Preparation method of calcium-manganese-based adsorbent, calcium-manganese-based adsorbent and its application

Abstract

The present invention discloses a new method for carbon reduction and resource utilization of steel slag, belonging to the technical field of resources and environment. First, the steel slag is mixed with dilute nitric acid under stirring conditions for a certain time to achieve the leaching of all elements in the steel slag; then, sodium hydroxide is added to the leaching solution to adjust the pH value, and the main elements iron, silicon, and aluminum are precipitated and separated in one step; a certain amount of calcium carbonate powder is added to the separation solution, and then a soluble carbonate solution is added to adjust the pH value until the coprecipitation of calcium and manganese elements is achieved. After solid-liquid separation, a precursor solid is obtained. The precursor solid is dried and calcined to obtain a calcium-manganese-based adsorbent. The treatment process of the present invention is simple and low-cost, can realize the large-scale resource utilization of steel slag, and improves the reaction activity and cycle stability of the absorbent, and is an ideal absorbent for capturing CO2 in industrial flue gas.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of carbon capture materials, and relates to a preparation method of a calcium-manganese-based adsorbent using steel slag as a raw material, the calcium-manganese-based adsorbent, and its application. Background Art

[0002] Due to the intensification of global climate change and the increase in extreme weather, the capture and separation of CO2 not only has important strategic significance but also concerns the survival of humanity. As the main carbon emission source, industrial flue gas carbon capture is an important way to save energy, reduce emissions, and achieve the goal of carbon neutrality in industrial production. Calcium oxide-based adsorbents have the advantages of high theoretical carbon capacity, wide source, and low cost, and are considered to be ideal flue gas carbon capture materials. However, during the initial multiple cycles of CO2 capture by adsorption and desorption of pure calcium oxide prepared by calcining natural limestone, serious deactivation phenomena occur with the increase of particle size. A large number of studies have shown that adding certain inert substances such as manganese, cerium, aluminum, and titanium between calcium oxide particles can greatly improve the deactivation problem. However, the reported preparation processes are relatively complex and the raw material costs are relatively high, and they do not have the prospect of industrial application.

[0003] Steel slag is a solid waste discharged after steelmaking. Most of this solid waste is used as a roadbed backfill material, and its utilization rate has been very low, which not only occupies a large amount of urban land but also causes serious pollution to the environment and air.

[0004] The applicant has found through a large number of experiments that the methods for preparing calcium-based carbon capture materials using steel slag in the prior art mostly adopt the acetic acid leaching process, the refining process is relatively complex, and it is impossible to avoid the poisoning effect of harmful elements on calcium oxide, and the overall development cost is very high. And the ammonium-based solution leaching process in the prior art cannot achieve the full leaching of metal elements.

[0005] Therefore, it is necessary to develop a preparation method of a calcium-manganese-based adsorbent using steel slag as a raw material, which can not only simply carry out step-by-step resource recovery treatment on steel slag, but also prepare a calcium-manganese-based carbon capture material with high stability, and at the same time achieve the dual goals of steel slag resource utilization and carbon emission reduction. Summary of the Invention

[0006] In order to achieve the above dual goals of steel slag resource utilization and carbon emission reduction, the present invention provides a new method for step-by-step recovery of valuable resources from steel slag and preparation of a carbon capture adsorbent, and provides a calcium-manganese-based carbon capture material based on steel slag, which can stably and cyclically capture CO2 from industrial flue gas.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] First technical solution: A preparation method of a calcium-manganese-based adsorbent using steel slag as a raw material, the method comprising the following steps: (1) Leaching the steel slag containing calcium, silicon, iron, manganese, magnesium, and aluminum elements with a dilute nitric acid solution, filtering out the residue to obtain a full-element leaching solution; (2) Gradually adding an aqueous sodium hydroxide solution to the full-element leaching solution, adjusting the pH value to 5 ≤ pH ≤ 5.5. At this time, one-step precipitation of silicon, iron, and aluminum elements is achieved to obtain a calcium-manganese-magnesium mixed enrichment solution; (3) Adding insoluble calcium carbonate powder to the calcium-manganese-magnesium mixed enrichment solution, and gradually adding a soluble carbonate solution dropwise under stirring conditions, adjusting the pH value to 8.5 ≤ pH ≤ 9.0. At this time, coprecipitation of manganese and calcium elements is achieved, and after solid-liquid separation, a calcium-manganese-based precursor is obtained; (4) After washing, drying, and calcining the calcium-manganese-based precursor, a calcium-manganese-based adsorbent material is obtained.

