A method for improving ore carbonation efficiency

Abstract

The present invention relates to a method for improving the efficiency of ore carbonation. The method for improving the efficiency of ore carbonation comprises the following steps: mixing ore and a grinding aid and ball milling to obtain ore powder; adding sodium bicarbonate solution and EDTA solution to a sodium salt solution to obtain a mixed solution, adding ore powder to the mixed solution to obtain a solid-liquid mixture; cooling the solid-liquid mixture to a temperature less than or equal to a first preset temperature, then introducing carbon dioxide (pre-liquefied), and then step-by-step heating with a second preset temperature as a gradient until the temperature reaches a third preset temperature, and then starting a stirring reaction at a preset stirring rate for at least a preset time to obtain carbonated ore, so as to achieve carbonation of the ore. The present invention solves the problem of low mineral carbonation rate and efficiency in the existing intermittent reaction method, and also solves the problem of slow and uncontrollable pressure increase in the existing intermittent reaction method.

Description

Technical Field

[0001] The invention relates to the technical field of ore carbonation, and in particular to a method for improving ore carbonation efficiency. Background Art

[0002] Global warming will lead to the melting of polar ice caps and permafrost, which will in turn lead to a series of consequences such as rising sea levels. The root cause of this phenomenon is the continuous increase in industrial CO2 concentration in the atmosphere. Carbon capture and storage technology is particularly important.

[0003] Injecting CO2 into underground reservoirs in sedimentary basins is a common method for physical capture of carbon. Although effective, it has many limitations, such as the lack of silicate-bound divalent metal ions, limited storage media, and the easy migration of CO2 back to the surface. Therefore, the in-situ mineral carbonation method has gradually gained attention. This method injects captured carbon into reactive rocks such as mafic or ultramafic rocks, prompting the reactive ions to quickly convert into carbonate minerals such as calcite, dolomite, and magnesite, thereby accelerating the carbon sequestration process.

[0004] Laboratory-scale carbonation research focuses on the kinetic mechanism of mineral carbon fixation reactions, reaction path simulation, and characterization of physical parameters, providing a solid theoretical basis for field carbon sequestration projects. However, the current mainstream carbonation methods still face technical bottlenecks, such as limitations in experimental environment simulation, reaction condition setting, and product collection, making it difficult to quickly achieve mineral carbonation.

[0005] Existing mineral carbonation methods can be roughly divided into two categories: one is a continuous flow steady-state reaction carried out in a large-scale water-rock reaction simulation system, and the other is an intermittent reaction achieved using a small high-temperature and high-pressure reactor.

[0006] Large-scale water-rock reaction simulation systems usually rely on external HPLC pumps to inject fluids and gases and maintain constant pressure. Such reactors are mostly tubular in design and lack stirring devices, and their dynamic water-rock reaction parameters are controlled online by software. Thanks to the constant speed and constant pressure pump device, this method can ensure that the reaction is carried out according to the preset feeding and discharging rates, which is convenient for maintaining material concentration and improving equipment utilization. This method is often used to study traditional basic rock samples such as basalt cores, because their reaction cycle is long and materials need to be continuously replenished to maintain steady state. However, given the complexity of the gas-liquid pipelines of large-scale reaction equipment, it is particularly difficult to simulate the reaction environment of a specific gas partial pressure under the condition of continuous fluid injection. Therefore, it is difficult to simulate the gas conditions for rapid carbonation of minerals.

[0007] Small high-temperature and high-pressure intermittent reaction equipment is directly connected to a gas cylinder with a pressure reducing valve, and does not require HPLC or ISCO gas-liquid pumps for fluid transportation. The reaction materials only need to be put in once to meet the needs of intermittent reactions. This type of reactor is mostly a kettle design, usually first raised to the target temperature, and then the gas is introduced for reaction. It is flexible in operation, and the in-situ measurement technology for parameters such as temperature, pressure, and pH is becoming increasingly mature, which is convenient for regular sampling and testing, and is more suitable for studying the reaction mechanism of the main mineral components of basic rocks and ultrabasic rocks such as olivine powder. It has a short reaction cycle and does not require regular replenishment of materials, which is more suitable for laboratories to carry out carbonation reaction-related research.

[0008] However, the implementation of rapid carbonation reactions in small batch reactors also faces many technical challenges. For mineral powder samples, if the carbonation efficiency is insufficient, as the reaction deepens, the system will deviate from the initial water-rock ratio and fluid concentration. Therefore, the intermittent reaction method is difficult to ensure a fast and efficient level of mineral carbonation reaction, and will affect the initial solid-liquid ratio and steady-state conditions of the reaction. In addition, the intermittent reactor itself has the characteristics of slow and uncontrollable pressure increase, and the design pressure is limited (usually not more than 22MPa). It is difficult to increase the partial pressure to above the half-range value (such as 10MPa) and safety issues need to be considered. Furthermore, in order to study the intermediate product phase of the high-speed reaction, sampling is required in a closed system, which places higher requirements on the strategic design of the carbonation reaction. Summary of the invention

[0009] In view of this, the purpose of the present invention is to provide a method for improving the efficiency of ore carbonation, so as to solve the problems of low mineral carbonation rate and efficiency in the existing intermittent reaction method, and also solve the problem of slow and uncontrollable pressure increase in the existing intermittent reaction method.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] A method for improving ore carbonation efficiency comprises the following steps:

[0012] S1, mixing ore and grinding aid and ball milling to obtain ore powder;

[0013] S2, adding a buffering agent and a ligand solution to a sodium salt solution to obtain a mixed solution, and adding ore powder to the mixed solution to obtain a solid-liquid mixture;

[0014] S3, cooling the solid-liquid mixture to a temperature less than or equal to a first preset temperature, then introducing carbon dioxide, and then step-by-step increasing the temperature with a second preset temperature as a gradient until the temperature reaches a third preset temperature, and then starting stirring the reaction at a preset stirring rate for at least a preset time to obtain carbonated ore, so as to achieve carbonation of the ore.

