A method for resource utilization of steel slag and carbon dioxide

Abstract

The application provides a resource utilization method of steel slag and carbon dioxide, and relates to the technical field of steel slag recycling. The resource utilization method is as follows: the steel slag is crushed and screened to obtain coarse-grained steel slag and fine mud; a carbonated inorganic salt solution and water are added to the coarse-grained steel slag, and the mixture is stirred to obtain a steel slag slurry; the steel slag slurry is placed in a reactor with a distributed electric field, CO2 gas is introduced and stirred, and an induced carbonation reaction is carried out, and then solid-liquid separation is performed to obtain carbonated steel slag precipitate and inorganic salt solution; the carbonated steel slag precipitate is screened to obtain coarse-grained carbonated steel slag and carbonated fine mud, the coarse-grained carbonated steel slag is used as machine-made sand, and the carbonated fine mud and the fine mud are jointly floated and separated to obtain calcium concentrate and magnesium concentrate; and the inorganic salt solution is recycled as an inorganic salt solution. The application innovates the method for strengthening the carbonation depth, the products obtained by indirect carbonation and the inorganic salt solution can be efficiently utilized, and the application is conducive to large-scale industrial production and popularization and use.

Description

Technical Field

[0001] This invention relates to the technical field of steel slag recycling, and more particularly to a method for the resource utilization of steel slag and carbon dioxide. Background Technology

[0002] Currently, there is no ideal solution for the disposal or resource utilization of steel slag generated from steel manufacturing.

[0003] Currently, the main method for reusing steel slag from steel manufacturing is to grind the tailings from magnetic separation and use it as a concrete admixture. However, the amount of steel slag used as an admixture is less than 10% of the total concrete volume, resulting in extremely low utilization. Furthermore, the saturation of the construction market and the limited consumption of concrete in recent years have restricted the large-scale application of steel slag admixture technology in concrete.

[0004] In recent years, the production practice of using steel slag for mine backfilling has been carried out one after another, but this utilization method is limited by underground mining and it is difficult to solve the problem of steel slag utilization from a global perspective.

[0005] Some steel slag recycling processes use solution-induced methods, but these require high-cost organic solutions such as amino acids. Therefore, there is an urgent need to develop universal resource utilization technologies for steel slag.

[0006] For example, Chinese patent CN116040973A discloses a method for preparing carbonized modified steel slag with improved hydration activity, as well as modified steel slag and active admixtures for cement-based cementitious materials. In this method, a large amount of high-cost amino acids are used to induce modification. The reaction process occurs between active calcium oxide, magnesium oxide and CO2 gas in the steel slag, which cannot achieve deep carbonization of the steel slag. The utilization rate of steel slag is low, and the proportion of modified steel slag in cementitious materials is mostly around 10%.

[0007] In order to make better use of steel slag, Chinese patent CN219217860U discloses a steel slag sulfidation and carbonization device. Although the device can adsorb carbon dioxide and sulfur dioxide at the same time using steel slag as raw material, the carbonization still cannot achieve deep carbonization of steel slag, resulting in low utilization rate of steel slag. Moreover, the purpose is to improve the mechanical strength of recycled aggregate from steel slag, which obviously results in low utilization rate of steel slag.

[0008] Although Chinese patent CN114538806A discloses a hydrated carbonization composite hardening cementitious material based on steel slag and its preparation method, the utilization rate of steel slag in the prepared hydrated carbonization composite hardening cementitious material is only about 42%. It requires magnetic iron separation of the raw materials and uses relatively expensive quicklime. The utilization rate of steel slag is obviously not very high, and it cannot fully, rationally and effectively utilize the steel slag and the materials in the preparation process.

[0009] Chinese patent CN115448628A discloses a carbonized porous steel slag aggregate and its preparation method. The aggregate consists of 45-68% steel slag powder, 15-30% rapid-hardening sulfur-alumina cement, 15-20% carbide slag, and 2-5% paraffin powder. The preparation process requires heating, granulation, and dewaxing, and the curing and carbonization times are also relatively long. Furthermore, the steel slag powder requires special treatment. The carbonization depth is increased by adding solid waste carbide slag and dewaxing, which increases the time and number of process steps. This is especially evident in the secondary carbonization reaction, which also increases production costs and results in low production efficiency.

[0010] Chinese patent CN115340306A discloses a method for preparing carbonized steel slag by capturing carbon dioxide using hypergravity. This method requires operating a high-cost hypergravity rotating packed bed for the carbonization process. However, the utilization rate of the prepared carbonized steel slag powder in cement products is only up to 30%, indicating a low utilization rate. Furthermore, the obtained solid carbonized steel slag requires drying and grinding, which increases production costs. The use of a hypergravity field further increases the cost and makes it unsuitable for industrial production.

