Method for mineralizing co 2 by means of strengthened forsterite

Abstract

The present invention relates to the fields of carbon sequestration and mineral utilization, and particularly relates to a method for mineralizing CO2 by means of strengthened forsterite. The method comprises the following steps: pretreating forsterite by using a strong acid, so as to obtain pretreated forsterite and a magnesium-containing solution; activating the pretreated forsterite, so as to obtain activated forsterite; heating the activated forsterite and ammonium sulfate for a reaction, so as to obtain magnesium sulfate and ammonia gas; and mixing the magnesium-containing solution, the magnesium sulfate, the ammonia gas and a CO2-containing gas, so as to obtain magnesium carbonate and ammonium sulfate. In the present invention, by means of a pretreatment and activation, the reaction activity of forsterite is improved, conditions are provided for achieving a high conversion rate in a subsequent solid-solid contact reaction, and the problems of high energy consumption of traditional thermal decomposition of ammonium sulfate and a low conversion rate of a solid-solid reaction are solved.

Description

Method for strengthening magnesio-olivine mineralization of CO2 The present application claims priority to the Chinese patent application No. 2024106822554, filed on May 29, 2024, and entitled "Method for strengthening magnesio-olivine mineralization of CO2", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0001] The present application relates to the field of carbon sequestration and mineral utilization, in particular to a method for strengthening magnesio-olivine mineralization of CO2. BACKGROUND

[0002] Climate change caused by greenhouse gas CO2 emissions is gradually beginning to affect human survival and production and life. Carbon dioxide geological storage is considered as one of the important strategies for reducing carbon emissions and developing technology from demonstration scale to large-scale industrial scale. However, geological storage is a very location-dependent technology. Many countries cannot find suitable geological structures, or the distance from the storage site to the carbon dioxide generation site can be thousands of kilometers, which results in high cost of pipeline construction.

[0003] CO2 mineralization is another potential option for long-term storage of CO2. Mineral carbonation (mineralization) refers to the process of reacting magnesium-rich minerals such as olivine (Mg2SiO4) with carbon dioxide to form stable mineral carbonates, which simulates the naturally occurring rock weathering process and can form stable magnesium carbonates. The current technology is to use CO2-containing gas to directly contact with olivine solid for mineralization, but the gas-solid direct reaction process is extremely slow and needs to be carried out under high temperature and high pressure conditions, and the utilization rate of magnesium is usually low. Another type is to use an indirect mineralization process, i.e. by introducing a strong acid (such as sulfuric acid) to dissolve magnesium (such as magnesium sulfate) in the olivine into a solution, and then reacting with CO2 under alkaline conditions to form magnesium carbonate. This process strengthens the reaction rate of the dissolution and mineralization processes by introducing acid and base, respectively, but the process consumes a large amount of acid and base. Even if ammonium salt thermal decomposition is used to obtain acid and base for recycling, the thermal decomposition process also consumes a large amount of energy, which cannot be used for large-scale application and "carbon negative".

[0004] In view of this, the present application is proposed. SUMMARY

[0005] The purpose of the present application is to provide a method for strengthening magnesio-olivine mineralization of CO2. The present application improves the reactivity of magnesio-olivine through pretreatment and activation, which provides conditions for high conversion rate of subsequent solid-solid contact reaction, and solves the problems of high energy consumption of traditional ammonium sulfate thermal decomposition and low conversion rate of solid-solid reaction.

[0006] The present application provides a method for strengthening magnesio-olivine mineralization of CO2, comprising the following steps:

[0007] S1, pre-treating forsterite by using strong acid to obtain pre-treated forsterite and a magnesium-containing solution;

[0008] S2, activating the pre-treated forsterite to obtain activated forsterite;

[0009] S3, heating and reacting the activated forsterite with ammonium sulfate to obtain magnesium sulfate and ammonia gas;

[0010] S4, mixing the magnesium-containing solution, the magnesium sulfate, the ammonia gas and a CO2-containing gas to obtain magnesium carbonate and ammonium sulfate.