[0015] According to the above technical means, the ore is ball-milled by using a grinding aid, which effectively promotes the formation of smaller, more uniform, and rounder ore powder; by adding a buffering aid and a ligand solution to the sodium salt solution, while promoting the carbonation of the ore, the dissolution and enrichment of valuable metals in the ore are improved; by first cooling the solid-liquid mixture and then introducing carbon dioxide, and then gradually and slowly heating it up in a step-by-step manner, the introduced carbon dioxide is rapidly liquefied under low temperature conditions and then evaporates by absorbing heat, thereby obtaining a higher gas partial pressure. The two work synergistically to effectively ensure a stable gas partial pressure, thereby improving the mineral carbonation rate and efficiency, solving the problems of low mineral carbonation rate and efficiency in the existing intermittent reaction method, and also solving the problem of slow and uncontrollable pressure increase in the existing intermittent reaction method.

[0016] The carbon dioxide introduced into S3 is pre-liquefied carbon dioxide.

[0017] Preferably, the buffer aid is selected from at least one of sodium bicarbonate solution, boric acid and Tris buffer.

[0018] Preferably, the ligand solution is selected from one or two of an EDTA solution and a disodium ethylenediaminetetraacetate (NTA) solution.

[0019] Preferably, the buffer aid is selected from sodium bicarbonate solution; and the ligand solution is selected from EDTA solution.

[0020] Among them, by adding NaHCO3 solution to the solid-liquid mixture, NaHCO3 plays a buffering and complexing effect in the solution and effectively inhibits the formation of the oxidation phase. EDTA solution is used as a ligand to selectively extract Ni and Co elements, realizing resource recycling.

[0021] Preferably, the ore is olivine.

[0022] Preferably, the maximum particle size of the ore powder is 25 μm.

[0023] Preferably, the grinding aid is selected from one or both of anhydrous ethanol and acetone.

[0024] Preferably, the grinding balls used in the ball mill include grinding balls with diameters of 3 mm, 5 mm and 10 mm;

[0025] The number ratio of the grinding balls with a diameter of 3 mm, the grinding balls with a diameter of 5 mm, and the grinding balls with a diameter of 10 mm is 0.8-1.2:0.8-1.2:0.8-1.2.

[0026] Preferably, the number ratio of the grinding balls with a diameter of 3 mm, the grinding balls with a diameter of 5 mm, and the grinding balls with a diameter of 10 mm is 1:1:1.

[0027] Preferably, the ball milling method is ball milling for 10 minutes, with a break of 5 minutes, and the total ball milling time is 8 hours.

[0028] Preferably, the ball milling uses a planetary ball mill to wet grind the ore.

[0029] Preferably, the sodium salt solution is selected from sodium chloride solution.

[0030] Preferably, the concentration of sodium salt in the sodium salt solution is 1 mol / L.

[0031] Preferably, the concentration of sodium bicarbonate in the sodium bicarbonate solution is 1 mol / L.

[0032] Preferably, the concentration of the ligand in the ligand solution is 0.1 mol / L.

[0033] Preferably, the concentration of EDTA in the EDTA solution is 0.1 mol / L. The concentration of disodium ethylenediaminetetraacetate (NTA) in the NTA solution is 0.1 mol / L.

[0034] Preferably, the mass ratio of the mixed solution to the ore is 8-12:1.

[0035] Preferably, the mass ratio of the mixed solution to the ore is 10:1.

[0036] Preferably, the first preset temperature is 3-8°C.

[0037] Preferably, the first preset temperature is 5°C.

[0038] Preferably, the second preset temperature is 15-25°C.

[0039] By precisely controlling the second preset temperature, the problem of excessive furnace temperature due to a one-time heating operation, which results in the inability to obtain a higher saturated evaporation pressure due to rapid vaporization of liquefied CO2, is effectively avoided.

[0040] Preferably, the second preset temperature is 20°C.

[0041] Preferably, the third preset temperature is 170-200°C.

[0042] Preferably, the third preset temperature is 185°C.

[0043] Preferably, the preset stirring rate is 500 rpm to 1000 rpm.

[0044] Preferably, the preset stirring rate is 500 rpm.

[0045] Experimental verification shows that this stirring rate range is most conducive to heat and mass transfer, and can also eliminate the SiO2 passivation layer formed during the reaction, avoiding the diffusion control mechanism that hinders the carbonation reaction rate.

[0046] Preferably, the preset time is 6 to 10 hours.

[0047] Preferably, the preset time is 8 hours.

[0048] Beneficial effects of the present invention:

[0049] The method for improving the efficiency of ore carbonation of the present invention ball-mills the ore with a grinding aid, thereby effectively promoting the formation of smaller, more uniform and more round ore powder; by adding a buffering aid and a ligand solution to a sodium salt solution, while promoting the carbonation of the ore, the dissolution and enrichment of valuable metals in the ore are improved; by first cooling the solid-liquid mixture and then introducing carbon dioxide, and then gradually and slowly heating it in a step-by-step heating manner, the introduced carbon dioxide is rapidly liquefied under low temperature conditions and then evaporates by absorbing heat, thereby obtaining a higher gas partial pressure, and the two act synergistically to effectively ensure a stable gas partial pressure, thereby improving the rate and efficiency of mineral carbonation, solving the problem of low mineral carbonation rate and efficiency in the existing intermittent reaction method, and solving the problem of slow and uncontrollable pressure increase in the existing intermittent reaction method, and having promotion and application value in the field of ore carbonation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A flow chart of a method for improving the efficiency of ore carbonation;

[0051] Figure 2 This is a comparison chart of the particle sizes of powder particles obtained after wet grinding and dry grinding of olivine;

[0052] Figure 3 This is the result of measuring the pH value of the supernatant;

[0053] Figure 4 The XRD patterns of the solid and the lower precipitate in Examples 1 to 3 and Comparative Example 3;

[0054] Figure 5 The XRD diagrams of the solid and the lower precipitate in Example 1 and Comparative Example 1 and Comparative Example 2;

[0055] Figure 6 This is the result graph of carbonation efficiency. DETAILED DESCRIPTION

[0056] The following will describe the embodiments of the present invention with reference to the preferred embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0057] The present invention intends to disclose a method for improving the efficiency of ore carbonation to solve the problems of low mineral carbonation rate and efficiency in the existing intermittent reaction method, and can also solve the problem of slow and uncontrollable pressure increase in the existing intermittent reaction method.