[0011] Chinese patent CN113955999A discloses a retro brick prepared based on steel slag carbonization and its preparation method. It uses steel slag in the preparation of retro bricks. However, according to calculations, the proportion of dry frying in the raw materials is about 37-47%, which is obviously not high and does not achieve the technical effect of overall comprehensive utilization. Moreover, the carbonization treatment needs to be combined with the hydration treatment of fly ash, which prolongs the process time. It also needs to consider the traditional carbonization pressure, which makes the operation difficult and inefficient. Summary of the Invention

[0012] The technical problem to be solved by this invention is that current steel slag recycling technologies have technical defects such as high cost, low utilization rate, complex preparation process, high operation difficulty, long process and low efficiency. Moreover, most carbonization deepening methods adopt the method of adding materials and increasing production costs, which cannot achieve the overall comprehensive utilization of steel slag and are not suitable for industrial production.

[0013] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0014] A method for the resource utilization of steel slag and carbon dioxide, comprising the following steps:

[0015] S1. The steel slag is crushed and screened to obtain coarse steel slag and fine mud;

[0016] S2. Add carbonate-containing inorganic salt solution and water to the coarse steel slag of S1, and stir to obtain steel slag slurry.

[0017] S3. Place the steel slag slurry from S2 into a reactor with a distributed electric field, introduce CO2 gas and stir to induce a carbonization reaction, and then separate the solid and liquid to obtain carbonized steel slag precipitate and inorganic salt solution.

[0018] S4. The carbide steel slag sediment from S3 is screened to obtain coarse carbide steel slag and fine carbide mud. The coarse carbide steel slag is used as manufactured sand. The fine carbide mud and the fine mud from S1 are combined by flotation to separate calcium concentrate and magnesium concentrate.

[0019] S5. The inorganic salt solution of S3 is recycled as the inorganic salt solution of S2.

[0020] Preferably, the coarse steel slag in S1 has a particle size of 0.3-4.75 mm, and the fine mud has a particle size of no more than 0.3 mm.

[0021] Preferably, the carbonate-containing inorganic salt solution in S2 includes at least one of sodium carbonate, lithium carbonate, potassium carbonate, and carbonate-containing industrial waste liquid, and the solid concentration of the steel slag slurry is 100-865 g / L.

[0022] Preferably, the inorganic salt solution containing carbonate in S2 is an industrial waste liquid containing 2.3-56 g / L of carbonate, and the solid concentration of the steel slag slurry is 300-500 g / L.

[0023] Preferably, the carbonate-containing inorganic salt solution in S2 is an industrial waste liquid containing 33.6-39.2 g / L of carbonate. Alkali metal carbonates act as inducing agents to enhance the reaction between steel slag slurry and CO2 under the action of an electric field. The carbonate is provided by both steel slag and alkali metal carbonates. During the preparation process, the amount of alkali metal carbonate added is determined by measuring the mass dispersion of carbonates in the slurry.

[0024] Preferably, the process parameters of the distributed electric field in reactor S3 are set such that the current density flowing through the slurry cross-section is 1.21-555 A / m. 2 The volume percentage of CO2 gas introduced is 8.9-99.6%.

[0025] Preferably, the process parameters of the distributed electric field in reactor S3 are set such that the current density flowing through the slurry cross-section is 5-350 A / m. 2 The CO2 gas is obtained by simultaneously reducing CO2 emissions from CO2-rich gas enriched from flue gas, with CO2 accounting for 30-99.6% of the gas by volume.

[0026] Preferably, under the influence of the distributed electric field in reactor S3, carbonate ions in the solution move directionally, increasing the probability of their interaction with active calcium oxide and magnesium oxide in the particles; however, the electric field strength exceeds 350 A / m. 2 The electrolysis reaction is intense, consuming carbonate ions in the solution.

[0027] Preferably, the stirring in S3 includes mechanical stirring, electromagnetic stirring, or gas stirring.

[0028] Preferably, the carbonization reaction time in S3 is 3-72 hours, more preferably 10-30 hours; the total carbon content of the steel slag increases by 2-13% after carbonization.

[0029] Preferably, the solid-liquid separation in S3 is at least one of sedimentation, coagulation, and filtration.

[0030] Preferably, the coarse-grained carbonized steel slag in S4 is composed of silicates, aluminosilicates and newly formed calcite minerals, with a particle size of 0.3-4.75 mm; the fine carbonized mud is mostly calcite, with a particle size not exceeding 0.3 mm.

[0031] Preferably, the carbide steel slag in S4 meets the Class II sand requirements of "Construction Sand" (GB / T 14684); the calcium concentrate and magnesium concentrate are calcite and magnesite, respectively, with calcite having a CaO content of 53.96-55.25% and a calcite content of 90.75-93% (total carbon content of 10.89-11.16%); and magnesite having an MgO content of 52.23-55.27% and a magnesite content of 87.06-92.11%.

