Method for extracting valuable components in refining slag

Abstract

The invention discloses a method for extracting valuable components in refining slag, and belongs to the technical field of solid waste resource utilization. The method comprises the steps of refining slag leaching, CO2 mineralization, silicon oxide product separation, aluminum oxide product separation and the like, efficient leaching of valuable components in the solid waste is achieved by using ammonium bisulfate as a circulating auxiliary and adopting an indirect mineralization means, and finally the refining slag solid waste is converted into products such as light carbonate, silicon oxide and aluminum oxide, so that the method is suitable for industrial production. The method can be used as a building material and a raw material for iron and steel smelting, and solves the problems of low utilization rate of refining slag, low reaction efficiency in the valuable component extraction process, difficult auxiliary recovery, high process energy consumption and the like in the prior art. According to the method, resource utilization of valuable components such as calcium, magnesium, aluminum and silicon in the refining slag can be achieved, CO2 emission reduction in the iron and steel industry can be achieved, and good economic benefits and environmental benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization, and specifically relates to a method for extracting valuable components in refined slag. Background Art

[0002] Refined slag is the residual waste slag produced in the process of steel refining. Its main components are solid slag such as calcium oxide, aluminum oxide, and silicon oxide that have not yet reacted completely. It may also contain a small amount of other metals such as iron, manganese, chromium, and their oxides, sulfides, phosphides and other non-metallic impurities. It can be seen that the composition of refined slag is relatively complex and contains a variety of harmful elements and impurities, which makes it difficult to handle. At present, the annual discharge of refined slag in the country is as high as 20 million tons, of which only about 7 million tons are effectively utilized for the production of slag cement, slag powder and other building materials; the remaining 13 million tons of refined slag are piled up for treatment and have not been effectively disposed of and utilized. At present, nearly 100 million tons of refined slag are piled up in the country. If not properly handled, the heavy metals in the refined slag may penetrate into the soil and water bodies, causing heavy metal pollution; the stacking of tailings may also occupy a large amount of land resources and affect the ecological environment. Therefore, in response to the major needs of low-carbon and solid waste management in the steel industry, it is necessary to reasonably handle and utilize refined slag, which is of great significance for protecting the environment and achieving sustainable utilization of resources.

[0003] Common methods for treating refining tailings include direct use as paving materials, brick making, and foundation backfill, which has a great impact on the environment; stabilization of the refined slag, such as using high-pressure steam to stabilize the refined slag, and direct carbon fixation stabilization, but the refined slag is still difficult to use after stabilization; separation and resource utilization of the refined slag, such as alkali separation and treatment to prepare 4A molecular sieves, but the product market capacity is small and the application is limited. The existing methods for treating and utilizing refined slag have certain limitations. Therefore, developing a more efficient green resource utilization technology for refined slag is an urgent problem to be solved. Summary of the invention

[0004] In view of the above-mentioned prior art, the present invention provides a method for extracting valuable components from refined slag, which solves the problems of low utilization rate of refined slag, low reaction efficiency during valuable component extraction, difficulty in recovering additives, and high process energy consumption in the prior art.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: to provide a method for extracting valuable components in refined slag, comprising the following steps:

[0006] (1) leaching of refined slag: a mixture of refined slag and hydrogen sulfate and water is prepared into a refined slag slurry at a liquid-to-solid ratio of 0.70-1.60 mL:1 g, and the mineralized liquid phase product obtained in step (2) is added thereto, and stirred at a speed of 400-600 rpm for 10-60 min at 40-60° C. to obtain a leaching slurry; the leaching slurry is subjected to solid-liquid separation to obtain a leaching filtrate and a leaching filter cake; the refined slag is a refined slag containing calcium oxide, magnesium oxide, aluminum oxide and silicon oxide; the mass ratio of hydrogen sulfate to refined slag is 2.5-4.0:1;

[0007] (2) CO2 mineralization: At a temperature of 20 to 30°C and a stirring speed of 400 to 600 rpm, a CO2 gas with a volume concentration of 10% to 100% is introduced into the leaching filtrate for 0.5 to 2.0 hours to obtain a mineralized slurry; the mineralized slurry is subjected to solid-liquid separation to obtain a light carbonate product and a mineralized liquid product;

[0008] (3) Separation of silicon oxide product: preparing a dissolving slurry with a sulfuric acid solution and a leached filter cake according to a liquid-solid ratio of 2 to 5 mL:1 g; performing solid-liquid separation on the dissolving slurry to obtain a silicon oxide product and a filtrate; the concentration of the sulfuric acid solution is 1.2 to 1.8 mol / L;

[0009] (4) Separation of alumina products: adding an alkaline solvent to the filtrate at a temperature of 20 to 30°C and a stirring speed of 400 to 600 rpm until the pH of the solution is 7 to 9 to obtain an alkaline precipitate slurry; subjecting the alkaline precipitate slurry to solid-liquid separation, collecting and calcining the solid phase product to obtain an alumina product; the concentration of the alkaline solvent is 2.5 to 3.5 mol / L, and the alkaline solvent is aqueous ammonia, sodium bicarbonate solution or organic amine solution.