[0058] Among them, Figure 1 As shown, a method for improving the carbonation efficiency of ore comprises the following steps:

[0059] S1, mixing ore and grinding aid and ball milling to obtain ore powder;

[0060] S2, adding a buffering agent and a ligand solution to a sodium salt solution to obtain a mixed solution, and adding ore powder to the mixed solution to obtain a solid-liquid mixture;

[0061] S3, cooling the solid-liquid mixture to a temperature less than or equal to a first preset temperature, then introducing carbon dioxide (pre-liquefied), and then step-by-step increasing the temperature with a second preset temperature as a gradient until the temperature reaches a third preset temperature, and then starting stirring the reaction at a preset stirring rate for at least a preset time to obtain carbonated ore, so as to achieve carbonation of the ore.

[0062] The above method uses a grinding aid to ball-mill the ore, which effectively promotes the formation of smaller, more uniform, and more round ore powder; adds a buffering aid and a ligand solution to the sodium salt solution, while promoting the carbonation of the ore, the dissolution and enrichment of valuable metals in the ore are improved; the solid-liquid mixture is first cooled and then pre-liquefied carbon dioxide is introduced, and then the temperature is gradually and slowly increased by a step-by-step heating method, so that the introduced carbon dioxide is rapidly liquefied under low temperature conditions and then evaporates by absorbing heat, thereby obtaining a higher gas partial pressure. The two act synergistically to effectively ensure a stable gas partial pressure, thereby improving the mineral carbonation rate and efficiency, solving the problem of low mineral carbonation rate and efficiency in the existing intermittent reaction method, and solving the problem of slow and uncontrollable pressure increase in the existing intermittent reaction method.

[0063] In some embodiments, the buffer aid is selected from at least one of sodium bicarbonate solution, boric acid, and Tris buffer.

[0064] In some embodiments, the ligand solution is selected from one or both of an EDTA solution and a disodium ethylenediaminetetraacetate (NTA) solution.

[0065] Exemplarily, the buffer aid is selected from sodium bicarbonate solution; and the ligand solution is selected from EDTA solution.

[0066] Among them, by adding NaHCO3 solution to the solid-liquid mixture, NaHCO3 plays a buffering and complexing effect in the solution and effectively inhibits the formation of the oxidation phase. EDTA solution is used as a ligand to selectively extract Ni and Co elements, realizing resource recycling.

[0067] In some embodiments, the mineral is olivine.

[0068] In some embodiments, the maximum particle size of the ore powder is 25 μm.

[0069] In some embodiments, the grinding aid is selected from one or both of anhydrous ethanol and acetone.

[0070] In some embodiments, the grinding balls used in ball milling include grinding balls with diameters of 3 mm, 5 mm, and 10 mm;

[0071] The number ratio of the grinding balls with a diameter of 3 mm, the grinding balls with a diameter of 5 mm, and the grinding balls with a diameter of 10 mm is 0.8~1.2:0.8~1.2:0.8~1.2.

[0072] Exemplarily, the number ratio of the grinding balls with a diameter of 3 mm, the grinding balls with a diameter of 5 mm, and the grinding balls with a diameter of 10 mm is 1:1:1.

[0073] In some embodiments, the ball milling method is ball milling for 10 minutes, with a rest period of 5 minutes, and the total ball milling time is 8 hours.

[0074] In some embodiments, ball milling uses a planetary ball mill to wet grind the ore.

[0075] Exemplarily, a planetary ball mill is used to wet-grind olivine with a grinding aid to 25 μm for carbonation reaction, which effectively ensures rapid carbonation efficiency.

[0076] In some embodiments, the sodium salt solution is selected from sodium chloride solution.

[0077] In some embodiments, the concentration of the sodium salt in the sodium salt solution is 1 mol / L.

[0078] In some embodiments, the concentration of sodium bicarbonate in the sodium bicarbonate solution is 1 mol / L.

[0079] In some embodiments, the concentration of the ligand in the ligand solution is 0.1 mol / L.

[0080] For example, the concentration of EDTA in the EDTA solution is 0.1 mol / L. The concentration of disodium ethylenediaminetetraacetate (NTA) in the NTA solution is 0.1 mol / L.

[0081] In some embodiments, the mass ratio of the mixed solution to the ore is 8-12:1.

[0082] Exemplarily, the mass ratio of the mixed solution to the ore is 10:1.

[0083] In some embodiments, the first preset temperature is 3-8°C.

[0084] Exemplarily, the first preset temperature is 5°C.

[0085] In some embodiments, the second preset temperature is 15-25°C.

[0086] Exemplarily, the second preset temperature is 20°C.

[0087] In some embodiments, the third preset temperature is 170-200°C.

[0088] Exemplarily, the third preset temperature is 185°C.

[0089] In some embodiments, the preset stirring rate is 500 rpm to 1000 rpm.

[0090] Exemplarily, the preset stirring rate is 500 rpm.

[0091] Experimental verification has shown that this rate range is most conducive to heat and mass transfer, and can also eliminate the SiO2 passivation layer formed during the reaction, avoiding the diffusion control mechanism that hinders the carbonation reaction rate.

[0092] In some embodiments, the preset time is 6 to 10 hours.

[0093] Exemplarily, the preset time is 8 hours.