[0032] Technical principle of this invention:

[0033] This invention provides a method for the resource utilization of steel slag and carbon dioxide. First, the steel slag is crushed. CO2 gas is introduced into the steel slag slurry. An inorganic salt solution is used as an inducer to enhance the reaction between the steel slag slurry and CO2 under the action of an electric field, and the slurry is stirred. An electric field is distributed in the container holding the inorganic salt solution and the steel, and current flows through the cross-section of the slurry. After carbonization, the residue is separated from the inorganic salt solution through sedimentation, coagulation, and filtration. Coarse-grained carbonized steel slag is screened out for use as manufactured sand, while fine sludge is used to separate calcite and magnesite. The inorganic salt solution is recycled.

[0034] In this invention, an inorganic salt solution containing carbonate ions is used as the inducing medium to induce indirect carbonation. Indirect carbonation occurs in the presence of CO3 in activated calcium oxide, magnesium oxide, and an inorganic salt solution containing carbonate ions. 2- In between, CO2 gas introduced into an inorganic salt solution containing carbonate reacts with the solution to regenerate CO3. 2- Carbonization efficiency is significantly improved, and steel slag can be comprehensively utilized.

[0035] The above technical solution has at least the following advantages compared with the existing technology:

[0036] The above-mentioned solution proposes a method for the resource utilization of steel slag and carbon dioxide, which can solve the technical defects of existing steel slag recycling technologies, such as high cost, low utilization rate, complex preparation process, high operation difficulty, long process and low efficiency, so that steel slag can achieve resource utilization of all components.

[0037] This invention enhances the reaction between traditional steel slag slurry and CO2 under the action of an electric field by using an inorganic salt solution containing carbonate ions as an inducer. This transforms the direct carbonization of steel slag with CO2 into indirect carbonization, effectively strengthening not only the carbonization depth of the steel slag but also significantly enhancing its stability and activity. This solves the technical problem of poor stability of steel slag particles and the inability of the product to be directly used as manufactured sand.

[0038] The present invention provides a method for reusing steel slag that effectively utilizes both the prepared carbide steel slag precipitate and inorganic salt solution. The amount of steel slag that can be disposed of is higher than that used in the production of concrete, cement, and antique bricks. Moreover, the process is not complicated, easy to operate, has low production costs, and a short process, which is conducive to large-scale production.

[0039] In summary, compared with other traditional methods, the method of this invention innovates a method to enhance the carbonization depth. The product and inorganic salt solution obtained by the indirect carbonization method can be efficiently utilized, with a wide range of applications. The process is simple, and the utilization method is low-cost and highly efficient, which is conducive to large-scale industrial production and widespread use. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a process flow diagram of a method for the resource utilization of steel slag and carbon dioxide according to the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0043] A method for the resource utilization of steel slag and carbon dioxide, wherein the method for the resource utilization of steel slag and carbon dioxide is combined with Figure 1 The following steps are required:

[0044] S1. The steel slag is crushed and screened to obtain coarse steel slag and fine mud;

[0045] S2. Add carbonate-containing inorganic salt solution and water to the coarse steel slag of S1, and stir to obtain steel slag slurry.

[0046] S3. Place the steel slag slurry from S2 into a reactor with a distributed electric field, introduce CO2 gas and stir to induce a carbonization reaction, and then separate the solid and liquid to obtain carbonized steel slag precipitate and inorganic salt solution.

[0047] S4. The carbide steel slag sediment from S3 is screened to obtain coarse carbide steel slag and fine carbide mud. The coarse carbide steel slag is used as manufactured sand. The fine carbide mud and the fine mud from S1 are combined by flotation to separate calcium concentrate and magnesium concentrate.

[0048] S5. The inorganic salt solution of S3 is recycled as the inorganic salt solution of S2.

[0049] Specifically, the particle size of coarse steel slag in S1 is 0.3-4.75 mm, and the particle size of fine mud does not exceed 0.3 mm.

[0050] Specifically, the carbonate-containing inorganic salt solution in S2 includes at least one of sodium carbonate, lithium carbonate, potassium carbonate, and carbonate-containing industrial waste liquid, and the solid concentration of the steel slag slurry is 100-865 g / L.

[0051] Specifically, the carbonate-containing inorganic salt solution in S2 is an industrial waste liquid containing 2.3-56 g / L of carbonate, and the solid concentration of the steel slag slurry is 300-500 g / L.

[0052] Specifically, the carbonate-containing inorganic salt solution in S2 is an industrial waste liquid containing 33.6-39.2 g / L of carbonate. Alkali metal carbonates act as inducing agents, enhancing the reaction between steel slag slurry and CO2 under the influence of an electric field. The carbonate is provided by both steel slag and alkali metal carbonates. The amount of alkali metal carbonate added is determined by measuring the mass dispersion of carbonate in the slurry during the preparation process.

