Method for preparing poly-aluminum and functional silicon material by activating coal gasification slag and waste hydrochloric acid through microwave synergistic mechanical force

Abstract

The invention provides a method for preparing a poly-aluminum and functional silicon material by activating coal gasification slag and waste hydrochloric acid through microwave synergistic mechanical force, and belongs to the technical field of industrial solid waste recycling. The method comprises the following steps that the coal gasification slag is sequentially subjected to microwave radiation treatment and ball milling, activated slag and waste hydrochloric acid are subjected to an acid leaching reaction, and aluminum-iron-containing leachate and silicon-rich slag are obtained; extracting the aluminum-iron-containing leaching solution to obtain an iron-rich organic phase and a purified aluminum chloride solution; performing thermal polymerization reaction on the purified aluminum chloride solution to obtain polyaluminum chloride; the method comprises the following steps: carrying out alkaline leaching reaction on silicon-rich slag and waste alkali liquor, adding a structure-directing agent into a sodium silicate solution, and sequentially carrying out aging, solution pH value adjustment and crystallization precipitation to obtain mesoporous silica. According to the method, the aluminum-silicon leaching rate is remarkably increased through microwave-mechanical force synergistic activation, synergistic and efficient treatment of the three kinds of waste including the coal gasification slag, the waste hydrochloric acid and the waste alkali liquid is achieved, the technological process is closed, the product additional value is high, and the environmental and economic benefits are remarkable.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste resource utilization technology, and in particular to a method for preparing polyaluminum and functional silicon materials by microwave-assisted mechanical activation of coal gasification slag and waste hydrochloric acid. Background Technology

[0002] Coal gasification slag is an industrial solid waste generated during coal gasification. Its main components include SiO2, Al2O3, Fe2O3, and small amounts of carbon and heavy metals. Approximately 0.5-1 ton of coal gasification slag is produced for every ton of synthetic ammonia produced. Large-scale accumulation not only occupies land resources but also causes environmental pollution due to heavy metal leaching and dust. Meanwhile, the chlor-alkali and steel industries generate large amounts of waste hydrochloric acid, which has a high acid content and complex composition. Direct discharge of this waste hydrochloric acid can severely corrode equipment and pollute water and soil. How to achieve the co-processing and resource utilization of coal gasification slag and waste hydrochloric acid is an important research direction in the current environmental protection field.

[0003] Existing technologies include studies on the preparation of polyaluminum chloride from coal gasification slag and waste hydrochloric acid. Mechanochemical activation is typically used to enhance the reactivity of the coal gasification slag. However, mechanical activation alone suffers from high energy consumption and insufficient breaking of silicon-aluminum bonds, resulting in aluminum leaching rates generally below 70%, thus limiting resource recovery efficiency. Furthermore, the utilization efficiency of the silica-rich slag after acid leaching is low, with most being discarded as waste, failing to achieve high-value-added utilization of silicon resources. Simultaneously, poor iron ion separation also affects the product quality of polyaluminum chloride.

[0004] Microwave technology, as a highly efficient heating method, features uniform heating, high speed, and low energy consumption. Its non-thermal effects can also disrupt the crystal structure of substances and promote the breaking of chemical bonds. Combining microwave technology with mechanical activation in the pretreatment of coal gasification slag is expected to overcome the shortcomings of mechanical activation alone, improve the leaching efficiency of aluminum and silicon, and provide a new approach for the synergistic and efficient resource utilization of coal gasification slag and waste hydrochloric acid. Summary of the Invention