[0011] In the method for mineralizing CO2 by strengthening forsterite in the application, first, strong acid is added to the forsterite for pre-treatment, on one hand, the corrosion of the strong acid increases the specific surface area of the forsterite, and further increases the contact area of the ammonium sulfate solid and the forsterite; on the other hand, the forsterite is a discrete silicate, and the SiO4 4- tetrahedron is connected with the metal ion Mg 2+ , in the process of the strong acid treatment, the Mg 2+ in the crystal structure is replaced by a proton, therefore, the strong acid can destroy the crystal lattice of the forsterite, and further reduce the crystal lattice energy and improve the reaction activity.

[0012] Then, the pre-treated forsterite is activated to make the serpentine mineral phase (Mg3Si2O5(OH)4) with lower activity in the forsterite change to the olivine phase (Mg2SiO4) and the clinoenstatite (MgSiO3) mineral phase with relatively higher activity, and the chemical reaction is as follows:

[0013] Mg3Si2O5(OH)4→Mg2SiO4+MgSiO3+2H2O

[0014] The application further mixes the activated forsterite solid with the ammonium sulfate solid and performs heating reaction, the extraction of magnesium and the regeneration of alkali are completed in one step by using the direct reaction of the ammonium salt and the forsterite solid, and raw materials and an alkaline environment are provided for the subsequent CO2 mineralization process, and the reaction equation is as follows:

[0015] Mg2SiO4+2(NH4)2SO4→2MgSO4+SiO2+2H2O+4NH3↑

[0016] Finally, the magnesium-containing solution, the magnesium sulfate, the ammonia gas and the CO2-containing gas are mixed to perform the mineralization reaction of CO2, the generated ammonium sulfate is separated by crystallization and other steps to obtain ammonium sulfate solid which can be further recycled, and the reaction equation is as follows:

[0017] MgSO4+H2O+2NH3+CO2→MgCO3↓+(NH4)2SO4

[0018] Therefore, the application improves the reaction activity of forsterite by pretreatment and activation, provides conditions for high conversion rate of subsequent solid-solid contact reaction, improves the extraction rate of magnesium, and solves the problems of high energy consumption and low conversion rate of solid-solid reaction in traditional ammonium sulfate thermal decomposition.

[0019] As the preferred technical solution, in step S1, the strong acid includes but is not limited to any one or more of sulfuric acid, nitric acid and hydrochloric acid, and the selection of the strong acid needs to consider not only that it can increase the specific surface area of forsterite, destroy the crystal lattice of forsterite and reduce the lattice energy, but also that the final product ammonium sulfate is easy to separate from other ammonium salts.

[0020] As the preferred technical solution, in step S1, the amount of the strong acid is calculated based on the molar ratio of hydrogen ions in the strong acid to magnesium oxide in the forsterite, which is 1:(25-40), and preferably 1:30.

[0021] The application does not strictly limit the mass fraction of strong acids such as sulfuric acid, hydrochloric acid and nitric acid. For example, the mass fraction of sulfuric acid can be 75-98%, the mass fraction of hydrochloric acid can be 15-35%, and the mass fraction of nitric acid can be 20-45%.

[0022] As the preferred technical solution, the specific surface area of the pretreated forsterite should be not less than 2 m 2 / g.

[0023] As the preferred technical solution, in step S2, the activation specifically refers to heating treatment of the pretreated forsterite, and when heating, the pretreated forsterite can be heated to 200-500℃ and kept for 2-6h, so that the active serpentine mineral phase (Mg3Si2O5(OH)4) in the forsterite is converted to the olivine phase (Mg2SiO4) and the clinohedralite (MgSiO3) mineral phase with relatively high activity.

[0024] As the preferred technical solution, in step S3, the activated forsterite and ammonium sulfate are fully mixed and then heated to react, water is used to absorb the generated ammonia gas during the reaction, after the reaction is completed, water is added to the mixed solid obtained by the reaction to dissolve the generated magnesium sulfate, and then washing and filtering are performed to remove the iron and aluminum precipitates.

[0025] Since the activated forsterite and ammonium sulfate are both solids, in order to improve the reaction efficiency of the two, the activated forsterite and ammonium sulfate need to be fully mixed by grinding, stirring, sieving and the like, and the application does not strictly limit the way of fully mixing the two.