[0053] Specifically, the process parameters for the distributed electric field in reactor S3 need to be set so that the current density flowing through the slurry cross-section is 1.21-555 A / m. 2 The volume percentage of CO2 gas introduced is 8.9-99.6%.

[0054] Specifically, the process parameters for the distributed electric field in reactor S3 need to be set so that the current density flowing through the slurry cross-section is 5-350 A / m. 2The CO2 gas is obtained by simultaneously reducing CO2 emissions from CO2-rich gas enriched from flue gas, with CO2 accounting for 30-99.6% of the gas by volume.

[0055] Specifically, in reactor S3, the distributed electric field causes carbonate ions in the solution to move directionally, increasing their chances of interacting with active calcium oxide and magnesium oxide in the particles; however, the electric field strength exceeds 350 A / m. 2 The electrolysis reaction is intense, consuming carbonate ions in the solution.

[0056] Specifically, the stirring in S3 includes mechanical stirring, electromagnetic stirring, or gas stirring.

[0057] Specifically, the induction time for carbonization reaction in S3 is 3-72 h, more preferably 10-30 h; the total carbon content of the steel slag increases by 2-13% after carbonization.

[0058] Specifically, in S3, solid-liquid separation includes at least one of sedimentation, coagulation, and filtration.

[0059] Specifically, the coarse-grained carburized steel slag in S4 is composed of silicates, aluminosilicates and newly formed calcite minerals, with a particle size of 0.3-4.75 mm; the fine carburized mud is mostly calcite, with a particle size of no more than 0.3 mm.

[0060] Specifically, the carbide steel slag in S4 meets the Class II sand requirements of "Construction Sand" (GB / T 14684); the calcium concentrate and magnesium concentrate are calcite and magnesite, respectively, with calcite having a CaO content of 53.96-55.25% and a calcite content of 90.75-93% (total carbon content of 10.89-11.16%); and magnesite having an MgO content of 52.23-55.27% and a magnesite content of 87.06-92.11%.

[0061] Example 1

[0062] A method for the resource utilization of steel slag and carbon dioxide, wherein the method for the resource utilization of steel slag and carbon dioxide is combined with Figure 1 The following steps are required:

[0063] S1. 10 kg of steel slag is crushed and screened to obtain coarse steel slag and fine mud. The particle size of the coarse steel slag is 0.3-4.75 mm, and the particle size of the fine mud does not exceed 0.3 mm. Among them, the steel slag is untreated converter steel slag from a certain place in Northeast China. After multiple tests, its main components by mass percentage are: TFe 15.25-26.16%, Ca 13.21-27.92%, Mg 2.01-9.86%, SiO2 21.39-25.72%.

[0064] S2. Add sodium carbonate industrial waste liquid containing >2g / L carbonate and water to the coarse steel slag in S1, and stir to obtain steel slag slurry. The solid concentration of the steel slag slurry is 123.2-131.5g / L. Determine whether the carbonate content in the sodium carbonate industrial waste liquid is 2.3g / L. If not, add sodium carbonate to make up the difference.

[0065] S3. The steel slag slurry from S2 is placed in a reactor with a distributed electric field. CO2 gas with a concentration between 39.29% and 50.6% is introduced and the slurry is stirred under high pressure for 63-72 hours to induce carbonization. After carbonization, the total carbon content of the carbonized steel slag increases by 2-5%. Solid-liquid separation is then performed to obtain carbonized steel slag precipitate and an inorganic salt solution. The current density flowing through the cross-section of the steel slag slurry is controlled at 555 A / m. 2 Solid-liquid separation includes at least one of sedimentation, coagulation, and filtration;

[0066] S4. The carbide steel slag sediment from S3 is screened to obtain coarse carbide steel slag and fine carbide mud. The coarse carbide steel slag is composed of silicates, aluminosilicates and newly formed calcite minerals, with a particle size of 0.3-4.75 mm. The fine carbide mud is mostly calcite, with a particle size of no more than 0.3 mm. Therefore, the coarse carbide steel slag is used as manufactured sand, and the fine carbide mud and the fine mud from S1 are combined by flotation to separate calcite and magnesite.

[0067] S5. The inorganic salt solution of S3 is recycled as the inorganic salt solution of S2.

[0068] The calcite product has a CaO content of 53.96% and a calcite content of 92.25% (total carbon content of 11.07%); the magnesite product has an MgO content of 52.23% and a magnesite content of 87.06%; and the carbonized steel slag product meets the Class I sand requirements of "Construction Sand" (GB / T 14684).