[0005] The purpose of this invention is to address the problems of low activation efficiency of coal gasification slag, low aluminum leaching rate, low added value of silicon resource utilization, and poor co-processing effect of waste in the existing technology. It provides a method for preparing polyaluminum and functional silicon materials by microwave-assisted mechanical activation of coal gasification slag and waste hydrochloric acid. The activation effect is enhanced by the synergistic effect of microwave and mechanical force, realizing the efficient separation and high-value-added resource utilization of aluminum, iron and silicon, while co-processing waste hydrochloric acid and waste alkali, reducing environmental risks.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing polyaluminum and functional silicon materials by microwave-assisted mechanical activation of coal gasification slag and waste hydrochloric acid, comprising the following steps: 1) The coal gasification slag is subjected to microwave radiation treatment and ball milling in sequence to obtain activated slag; 2) After acid leaching of the activated slag and waste hydrochloric acid, solid-liquid separation is performed to obtain aluminum-iron leachate and silicon-rich slag; 3) Extraction was carried out by adding an extractant solution to the aluminum-containing iron leachate to obtain an iron-rich organic phase and a purified aluminum chloride solution; 4) After back-extraction of the iron-rich organic phase and hydrochloric acid, the mixture is evaporated, concentrated, cooled, and crystallized to obtain ferric chloride crystals; after adjusting the pH value of the purified aluminum chloride solution, a thermal polymerization reaction is carried out to obtain polyaluminum chloride. 5) After alkaline leaching of silica-rich slag and waste alkaline solution, solid-liquid separation is performed to obtain sodium silicate solution and residue; 6) Add a structure-directing agent to a sodium silicate solution and proceed with aging, purging carbon dioxide to adjust the pH of the solution, and crystallization to precipitate, to obtain mesoporous silica.

[0007] Preferably, the microwave radiation treatment in step 1) has a power of 300~800W and a time of 10~30min. The microwave radiation treatment is carried out under a protective gas, which is nitrogen or argon, and the flow rate of the protective gas is 0.5~1.5L / min.

[0008] Preferably, in step 1), the ball-to-material ratio during ball milling is 10-20:1, the ball milling speed is 300-500 r / min, the ball milling time is 30-90 min, and the specific surface area of ​​the activated slag is ≥65 m². 2 / g, particle size ≤100μm.

[0009] Preferably, in step 2), the mass fraction of the waste hydrochloric acid is 10-20%, the liquid-to-solid ratio of the activated slag and the waste hydrochloric acid is 5-10:1, the temperature of the acid leaching reaction is 80-100℃, the time is 2-4h, and the acid leaching reaction is stirred at a rate of 200-400r / min.

[0010] Preferably, the extraction temperature in step 3) is 25~40℃, the ratio is 1~3:1, the time is 10~20min, and the stirring is carried out during the extraction process at a stirring rate of 300~500r / min; The solvent of the extractant solution is kerosene, and the extractant is tributyl phosphate or primary amine N1923. The volume fraction of the extractant in the extractant solution is 10-30%.

[0011] Preferably, the concentration of hydrochloric acid in step 4) is 1~3 mol / L, the back-extraction temperature is 40~50℃, the ratio is 2~4:1, and the time is 20~30 min; The pH of the purified aluminum chloride solution was adjusted to 3.0-4.0 using sodium hydroxide solution with a mass fraction of 10-20%. The temperature of the thermal polymerization reaction was 100-120℃, and the reaction time was 2-3 hours.

[0012] Preferably, in step 5), the silica-rich slag is washed until neutral and then mixed with the waste alkaline solution. The liquid-to-solid ratio of the silica-rich slag to the waste alkaline solution is 8-12:1, and the mass fraction of sodium hydroxide in the waste alkaline solution is 8-15%. The alkaline leaching reaction is carried out at a temperature of 90~120℃ for 3~5 hours; the moisture content of the residue is ≤15%, and the concentration of SiO2 in the sodium silicate solution is 20~40g / L.

[0013] Preferably, the structure directing agent in step 6) is hexadecyltrimethylammonium bromide or polyethylene glycol; the molar ratio of the structure directing agent to silicon in the sodium silicate solution is 0.1~0.3:1.

[0014] Preferably, in step 6), the aging temperature is 40~60℃, the time is 1~2h, and the aging is carried out by stirring; the carbon dioxide is introduced at a rate of 10~20mL / min, the pH of the solution is adjusted to 7~8 by introducing carbon dioxide, and the crystallization precipitation temperature is 80~100℃, and the time is 2~4h.