[0009] The technical solution of the present invention uses the solid waste steel slag from iron and steel smelting as a raw material, wherein the steel slag is converter slag. The total content of oxides of Ca, Si, Al, Mg, Fe, and Mn elements in the steel slag reaches 80-95%, by mass fraction. The steel slag composition includes: 37-59% CaO, 9-20% SiO2, 5-20% FeO, 1.3-10% MnO, 0.6-8% MgO, 0.1-2.5% Al2O3, and other impurities.

[0010] In this technical solution, a suitable dilute nitric acid solution is used to leach the steel slag to obtain a leaching solution and leaching residue. The calcium, silicon, iron, manganese, magnesium, and aluminum elements in the steel slag are dissolved in the leaching solution, that is, a full-element leaching solution is obtained, while impurities such as vanadium and chromium remain in the leaching residue in the form of precipitates. Different from the prior art using acetic acid solution as the leaching solvent, in order to increase the leaching amount of manganese, the applicant has proved through a large number of experiments that under the condition of low-concentration nitric acid, it is beneficial to significantly increase the content of manganese element in the leaching solution. Preferably, the dilute nitric acid solution is selected from dilute nitric acid with a concentration of 5-15 wt%. To further improve the leaching efficiency, before step (1), the steel slag can be mechanically crushed and ball-milled to obtain steel slag with a particle size ≤ 1 mm, or leaching can be carried out under some auxiliary conditions such as normal temperature and pressure, high temperature and pressure, or continuous multi-stage leaching method can also be used for leaching.

[0011] The leaching time and leaching temperature are not particularly limited as long as the calcium, silicon, iron, manganese, magnesium, and aluminum elements in the steel slag can be fully leached. Preferably, the leaching temperature is 25-45 °C, and the leaching time is 2-4 hours. The leaching time of 2 hours is the minimum time required to completely leach the calcium, silicon, iron, manganese, magnesium, and aluminum elements in the steel slag. The longer the leaching time, the more calcium, silicon, iron, manganese, magnesium, and aluminum elements in the leaching system. When the leaching time reaches 4 hours, the leaching system has reached equilibrium.

[0012] In this technical solution, an alkaline sodium hydroxide aqueous solution is added dropwise to the full-element leaching solution to adjust the pH value to 5 ≤ pH ≤ 5.5. Silicon, iron, and aluminum elements are mainly precipitated in the form of silicon hydroxide, silicic acid, iron silicate, iron hydroxide, ferrous hydroxide, iron-rich minerals, and aluminum hydroxide. Through precise pH regulation, high-efficiency recovery of iron, aluminum, and silicon elements can be achieved in one step, with a recovery rate of over 98%. After filtering out the solid precipitates, a calcium-manganese-magnesium mixed enriched solution is obtained. Calcium carbonate powder is added to the calcium-manganese-magnesium mixed enriched solution, and then a carbonate solution is used as a precipitating agent. Under normal temperature and magnetic stirring conditions, the soluble carbonate solution is added dropwise to the calcium-manganese-magnesium mixed enriched solution to adjust the pH value to 8.5 ≤ pH ≤ 9.0. At this time, calcium and manganese elements are mainly precipitated in the form of calcium carbonate, calcium bicarbonate, manganese carbonate, and manganese bicarbonate. Through precise pH regulation, calcium-manganese coprecipitation can be achieved, and the calcium-manganese recovery rate is over 98%. After solid-liquid separation, a filtrate and a calcium-manganese-based precursor are obtained, while magnesium elements are enriched in the filtrate.