[0026] As the preferred technical solution, in step S3, the reaction temperature can be controlled to be 300-450 DEG C, and the reaction time is 2-6 h, and the application does not strictly limit the reaction conditions to ensure that the activated forsterite and ammonium sulfate can be fully reacted.

[0027] As the preferred technical solution, in step S3, the mass ratio of the activated forsterite to ammonium sulfate is preferably 1: (3-6), and the ammonium sulfate is excessive relative to the activated forsterite, thereby improving the extraction rate of magnesium.

[0028] As the preferred technical solution, in step S4, the magnesium-containing solution, the magnesium sulfate solution and the ammonia solution are mixed, and the pH value of the mixed solution is controlled to be 8-9, and research shows that under the condition of alkaline, the mineralization reaction of magnesium sulfate can be promoted.

[0029] As the preferred technical solution, in step S4, the volume fraction of CO2 in the CO2-containing gas is 10-90%, and the application does not strictly limit it, and the gas flow can be adjusted according to the volume fraction of CO2 during use, thereby controlling the progress of the mineralization reaction.

[0030] As the preferred technical solution, in step S4, the ammonium sulfate solution obtained by the reaction is subjected to crystallization treatment to obtain ammonium sulfate solid, which is repeatedly used.

[0031] For example, when the strong acid used is sulfuric acid, the mineralization reaction obtains magnesium carbonate precipitate and ammonium sulfate solution, the ammonium sulfate solution is subjected to evaporation and crystallization treatment, and ammonium sulfate solid is obtained, which is repeatedly used for solid-solid reaction with the activated forsterite;

[0032] When the strong acid used is hydrochloric acid, the mineralization reaction obtains magnesium carbonate precipitate, ammonium sulfate solution and ammonium chloride solution, at this time, the ammonium sulfate and the ammonium chloride can be separated by repeated evaporation and dissolution process according to the different solubility of ammonium sulfate and ammonium chloride, and the obtained ammonium sulfate solid can be repeatedly used for solid-solid reaction with the activated forsterite.

[0033] When the strong acid used is nitric acid, the mineralization reaction obtains magnesium carbonate precipitate, ammonium sulfate solution and ammonium nitrate solution, and the ammonium sulfate and the ammonium nitrate can be separated according to the different solubility of ammonium sulfate and ammonium nitrate, and the obtained ammonium sulfate solid can be repeatedly used for solid-solid reaction with the activated forsterite.

[0034] The method for strengthening the mineralization of forsterite CO2 has at least the following beneficial effects:

[0035] In the method of the present application, the magnesium olivine after crystal modification and activation can be obtained by strong acid pretreatment and activation means, the activated magnesium olivine is fully mixed with solid ammonium sulfate and heated, the magnesium extraction and alkali regeneration are completed in one step, not only the heat release of magnesium leaching and the heat absorption of ammonium sulfate decomposition are integrated, the comprehensive utilization of energy is realized, and the ammonium sulfate can be regenerated and recycled through the subsequent CO2 mineralization process. Therefore, the pretreatment and activation of the present application improve the reaction activity of the magnesium olivine, provide conditions for the high conversion rate of the subsequent solid-solid contact reaction, and solve the problems of high energy consumption of traditional ammonium sulfate thermal decomposition and low conversion rate of solid-solid reaction. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0037] Fig. 1 is the XRD pattern of the magnesium olivine of the present application;

[0038] Fig. 2 is the SEM diagram of the magnesium olivine before and after pretreatment of the present application;

[0039] Fig. 3 is the XRD pattern of the magnesium olivine before and after activation of the present application;

[0040] Fig. 4 is a comparison diagram before and after the solid-solid reaction of the present application. DETAILED DESCRIPTION

[0041] It should be pointed out that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0042] It should be noted that the terms used herein are only for the purpose of describing the specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form also includes the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0043] The technical solutions of the present application will be clearly and completely described below in combination with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0044] Embodiment 1

[0045] The main components of the forsterite selected in this embodiment are as follows: magnesium oxide 32.71%, silicon dioxide 51.88%, diiron trioxide 10.62%, and calcium oxide 2.67%.