[0069] Example 2

[0070] A method for the resource utilization of steel slag and carbon dioxide, wherein the method for the resource utilization of steel slag and carbon dioxide is combined with Figure 1 The following steps are required:

[0071] S1. 10 kg of steel slag is crushed and screened to obtain coarse steel slag and fine mud. The particle size of the coarse steel slag is 0.3-4.75 mm, and the particle size of the fine mud does not exceed 0.3 mm. Among them, the steel slag is electric furnace steel slag from a factory in North China. After multiple tests, its main components, by mass percentage, are: TFe 18.39-27.26%, Ca 13.21-27.92%, Mg 2.01-9.86%, SiO2 21.39-25.72%.

[0072] S2. Add sodium carbonate industrial waste liquid containing >10g / L carbonate and water to the coarse steel slag in S1, and stir to obtain steel slag slurry. The solid concentration of the steel slag slurry is 220-230g / L. Determine whether the carbonate content in the sodium carbonate industrial waste liquid is 16g / L. If not, add sodium carbonate to make up the difference.

[0073] S3. The steel slag slurry from S2 is placed in a reactor with a distributed electric field. CO2 gas with a concentration between 39.29% and 50.6% is introduced, and the slurry is stirred by an impeller for 45-56 hours to induce a carbonization reaction. After carbonization, the total carbon content of the carbonized steel slag increases by 5-6%. Then, solid-liquid separation is performed to obtain carbonized steel slag precipitate and inorganic salt solution. The current density flowing through the cross-section of the steel slag slurry is controlled at 350 A / m. 2 Solid-liquid separation includes at least one of sedimentation, coagulation, and filtration; the stirring speed is 50-125 rpm;

[0074] S4. The carbide steel slag sediment from S3 is screened to obtain coarse carbide steel slag and fine carbide mud. The coarse carbide steel slag is composed of silicates, aluminosilicates and newly formed calcite minerals, with a particle size of 0.3-4.75 mm. The fine carbide mud is mostly calcite, with a particle size of no more than 0.3 mm. Therefore, the coarse carbide steel slag is used as manufactured sand, and the fine carbide mud and the fine mud from S1 are combined by flotation to separate calcite and magnesite.

[0075] S5. The inorganic salt solution of S3 is recycled as the inorganic salt solution of S2.

[0076] The calcite product has a CaO content of 55.25% and a calcite content of 93% (total carbon content of 11.16%); the magnesite product has an MgO content of 53.16% and a magnesite content of 88.54%; and the carbide steel slag product meets the Class II sand requirements of "Construction Sand" (GB / T 14684).

[0077] Example 3

[0078] A method for the resource utilization of steel slag and carbon dioxide, wherein the method for the resource utilization of steel slag and carbon dioxide is combined with Figure 1 The following steps are required:

[0079] S1. 10 kg of steel slag is crushed and screened to obtain coarse steel slag and fine mud. The particle size of the coarse steel slag is 0.3-4.75 mm, and the particle size of the fine mud does not exceed 0.3 mm. Among them, the steel slag is hot-quenched steel slag from a factory in Northwest China. After multiple tests, its main components, by mass percentage, are: TFe 16.27-23.35%, Ca 12.23-26.81%, Mg 4.21-9.27%, SiO2 21.39-25.72%.

[0080] S2. Add sodium carbonate industrial waste liquid containing >30g / L carbonate and water to the coarse steel slag in S1, and stir to obtain steel slag slurry. The solid concentration of the steel slag slurry is 220-230g / L. Determine whether the carbonate content in the sodium carbonate industrial waste liquid is 36g / L. If not, add sodium carbonate to make up the difference.

[0081] S3. Place the steel slag slurry from S2 into a reactor with a distributed electric field, introduce CO2 gas with a concentration between 38% and 50%, and stir the steel slag slurry with an impeller for 10-22 hours to induce a carbonization reaction. After carbonization, the total carbon content of the carbonized steel slag increases by 6-8%. Then, solid-liquid separation is performed to obtain carbonized steel slag precipitate and inorganic salt solution. The current density flowing through the cross-section of the steel slag slurry is controlled at 150 A / m. 2 Solid-liquid separation includes at least one of sedimentation, coagulation, and filtration; the stirring speed is 50-125 rpm;

[0082] S4. The carbide steel slag sediment from S3 is screened to obtain coarse carbide steel slag and fine carbide mud. The coarse carbide steel slag is composed of silicates, aluminosilicates and newly formed calcite minerals, with a particle size of 0.3-4.75 mm. The fine carbide mud is mostly calcite, with a particle size of no more than 0.3 mm. Therefore, the coarse carbide steel slag is used as manufactured sand, and the fine carbide mud and the fine mud from S1 are combined by flotation to separate calcite and magnesite.