[0013] Any suitable solid-liquid separation technique can be used, including filtration, sedimentation, centrifugation, cyclone separation, elution, etc. The present invention should not be considered limited to the specific solid-liquid separation technique used.

[0014] In the above step (1), the solid-liquid ratio of the steel slag to the dilute acid solution ranges from 1:(5 - 20) g / mL, preferably 1:(10 - 20) g / mL, and more preferably 1:(15 - 20) g / mL. The applicant has demonstrated through a large number of experiments that the leaching amounts of calcium and manganese metal elements both increase gradually with the increase of the solid-liquid ratio. According to the present invention, not only good manganese leaching effects can be obtained when the leaching solid-liquid ratio is high, but also when the leaching solid-liquid ratio is less than 1:20 g / mL, the concentration of manganese elements in the obtained leaching solution is still sufficient to prepare the calcium-manganese-based adsorbent.

[0015] After the extraction in the above step (1), the calcium-manganese molar ratio (by element) in the full-element leaching solution is (6 - 10):1.

[0016] As a preferred solution, in the above step (3), the soluble carbonate is one or more of potassium carbonate and sodium carbonate.

[0017] As a preferred solution, in the above step (3), the addition amount of calcium carbonate is 1.7 - 3 times the mass of the steel slag. The calcium carbonate is derived from any one or more of limestone, marble, calcite, light calcium powder, or nano-calcium carbonate.

[0018] As a preferred solution, in the above step (4), the calcination treatment is as follows: after the precursor is ground evenly, it is placed in a muffle furnace and calcined at 750 - 900 °C for 1 - 4 hours. The sample obtained after calcination is the calcium-manganese-based adsorbent.

[0019] The second technical solution is a calcium-manganese-based adsorbent prepared by the preparation method of the calcium-manganese-based adsorbent using steel slag as the raw material as described above.

[0020] The third technical solution is an application of a calcium-manganese-based adsorbent with a CO2 cyclic capture function in the adsorption and capture of CO2. The calcium-manganese-based adsorbent is prepared by the preparation method of the calcium-manganese-based adsorbent using steel slag as the raw material as described above.

[0021] The fourth technical solution is a carbon capture process, which is characterized in that it uses the above-mentioned calcium-manganese-based adsorbent to adsorb and capture CO2.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention discloses a preparation method of a calcium-manganese-based adsorbent for carbon capture. The preparation method mainly realizes a high leaching rate of calcium and manganese elements by performing a full leaching treatment on the soluble elements in steel slag with dilute nitric acid. Through precise pH regulation, using the characteristics of different metal hydroxides precipitating out at different pH values, the high-efficiency recovery of high-grade iron, aluminum, and silicon elements is achieved in one step, and the recovery rate is as high as 98%. The treatment process is simple and easy to operate, and the reagents used have low costs. The recovered iron, aluminum, and silicon can be further purified to alleviate the current shortage of corresponding elements. Then, insoluble carbonates (such as calcium carbonate) are added. Using the principle of precipitation conversion, manganese ions are precipitated as carbonates with lower solubility. Then, soluble carbonates (such as sodium carbonate and potassium carbonate) are added. Through precise pH regulation, the remaining manganese ions and calcium ions in the water that have not precipitated are precipitated as insoluble carbonates, realizing the synchronous precipitation of manganese and calcium.

[0024] 2. Calcium and manganese are the main elements contained in the calcium-manganese-based adsorbent of the present invention. Due to the need for material functions, the present invention adopts relatively favorable leaching conditions during the acid leaching of steel slag to ensure the leaching efficiency of manganese elements, and then regulates the proportion of manganese elements in the obtained calcium-manganese-based precursor.