[0015] The beneficial effects of this invention are: 1) Significantly improved activation efficiency: This invention uses microwave-mechanical synergistic activation instead of mechanical activation alone. The thermal and non-thermal effects of microwaves initially open the silicon-aluminum bonds, while mechanical activation further refines the particles, increasing the specific surface area of ​​the activated slag from ≥50m² in existing technologies. 2 / g increased to ≥65m 2 / g, the aluminum leaching rate increased from less than 70% to more than 85%, the silicon leaching rate increased to more than 90%, and the energy consumption of mechanical activation was reduced by 20-30%.

[0016] 2) Good co-processing effect of waste: The method of the present invention simultaneously processes three types of waste: coal gasification slag, waste hydrochloric acid and waste alkali liquid. The utilization rate of coal gasification slag is ≥95%, and the acid and alkali of waste hydrochloric acid and waste alkali liquid are fully neutralized and utilized, realizing the circular economy model of "treating waste with waste" and reducing the cost of waste treatment.

[0017] 3) High added value of products: The method of this invention not only produces polyaluminum chloride products that meet national standards, but also recovers iron resources to prepare ferric chloride crystals, and at the same time converts silicon-rich slag into high-value-added mesoporous silica. Compared with the existing technology that only recovers aluminum, the economic benefits are increased by 40-60%.

[0018] 4) Closed-loop environmentally friendly process: The entire process of this invention has no wastewater or waste residue discharge. The final residue can be reused as building aggregate, and the extractant can be recycled, which meets the requirements of green production and has significant environmental benefits. Detailed Implementation

[0019] This invention provides a method for preparing polyaluminum and functional silicon materials by microwave-assisted mechanical activation of coal gasification slag and waste hydrochloric acid, comprising the following steps: 1) The coal gasification slag is subjected to microwave radiation treatment and ball milling in sequence to obtain activated slag; 2) After acid leaching of the activated slag and waste hydrochloric acid, solid-liquid separation is performed to obtain aluminum-iron leachate and silicon-rich slag; 3) Extraction was carried out by adding an extractant solution to the aluminum-containing iron leachate to obtain an iron-rich organic phase and a purified aluminum chloride solution; 4) After back-extraction of the iron-rich organic phase and hydrochloric acid, the mixture is evaporated, concentrated, cooled, and crystallized to obtain ferric chloride crystals; after adjusting the pH value of the purified aluminum chloride solution, a thermal polymerization reaction is carried out to obtain polyaluminum chloride. 5) After alkaline leaching of silica-rich slag and waste alkaline solution, solid-liquid separation is performed to obtain sodium silicate solution and residue; 6) Add a structure-directing agent to a sodium silicate solution and proceed with aging, purging carbon dioxide to adjust the pH of the solution, and crystallization to precipitate, to obtain mesoporous silica.

[0020] In this invention, the power of the microwave radiation treatment in step 1) is preferably 300~800W, more preferably 400~700W, and even more preferably 500~600W. The microwave radiation treatment time is preferably 10~30min, more preferably 15~25min, and even more preferably 20min. The microwave radiation treatment is preferably carried out under a protective gas, preferably nitrogen or argon. The flow rate of the protective gas is preferably 0.5~1.5L / min, more preferably 0.8~1.2L / min, and even more preferably 1L / min.

[0021] In step 1) of this invention, during the ball milling process, the ball-to-material ratio is preferably 10-20:1, more preferably 12-18:1, and even more preferably 15-16:1; the ball milling speed is preferably 300-500 r / min, more preferably 350-450 r / min, and even more preferably 400 r / min; the ball milling time is preferably 30-90 min, more preferably 40-80 min, and even more preferably 50-60 min; and the specific surface area of ​​the activated slag is preferably ≥65 m². 2 / g, with a preferred particle size of ≤100μm.