[0083] S5. The inorganic salt solution of S3 is recycled as the inorganic salt solution of S2.

[0084] The calcite product has a CaO content of 54.91% and a calcite content of 90.75% (total carbon content of 10.89%); the magnesite product has an MgO content of 55.27% and a magnesite content of 92.11%; and the carbide steel slag product meets the Class I sand requirements of "Construction Sand" (GB / T 14684).

[0085] Comparative Example 1:

[0086] In the induced carbonization reaction of step S3 in this comparative example, the distributed electric field inside the reactor as in Example 1 was not applied, and the other steps were the same as in Example 1.

[0087] The calcite product was found to have a CaO content of 55.63% and a calcite content of 85.42% (total carbon content 10.25%); the magnesite product had an MgO content of 53.61% and a magnesite content of 89.35%; the grades of calcite and magnesite were slightly lower than those in Example 3, and the carbonized steel slag product only met the Class II sand requirements of "Construction Sand" (GB / T 14684).

[0088] Comparative Example 2:

[0089] In step S2 of this comparative example, coarse-grained steel slag with a particle size of 0.3 mm to 4.75 mm was placed in sodium carbonate industrial waste liquid containing 0 g / L carbonate ions to obtain a steel slag slurry. During the treatment process, the solid concentration in the slurry was 123.2-131.5 g / L, and the mass fraction of carbonate ions in the steel slag slurry was determined to be 0%. Other experimental procedures were the same as in Example 1.

[0090] The CaO content of the calcite product was determined to be 43.96%, and the calcite content was 78.5% (total carbon content 9.42%). The grades of calcite and magnesite were lower than those in Example 3, and the product did not meet the requirements of various grades of sand in "Construction Sand" (GB / T 14684).

[0091] Example 4

[0092] A method for the resource utilization of steel slag and carbon dioxide, wherein the method for the resource utilization of steel slag and carbon dioxide is combined with Figure 1 The following steps are required:

[0093] S1. 10 kg of steel slag is crushed and screened to obtain coarse steel slag and fine mud. The particle size of the coarse steel slag is 0.3-4.75 mm, and the particle size of the fine mud does not exceed 0.3 mm. Among them, the steel slag is hot-quenched steel slag from a factory in Northwest China. After multiple tests, its main components, by mass percentage, are: TFe 23.41-24.63%, CaO 12.23-26.81%, MgO 8.45-9.31%, SiO 29.36-11.23%.

[0094] S2. Add sodium carbonate industrial waste liquid containing >50g / L carbonate and water to the coarse steel slag in S1, and stir to obtain steel slag slurry. The solid concentration of the steel slag slurry is 865g / L. Determine whether the carbonate content in the sodium carbonate industrial waste liquid is 56g / L. If not, add sodium carbonate to make up the difference.

[0095] S3. The steel slag slurry from S2 is placed in a reactor with a distributed electric field. CO2 gas with a concentration between 38% and 50% is introduced, and the slurry is stirred by an impeller for 3-6 hours to induce a carbonization reaction. After carbonization, the total carbon content of the carbonized steel slag increases by 8-9%. Solid-liquid separation is then performed to obtain carbonized steel slag precipitate and an inorganic salt solution. The current density flowing through the cross-section of the steel slag slurry is controlled at 1.21 A / m. 2 Solid-liquid separation includes at least one of sedimentation, coagulation, and filtration; the stirring speed is 50-125 rpm;

[0096] S4. The carbide steel slag sediment from S3 is screened to obtain coarse carbide steel slag and fine carbide mud. The coarse carbide steel slag is composed of silicates, aluminosilicates and newly formed calcite minerals, with a particle size of 0.3-4.75 mm. The fine carbide mud is mostly calcite, with a particle size of no more than 0.3 mm. Therefore, the coarse carbide steel slag is used as manufactured sand, and the fine carbide mud and the fine mud from S1 are combined by flotation to separate calcite and magnesite.

[0097] S5. The inorganic salt solution of S3 is recycled as the inorganic salt solution of S2.

[0098] The calcite product has a CaO content of 54.73% and a calcite content of 92.41%; the magnesite product has an MgO content of 55.36% and a magnesite content of 92.37%; and the carbide steel slag product meets the Class I sand requirements of "Construction Sand" (GB / T 14684).

[0099] Example 5

[0100] A method for the resource utilization of steel slag and carbon dioxide, wherein the method for the resource utilization of steel slag and carbon dioxide is combined with Figure 1 The following steps are required:

[0101] S1. 10 kg of steel slag is crushed and screened to obtain coarse steel slag and fine mud. The particle size of the coarse steel slag is 0.3-4.75 mm, and the particle size of the fine mud does not exceed 0.3 mm. Among them, the steel slag is hot-quenched steel slag from a factory in Northwest China. After multiple tests, its main components, by mass percentage, are: TFe 23.41-24.63%, CaO 12.23-26.81%, MgO 8.45-9.31%, SiO 29.36-11.23%.