[0025] 3. CaO is carbonated into CaCO3 at high temperature and then regenerated into CaO after thermal decarbonization. The exothermic carbonation reaction and endothermic calcination reaction of calcium oxide and CO2 form a cyclic process as shown in equations (1) and (2), and this process is also called the calcium cycle:

[0026] CaO(s) + CO2(g) → CaCO3(s) (1)

[0027] CaCO3(s) → CaO(s) + CO2(g) (2);

[0028] Under the reasonable calcium-manganese ratio of the present invention, the calcium-manganese based adsorbent can achieve a single CO2 adsorption capacity as high as 0.56 g / g. After 20 cycles, the adsorption capacity of the calcium-manganese based carbon capture material for CO2 is still as high as 0.51 g / g. After 30 cycles, the adsorption capacity of the calcium-manganese based carbon capture material for CO2 is still as high as 0.48 g / g. That is, after 30 cycles, the adsorption capacity attenuation does not exceed 15%. Compared with the 70% attenuation of commercial calcium carbonate after 30 cycles, the cyclic stability of the adsorbent prepared in the present invention is improved significantly. Description of the Drawings

[0029] Figure 1 SEM image of the calcium-manganese based adsorbent prepared according to Example 21 of the present invention;

[0030] Figure 2 CO2 adsorption cycle curve of the calcium-manganese based adsorbent prepared according to Example 21 of the present invention. Detailed Description of the Invention

[0031] The technical solutions of the present invention are further described below by way of examples.

[0032] Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meaning understood by those with ordinary skills in the field to which the present invention belongs.

[0033] All terms (including technical terms or scientific terms) used in the present disclosure have the same meaning as understood by those of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in a general dictionary, such as those, should be understood to have a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an idealized or overly formal sense, unless specifically defined as such herein.

[0034] For technologies, methods, and devices known to those of ordinary skill in the relevant art, they may not be discussed in detail, but in appropriate cases, the said technologies, methods, and devices should be regarded as part of the specification.

[0035] The steel slag used in the following examples comes from Maanshan Iron & Steel Co., Ltd., Anhui Province, China. After ball milling, crushing, screening, and drying, steel slag powders with two particle size ranges of <0.1 mm, 0.1 mm ≤ particle size < 0.5 mm, and 0.5 mm ≤ particle size ≤ 1 mm are obtained by screening. An XRF-1800 type X-ray fluorescence analyzer (Shimadzu, Japan) is used to quantitatively determine the elemental composition (expressed in the form of oxides) and content of the steel slag powder. After measuring 3 times and taking the average value, the results are shown in Table 1:

[0036] Table 1 Full Elemental Composition of Steel Slag Samples

[0037]

[0038] Example 1

[0039] Step 1 Acid Leaching: Add 5 g of steel slag sample 2 into 100 mL of dilute nitric acid solution with a concentration of 9.5 wt%, stir on a magnetic stirrer at a speed of 500 r / min for leaching treatment, the leaching temperature is 40 °C, and the leaching time is 2 hours. Then filter out the residue to obtain the leachate;

[0040] Step 2 First-step Precipitation of the Leachate: Prepare a sodium hydroxide solution with a concentration of 1 wt%, dropwise add it into the leachate, and continuously detect the pH value of the solution. Stop adding when the pH value reaches 5.5; then perform suction filtration to separate the silicon, iron, and aluminum elements of the first-step precipitation to obtain a mixed enrichment solution;

[0041] Step 3 Second-step Precipitation of the Leachate: Add 10 g of calcium carbonate powder into the mixed enrichment solution, stir continuously, prepare a sodium carbonate solution with a concentration of 1 wt%, dropwise add it into the mixed enrichment solution, and continuously detect the pH value of the solution. Stop adding when the pH value reaches 9.0; then perform suction filtration, and wash and dry the separated solid to obtain the precursor;

[0042] Step 4 Calcination Treatment: After grinding the precursor evenly, put it into a muffle furnace and calcine it at 900 °C for 1.5 hours. The sample obtained after calcination is the calcium-manganese-based adsorbent.

[0043] Example 2

[0044] The difference between Example 2 and Example 1 is that in Step 1, the dilute nitric acid with a mass concentration of 9.5 wt% is replaced by dilute nitric acid with a mass concentration of 5 wt%.

[0045] Example 3

[0046] The difference between Example 3 and Example 1 is that in Step 1, the dilute nitric acid with a mass concentration of 9.5 wt% is replaced by dilute nitric acid with a mass concentration of 15 wt%.