[0022] In this invention, microwave radiation treatment under a protective gas atmosphere can prevent residual carbon in coal gasification slag from burning under microwave radiation, ensuring the stability of the activation effect. Microwave radiation can rapidly heat the material, using the thermal effect to generate stress inside the particles. At the same time, the non-thermal effect destroys the crystal structure of aluminosilicates, initially opening the silicon-aluminum bonds. Subsequent ball milling (mechanical activation) further refines the particle size and increases the specific surface area. The synergistic effect of the two significantly improves the activation efficiency. The ball milling is carried out in a high-energy ball mill.

[0023] In this invention, the mass fraction of the waste hydrochloric acid in step 2) is preferably 10-20%, more preferably 12-18%, and even more preferably 15-16%. The liquid-to-solid ratio of the activated slag and the waste hydrochloric acid is preferably 5-10:1, more preferably 6-9:1, and even more preferably 7-8:1. The temperature of the acid leaching reaction is preferably 80-100℃, more preferably 85-95℃, and even more preferably 90℃. The time of the acid leaching reaction is preferably 2-4h, more preferably 2.5-3.5h, and even more preferably 3h. During the acid leaching reaction, stirring is carried out at a rate of preferably 200-400 r / min, more preferably 250-350 r / min, and even more preferably 300 r / min.

[0024] In this invention, the waste hydrochloric acid in step 2) is industrial waste hydrochloric acid, preferably by-product hydrochloric acid from the chlor-alkali industry or waste hydrochloric acid from steel pickling; controlling the liquid-to-solid ratio and reaction temperature ensures sufficient leaching of aluminum while avoiding excessive leaching of impurities; the solid-liquid separation uses a plate and frame filter press, which improves the solid-liquid separation efficiency and reduces the solid content in the leachate; the aluminum-containing iron leachate contains Al... 3+ The preferred concentration is 15-30 g / L, more preferably 20-25 g / L, Fe 3+ The preferred concentration is 2-8 g / L, and more preferably 3-5 g / L.

[0025] In this invention, the extraction temperature in step 3) is preferably 25~40℃, more preferably 28~35℃, and even more preferably 30~33℃; the extraction ratio is preferably 1~3:1, more preferably 1.5~2.5:1, and even more preferably 2:1; the extraction time is preferably 10~20min, more preferably 12~18min, and even more preferably 15~16min; stirring is performed during the extraction process, and the stirring rate is preferably 300~500r / min, more preferably 350~450r / min, and even more preferably 400r / min. The solvent of the extractant solution is preferably kerosene, the extractant is preferably tributyl phosphate (TBP) or primary amine N1923, and the volume fraction of the extractant in the extractant solution is preferably 10-30%, more preferably 15-25%, and even more preferably 20%.

[0026] In this invention, the extraction in step 3) is a selective extraction of iron ions; by selecting a specific concentration of extractant and controlling the extraction conditions, highly selective separation of iron ions can be achieved, with an aluminum-iron separation rate preferably ≥98.7%, more preferably ≥99%, and even more preferably ≥99.3%, ensuring the quality of the subsequent polyaluminum chloride product; the purification of Fe in the aluminum chloride solution in step 3) 3+ The content is preferably ≤0.05g / L, and more preferably ≤0.03g / L.

[0027] In this invention, the concentration of hydrochloric acid in step 4) is preferably 1~3 mol / L, more preferably 1.5~2.5 mol / L, and even more preferably 2 mol / L; the back-extraction temperature is preferably 40~50℃, more preferably 42~48℃, and even more preferably 45~46℃; the back-extraction ratio is preferably 2~4:1, more preferably 2.5~3.5:1, and even more preferably 3:1; and the back-extraction time is preferably 20~30 min, and even more preferably 25 min. The pH value of the purified aluminum chloride solution is preferably adjusted to 3.0-4.0, more preferably to 3.3-3.6. The reagent for adjusting the pH value is preferably sodium hydroxide solution, and the mass fraction of sodium hydroxide solution is preferably 10-20%, more preferably 12-18%, and more preferably 15-16%. The temperature of the thermal polymerization reaction is preferably 100-120℃, more preferably 105-115℃, and more preferably 110℃. The time is preferably 2-3h, and more preferably 2.5h.