[0046] S1, 100g of the forsterite with a mesh size of 200 above is stirred in 157ml of a sulfuric acid solution with a mass fraction of 85% (the molar ratio of hydrogen ions in the strong acid to magnesium oxide in the forsterite is 1:30) for 30 minutes, and then filtered and dried to obtain 99.4g of the pretreated forsterite;

[0047] S2, the pretreated forsterite is heated to 250℃ for activation and maintained for 2h;

[0048] S3, the activated forsterite is uniformly mixed with 324g of ammonium sulfate (the mass ratio of the forsterite to the ammonium sulfate solid is 1:3.3) by grinding, heated to 380℃, and maintained for 4h, the generated ammonia gas is absorbed by 1 liter of water, 1 liter of water is added to the mixed solid after the reaction to dissolve the generated magnesium sulfate into a magnesium sulfate solution, the iron and aluminum precipitates in the mixed solution are removed by washing and filtering, and the extraction rate of magnesium in the forsterite is calculated according to the magnesium content in the solution, which is 89.2%;

[0049] S4, after the magnesium-containing liquid, the magnesium sulfate solution and part of the ammonia water solution are mixed, the pH of the solution is controlled to be 8.5, and the mineralization reaction is carried out by introducing the CO2-containing gas with a CO2 volume fraction of 20%, to obtain 61.2g of magnesium carbonate precipitate and ammonium sulfate solution;

[0050] S5, the ammonium sulfate solution is repeatedly used for mixing with the forsterite after evaporation and crystallization.

[0051] Fig. 1 is the XRD pattern of the forsterite, and it can be seen that the main mineral phases of the natural forsterite are olivine (Mg2SiO4), serpentine and talc, etc.;

[0052] Fig. 2 is the SEM diagram of the forsterite before and after the strong acid treatment, and it can be seen that the forsterite appears a porous structure after the acid treatment, and the specific surface area of the forsterite is measured to be 2.64m 2 / g;

[0053] Figure 3 is a XRD diagram of the crystal form change of the forsterite before and after activation in the embodiment, it can be seen that the serpentine phase in the forsterite is reduced, and the olivine phase (Mg2SiO4) and the clinohedrite (MgSiO3) phase are increased;

[0054] Figure 4 is a comparison diagram of the solid-solid reaction before and after the reaction in the embodiment, the color of the reactant is obviously different from that of the product, indicating that the forsterite solid and the ammonium sulfate solid can directly react and generate the magnesium sulfate solid.

[0055] Example 2

[0056] In the embodiment, the forsterite in the example 1 is selected as the raw material, and the operation and process are basically the same as those in the example 1, and the difference is that the hydrochloric acid is selected as the strong acid pretreatment agent in the embodiment.

[0057] S1, 100g of the forsterite with a mesh size of 200 is stirred in 497ml of a hydrochloric acid solution with a mass fraction of 20% (the molar ratio of hydrogen ions in the strong acid to magnesium oxide in the forsterite is 1:30) for 30 minutes, and then filtered and dried to obtain 99.3g of the pretreated forsterite. The specific surface area of the pretreated forsterite is measured to be 2.74m 2 / g;

[0058] S2, the pretreated forsterite is heated to 250℃ for activation and maintained for 2h;

[0059] S3, the activated forsterite is uniformly mixed with 323g of ammonium sulfate (the mass ratio of the forsterite to the ammonium sulfate solid is 1:3.3) by grinding, heated to 380℃, and maintained for 4h. The generated ammonia gas is absorbed by 1 liter of water. 1 liter of water is added to the mixed solid after the reaction to dissolve the generated magnesium sulfate into a magnesium sulfate solution. The iron and aluminum precipitates in the mixed solution are removed by washing and filtering. According to the determination of the magnesium content in the solution, the extraction rate of magnesium in the forsterite is 90.7%;

[0060] S4, after the magnesium-containing solution, the magnesium sulfate solution and part of the ammonia solution are mixed, the pH of the solution is controlled to be 8.5, and the CO2-containing gas with a CO2 volume fraction of 30% is introduced for mineralization reaction to obtain 62.3g of magnesium carbonate precipitate and ammonium sulfate, ammonium chloride solution;

[0061] S5, by virtue of the different solubilities of the ammonium sulfate and the ammonium chloride, the ammonium sulfate and the ammonium chloride are separated through repeated evaporation and dissolution processes. The obtained ammonium sulfate can be repeatedly used for mixing with the forsterite.