[0047] Example 4

[0048] The difference between Example 4 and Example 1 is that in Step 1, 100 mL is replaced by 75 mL, that is, the solid-liquid ratio of 1:20 g / mL is replaced by 1:15 g / mL.

[0049] Example 5

[0050] Example 5 is different from Example 1 in that in step 1, 100 mL is replaced with 50 mL, that is, the solid-liquid ratio of 1:20 g / mL is replaced with 1:10 g / mL.

[0051] Example 6

[0052] Example 6 is different from Example 1 in that in step 1, 100 mL is replaced with 25 mL, that is, the solid-liquid ratio of 1:20 g / mL is replaced with 1:5 g / mL.

[0053] Example 7

[0054] Example 7 is different from Example 1 in that in step 1, the leaching temperature of 40 °C is replaced with a leaching temperature of 45 °C.

[0055] Example 8

[0056] Example 8 is different from Example 1 in that in step 1, the leaching temperature of 40 °C is replaced with a leaching temperature of 25 °C.

[0057] Example 9

[0058] Example 9 is different from Example 1 in that in step 1, the leaching time of 2 hours is replaced with a leaching time of 4 hours.

[0059] Example 10

[0060] Example 10 is different from Example 1 in that in step 1, the leaching time of 2 hours is replaced with a leaching time of 3 hours.

[0061] Example 11

[0062] Example 11 is different from Example 1 in that in step 2, the addition is stopped when the pH value reaches 5.5 is replaced with the addition is stopped when the pH value reaches 5.

[0063] Example 12

[0064] Example 12 is different from Example 1 in that in step 3, 10 g of calcium carbonate powder is replaced with 8.5 g of calcium carbonate powder.

[0065] Example 13

[0066] Example 13 is different from Example 1 in that in step 3, 10 g of calcium carbonate powder is replaced with 15 g of calcium carbonate powder.

[0067] Example 14

[0068] Example 14 is different from Example 1 in that in step 3, the addition is stopped when the pH value reaches 9.0 is replaced with the addition is stopped when the pH value reaches 8.5.

[0069] Example 15

[0070] Example 15 is different from Example 1 in that in step 4, 900 °C is replaced by 750 °C.

[0071] Example 16

[0072] Example 16 is different from Example 1 in that in step 4, 900 °C is replaced by 800 °C.

[0073] Example 17

[0074] Example 17 is different from Example 1 in that in step 4, 1.5 hours is replaced by 1 hour.

[0075] Example 18

[0076] Example 18 is different from Example 1 in that in step 4, 1.5 hours is replaced by 4 hours.

[0077] Example 19

[0078] Example 19 is different from Example 1 in that in step 1, steel slag sample 3 is replaced by steel slag sample 2.

[0079] Example 20

[0080] Step 1 Acid leaching: Add 5 g of steel slag sample 2 to 100 mL of 10 wt% dilute nitric acid solution, stir on a magnetic stirrer at a speed of 500 r / min for leaching treatment, the leaching temperature is 40 °C, and the leaching time is 2 hours. Then filter out the residue by suction filtration to obtain the leaching solution;

[0081] Step 2 First-step precipitation of the leaching solution: Prepare a 1 wt% sodium hydroxide solution, add it dropwise to the leaching solution, and continuously detect the pH value of the solution. Stop adding when the pH value reaches 5.2; then perform suction filtration to separate the silicon, iron, and aluminum elements of the first-step precipitation to obtain a mixed enriched solution;

[0082] Step 3 Second-step precipitation of the leaching solution: Add 12 g of calcium carbonate powder to the mixed enriched solution, stir continuously, prepare a 1 wt% sodium carbonate solution, add it dropwise to the mixed enriched solution, and continuously detect the pH value of the solution. Stop adding when the pH value reaches 9.0; then perform suction filtration, and wash and dry the separated solid to obtain the precursor;

[0083] Step 4 Calcination treatment: After the precursor is ground evenly, put it into a muffle furnace and calcine at 900 °C for 1.5 hours. The sample obtained after calcination is the calcium-manganese-based adsorbent.