[0010] The beneficial effect of the above technical solution adopted by the present invention is: the present invention uses ammonium bisulfate as a circulation aid and adopts indirect mineralization to achieve efficient leaching of valuable components in solid waste, including the steps of leaching valuable components of refined slag, mineralization separation of calcium and magnesium components, separation of silicon oxide and separation of aluminum oxide, and finally converting the refined slag solid waste into light carbonate, silicon oxide and aluminum oxide products, which can be used as building materials and raw materials for steel smelting. This method can not only realize the resource utilization of magnesium oxide, calcium oxide, aluminum oxide and silicon oxide in waste slag, but also realize carbon emission reduction in the steel industry, and has the characteristics of green and low carbon, high economic benefits, and recycling of process by-products and raw materials. This method mainly involves two main reactions: preparing carbonate by mineralization reaction and preparing aluminum oxide by reaction of ammonium aluminum sulfate and ammonia water.

[0011] (1) The principle of preparing carbonate by mineralization reaction includes the following three steps:

[0012] ① Mg in refined slag 2+ , Ca 2+Dissolve into solution,

[0013] CaO+2H + →Ca 2+ +H2O (1)

[0014] MgO+2H + →Mg 2+ +H2O (2)

[0015] ②CO2 in the gas phase dissolves into the water phase.

[0016] CO2+H2O→H2CO3 (3)

[0017]

[0018]

[0019] ③CO3 in water phase 2- and Mg 2+ , Ca 2+ Produce magnesium carbonate and calcium carbonate,

[0020]

[0021]

[0022] (2) The principle of preparing alumina by the reaction of ammonium aluminum sulfate and ammonia water is as follows:

[0023] NH4Al(SO4)2+3NH3·H2O→AlOOH+2(NH4)2 SO4+H2O (8)

[0024] AlOOH→Al2O3+H2O (9)

[0025] Based on the above technical solution, the present invention can also be improved as follows.

[0026] Furthermore, the total content of calcium oxide and magnesium oxide in the refined slag exceeds 45wt%; its particle size does not exceed 200 meshes; the bisulfate is ammonium bisulfate, potassium bisulfate or sodium bisulfate, the liquid-to-solid ratio of the mixture of the refined slag and the bisulfate to water is 0.94-1.20mL:1g, and the mass ratio of the bisulfate to the refined slag is 3.2-4.0:1.

[0027] Furthermore, the hydrogen sulfate is ammonium hydrogen sulfate, and the liquid-to-solid ratio of the mixture of the refined slag, the ammonium hydrogen sulfate and water is 0.94 mL:1 g.

[0028] Furthermore, a gas containing CO2 is introduced into the leaching filtrate by bubbling, with a gas flow rate of 0.1 to 0.2 m 3 / h.

[0029] Furthermore, the calcination temperature is 650-750° C., and the calcination time is 1.5-2.5 hours; and the organic amine solution is ethanolamine solution or N-methyldiethanolamine solution.

[0030] Furthermore, the calcination temperature is 700°C and the calcination time is 2h.

[0031] Furthermore, the solid-liquid separation methods in steps (1) to (4) are all natural precipitation, filtration, centrifugation or suction filtration.

[0032] Furthermore, the method of liquid-solid separation is suction filtration.

[0033] Furthermore, after solid-liquid separation in steps (2) to (4), the solid phase product is washed and dried at a temperature of 60° C. for 24 h.

[0034] Furthermore, in step (1), the stirring temperature is 50° C., the stirring speed is 500 rpm, the time is 30 min, and the mass ratio of hydrogen sulfate to refined slag is 3.2:1; in step (2), the stirring temperature is 30° C., the stirring speed is 500 rpm; the volume concentration of CO2 in the gas introduced into the leaching filtrate is 12%, and the time is 0.5 h; in step (3), the concentration of sulfuric acid solution is 1.5 mol / L, and the liquid-solid ratio of sulfuric acid solution to leaching filter cake is 2 mL:1 g; in step (4), the stirring temperature is 30° C., the stirring speed is 500 rpm; the alkaline solvent is ammonia water with a concentration of 3 mol / L, and when the solution pH is 9, stirring is continued for 10 min to obtain an alkaline precipitation slurry.