[0062] Example 3

[0063] In the embodiment, the forsterite in the example 1 is selected as the raw material, and the operation and process are basically the same as those in the example 1, and the difference is that the nitric acid is selected as the strong acid pretreatment agent in the embodiment.

[0064] S1, 100 g of the above forsterite with 200 mesh was stirred in 430 ml of a 30% by mass nitric acid solution (the molar ratio of hydrogen ions in the strong acid to magnesium oxide in the forsterite was 1:40) for 30 minutes, and after filtration and drying, 99.6 g of pretreated forsterite was obtained. The specific surface area of the pretreated forsterite was measured to be 2.53 m 2 / g;

[0065] S2, the above pretreated forsterite was heated to 500°C for activation and maintained for 2 h;

[0066] S3, the activated forsterite was uniformly mixed with 295 g of ammonium sulfate (the mass ratio of forsterite to ammonium sulfate solid was 1:3) by grinding, heated to 450°C, and maintained for 2 h. The generated ammonia gas was absorbed with 1 liter of water. 1 liter of water was added to the mixed solid after the reaction to dissolve the generated magnesium sulfate into a magnesium sulfate solution. The iron and aluminum precipitates in the mixed solution were removed by washing and filtration. According to the determination of the magnesium content in the solution, the extraction rate of magnesium in the forsterite was 86.3%;

[0067] S4, after mixing the magnesium-containing solution, the magnesium sulfate solution, and part of the ammonia water solution, the pH of the solution was controlled to 9, and a CO2-containing gas with a CO2 volume fraction of 50% was introduced for mineralization reaction to obtain 59.2 g of magnesium carbonate precipitate and ammonium sulfate, ammonium nitrate solution;

[0068] S5, by virtue of the different solubilities of ammonium sulfate and ammonium nitrate, ammonium sulfate and ammonium nitrate were separated by repeated evaporation and dissolution processes. The obtained ammonium sulfate can be repeatedly used for mixing with forsterite.

[0069] Example 4

[0070] In this example, the forsterite in Example 1 was selected as the raw material, and the operation and process were basically the same as in Example 1, except that the reaction conditions in each step were different.

[0071] S1, 100 g of the above forsterite with 200 mesh was stirred in 398 ml of a 30% by mass hydrochloric acid solution (the molar ratio of hydrogen ions in the strong acid to magnesium oxide in the forsterite was 1:25) for 60 minutes, and after filtration and drying, 99.3 g of pretreated forsterite was obtained. The specific surface area of the pretreated forsterite was measured to be 2.67 m 2 / g;

[0072] S2, the above pretreated forsterite was heated to 200°C for activation and maintained for 6 h;

[0073] S3, the activated forsterite is mixed with 588 g of ammonium sulfate (the mass ratio of forsterite to ammonium sulfate is 1:6) by grinding, heated to 300°C and maintained for 6 hours, the generated ammonia is absorbed by 1 liter of water, 1 liter of water is added to the mixed solid after the reaction to dissolve the generated magnesium sulfate into a magnesium sulfate solution, the iron and aluminum precipitates in the mixed solution are removed by washing and filtering, and the extraction rate of magnesium in the forsterite is calculated according to the magnesium content in the solution, which is 93.8%;

[0074] S4, after the magnesium-containing solution, the magnesium sulfate solution and part of the ammonia solution are mixed, the pH of the solution is controlled to be 8, CO2 gas with a CO2 volume fraction of 85% is introduced for mineralization reaction, 64.4 g of magnesium carbonate precipitate and ammonium sulfate and ammonium chloride solution are obtained;

[0075] S5, ammonium sulfate and ammonium chloride are separated by repeated evaporation and dissolution processes according to their different solubilities, and the obtained ammonium sulfate can be repeatedly used for mixing with forsterite.