[0094] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the method for improving the efficiency of ore carbonation of the present invention will be further described in detail below in conjunction with specific embodiments and drawings. Obviously, the specific embodiments described are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually merely illustrative and is by no means intended to limit the present application and its applications. Based on the specific embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0095] If no specific techniques or conditions are specified in the specific embodiments, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0096] Example 1

[0097] like Figure 1 As shown, a method for improving the carbonation efficiency of ore comprises the following steps:

[0098] S1. Use a Focucy planetary ball mill to ball-mill the carefully sorted olivine particles. The grinding jar and balls are made of tungsten carbide. Add 20g of olivine fine particles and 160g of grinding balls in each ball mill. The number ratio of grinding balls with diameters of 3mm, 5mm and 10mm is 1:1:1. Use anhydrous ethanol as a grinding aid to promote the formation of smaller, more uniform and rounder powders. The grinding cycle is 10min with an interval of 5min, and the total time is 8h. After grinding, dry to remove the grinding aid to obtain olivine powder with a maximum particle size of 25μm.

[0099] S2, adding a 1 mol / L sodium bicarbonate solution as an auxiliary agent to a 1 mol / L sodium chloride (NaCl) solution, and adding a 0.1 mol / L EDTA solution to obtain a mixed solution, and transferring the mixed solution to a stainless steel reactor, wherein ultrasonic oscillation is required before transferring the mixed solution to the stainless steel reactor to prevent the solubility of the solid at room temperature from being too low and causing a pipetting error; then adding the 25 μm olivine powder in S1 to the stainless steel reactor to obtain a solid-liquid mixture, wherein the water-rock mass ratio in the solid-liquid mixture is 10:1, and the solid-liquid mixture is pre-stirred with a glass rod;

[0100] S3, put the reactor containing the solid-liquid mixture in S2 into a condensing device and cool it down to 1°C, cover the reactor to ensure airtightness, and then connect the pre-liquefied CO2 gas cylinder to the pressure reducing valve to ventilate the reactor for 3 minutes to obtain an initial gas partial pressure of 6MPa; because the pressure of the gas cylinder itself is relatively high, if the pressure reducing valve is not connected, there is a risk of exceeding the alarm pressure of the reactor. Since the temperature of the reactor is relatively low, the carbon dioxide introduced into the reactor is in a supercritical state under the conditions of a pressure of 6MPa and a temperature of less than 5°C and can be rapidly liquefied. The liquefied CO2 can obtain a higher gas partial pressure accompanied by an endothermic evaporation process; then start heating, and use a step temperature control strategy with a gradient of 20°C. Control the actual reactor body temperature to increase by 20°C before operating the control panel to start the next stage of heating, so as to prevent the furnace temperature from being too high due to a one-time heating operation, resulting in the rapid vaporization of liquefied CO2 and the inability to obtain a higher saturated evaporation pressure; until the temperature rises to 185°C and the gas partial pressure reaches a steady-state reaction condition of 14MPa;

[0101] S4. After heating to 185°C, stir at a rate of 500 rpm. After every 1h of reaction, collect the fluid from the discharge valve without stopping stirring to obtain a suspension containing solid products. Collect 8 times in total. After standing and stratifying, measure the pH value of the supernatant and simulate the in-situ value with PHREEQC. After 48h of reaction, collect the remaining solids in the reactor and put them into a 70°C oven for drying to obtain carbonated ore to achieve carbonation of the ore.

[0102] Example 2

[0103] like Figure 1 As shown, a method for improving the carbonation efficiency of ore comprises the following steps:

[0104] S1. Use a Focucy planetary ball mill to ball-mill the carefully sorted olivine particles. The grinding jar and balls are made of tungsten carbide. Add 20g of olivine fine particles and 160g of grinding balls in each ball mill. The number ratio of grinding balls with diameters of 3mm, 5mm and 10mm is 1:1:1. Use anhydrous ethanol as a grinding aid to promote the formation of smaller, more uniform and rounder powders. The grinding cycle is 10min with an interval of 5min, and the total time is 8h. After grinding, dry to remove the grinding aid to obtain olivine powder with a maximum particle size of 25μm.

[0105] S2, adding a 1 mol / L sodium bicarbonate solution as an auxiliary agent to a 1 mol / L sodium chloride (NaCl) solution, and adding a 0.1 mol / L EDTA solution to obtain a mixed solution, and transferring the mixed solution to a stainless steel reactor, wherein ultrasonic oscillation is required before transferring the mixed solution to the stainless steel reactor to prevent the solubility of the solid at room temperature from being too low and causing a pipetting error; then adding the 25 μm olivine powder in S1 to the stainless steel reactor to obtain a solid-liquid mixture, wherein the water-rock mass ratio in the solid-liquid mixture is 10:1, and the solid-liquid mixture is pre-stirred with a glass rod;

[0106] S3, put the reactor containing the solid-liquid mixture in S2 into a condensing device and cool it down to 1°C, cover the reactor to ensure airtightness, and then connect the pre-liquefied CO2 cylinder to the pressure reducing valve to ventilate the reactor for 3 minutes to obtain an initial gas partial pressure of 5MPa; because the pressure of the cylinder itself is relatively high, if the pressure reducing valve is not connected, there is a risk of exceeding the alarm pressure of the reactor. Due to the low temperature of the reactor, the carbon dioxide introduced into the reactor is in a supercritical state under the conditions of a pressure of 5MPa and a temperature of less than 5°C and can be rapidly liquefied. The liquefied CO2 can obtain a higher gas partial pressure accompanied by an endothermic evaporation process; then start heating, and use a step temperature control strategy with a gradient of 20°C. Control the actual reactor body temperature to increase by 20°C before operating the control panel to start the next stage of heating, so as to prevent the furnace temperature from being too high due to a one-time heating operation, resulting in the rapid vaporization of liquefied CO2 and the inability to obtain a higher saturated evaporation pressure; until the temperature rises to 185°C and the gas partial pressure reaches a steady-state reaction condition of 11MPa;

[0107] S4. After heating to 185°C, stir at a rate of 500 rpm. After every 1h of reaction, collect the fluid from the discharge valve without stopping stirring to obtain a suspension containing solid products. Collect 8 times in total. After standing and stratifying, measure the pH value of the supernatant and simulate the in-situ value with PHREEQC. After 48h of reaction, collect the remaining solids in the reactor and put them into a 70°C oven for drying to obtain carbonated ore to achieve carbonation of the ore.