[0102] S2. Add sodium carbonate industrial waste liquid containing >50g / L carbonate and water to the coarse steel slag in S1, stir to obtain steel slag slurry, the solid concentration of the steel slag slurry is 350g / L; determine whether the carbonate content in the sodium carbonate industrial waste liquid is 56g / L, if not, add sodium carbonate to make up the difference.

[0103] S3. The steel slag slurry from S2 is placed in a reactor with a distributed electric field. CO2 gas with a concentration between 38% and 50% is introduced, and the slurry is stirred by an impeller for 6-8 hours to induce a carbonization reaction. After carbonization, the total carbon content of the carbonized steel slag increases by 6-7%. Then, solid-liquid separation is performed to obtain carbonized steel slag precipitate and inorganic salt solution. The current density flowing through the cross-section of the steel slag slurry is controlled at 58 A / m. 2 Solid-liquid separation includes at least one of sedimentation, coagulation, and filtration; the stirring speed is 50-60 rpm;

[0104] S4. The carbide steel slag sediment from S3 is screened to obtain coarse carbide steel slag and fine carbide mud. The coarse carbide steel slag is composed of silicates, aluminosilicates and newly formed calcite minerals, with a particle size of 0.3-4.75 mm. The fine carbide mud is mostly calcite, with a particle size of no more than 0.3 mm. Therefore, the coarse carbide steel slag is used as manufactured sand, and the fine carbide mud and the fine mud from S1 are combined by flotation to separate calcite and magnesite.

[0105] S5. The inorganic salt solution of S3 is recycled as the inorganic salt solution of S2.

[0106] The calcite product has a CaO content of 54.25% and a calcite content of 89.27%; the magnesite product has an MgO content of 55.12% and a magnesite content of 91.89%; and the carbide steel slag product meets the Class I sand requirements of "Construction Sand" (GB / T 14684).

[0107] Example 6

[0108] A method for the resource utilization of steel slag and carbon dioxide, wherein the method for the resource utilization of steel slag and carbon dioxide is combined with Figure 1 The following steps are required:

[0109] S1. 10 kg of steel slag is crushed and screened to obtain coarse steel slag and fine mud. The particle size of the coarse steel slag is 0.3-4.75 mm, and the particle size of the fine mud does not exceed 0.3 mm. Among them, the steel slag is hot-quenched steel slag from a factory in Northwest China. After multiple tests, its main components, by mass percentage, are: TFe 23.41-24.63%, CaO 12.23-26.81%, MgO 8.45-9.31%, SiO 29.36-11.23%.

[0110] S2. Add sodium carbonate industrial waste liquid containing >10g / L carbonate and water to the coarse steel slag in S1, stir to obtain steel slag slurry, the solid concentration of the steel slag slurry is 100g / L; determine whether the carbonate content in the sodium carbonate industrial waste liquid is 25g / L, if not, add sodium carbonate to make up the difference.

[0111] S3. The steel slag slurry from S2 is placed in a reactor with a distributed electric field. CO2 gas with a concentration between 38% and 50% is introduced, and the slurry is stirred by an impeller for 10-15 hours to induce a carbonization reaction. After carbonization, the total carbon content of the carbonized steel slag increases by 8-9%. Then, solid-liquid separation is performed to obtain carbonized steel slag precipitate and inorganic salt solution. The current density flowing through the cross-section of the steel slag slurry is controlled at 100 A / m. 2 Solid-liquid separation includes at least one of sedimentation, coagulation, and filtration; the stirring speed is 50-60 rpm;

[0112] S4. The carbide steel slag sediment from S3 is screened to obtain coarse carbide steel slag and fine carbide mud. The coarse carbide steel slag is composed of silicates, aluminosilicates and newly formed calcite minerals, with a particle size of 0.3-4.75 mm. The fine carbide mud is mostly calcite, with a particle size of no more than 0.3 mm. Therefore, the coarse carbide steel slag is used as manufactured sand, and the fine carbide mud and the fine mud from S1 are combined by flotation to separate calcite and magnesite.

[0113] S5. The inorganic salt solution of S3 is recycled as the inorganic salt solution of S2.

[0114] The calcite product has a CaO content of 54.11% and a calcite content of 88.97%; the magnesite product has an MgO content of 55.36% and a magnesite content of 93.76%; and the carbide steel slag product meets the Class I sand requirements of "Construction Sand" (GB / T 14684).

[0115] The above-mentioned solution proposes a method for the resource utilization of steel slag and carbon dioxide, which can solve the technical defects of existing steel slag recycling technologies, such as high cost, low utilization rate, complex preparation process, high operation difficulty, long process and low efficiency, so that steel slag can achieve resource utilization of all components.