[0035] The beneficial effect of the above further technical solution adopted by the present invention is that the method can efficiently extract components such as calcium, magnesium, silicon and aluminum in the refined slag, and make full use of the high calcium and magnesium components therein to absorb and mineralize CO2, which can simultaneously realize the resource utilization of solid waste and the mineralization and emission reduction of CO2. Since the direct CO2 mineralization reaction rate of refined slag is slow, the addition of additives in the mineralization process is inevitable. The method uses bisulfate as a circulating additive and adopts indirect mineralization to carbonate the calcium and magnesium active components in the refined slag, so that the efficient sealing of CO2 can be achieved while the ammonium bisulfate can be recycled, reducing the loss of additives.

[0036] The beneficial effects of the present invention are:

[0037] (1) The present invention makes comprehensive resource utilization of refined slag solid waste produced by metallurgy. The prepared light carbonate product can be used as building coating after modification, thereby improving the economic benefits of the process technology; the prepared silicon oxide product and aluminum oxide product can be used as raw materials for steel smelting, reducing the external demand for raw materials and realizing a green, circular, low-carbon economy.

[0038] (2) The content of calcium and magnesium components in the refined slag is relatively high. This method utilizes CO2 in industrial flue gas to undergo mineralization reaction with calcium and magnesium components, which has a high storage rate and low energy consumption, and achieves carbon emission reduction and coordinated refined slag solid waste management, which is of positive significance for energy conservation, carbon reduction and green production in the steel industry.

[0039] (3) In the process of leaching refined slag, bisulfate is used as a circulating auxiliary agent, and the refined slag is subjected to carbonation reaction by indirect mineralization, so that CO2 can be efficiently sealed and ammonium bisulfate can be recycled, reducing the loss of the auxiliary agent.

[0040] (4) In the process of preparing alumina products, ammonium aluminum sulfate is used as aluminum salt, and an alkaline solvent, such as ammonia water, is used as a precipitant to generate boehmite (AlOOH) by precipitation method. In this reaction, nitrogen is retained in the solution in the form of ammonium hydrogen sulfate, which can avoid the large amount of harmful gases such as SO3 and NH3 released by direct roasting of ammonium aluminum sulfate and the loss of nitrogen caused by it; boehmite is roasted to generate Al2O3 and H2O, and the roasting temperature is low, the energy consumption is low, and it is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The process flow chart of the method for extracting valuable components from refined slag includes: 1. ball mill; 2. first constant temperature heating magnetic stirrer; 3. first three-necked flask; 4. first vacuum pump; 5. first suction flask; 6. N2 gas cylinder; 7. CO2 gas cylinder; 8. first mass flowmeter; 9. second mass flowmeter; 10. second constant temperature heating magnetic stirrer; 11. second three-necked flask; 12. CO2 infrared online analyzer; 13. second suction flask; 14. second vacuum pump; 15. beaker; 16. third vacuum pump; 17. third suction flask; 18. third constant temperature heating magnetic stirrer; 19. third three-necked flask; 20. fourth vacuum pump; 21. fourth suction flask;

[0042] Figure 2 Thermogravimetric-mass spectrometry of the solid phase product after mineralization of the calcium and magnesium leaching solution in Example 2;

[0043] Figure 3 Specific surface area and pore size distribution diagram of the product AlOOH at different pH values; wherein A is the specific surface area of ​​AlOOH at pH 9, B is the pore size distribution diagram of AlOOH at pH 9, C is the specific surface area of ​​AlOOH at pH 10, and D is the pore size distribution diagram of AlOOH at pH 10;

[0044] Figure 4 The SEM images of the product AlOOH at different pH values; A is pH 9, B is pH 10;

[0045] Figure 5The specific surface area and pore size distribution diagram of the calcined product Al2O3 in Example 2, wherein A is the specific surface area and B is the pore size distribution diagram;

[0046] Figure 6 This is the SEM image of the calcined product Al2O3 in Example 2. DETAILED DESCRIPTION

[0047] The process flow of the method for extracting valuable components from refined slag is as follows: Figure 1 As shown, the process is as follows:

[0048] (1) Refined slag leaching process: the refined slag is crushed in a ball mill 1 to obtain refined slag powder; the refined slag powder is mixed with ammonium bisulfate and water to prepare a refined slag slurry; the refined slag slurry and the mineralized liquid phase product obtained in step (2) are added to a first three-necked flask 3, heated in a water bath by a first constant temperature heating magnetic stirrer 2 and stirred to obtain a leaching slurry; the leaching slurry is filtered by a first vacuum pump 4 and a first suction flask 5 to separate the solid and the liquid, and a leaching filtrate rich in calcium and magnesium and a leaching filter cake rich in silicon and aluminum are obtained.

[0049] When the refined slag leaching process is performed for the first time, the mineralized liquid phase product obtained in step (2) is not obtained, so the refined slag slurry is directly added to the first three-necked flask 3 for the first time and subsequent operations are performed; when the refined slag leaching process is performed for the second time and above, the mineralized liquid phase product obtained in step (2) has been obtained, so the refined slag slurry and the mineralized liquid phase product are added together to the first three-necked flask 3 and subsequent operations are performed.