[0108] Example 3

[0109] like Figure 1 As shown, a method for improving the carbonation efficiency of ore comprises the following steps:

[0110] S1. Use Focucy planetary ball mill to ball mill the carefully sorted olivine particles. The grinding jar and balls are made of tungsten carbide. Add 20g of olivine fine particles and 160g of grinding balls to each ball mill. The ratio of the number of grinding balls with diameters of 3mm, 5mm and 10mm is 1:1:1. No grinding aid is used during ball milling, which can obtain powder with lower crystallinity and accelerate the reaction. The grinding cycle is 10min with an interval of 5min, and the total time is 1h. After grinding, dry to remove the grinding aid and obtain olivine powder with a maximum particle size of 50μm;

[0111] S2, adding a 1 mol / L sodium bicarbonate solution as an auxiliary agent to a 1 mol / L sodium chloride (NaCl) solution, and adding a 0.1 mol / L EDTA solution to obtain a mixed solution, and transferring the mixed solution to a stainless steel reactor, wherein ultrasonic oscillation is required before transferring the mixed solution to the stainless steel reactor to prevent the solubility of the solid at room temperature from being too low and causing a pipetting error; then adding the 50 μm olivine powder in S1 to the stainless steel reactor to obtain a solid-liquid mixture, wherein the water-rock mass ratio in the solid-liquid mixture is 10:1, and the solid-liquid mixture is pre-stirred with a glass rod;

[0112] S3, put the reactor containing the solid-liquid mixture in S2 into a condensing device and cool it down to 1°C, cover the reactor to ensure airtightness, and then connect the pre-liquefied CO2 cylinder to the pressure reducing valve to ventilate the reactor for 3 minutes to obtain an initial gas partial pressure of 6MPa; because the pressure of the cylinder itself is relatively high, if the pressure reducing valve is not connected, there is a risk of exceeding the alarm pressure of the reactor. Since the temperature of the reactor is relatively low, the carbon dioxide introduced into the reactor is in a supercritical state under the conditions of a pressure of 6MPa and a temperature of less than 5°C and can be rapidly liquefied. The liquefied CO2 can obtain a higher gas partial pressure accompanied by an endothermic evaporation process; then start heating, and use a step temperature control strategy with a gradient of 20°C. Control the actual reactor body temperature to increase by 20°C before operating the control panel to start the next stage of heating, so as to prevent the furnace temperature from being too high due to a one-time heating operation, resulting in the rapid vaporization of liquefied CO2 and the inability to obtain a higher saturated evaporation pressure; until the temperature rises to 185°C and the gas partial pressure reaches a steady-state reaction condition of 14MPa;

[0113] S4. After heating to 185°C, stir at a rate of 500 rpm. After every 1h of reaction, collect the fluid from the discharge valve without stopping stirring to obtain a suspension containing solid products. Collect 8 times in total. After standing and stratifying, measure the pH value of the supernatant and simulate the in-situ value with PHREEQC. After 48h of reaction, collect the remaining solids in the reactor and put them into a 70°C oven for drying to obtain carbonated ore to achieve carbonation of the ore.

[0114] Comparative Example 1

[0115] A method for improving the efficiency of conventional ore carbonation comprises the following steps:

[0116] S1. Use a Focucy planetary ball mill to ball-mill the carefully sorted olivine particles. The grinding jar and balls are made of tungsten carbide. Add 20g of olivine fine particles and 160g of grinding balls in each ball mill. The number ratio of grinding balls with diameters of 3mm, 5mm and 10mm is 1:1:1. Use anhydrous ethanol as a grinding aid to promote the formation of smaller, more uniform and rounder powders. The grinding cycle is 10min with an interval of 5min, and the total time is 8h. After grinding, dry to remove the grinding aid to obtain olivine powder with a maximum particle size of 25μm.

[0117] S2, add a 1 mol / L sodium bicarbonate solution as an auxiliary agent to a 1 mol / L sodium chloride (NaCl) solution, and add a 0.1 mol / L sodium citrate solution to obtain a mixed solution, and transfer the mixed solution to a stainless steel reactor, wherein ultrasonic oscillation is required before transferring the mixed solution to the stainless steel reactor to prevent the solubility of the solid at room temperature from being too low and causing a pipetting error; then add the 25 μm olivine powder in S1 to the stainless steel reactor to obtain a solid-liquid mixture, wherein the water-rock mass ratio in the solid-liquid mixture is 10:1, and the solid-liquid mixture is pre-stirred with a glass rod;

[0118] S3, put the reactor containing the solid-liquid mixture in S2 into a condensing device and cool it down to 1°C, cover the reactor to ensure airtightness, and then connect the CO2 gas cylinder to the pressure reducing valve to ventilate the reactor for 3 minutes to obtain an initial gas partial pressure of 6MPa; because the pressure of the gas cylinder itself is relatively high, if the pressure reducing valve is not connected, there is a risk of exceeding the alarm pressure of the reactor. Due to the low temperature of the reactor, the carbon dioxide introduced into the reactor is in a supercritical state under the conditions of a pressure of 6MPa and a temperature of less than 5°C and can be rapidly liquefied. The liquefied CO2 can obtain a higher gas partial pressure accompanied by an endothermic evaporation process; then start heating, and use a step temperature control strategy with a gradient of 20°C. Control the actual reactor body temperature to increase by 20°C before operating the control panel to start the next stage of heating, so as to prevent the furnace temperature from being too high due to a one-time heating operation, resulting in the rapid vaporization of liquefied CO2 and the inability to obtain a higher saturated evaporation pressure; until the temperature rises to 185°C and the gas partial pressure reaches a steady-state reaction condition of 14MPa;

[0119] S4. After heating to 185°C, stir at a rate of 500 rpm. After every 1h of reaction, collect the fluid from the discharge valve without stopping stirring to obtain a suspension containing solid products. Collect 8 times in total. After standing and stratifying, measure the pH value of the supernatant and simulate the in-situ value with PHREEQC. After 48h of reaction, collect the remaining solids in the reactor and put them into a 70°C oven for drying to obtain carbonated ore to achieve carbonation of the ore.