[0116] This invention enhances the reaction between traditional steel slag slurry and CO2 under the action of an electric field by using an inorganic salt solution containing carbonate ions as an inducer. This transforms the direct carbonization of steel slag with CO2 into indirect carbonization, effectively strengthening not only the carbonization depth of the steel slag but also significantly enhancing its stability and activity. This solves the technical problem of poor stability of steel slag particles and the inability of the product to be directly used as manufactured sand.

[0117] The present invention provides a method for reusing steel slag that effectively utilizes both the prepared carbide steel slag precipitate and inorganic salt solution. The amount of steel slag that can be disposed of is higher than that used in the production of concrete, cement, and antique bricks. Moreover, the process is not complicated, easy to operate, has low production costs, and a short process, which is conducive to large-scale production.

[0118] In summary, compared with other traditional methods, the method of this invention innovates a method to enhance the carbonization depth. The product and inorganic salt solution obtained by the indirect carbonization method can be efficiently utilized, with a wide range of applications. The process is simple, and the utilization method is low-cost and highly efficient, which is conducive to large-scale industrial production and widespread use.

[0119] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for the resource utilization of steel slag and carbon dioxide, characterized in that, The method for resource utilization of steel slag and carbon dioxide is as follows: S1. The steel slag is crushed and screened to obtain coarse steel slag and fine mud; S2. Add carbonate-containing inorganic salt solution and water to the coarse steel slag of S1, and stir to obtain steel slag slurry. S3. Place the steel slag slurry from S2 into a reactor with a distributed electric field, introduce CO2 gas and stir to induce a carbonization reaction, and then separate the solid and liquid to obtain carbonized steel slag precipitate and inorganic salt solution. S4. The carbide steel slag sediment from S3 is screened to obtain coarse carbide steel slag and fine carbide mud. The coarse carbide steel slag is used as manufactured sand. The fine carbide mud and the fine mud from S1 are combined by flotation to separate calcium concentrate and magnesium concentrate. S5. The inorganic salt solution of S3 is recycled as the inorganic salt solution of S2.

2. The method for resource utilization of steel slag and carbon dioxide according to claim 1, characterized in that, The particle size of coarse steel slag in S1 is 0.3-4.75 mm, and the particle size of fine mud does not exceed 0.3 mm.

3. The method for resource utilization of steel slag and carbon dioxide according to claim 1, characterized in that, The carbonate-containing inorganic salt solution in S2 includes at least one of sodium carbonate, lithium carbonate, potassium carbonate, and carbonate-containing industrial waste liquid, and the solid concentration of the steel slag slurry is 100-865 g / L.

4. The method for resource utilization of steel slag and carbon dioxide according to claim 1, characterized in that, The inorganic salt solution containing carbonate in S2 is an industrial waste liquid containing 2.3-56 g / L of carbonate, and the solid concentration of the steel slag slurry is 300-500 g / L.

5. The method for resource utilization of steel slag and carbon dioxide according to claim 1, characterized in that, The process parameters for the distributed electric field in reactor S3 need to be set so that the current density flowing through the slurry cross-section is 1.21-555 A / m. 2 The volume percentage of CO2 gas introduced is 8.9-99.6%.

6. The method for resource utilization of steel slag and carbon dioxide according to claim 1, characterized in that, The process parameters for the distributed electric field in reactor S3 need to be set so that the current density flowing through the slurry cross-section is 5-350 A / m. 2 The CO2 gas is obtained by simultaneously reducing CO2 emissions from CO2-rich gas enriched from flue gas, with CO2 accounting for 30-99.6% of the gas by volume.

7. The method for resource utilization of steel slag and carbon dioxide according to claim 1, characterized in that, Stirring in S3 includes mechanical stirring, electromagnetic stirring, or gas stirring.

8. The method for resource utilization of steel slag and carbon dioxide according to claim 1, characterized in that, In S3, solid-liquid separation includes at least one of sedimentation, coagulation, and filtration.

9. The method for resource utilization of steel slag and carbon dioxide according to claim 1, characterized in that, S4 coarse-grained carburized steel slag is composed of silicates, aluminosilicates and newly formed calcite minerals, with a particle size of 0.3-4.75 mm; the fine carburized mud is mostly calcite, with a particle size not exceeding 0.3 mm.

10. The method for resource utilization of steel slag and carbon dioxide according to claim 1, characterized in that, In S4, the calcium concentrate and magnesium concentrate are calcite and magnesite, respectively. The calcite has a CaO content of 53.96-55.25% and a total carbon content of 10.89-11.16%, accounting for 90.75-93% of the total. The magnesite has an MgO content of 52.23-55.27% and accounts for 87.06-92.11% of the total.

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