[0076] Comparative Example 1

[0077] In this comparative example, the forsterite in Example 1 is used as the raw material, and the operation and process are basically the same as those in Example 1, except that the forsterite is not pretreated with strong acid.

[0078] S1, the specific surface area of 200 mesh forsterite is measured to be 1.62 m 2 / g;

[0079] S2, 100 g of the above 200 mesh forsterite is heated to 250°C for activation and maintained for 2 hours;

[0080] S3, the activated forsterite is mixed with 330 g of ammonium sulfate (the mass ratio of forsterite to ammonium sulfate is 1:3.3) by grinding, heated to 380°C and maintained for 4 hours, the generated ammonia is absorbed by 1 liter of water, 1 liter of water is added to the mixed solid after the reaction to dissolve the generated magnesium sulfate into a magnesium sulfate solution, the iron and aluminum precipitates in the mixed solution are removed by washing and filtering, and the extraction rate of magnesium in the forsterite is calculated according to the magnesium content in the solution, which is 57.2%;

[0081] S4, after the magnesium-containing solution, the magnesium sulfate solution and part of the ammonia solution are mixed, the pH of the solution is controlled to be 8.5, CO2 gas with a CO2 volume fraction of 20% is introduced for mineralization reaction, 39.3 g of magnesium carbonate precipitate and ammonium sulfate solution are obtained;

[0082] S4, the ammonium sulfate solution is treated by evaporation and crystallization, and is repeatedly used for mixing with forsterite.

[0083] The results show that the specific surface area of the forsterite in the present example is lower than that of the forsterite in the comparative example 1, and the contact area of the solid-solid reaction is reduced, resulting in a decrease in the extraction rate of magnesium.

[0084] Comparative Example 2

[0085] The present example uses the forsterite in the example 1 as the raw material, and the operation and process are basically the same as those in the example 1, except that the forsterite in the present example is not activated.

[0086] S1, 100g of 200-mesh forsterite is stirred in 157ml of a 85wt% sulfuric acid solution (the molar ratio of hydrogen ions in the strong acid to magnesium oxide in the forsterite is 1:30) for 30 minutes, and then filtered and dried to obtain 99.3g of surface-treated forsterite. The specific surface area of the forsterite is measured to be 2.68m 2 / g;

[0087] S2, the pretreated forsterite is mixed with 327.7g of ammonium sulfate (the mass ratio of forsterite to ammonium sulfate is 1:3.3) by grinding, heated to 380℃ and maintained for 4h, the generated ammonia gas is absorbed with 1 liter of water, 1 liter of water is added to the mixed solid after the reaction to dissolve the generated magnesium sulfate into a magnesium sulfate solution, and the iron and aluminum precipitates in the mixed solution are removed by washing and filtering. The extraction rate of magnesium in the forsterite is calculated to be 71.6% according to the measured content of magnesium in the solution;

[0088] S3, after mixing the magnesium-containing solution, the magnesium sulfate solution and part of the ammonia solution, the pH of the solution is controlled to 8.5, and CO2 gas with a CO2 volume fraction of 20% is introduced for mineralization reaction to obtain 49.2g of magnesium carbonate precipitate and ammonium sulfate solution;

[0089] S4, the ammonium sulfate solution is evaporated and crystallized, and then repeatedly used for mixing with forsterite.

[0090] The results show that the forsterite in the present example is not activated, and the serpentine mineral phase in the forsterite does not change, resulting in a low reaction activity and a decrease in the extraction rate of magnesium.

[0091] Comparative Example 3

[0092] The present example uses the forsterite in the example 1 as the raw material, and the operation and process are basically the same as those in the example 1, except that the forsterite in the present example is not pretreated and activated.

[0093] S1, 100g of 200-mesh forsterite is mixed with 330g of ammonium sulfate (mass ratio of forsterite to ammonium sulfate solid is 1:3.3) by grinding, heated to 380℃ and maintained for 4h, the generated ammonia is absorbed by 1 liter of water, 1 liter of water is added to the mixed solid after the reaction to dissolve the generated magnesium sulfate into a magnesium sulfate solution, the iron and aluminum precipitates in the mixed solution are removed by washing and filtering, and the extraction rate of magnesium in the forsterite is calculated according to the magnesium content in the solution, which is 41.8%;

[0094] S2, after mixing the magnesium-containing solution, the magnesium sulfate solution and part of the ammonia solution, the pH of the solution is controlled to be 8.5, CO2 gas with a CO2 volume fraction of 20% is introduced for mineralization reaction, 28.7g of magnesium carbonate precipitate and ammonium sulfate solution are obtained;

[0095] S3, the ammonium sulfate solution is used repeatedly for mixing with forsterite after evaporation crystallization.