[0120] Comparative Example 2

[0121] A method for improving the efficiency of conventional ore carbonation comprises the following steps:

[0122] S1. Use a Focucy planetary ball mill to ball-mill the carefully sorted olivine particles. The grinding jar and balls are made of tungsten carbide. Add 20g of olivine fine particles and 160g of grinding balls in each ball mill. The number ratio of grinding balls with diameters of 3mm, 5mm and 10mm is 1:1:1. Use anhydrous ethanol as a grinding aid to promote the formation of smaller, more uniform and rounder powders. The grinding cycle is 10min with an interval of 5min, and the total time is 8h. After grinding, dry to remove the grinding aid to obtain olivine powder with a maximum particle size of 25μm.

[0123] S2, add a 1 mol / L sodium bicarbonate solution as an auxiliary agent to a 1 mol / L sodium chloride (NaCl) solution, and transfer the solution to a stainless steel reactor. Ultrasonic oscillation is required before transferring the solution to the stainless steel reactor to prevent the solubility of the solid at room temperature from being too low, resulting in a pipetting error; then add the 25 μm olivine powder in S1 to the stainless steel reactor to obtain a solid-liquid mixture, wherein the water-rock mass ratio in the solid-liquid mixture is 10:1, and the solid-liquid mixture is pre-stirred with a glass rod;

[0124] S3, put the reactor containing the solid-liquid mixture in S2 into a condensing device and cool it down to 1°C, cover the reactor to ensure airtightness, and then connect the CO2 gas cylinder to the pressure reducing valve to ventilate the reactor for 3 minutes to obtain an initial gas partial pressure of 6MPa; because the pressure of the gas cylinder itself is relatively high, if the pressure reducing valve is not connected, there is a risk of exceeding the alarm pressure of the reactor. Due to the low temperature of the reactor, the carbon dioxide introduced into the reactor is in a supercritical state under the conditions of a pressure of 6MPa and a temperature of less than 5°C and can be rapidly liquefied. The liquefied CO2 can obtain a higher gas partial pressure accompanied by an endothermic evaporation process; then start heating, and use a step temperature control strategy with a gradient of 20°C. Control the actual reactor body temperature to increase by 20°C before operating the control panel to start the next stage of heating, so as to prevent the furnace temperature from being too high due to a one-time heating operation, resulting in the rapid vaporization of liquefied CO2 and the inability to obtain a higher saturated evaporation pressure; until the temperature rises to 185°C and the gas partial pressure reaches a steady-state reaction condition of 14MPa;

[0125] S4. After heating to 185°C, stir at a rate of 500 rpm. After every 1h of reaction, collect the fluid from the discharge valve without stopping stirring to obtain a suspension containing solid products. Collect 8 times in total. After standing and stratifying, measure the pH value of the supernatant and simulate the in-situ value with PHREEQC. After 48h of reaction, collect the remaining solids in the reactor and put them into a 70°C oven for drying to obtain carbonated ore to achieve carbonation of the ore.

[0126] Comparative Example 3

[0127] A method for improving the efficiency of conventional ore carbonation comprises the following steps:

[0128] S1. Use a Focucy planetary ball mill to ball-mill the carefully sorted olivine particles. The grinding jar and balls are made of tungsten carbide. Add 20g of olivine fine particles and 160g of grinding balls in each ball mill. The number ratio of grinding balls with diameters of 3mm, 5mm and 10mm is 1:1:1. Use anhydrous ethanol as a grinding aid to promote the formation of smaller, more uniform and rounder powders. The grinding cycle is 10min with an interval of 5min, and the total time is 8h. After grinding, dry to remove the grinding aid to obtain olivine powder with a maximum particle size of 25μm.

[0129] S2, adding a 1 mol / L sodium bicarbonate solution as an auxiliary agent to a 1 mol / L sodium chloride (NaCl) solution, and adding a 0.1 mol / L EDTA solution to obtain a mixed solution, and transferring the mixed solution to a stainless steel reactor, wherein ultrasonic oscillation is required before transferring the mixed solution to the stainless steel reactor to prevent the solubility of the solid at room temperature from being too low and causing a pipetting error; then adding the 25 μm olivine powder in S1 to the stainless steel reactor to obtain a solid-liquid mixture, wherein the water-rock mass ratio in the solid-liquid mixture is 10:1, and the solid-liquid mixture is pre-stirred with a glass rod;

[0130] S3, put the reactor containing the solid-liquid mixture in S2 into a condensing device and cool it down to 1°C, cover the reactor to ensure airtightness, then connect the CO2 gas cylinder to the pressure reducing valve to ventilate the reactor for 3 minutes to obtain an initial gas partial pressure of 3MPa; then start heating to 185°C once, and the gas partial pressure reaches a steady-state reaction condition of 5MPa;

[0131] S4. After heating to 185°C, stir at a rate of 500 rpm. After every 1h of reaction, collect the fluid from the discharge valve without stopping stirring to obtain a suspension containing solid products. Collect 8 times in total. After standing and stratifying, measure the pH value of the supernatant and simulate the in-situ value with PHREEQC. After 48h of reaction, collect the remaining solids in the reactor and put them into a 70°C oven for drying to obtain carbonated ore to achieve carbonation of the ore.

[0132] Detection and analysis

[0133] 1) Particle size analysis

[0134] The particle size of the olivine powder obtained by wet grinding the olivine with anhydrous ethanol as a grinding aid and dry grinding the olivine without any grinding aid in Example 1 was measured by a laser particle size analyzer. The results are as follows: Figure 2 shown.

[0135] from Figure 2 From the analysis, it can be seen that by adding grinding aids to wet grind olivine, the particle size of olivine powder is effectively reduced and the particle size distribution is made more uniform.

[0136] 2) XRF test

[0137] The olivine used in Example 1 was subjected to XRF testing, and the results are shown in Table 1.

[0138] Table 1 shows the major element composition of olivine samples

[0139]

[0140] Among them, the Ca content can be ignored because the Fe element in the product is precipitated in the form of oxide rather than siderite precipitation, so only the case of conversion to MgCO3 is considered in the theoretical calculation.