[0050] (2) CO2 mineralization process: the leaching filtrate is added to the second three-necked flask 11, and N2 gas and CO2 gas are introduced into the leaching filtrate of the second three-necked flask 11 in the form of bubbling by a microporous aerator. The gas output of the N2 gas cylinder 6 and the CO2 gas cylinder 7 is controlled by the first mass flow meter 8 and the second mass flow meter 9. While the CO2-containing gas is introduced, the solution is heated in a water bath and stirred by a second constant temperature heating magnetic stirrer 10 to obtain a mineralized slurry. During the mineralization process, a thermometer is used to measure the temperature change of the solution, and a CO2 infrared online analyzer 12 is used to measure the concentration change of CO2 at the outlet of the second three-necked flask 11. The mineralized slurry is filtered by a second vacuum pump 14 and a second suction bottle 13 to separate the solid and liquid, and the obtained solid phase product is dried to obtain a light carbonate product. The obtained mineralized liquid phase product is introduced into the first three-necked flask 3 for use in the leaching process of the refined slag.

[0051] (3) Silicon oxide product separation process: sulfuric acid solution and leached filter cake are added to the beaker 15 to dissolve and obtain a dissolved slurry; the dissolved slurry is filtered through the third vacuum pump 16 and the third suction bottle 17 to separate the solid and liquid, and the obtained solid phase product is dried to obtain a silicon oxide product. The obtained liquid phase product is the filtrate, which is processed in the next step.

[0052] (4) Alumina product separation process: the filtrate is placed in a third three-necked flask 19, aqueous ammonia is added dropwise to the filtrate, and the solution is heated in a water bath and stirred by a third constant temperature heating magnetic stirrer 18 to obtain an alkaline precipitation slurry. During the process, a pH meter is used to detect the pH of the solution; the alkaline precipitation slurry is filtered by a third vacuum pump 20 and a third suction flask 21 to separate the solid and the liquid, and the obtained solid phase product is dried and calcined to obtain an alumina product.

[0053] The specific implementation modes of the present invention are described in detail below with reference to the embodiments.

[0054] Example 1

[0055] A method for extracting valuable components from refined slag, comprising the following steps:

[0056] (1) Refined slag leaching process: the refined slag is crushed in a ball mill 1 to obtain a refined slag powder with a particle size of less than 200 mesh; a mixture of the refined slag powder and ammonium bisulfate solid and water is prepared into a refined slag slurry at a liquid-to-solid ratio of 0.94 mL:1 g, wherein the refined slag powder is 100 g and the ammonium bisulfate is 320 g; the refined slag slurry and the mineralized liquid phase product obtained in step (2) are added into a first three-necked flask 3, and heated in a 50° C. water bath for 30 min. At the same time, a first constant temperature heating magnetic stirrer 2 is used to stir the refined slag slurry at a speed of 500 rpm to mix and disperse the refined slag slurry to obtain a leaching slurry; the leaching slurry is subjected to solid-liquid separation by suction filtration, and the obtained liquid phase product is a leaching filtrate rich in calcium and magnesium. The obtained solid phase product is then washed with water and dried at a drying temperature of 60° C. for 24 h to obtain a leaching filter cake rich in silicon and aluminum.

[0057] When the refined slag leaching process is performed for the first time, the mineralized liquid phase product obtained in step (2) is not obtained, so the refined slag slurry is directly added to the first three-necked flask 3 for the first time and subsequent operations are performed; when the refined slag leaching process is performed for the second time and above, the mineralized liquid phase product obtained in step (2) has been obtained, so the refined slag slurry and the mineralized liquid phase product are added together to the first three-necked flask 3 and subsequent operations are performed.

[0058] (2) CO2 mineralization process: The leaching filtrate is added to the second three-necked flask 11, and the output of the N2 gas cylinder 6 and the CO2 gas cylinder 7 are controlled by the first mass flow meter 8 and the second mass flow meter 9 to obtain a simulated flue gas with a CO2 volume concentration of 12%. The simulated flue gas is introduced into the leaching filtrate of the second three-necked flask 11 in the form of bubbling, and the flow rate of the simulated flue gas is 0.15m 3 / h, while introducing simulated flue gas, the second constant temperature heating magnetic stirrer is heated in a 30°C water bath and stirred at 500rpm, and a mineralization reaction is carried out for 30 minutes to obtain a mineralized slurry; during the mineralization process, a thermometer is used to measure the temperature change of the solution, and a CO2 infrared online analyzer 12 is used to measure the change of CO2 concentration at the outlet of the second three-necked flask 11 over time; the mineralized slurry is separated into solid and liquid by suction filtration, and the solid phase product obtained is washed with water and dried to obtain a light carbonate product, the drying temperature is 60°C, and the drying time is 24h; the obtained liquid phase product is a mineralized liquid phase product.