[0096] The results show that, due to the fact that the forsterite is not pretreated and activated, the solid-solid contact surface is small, and the serpentine mineral phase in the forsterite does not change, the reaction activity is low, and the extraction rate of magnesium is very low.

[0097] Table 1 is the extraction rate of magnesium in the forsterite of examples 1-3 and comparative examples 1-3.

[0098] Table 1

[0099]

[0100]

[0101] In summary, by means of strong acid pretreatment and activation, the forsterite with changed crystal form and activation can be obtained, the activated forsterite is mixed with ammonium sulfate solid, heated, the extraction of magnesium and regeneration of alkali are completed in one step, not only the heat release of magnesium leaching and the heat absorption of ammonium sulfate decomposition are integrated, the comprehensive utilization of energy is realized, but also the ammonium sulfate can be regenerated and recycled through the subsequent mineralization process of CO2. Therefore, the reaction activity of the forsterite is improved by pretreatment and activation, the conditions for high conversion rate of subsequent solid-solid contact reaction are provided, the extraction rate of magnesium is improved, the process is simple and easy to operate, the problems of high energy consumption of traditional ammonium sulfate thermal decomposition and low conversion rate of solid-solid reaction are solved.

[0102] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of mineralizing CO2 with forsterite-strengthening, characterized by, The method comprises the following steps: S1, pretreating forsterite by using strong acid to obtain pretreated forsterite and a magnesium-containing solution; S2, activating the pretreated forsterite to obtain activated forsterite; S3, heating and reacting the activated forsterite with ammonium sulfate to obtain magnesium sulfate and ammonia gas; S4, mixing the magnesium-containing solution, the magnesium sulfate, the ammonia gas and a CO2-containing gas to obtain magnesium carbonate and ammonium sulfate.

2. The method of mineralizing CO2 with forsterite according to claim 1, characterized in that, In step S1, the strong acid comprises any one or more of sulfuric acid, nitric acid and hydrochloric acid.

3. The method of mineralizing CO2 with forsterite according to claim 1, characterized in that, In step S1, the amount of the strong acid is calculated by the molar ratio of hydrogen ions in the strong acid to magnesium oxide in the forsterite, which is 1:(25-40).

4. The method of mineralizing CO2 with forsterite according to claim 1, characterized in that, In step S2, the pretreated forsterite is heated to 200-500℃ and kept for 2-6h.

5. The method of mineralizing CO2 with forsterite according to claim 1, characterized in that, In step S3, the activated forsterite is fully mixed with ammonium sulfate before the heating reaction, and after the reaction, water is added to the obtained mixed solid, and then the solution is dissolved, washed and filtered.

6. The method for enhancing the mineralization of CO2 in magnesium olivine according to claim 1, characterized in that, In step S3, the temperature is controlled to be 300-450℃ and the time is controlled to be 2-6h during the heating reaction.

7. The method of mineralizing CO2 with forsterite according to claim 1, characterized in that, In step S3, the mass ratio of the activated forsterite to ammonium sulfate is 1:(3-6).

8. The method of mineralizing CO2 with forsterite according to claim 1, characterized in that, In step S4, the magnesium-containing solution, the magnesium sulfate solution and the ammonia solution are mixed, and the pH value of the mixed solution is controlled to be 8-9.

9. The method of mineralizing CO2 with forsterite according to claim 1, characterized in that, In step S4, the volume fraction of CO2 in the CO2-containing gas is 10-90%.

10. The method of mineralizing CO2 with forsterite according to claim 1, characterized in that, In step S4, the obtained ammonium sulfate solution is crystallized to obtain ammonium sulfate solid, which is repeatedly used.

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