[0141] 3) The supernatants of the 8 suspensions in Examples 1 to 3 and Comparative Example 1 were collected with a syringe, and the pH values ​​were measured. The results were as follows: Figure 3 shown.

[0142] Figure 3 5MPa-W corresponds to Control Example 3, 11MPa-W corresponds to Example 2, 14MPa-W corresponds to Example 1, and 14MPa-D corresponds to Example 3.

[0143] from Figure 3 From the analysis, we can see that due to the addition of NaHCO3, HCO3 is ionized. - With its weak hydrolysis effect, the pH of the system can be adjusted to a weak alkaline state, and the pH shows a trend of increasing first and then decreasing. The mechanism by which the addition of NaHCO3 promotes the dissolution of olivine minerals is different from the traditional mechanism of Mg in acidic solutions. 2+ , Fe 2+ priority release.

[0144] Under alkaline conditions, the rate of Mg-O bond breaking is slower than that of Si-O bond breaking, which is the rate-determining step in the dissolution of basic rock minerals. Therefore, Si is released first and consumes protons to extract orthosilicic acid, which increases the pH at the beginning of the reaction. The high NaHCO3 concentration and the strong polarity brought by high pCO2 make SiO2 in orthosilicic acid tend to enter the solution quickly rather than forming an amorphous passivation layer, and then Mg 2+ Released Mg(OH)2 + Silicon-poor group, this group is also in HCO3 - / CO3 2- The ion pair complexation forms Mg(HCO3) +ions, realizing the transformation of mineral dissolution into precipitation and further increasing pH. In the later stage, due to the consumption of pCO2, carbonate products began to transform into bicarbonate, and the overall environment became favorable for Fe 3+ The oxidation state of the ions changes, which leads to a decrease in pH.

[0145] The contribution of wet grinding to the degradation of the passivation layer is similar to that of increasing NaHCO3 concentration. The wet grinding product has a smaller particle size and SiO2 and Mg(OH)2 + The passivation layer is preferentially dissolved as the slurry flows, so it does not rely too much on the hydrolysis of bicarbonate to destroy the passivation layer, so the overall pH of the wet grinding group is lower. The dry grinding group has a larger particle size, and the stronger hydrolysis of bicarbonate provides a slightly higher pH value.

[0146] 4) The supernatants of the eight suspensions in Examples 1 to 3 and Comparative Example 1 were collected with a syringe, filtered through a 40 μm water-based membrane, diluted 10 times, and then acidified for ICP-AES element determination.

[0147] After adding EDTA to the solution after the reaction (i.e., the supernatant of the 8th suspension in Example 1), ICP-AES detection showed that Ni and Co elements were enriched in the form of ion complexes at concentrations of 437 mg / L and 27.9 mg / L, respectively, which was 3 orders of magnitude higher than the concentrations of Ni and Co in the reaction with the addition of sodium citrate weak ligand (i.e., the supernatant of the 8th suspension in Control Example 1) and without the addition of ligand (i.e., the supernatant of the 8th suspension in Control Example 2). (The concentration of Ni in the reaction solution with the addition of weak ligand (i.e., the supernatant of the 8th suspension in Control Example 1) was 7 mg / L, and the concentration of Co was 0.2 mg / L, while the concentrations of Ni and Co in the reaction solution without the addition of ligand (i.e., the supernatant of the 8th suspension in Control Example 2) were both lower than the detection limit of 0.1 mg / L.

[0148] 5) After the 48h reaction, the remaining solids in the reactor were collected and mixed with the lower precipitate after 8 suspension layer separations, washed with water, and centrifuged at 3500rpm in a high-speed centrifuge to wash away the precipitated NaCl and NaHCO3 solids. The washed solids were then dried for XRD and TCA tests. The XRD test results Figure 4 and Figure 5 shown.

[0149] Figure 4 5MPa-W corresponds to Control Example 3, 11MPa-W corresponds to Example 2, 14MPa-W corresponds to Example 1, and 14MPa-D corresponds to Example 3.

[0150] from Figure 4It can be seen from the analysis that, compared with the PDF#08-0479 standard card, the main components of the physical phases of 5MPa-W, 11MPa-W, 14MPa-W, and 14MPa-D are all magnesium carbonate. The W% contents are semi-quantitatively calculated by the RIR value of Jade software to be 72.3%, 91.7%, 96.2%, and 85.3%, respectively.

[0151] Figure 5 In the above, NaHCO3+SC corresponds to Control Example 1, NaHCO3+EDTA corresponds to Example 1, and NaHCO3 corresponds to Control Example 2.

[0152] from Figure 5 It can be seen from the analysis that, compared with the PDF#08-0479 standard card, under the same temperature and pressure conditions, the main components of the physical phases of NaHCO3+EDTA, NaHCO3+SC, and NaHCO3 are all magnesium carbonate. The semi-quantitative calculation of their W% contents by the RIR value of Jade software is 96.2%, 93.7%, and 94.9%, respectively.

[0153] Among them, the calculation of TCA is:

[0154] Carbonation potential per gram of olivine

[0155] Carbonation efficiency

[0156] TCA is the carbon analysis value measured by the carbon-sulfur analyzer, which is the mass percentage of carbon in the product. The carbonation efficiency is calculated as Figure 6 shown.

[0157] Figure 6 5MPa-W corresponds to Control Example 3, 11MPa-W corresponds to Example 2, 14MPa-W corresponds to Example 1, and 14MPa-D corresponds to Example 3.

[0158] from Figure 6 It can be seen from the analysis that, according to the TCA test, the carbonation efficiency of wet-ground mineral powders reacting for 8 hours under 14MPa conditions is as high as 71.54%, the carbonation efficiency of dry-ground mineral powders reacting for 8 hours under the same temperature and pressure is 58.61%, and the carbonization efficiency of wet-ground mineral powders reacting for 8 hours under 11MPa conditions with reduced partial pressure is 67.09%. The carbonization efficiency of wet-ground products reacting for 8 hours under conventional conditions of 5MPa is only 47.68%, which is low. Because wet grinding can obtain finer particle sizes than dry grinding, the reactants can be activated, breaking the limitations of diffusion control, and the larger partial pressure can supplement the carbon source, so that the carbonate precipitate can crystallize well, rather than forming a passivation layer to slow down the reaction rate.