[0059] (3) Silicon oxide product separation process: add a sulfuric acid solution with a concentration of 1.5 mol / L and the leached filter cake into a beaker 15 for dissolution, with a liquid-to-solid ratio of 2 mL:1 g to obtain a dissolved slurry; use suction filtration to separate the dissolved slurry into solid and liquid, and wash the obtained solid phase product with water and dry it to obtain a silicon oxide product. The drying temperature is 60°C and the drying time is 24 h; the obtained liquid phase product is the filtrate, which is used for the next step of the aluminum oxide product separation process.

[0060] (4) Alumina product separation process: The filtrate is placed in a third three-necked flask 19, and under the condition of heating in a water bath at 30°C, a 3.0 mol / L ammonia solution is slowly added dropwise to the solution, and at the same time, the third constant temperature heating magnetic stirrer 18 is stirred at a speed of 500 rpm to disperse and mix the solution; during the process, a pH meter is used to detect the pH of the reaction solution, and when the pH reaches 9, the addition of ammonia solution is stopped, and the mixture is stirred for another 10 minutes to obtain an alkaline precipitate slurry; the alkaline precipitate slurry is subjected to solid-liquid separation by suction filtration, and the obtained solid phase product is washed with water and anhydrous ethanol in turn and dried at a drying temperature of 60°C for 24 hours, and then roasted at a roasting temperature of 700°C for 2 hours to obtain an alumina product.

[0061] Example 2

[0062] A method for extracting valuable components from refined slag, comprising preparing a mixture of refined slag powder and ammonium bisulfate solid with water at a liquid-to-solid ratio of 0.71 mL:1 g to prepare a refined slag slurry, and the remaining implementation steps are the same as those in Example 1.

[0063] Example 3

[0064] A method for extracting valuable components from refined slag. During the leaching process of the refined slag, heating is performed in a 40° C. water bath for 30 minutes, and the remaining implementation steps are the same as those in Example 1.

[0065] Example 4

[0066] A method for extracting valuable components from refined slag. During the leaching process of the refined slag, heating is performed in a 50° C. water bath for 60 minutes, and the remaining implementation steps are the same as those in Example 1.

[0067] Example 5

[0068] A method for extracting valuable components from refined slag. During the refined slag leaching process, 100 g of refined slag powder and 400 g of ammonium bisulfate are used, and the remaining implementation steps are the same as those in Example 1.

[0069] Example 6

[0070] A method for extracting valuable components from refined slag, a CO2 mineralization process, using simulated flue gas with a CO2 volume concentration of 90%, and the remaining implementation steps are the same as Example 1.

[0071] Example 7

[0072] A method for extracting valuable components from refined slag, a CO2 mineralization process, a 2h mineralization reaction, and the remaining implementation steps are the same as in Example 1.

[0073] Example 8

[0074] A method for extracting valuable components from refined slag, during the separation process of aluminum oxide products, when the pH reaches 10, stop adding ammonia solution, and stir for 10 minutes. The remaining implementation steps are the same as those in Example 1.

[0075] Comparative Example

[0076] A method for extracting valuable components from refined slag, comprising the following steps:

[0077] (1) Refined slag leaching process: The refined slag is crushed in a ball mill 1 to obtain a refined slag powder with a particle size of less than 200 mesh; 100 g of the refined slag powder and water are mixed at a liquid-to-solid ratio of 0.94 mL:1 g to prepare a refined slag slurry, and the refined slag slurry is added to a first three-necked flask 3, and heated in a 50° C. water bath for 30 min. At the same time, the first constant temperature heating magnetic stirrer 2 is stirred at a speed of 500 rpm to mix and disperse the refined slag slurry to obtain a leaching slurry; the leaching slurry is subjected to solid-liquid separation by suction filtration, and the obtained liquid phase product is a leaching filtrate rich in calcium and magnesium. The obtained solid phase product is then washed with water and dried at a drying temperature of 60° C. and a drying time of 24 h to obtain a leaching filter cake rich in silicon and aluminum.

[0078] (2) CO2 mineralization process: The leached filtrate is added to the second three-necked flask 11, and the output of the N2 gas cylinder 6 and the CO2 gas cylinder 7 is controlled by the first mass flow meter 8 and the second mass flow meter 9 to obtain a simulated flue gas with a CO2 volume concentration of 12%. The simulated flue gas is introduced into the leached filtrate of the second three-necked flask 11 in the form of bubbling, and the simulated flue gas flow rate is 0.15m 3 / h, while introducing simulated flue gas, the second constant temperature heating magnetic stirrer is heated in a 30°C water bath and stirred at 500rpm, and a mineralization reaction is carried out for 30 minutes to obtain a mineralized slurry; during the mineralization process, a thermometer is used to measure the temperature change of the solution, and a CO2 infrared online analyzer 12 is used to measure the change of CO2 concentration at the outlet of the second three-necked flask 11 over time; the mineralized slurry is separated into solid and liquid by suction filtration, and the solid phase product obtained is washed with water and dried to obtain a light carbonate product, the drying temperature is 60°C, and the drying time is 24h.