[0084] Example 21

[0085] Step 1 Acid leaching: Add 5 g of steel slag sample 2 into 100 mL of dilute nitric acid solution with a concentration of 9.5 wt%, stir on a magnetic stirrer at a speed of 500 r / min for leaching treatment, with the leaching temperature being 40 °C and the leaching time being 2 hours. Then filter out the residue by suction filtration to obtain the leaching solution;

[0086] Step 2 First precipitation of the leaching solution: Prepare a sodium hydroxide solution with a concentration of 1 wt%, dropwise add it into the leaching solution, and continuously detect the pH value of the solution. Stop dropping when the pH value reaches 5.0; then perform suction filtration to separate the silicon, iron, and aluminum elements in the first-step precipitation to obtain the mixed enrichment solution;

[0087] Step 3 Second precipitation of the leaching solution: Add 9 g of calcium carbonate powder into the mixed enrichment solution, stir continuously, prepare a sodium carbonate solution with a concentration of 1 wt%, dropwise add it into the mixed enrichment solution, and continuously detect the pH value of the solution. Stop dropping when the pH value reaches 9.0; then perform suction filtration, and wash and dry the separated solid to obtain the precursor;

[0088] Step 4 Calcination treatment: After grinding the precursor evenly, put it into a muffle furnace and calcine it at 900 °C for 1.5 hours. The sample obtained after calcination is the calcium-manganese-based adsorbent.

[0089] Comparative Example 1

[0090] The difference between Comparative Example 1 and Example 1 is that in Step 1, the dilute nitric acid with a mass concentration of 9.5 wt% is replaced with an acetic acid solution with a mass concentration of 20 wt%.

[0091] Comparative Example 2

[0092] The difference between Comparative Example 2 and Example 1 is that in Step 1, the dilute nitric acid with a mass concentration of 9.5 wt% is replaced with an ammonium-based solution with a concentration of 0.5 mol / L, and the operations in Steps 2 - 4 are no longer carried out.

[0093] Comparative Example 3

[0094] The difference between Comparative Example 3 and Example 1 is that in Step 1, 100 mL is replaced with 125 mL, that is, the solid-liquid ratio of 1:20 g / mL is replaced with 1:25 g / mL.

[0095] Comparative Example 4

[0096] The difference between Comparative Example 4 and Example 1 is that in Step 1, 100 mL is replaced with 20 mL, that is, the solid-liquid ratio of 1:20 g / mL is replaced with 1:4 g / mL.

[0097] Comparative Example 5

[0098] In Comparative Example 5, different from Example 1, in Step 1, the leaching temperature of 40°C was replaced with a leaching temperature of 55°C.

[0099] Comparative Example 6

[0100] In Comparative Example 6, different from Example 1, in Step 2, the addition was stopped when the pH reached 5.5 was replaced with the addition was stopped when the pH reached 4.5.

[0101] Comparative Example 7

[0102] In Comparative Example 7, different from Example 1, in Step 3, 10 g of calcium carbonate powder was replaced with no addition of calcium carbonate powder.

[0103] Comparative Example 8

[0104] In Comparative Example 8, different from Example 1, in Step 3, 10 g of calcium carbonate powder was replaced with 7.5 g of calcium carbonate powder.

[0105] Comparative Example 9

[0106] In Comparative Example 9, different from Example 1, in Step 3, the addition was stopped when the pH reached 9.0 was replaced with the addition was stopped when the pH reached 9.5.

[0107] Comparative Example 10

[0108] In Comparative Example 10, different from Example 1, in Step 3, the addition was stopped when the pH reached 9.0 was replaced with the addition was stopped when the pH reached 8.0.

[0109] Comparative Example 11

[0110] In Comparative Example 11, different from Example 1, in Step 1, steel slag sample 3 was replaced with steel slag sample 1.

[0111] <Example and Comparative Example Test>

[0112] I. The contents of calcium, manganese, magnesium, silicon, iron, and aluminum in the leachate obtained in Step 1 above were determined using the ICP method, and the results are shown in Table 2.

