injected from the CO2 gas tank into the gas booster pump, wherein the CO2 gas flow rate is controlled by a CO2 flow controller; the CO2 gas is pressurized by the gas booster pump and then transported to the heating device to prepare the gaseous CO2 into a supercritical state, i.e., the temperature is higher than 31.1°C and the pressure is higher than 7.38MPa, and is stored in the supercritical carbon dioxide gas tank for subsequent mineralization and sealing; S3. Mineralization storage: To achieve large-scale mineralization storage of CO2 in mines, the mineralization storage steps include the mineralization filling slurry preparation process and the carbon injection mineralization process; in Preparation process of mineralized filling slurry: open the water inlet valve to inject water into the stirring tank, and at the same time open the gas flow control valve a on the supercritical carbon dioxide gas storage tank to inject the supercritical carbon dioxide into the stirring tank, fully stir and mineralize with the thickened whole tailings and cementitious materials to prepare the mineralized filling slurry; Carbon injection mineralization process: After the mineralized filling slurry is prepared, open the gas flow control valve b on the supercritical carbon dioxide gas storage tank, continue to inject the supercritical carbon dioxide for mineralization, and transport the mineralized filling slurry and the supercritical carbon dioxide together to the underground goaf by gravity transportation or plunger pumping.

2. The supercritical carbon dioxide mineralization storage method based on paste filling technology according to claim 1 is characterized in that: The stirring tank is sealed by a sealing cover plate and is provided with a pressure safety valve to ensure that no accidents occur during the supercritical carbon dioxide mineralization process due to excessive pressure.

3. The supercritical carbon dioxide mineralization storage method based on paste filling technology according to claim 1 is characterized in that: The tops of the CO2 gas storage tank in step S2 and the supercritical carbon dioxide gas storage tank are both sealed with a sealing cover plate.

4. The supercritical carbon dioxide mineralization storage method based on paste filling technology according to claim 1 is characterized in that: In step S2, the outer wall of the high-pressure pipeline is wrapped with a layer of rubber-plastic insulation material to insulate the pipeline.

5. The supercritical carbon dioxide mineralization storage method based on paste filling technology according to claim 1 is characterized in that: In step S3, the slurry undergoes a mineralization reaction with the supercritical carbon dioxide to generate the mineralized filling slurry: CaO+H2O→Ca(OH)2(aq), Ca(OH)2(aq) + CO2→CaCO3 + H2O.

6. The supercritical carbon dioxide mineralization storage method based on paste filling technology according to claim 1 is characterized in that: The injection amount of the supercritical carbon dioxide during the mineralization storage process is determined by the content and amount of CaO in the whole tailings and cementitious materials.

7. The supercritical carbon dioxide mineralization storage method based on paste filling technology according to claim 1 is characterized in that: After the mineralization and filling process is completed, the CO2 intake valve is closed, the air intake valve is opened, and after the gas booster pump is pressurized, the high-pressure gas is used to push clean water to clean the filling pipeline.

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