[0079] (3) Silicon oxide product separation process: A sulfuric acid solution with a concentration of 1.5 mol / L was added to the beaker 15 to dissolve the leached filter cake, with a liquid-to-solid ratio of 2 mL:1 g, to obtain a dissolved slurry; the dissolved slurry was subjected to solid-liquid separation by suction filtration, and the obtained solid phase product was then washed with water and dried to obtain a silicon oxide product, with a drying temperature of 60°C and a drying time of 24 h; the obtained liquid phase product was the filtrate, which was used for the next step of the aluminum oxide product separation process.

[0080] (4) Alumina product separation process: The filtrate is placed in a third three-necked flask 19, and under the condition of heating in a water bath at 30°C, a 3.0 mol / L ammonia solution is slowly added dropwise to the solution, and at the same time, the third constant temperature heating magnetic stirrer 18 is stirred at a speed of 500 rpm to disperse and mix the solution; during the process, a pH meter is used to detect the pH of the reaction solution, and when the pH reaches 9, the addition of ammonia solution is stopped, and the mixture is stirred for another 10 minutes to obtain an alkaline precipitate slurry; the alkaline precipitate slurry is subjected to solid-liquid separation by suction filtration, and the obtained solid phase product is washed with water and anhydrous ethanol in turn and dried at a drying temperature of 60°C for 24 hours, and then roasted at a roasting temperature of 700°C for 2 hours to obtain an alumina product.

[0081] Experimental example

[0082] 1. The phase composition of the refined slag was analyzed by X-ray fluorescence spectrometry, and the results are shown in Table 1. It can be seen that the total calcium and magnesium content that can be mineralized in the refined slag reaches 45wt%, the aluminum content reaches 16wt%, and the silicon content reaches 33wt%. The selective and efficient separation of these high-content valuable components can realize the resource utilization of refined slag solid waste.

[0083] Table 1 Main components of refined slag samples

[0084]

[0085] 2. The calcium and magnesium ion contents in the leaching filtrate were measured by inductively coupled plasma emission spectrometry. The mass change of the refined slag before and after leaching and the volume of the leaching filtrate were measured by weighing method. The conversion rates (R) of magnesium and calcium were calculated by equations (10) and (11), respectively.

[0086]

[0087]

[0088] Wherein m1 is the mass of the refined slag taken in the leaching experiment (g), ω1 and ω2 are the mass percentages (wt%) of magnesium and calcium in the refined slag, respectively; V is the volume of the leaching filtrate (L), c1 and c2 are the concentrations of magnesium ions and calcium ions in the leaching solution, respectively (g / L), m2 is the mass of the leaching filter cake (g), and ω3 is the mass fraction (wt%) of calcium in the form of calcium sulfate in the leaching slag.

[0089] The extraction rates of magnesium and calcium in Example 1 were calculated to be 98.2% and 100%, respectively, and the extraction rates of magnesium and calcium in the comparative example were 68.7% and 73.4%, respectively. The results show that in the comparative example, water is used as the leaching solvent to make CO2 directly react with the refined slag slurry for mineralization. Although the process energy consumption cost caused by the introduction of additives can be avoided, the leaching efficiency is low. The ammonium bisulfate solution used in the present invention can fully leach the calcium and magnesium components in the refined slag, and realize the efficient and selective separation of the calcium and magnesium components and the silicon and aluminum components in the refined slag.

[0090] Calculate the magnesium and calcium extraction rates of Examples 2 to 5, and analyze the effects of different liquid-to-solid ratios, reaction time and reaction temperature on the extraction rates of calcium and magnesium ions:

[0091] In Example 2, the extraction rates of magnesium and calcium are 92.1% and 89.8% respectively. Compared with Example 1, it can be seen that the larger the liquid-to-solid ratio in the leaching process, the smaller the viscosity of the slurry, the faster the mass transfer rate, and the more complete the reaction.

[0092] In Example 3, the extraction rates of magnesium and calcium are 92.3% and 92.8%, respectively. Compared with Example 1, it can be seen that the reaction temperature has a certain influence on the extraction of calcium and magnesium ions. Within a certain range, the higher the temperature, the greater the extraction rate of calcium and magnesium ions in the same time, and the faster the reaction rate. This is because the increase in temperature increases the number of activated molecules of ammonium bisulfate, making the dissociation reaction of ammonium bisulfate easier to proceed. When the temperature is increased to 50°C, the reaction is basically complete, and further increasing the temperature will lead to an increase in heat exchange energy consumption.