[0113] Table 2

[0114]

[0115]

[0116] It can be seen from the data in Table 2 that:

[0117] Compared with Example 1, in Comparative Example 1, instead of using dilute nitric acid as the acid leaching reagent, a 20 wt% acetic acid solution was used, resulting in the manganese element leaching concentration in Comparative Example 1 being only 35.4% of that in Example 1.

[0118] Comparative Example 2 is compared with Example 1. In Comparative Example 1, dilute nitric acid was not used as the acid leaching reagent, but an ammonium-based solution with a concentration of 0.5 mol / L was used, resulting in the leaching concentration of manganese in Comparative Example 2 being only 12.5% of that in Example 1.

[0119] Comparative Examples 3 and 4 are compared with Example 1. In Comparative Example 3, the amount of the acid leaching reagent was excessive, but the leaching concentration of manganese in Comparative Example 3 was slightly lower than that in Example 1. Considering the production cost, a solid-liquid ratio of 1:20 g / mL was significantly better than a solid-liquid ratio of 1:25 g / mL; in Comparative Example 4, the amount of the acid leaching reagent was too small, and the leaching concentration of manganese in Comparative Example 4 could not meet the requirements for preparing the calcium-manganese-based adsorbent.

[0120] Comparative Example 5 is compared with Example 1. In Comparative Example 5, the leaching temperature was too high, but the leaching concentration of manganese at the leaching temperature in Comparative Example 5 was much lower than that in Example 1. Considering the production cost, a leaching temperature of 40 °C was significantly better than a leaching temperature of 55 °C.

[0121] Comparative Example 11 is compared with Example 1. The MnO in the raw materials used in Comparative Example 11 was lower than that in Example 1, and the leaching concentration of manganese in Comparative Example 11 was only 68.4% of that in Example 1.

[0122] II. The contents of silicon, iron, and aluminum in the mixed enrichment liquid obtained in Step 2 above were measured by ICP method, and the results are shown in Table 3.

[0123] Table 3

[0124]

[0125] It can be seen from the data in Table 3 that:

[0126] Comparative Example 6 is compared with Example 1. Through precise pH regulation in Example 1, the high-efficiency recovery of iron, aluminum, and silicon elements can be achieved in one step, with a recovery rate of over 99%; while the recovery rate of iron in Comparative Example 6 was only about 64%, and the recovery rates of aluminum and silicon elements were also much lower than those in Example 1.

[0127] III. The contents of calcium and manganese in the filtrate obtained in Step 3 above were measured by ICP method, and the results are shown in Table 4.

[0128] Table 4

[0129]

[0130] It can be seen from the data in Table 4 that:

[0131] Comparative Example 7 is compared with Example 1. Without adding calcium carbonate powder and without adding insoluble calcium carbonate in Comparative Example 7, a large amount of manganese ions remained in the enrichment liquid, and only by dropping soluble carbonate could not completely precipitate out manganese ions and calcium ions.

[0132] Compared with Example 1, in Comparative Example 8, the addition amount of calcium carbonate powder was reduced, and there were still some manganese ions remaining in the enriched solution. Only by dropping soluble carbonate, manganese ions and calcium ions could not be completely precipitated.

[0133] Compared with Example 1, in Comparative Example 9, the pH value was too high. The residual amounts of calcium and manganese in the filtrate of Comparative Example 9 were basically the same as those in Example 1. Considering the production cost, it was preferably stopped dropping when the pH value reached 9.0. Compared with Example 1, in Comparative Example 10, the pH value was too low, and manganese ions and calcium ions could not be completely precipitated.

[0134] IV. Commercial calcium carbonate (purchased from Shanghai Hanhong Technology Co., Ltd., product number RE01010253) was processed according to "Step 4 Calcination treatment: After the precursor was ground evenly, it was put into a muffle furnace and calcined at 900 °C for 1.5 hours" to obtain a commercial adsorbent. The adsorbents obtained in Example 1, Examples 20 - 21 and Comparative Examples 1 - 11 were used to conduct carbonation-calcination cycle CO2 capture performance tests with the above commercial adsorbent, and the CO2 adsorption amounts for the first time, after 20 cycles and after 30 cycles were calculated, as well as the adsorption capacity attenuation percentages after 20 cycles and after 30 cycles. The results are shown in Table 5.