[0159] In summary, the method of improving the carbonation efficiency of the ore of the present invention is to first cool the solid-liquid mixture and then introduce carbon dioxide, and then gradually and slowly increase the temperature by a step-by-step heating method, so that the introduced carbon dioxide is rapidly liquefied under low temperature conditions and then evaporates by endothermic absorption, thereby obtaining a higher gas partial pressure. The two work together to safely and accurately control the water-rock reaction pressure at 185°C to 14MPa, thereby quickly and stably realizing the mineral carbonation reaction of olivine within 48 hours, and by adding EDTA, Ni and Co elements are recovered in the solution. According to the TCA test, the carbonation efficiency of wet-ground mineral powder under 14MPa conditions for 8h reaction is as high as 71.54%, and the mass fraction of MgCO3 in the final product according to XRD semi-quantitative analysis is 96.2%, and the carbonation process is successfully realized. The carbonization efficiency of dry-ground mineral powder after 8 hours of reaction at the same temperature and pressure was 58.61%, and the MgCO3 content was 85.3% according to XRD semi-quantitative analysis. The carbonization efficiency of wet-ground mineral powder after 8 hours of reaction under the condition of reduced partial pressure of 11MPa was 67.09%, and the MgCO3 content was 91.7% according to XRD semi-quantitative analysis. The carbonation efficiency of these two control experiments was reduced, but the cost and energy consumption were reduced to a certain extent. The carbonation efficiency of wet-ground products after 8 hours of reaction under the existing conventional conditions of 5MPa was only 47.68%, and the MgCO3 content of the final product was 72.3% according to XRD semi-quantitative analysis, and the carbonation efficiency was low. The solid samples collected in the first 8 hours were characterized by SEM-EDS and other methods to comprehensively analyze the intermediate products and reaction paths of high-temperature and high-pressure water-rock reactions, and further explore the kinetic control factors and reaction mechanisms of mineral carbonation. After adding EDTA to the solution after the reaction, ICP-AES detection showed that Ni and Co elements were enriched in the form of ion complexes at concentrations of 437 mg / L and 27.9 mg / L, respectively, which were 3 orders of magnitude higher than the Ni and Co concentrations of the reaction with weak sodium citrate ligands and without ligands. (The Ni concentration in the reaction solution with weak ligands was 7 mg / L and the Co concentration was 0.2 mg / L, and the Ni and Co concentrations in the reaction solution without ligands were both below the detection limit of 0.1 mg / L.) Subsequent hydrometallurgical operations can be performed to extract pure Ni and Co metals and obtain economic benefits, which has promotion and application value in the field of ore carbonation technology.

[0160] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent substitution or change made by a person skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A method for improving the carbonation efficiency of an ore, characterized in that: The following steps are involved: S1, mixing ore and grinding aid and ball milling to obtain ore powder; S2, adding a buffering agent and a ligand solution to a sodium salt solution to obtain a mixed solution, and adding ore powder to the mixed solution to obtain a solid-liquid mixture; S3, cooling the solid-liquid mixture to a temperature less than or equal to a first preset temperature, then introducing pre-liquefied carbon dioxide, so that the introduced carbon dioxide is in a supercritical state and can be rapidly liquefied, and the liquefied CO2 can obtain a higher gas partial pressure accompanied by an endothermic evaporation process, and then step-by-step heating is performed with the second preset temperature as a gradient until the temperature reaches a third preset temperature, and then stirring the reaction at a preset stirring rate for at least a preset time to obtain carbonated ore, so as to achieve carbonation of the ore; The buffer aid is selected from at least one of sodium bicarbonate solution, boric acid and Tris buffer; The ligand solution is selected from one or two of an EDTA solution and a disodium ethylenediaminetetraacetic acid solution; The first preset temperature is 3~8°C; The second preset temperature is 15~25℃; The third preset temperature is 170-200°C.

2. The method for improving ore carbonation efficiency according to claim 1, characterized in that: The ore is olivine; And / or, the maximum particle size of the ore powder is 25 μm.

3. The method for improving ore carbonation efficiency according to claim 1, characterized in that: The grinding aid is selected from one or both of anhydrous ethanol and acetone.

4. The method for improving ore carbonation efficiency according to claim 1, characterized in that: The grinding balls used in the ball mill include grinding balls with diameters of 3 mm, 5 mm and 10 mm; The number ratio of the grinding balls with a diameter of 3 mm, the grinding balls with a diameter of 5 mm and the grinding balls with a diameter of 10 mm is 0.8-1.2:0.8-1.2:0.8-1.2; And / or, the ball milling method is ball milling for 10 minutes, with a rest period of 5 minutes, and the total ball milling time is 8 hours; And / or, the ball milling uses a planetary ball mill to wet grind the ore.

5. The method for improving ore carbonation efficiency according to claim 1, characterized in that: The sodium salt solution is selected from sodium chloride solution.

6. The method for improving ore carbonation efficiency according to claim 1, characterized in that: The concentration of sodium salt in the sodium salt solution is 1 mol / L.

7. The method for improving ore carbonation efficiency according to claim 1, characterized in that: The concentration of sodium bicarbonate in the sodium bicarbonate solution is 1 mol / L.

8. The method for improving ore carbonation efficiency according to claim 1, characterized in that: The concentration of the ligand in the ligand solution is 0.1 mol / L.

9. The method for improving ore carbonation efficiency according to claim 1, characterized in that: The mass ratio of the mixed solution to the ore is 8-12:

1.

10. The method for improving ore carbonation efficiency according to claim 1, characterized in that: The preset stirring rate is 500 rpm to 1000 rpm; And / or, the preset time is 6 to 10 hours.

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