[0093] In Example 4, the extraction rates of magnesium and calcium are 98.4% and 100%, respectively. Compared with Example 1, it can be seen that there is no significant difference in the extraction rates of calcium and magnesium ions when the reaction time is 30 min and when the reaction time is 60 min, indicating that the reaction of ammonium bisulfate leaching refined slag is very rapid. A large amount of calcium and magnesium are converted into corresponding ions within just a few minutes. When the time reaches 30 min, the reaction is basically complete.

[0094] In Example 5, the extraction rates of magnesium and calcium are 98.9% and 100%, respectively. Compared with Example 1, it can be seen that the greater the content of ammonium bisulfate during the leaching process, the more sufficient the calcium and magnesium in the refined slag are leached. However, when the ratio of refined slag to refined slag is increased from 3.2:1 to 4.0:1, the extraction rate of calcium and magnesium in the refined slag is not significantly improved. Therefore, the amount of ammonium bisulfate can be reduced as much as possible while ensuring the extraction rate.

[0095] 3. The content of calcium carbonate and magnesium carbonate in the light carbonate product obtained in Example 2 was analyzed by thermogravimetric analyzer. The results are as follows: Figure 2 As shown. It can be seen that the thermogravimetric curve has two weight loss areas. The first weight loss area occurs within 100°C, which belongs to the desorption of adsorbed water of the mineralized product; the second weight loss area occurs at 550-800°C, corresponding to the mass spectrometry curve, with a large amount of CO2 overflowing, which is caused by the decomposition of calcium carbonate at high temperature. Through calculation, it can be known that the amount of light carbonate product obtained per ton of refined slag is 795.32kg, which can fix about 263.27kg of CO2, indicating that the use of this method makes the refined slag have a large CO2 fixation potential. Thermogravimetric analysis of the light carbonate products obtained in Example 6 and Example 7 shows that the amount of light carbonate products prepared per ton of refined slag is 802.15kg and 805.23kg. Compared with Example 1, in the CO2 mineralization process, more than 97% of calcium and magnesium ions can be reacted after 30 minutes of reaction with a CO2 volume concentration of 12%. Increasing the CO2 concentration and the mineralization reaction time can improve the mineralization utilization rate.

[0096] 4. The specific surface area and pore volume of the precipitated products obtained after adding ammonia water in Example 1 and Example 8 were analyzed by BET. The results are as follows: Figure 3 As shown in Table 2; SEM was used to observe the morphology of the precipitated product. Figure 4 As shown, it can be seen that the precipitated product is a boehmite (AlOOH) structure, and the higher the crystallinity, the more complete the crystal form. When the pH reaches 9 ( Figure 3 A and 3B) particles are the smallest and most uniform, far from the isoelectric point, there is a certain repulsion between particles, the agglomeration is relatively light, the specific surface area, pore volume, and average pore size are large, and they can be used as raw materials for calcining to prepare alumina products. When the pH reaches 10 ( Figure 3C and 3D) have the highest crystallinity, but the product structure is dense, with a plate-like block structure, the grain edges are not clear, and aggregation occurs. This is because the electrolyte concentration increases, the thickness of the counter ion layer around the agglomerate is very thin, and it may contact and grow, thus agglomeration intensifies and causes the surface area to drop to 377.72 m 2 ·g, the pore volume is also low, and at higher pH values, the product has greater viscosity and is difficult to filter, which increases the filtration cost in industry.

[0097] Table 2 Specific surface area, average pore volume and pore size of AlOOH products under different pH conditions

[0098]

[0099] 5. The specific surface area and pore volume of the solid phase product after calcination in Example 1 were analyzed by BET. The results are as follows: Figure 5 As shown in Table 3, Figure 5 The 700 in the figure indicates that the product was calcined at 700°C. The morphology of the solid phase product was observed by SEM. Figure 6 It can be seen that the alumina product has a mesoporous structure of type IV, the hysteresis loop is H3 type, and the specific surface area of ​​Al2O3 is 130.1m 2 g.

[0100] Table 3 Specific surface area, average pore volume and pore diameter of Al2O3 products calcined at 700℃

[0101]

[0102] The components of the solid phase product after calcination in Example 1 were analyzed by ICP-OES as shown in Table 4. It can be seen that the purity of the alumina product is high, reaching 99.96%, and the specific surface area of ​​γ-Al2O3 is large. It can be seen that boehmite, as a precursor, can produce γ-Al2O3 with high purity, high specific surface area, large pore size and pore volume, and bimodal distribution. γ-Al2O3 can be recycled as a raw material for a refining furnace, realizing a green circular economy.