[0135] Table 5

[0136]

[0137] It can be seen from the data in Table 5 that:

[0138] Compared with commercial calcium carbonate, the calcium-manganese-based adsorbent can achieve a single CO2 adsorption capacity as high as 0.56 g / g. After 20 cycles, the adsorption capacity of the calcium-manganese-based cyclic carbon capture material for CO2 is still as high as 0.51 g / g. After 30 cycles, the adsorption capacity of the calcium-manganese-based cyclic carbon capture material for CO2 is still as high as 0.48 g / g. That is, after 30 cycles, the adsorption capacity attenuation does not exceed 15%. Compared with the 80% attenuation of commercial calcium carbonate after 30 cycles, the cyclic stability of the adsorbent prepared in the present invention is improved very significantly.

[0139] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a calcium-manganese-based adsorbent using steel slag as a raw material, characterized in that, The method includes the following steps: (1) Leach the steel slag containing calcium, silicon, iron, manganese, magnesium, and aluminum elements with a dilute nitric acid solution, filter out the residue, and obtain a full-element leachate; (2) Dropwise add an aqueous sodium hydroxide solution to the full-element leachate, adjust the pH value to 5 ≤ pH ≤ 5.

5. At this time, one-step precipitation of silicon, iron, and aluminum elements is achieved, and a calcium-manganese-magnesium mixed enriched solution is obtained; (3) Add insoluble calcium carbonate powder to the calcium-manganese-magnesium mixed enriched solution. Under stirring conditions, dropwise add a soluble carbonate solution, and adjust the pH value to 8.5 ≤ pH ≤ 9.

0. At this time, coprecipitation of manganese and calcium elements is achieved, and a calcium-manganese-based precursor is obtained after solid-liquid separation; (4) After washing, drying, and calcining the calcium-manganese-based precursor, a calcium-manganese-based adsorbent is obtained; In the step (1), the solid-liquid ratio of the steel slag to the dilute nitric acid solution ranges from 1:(5 - 20) g / mL; the leaching temperature is 25 - 45 °C; The dilute nitric acid solution is selected from dilute nitric acid with a concentration of 5 - 15 wt%.

2. The method according to claim 1, wherein In step (1), the solid-liquid ratio of the steel slag to the dilute nitric acid solution ranges from 1:(10 - 20) g / mL.

3. The method according to claim 1, wherein In step (1), the solid-liquid ratio of the steel slag to the dilute nitric acid solution ranges from 1:(15 - 20) g / mL.

4. The method according to claim 1, characterized in that In step (3), the soluble carbonate is one or several of potassium carbonate and sodium carbonate.

5. The method according to claim 1, characterized in that In step (3), the addition amount of the calcium carbonate is 1.7 - 3 times the mass of the steel slag.

6. The method according to claim 1, wherein In step (4), the calcination treatment is as follows: After grinding the precursor evenly, put it into a muffle furnace and calcine it at 750 - 900 °C for 1 - 4 hours. The sample obtained after calcination is the calcium-manganese-based adsorbent.

7. The method according to claim 1, wherein In step (1), the leaching time is 2 - 4 hours.

8. A calcium-manganese-based adsorbent, characterized in that, It is prepared by the method for preparing a calcium-manganese-based adsorbent using steel slag as a raw material according to any one of claims 1 - 7.

9. Application of a calcium-manganese-based adsorbent with CO2 cyclic capture function in adsorbing and capturing CO2, characterized in that, The calcium-manganese-based adsorbent is prepared by the method for preparing a calcium-manganese-based adsorbent using steel slag as a raw material according to any one of claims 1 - 7.

10. A carbon capture process, characterized in that, It adsorbs and captures CO2 by using the calcium-manganese-based adsorbent as described in claim 8.

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