[0103] Table 4 Impurity content and purity of alumina products

[0104]

[0105]

[0106] Although the specific implementation of the present invention is described in detail in conjunction with the embodiments, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A method for extracting valuable components from refined slag, characterized in that: The following steps are involved: (1) leaching of refined slag: a mixture of refined slag and hydrogen sulfate and water is prepared into a refined slag slurry at a liquid-to-solid ratio of 0.70-1.60 mL:1 g, and the mineralized liquid phase product obtained in step (2) is added thereto, and stirred at a speed of 400-600 rpm for 10-60 min at 40-60° C. to obtain a leaching slurry; the leaching slurry is subjected to solid-liquid separation to obtain a leaching filtrate and a leaching filter cake; the refined slag is a refined slag containing calcium oxide, magnesium oxide, aluminum oxide and silicon oxide; the mass ratio of the hydrogen sulfate to the refined slag is 2.5-4.0:1; (2) CO2 mineralization: at a temperature of 20 to 30° C. and a stirring speed of 400 to 600 rpm, a CO2 gas having a volume concentration of 10% to 100% is introduced into the leaching filtrate for 0.5 to 2.0 hours to obtain a mineralized slurry; the mineralized slurry is subjected to solid-liquid separation to obtain a light carbonate product and a mineralized liquid phase product; (3) Separation of silicon oxide product: preparing a dissolving slurry with a sulfuric acid solution and the leached filter cake according to a liquid-solid ratio of 2 to 5 mL:1 g; performing solid-liquid separation on the dissolving slurry to obtain a silicon oxide product and a filtrate; the concentration of the sulfuric acid solution is 1.2 to 1.8 mol / L; (4) Separation of alumina products: adding an alkaline solvent to the filtrate at a temperature of 20 to 30°C and a stirring speed of 400 to 600 rpm until the pH of the solution is 7 to 9 to obtain an alkaline precipitation slurry; subjecting the alkaline precipitation slurry to solid-liquid separation, collecting and calcining the solid phase to obtain an alumina product; the concentration of the alkaline solvent is 2.5 to 3.5 mol / L, and the alkaline solvent is aqueous ammonia, sodium bicarbonate solution or organic amine solution.

2. The method for extracting valuable components from refined slag according to claim 1, characterized in that: The total content of calcium oxide and magnesium oxide in the refined slag exceeds 45wt%, and its particle size does not exceed 200 meshes; the bisulfate is ammonium bisulfate, potassium bisulfate or sodium bisulfate, the liquid-to-solid ratio of the mixture of the refined slag and the bisulfate to water is 0.94-1.20mL:1g, and the mass ratio of the bisulfate to the refined slag is 3.2-4.0:

1.

3. The method for extracting valuable components from refined slag according to claim 2, characterized in that: The bisulfate is ammonium bisulfate, and the liquid-to-solid ratio of the mixture of the refined slag and ammonium bisulfate to water is 0.94 mL:1 g.

4. The method for extracting valuable components from refined slag according to claim 1, characterized in that: The CO2-containing gas is introduced into the leaching filtrate by bubbling, and the gas flow rate is 0.1-0.2 m 3 / h.

5. The method for extracting valuable components from refined slag according to claim 1, characterized in that: The calcination temperature is 650-750° C., and the calcination time is 1.5-2.5 hours; the organic amine solution is ethanolamine solution or N-methyldiethanolamine solution.

6. The method for extracting valuable components from refined slag according to claim 5, characterized in that: The calcination temperature is 700° C. and the calcination time is 2 h.

7. The method for extracting valuable components from refined slag according to claim 1, characterized in that: The solid-liquid separation methods in steps (1) to (4) are all natural precipitation, filtration, centrifugation or suction filtration.

8. The method for extracting valuable components from refined slag according to claim 7, characterized in that: The liquid-solid separation method is suction filtration.

9. The method for extracting valuable components from refined slag according to claim 1, characterized in that: After solid-liquid separation in steps (1) to (4), the solid phase product is washed and dried at a temperature of 60° C. for 24 h.

10. The method for extracting valuable components from refined slag according to claim 1, characterized in that: In the step (1), the stirring temperature is 50° C., the stirring speed is 500 rpm, the time is 30 min, and the mass ratio of the hydrogen sulfate to the refined slag is 3.2:1; in the step (2), the stirring temperature is 30° C., the stirring speed is 500 rpm; the volume concentration of CO2 in the gas introduced into the leaching filtrate is 12%, and the time is 0.5 h; in the step (3), the concentration of the sulfuric acid solution is 1.5 mol / L, and the liquid-solid ratio of the sulfuric acid solution to the leaching filter cake is 2 mL:1 g; in the step (4), the stirring temperature is 30° C., the stirring speed is 500 rpm; the alkaline solvent is ammonia water with a concentration of 3 mol / L, and when the solution pH is 9, stirring is continued for 10 min to obtain an alkaline precipitation slurry.

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