[0028] In this invention, the evaporation and concentration temperature in step 4) is preferably 80~100℃, more preferably 85~95℃, and even more preferably 90℃. After evaporation and concentration to saturation, the product is cooled and crystallized to obtain ferric chloride crystals. The extractant after back-extraction can be recycled to reduce reagent costs. Controlling the pH value and the thermal polymerization reaction temperature is the key to ensuring the performance of polyaluminum chloride products. The obtained product meets the requirements of GB / T 22627-2014 standard and can be directly used in water treatment and other fields.

[0029] In this invention, after the thermal polymerization reaction in step 4) is completed, the solution is cooled to room temperature to obtain liquid polyaluminum chloride with an Al2O3 mass fraction ≥10% and a basicity of 40~90%, which meets the requirements of GB / T 22627-2014 standard. If a solid product is required, the liquid polyaluminum chloride is sent to a spray drying tower and dried under the conditions of an inlet air temperature of 200~250℃ and an outlet air temperature of 80~100℃ to obtain solid polyaluminum chloride.

[0030] In this invention, the silica-rich slag in step 5) is preferably washed to neutral before being mixed with the waste alkaline solution. The liquid-solid ratio of the silica-rich slag to the waste alkaline solution is preferably 8-12:1, more preferably 9-11:1, and even more preferably 10:1. The mass fraction of sodium hydroxide in the waste alkaline solution is preferably 8-15%, more preferably 10-14%, and even more preferably 11-12%. The silica-rich slag is preferably washed to a pH value of 7-8. The preferred temperature for the alkaline leaching reaction is 90~120℃, more preferably 100~110℃, and even more preferably 105℃. The preferred leaching time is 3~5h, more preferably 3.5~4.5h, and even more preferably 4h. The preferred moisture content of the residue is ≤15%, more preferably ≤13%. The preferred SiO2 concentration in the sodium silicate solution is 20~40g / L, more preferably 25~35g / L, and even more preferably 30g / L.

[0031] In this invention, the waste alkaline solution in step 5) is industrial waste alkaline solution, preferably a by-product dilute alkaline solution from a chlor-alkali plant or a waste caustic alkaline solution from the aluminum industry. Washing the silicon-rich slag to neutrality can prevent residual hydrochloric acid from reacting with the waste alkaline solution and consuming alkaline, thereby improving silicon leaching efficiency. The residue is mainly composed of unreacted inert impurities and can be reused as building aggregate or roadbed material to achieve zero waste discharge.

[0032] In this invention, the structure directing agent in step 6) is preferably hexadecyltrimethylammonium bromide (CTAB) or polyethylene glycol; the molar ratio of the structure directing agent to silicon in the sodium silicate solution is preferably 0.1~0.3:1, more preferably 0.15~0.25:1, and even more preferably 0.2:1.

[0033] In this invention, polyethylene glycol is preferably polyethylene glycol 400. As a nonionic surfactant, polyethylene glycol 400 can form an ordered micelle template through hydrogen bonding between its molecular chains and silicon species, thereby controlling the pore size and channel structure of mesoporous silica. It also has the advantages of low toxicity, easy removal, and lower cost than CTAB.

[0034] In this invention, the aging temperature in step 6) is preferably 40~60℃, more preferably 45~55℃, and even more preferably 50℃; the aging time is preferably 1~2h, and even more preferably 1.5h; the aging is carried out by stirring. The carbon dioxide introduction rate is preferably 10~20mL / min, more preferably 12~18mL / min, and even more preferably 15~16mL / min; the pH value of the solution is preferably adjusted to 7~8, and even more preferably 7.5; the crystallization precipitation temperature is preferably 80~100℃, more preferably 85~95℃, and even more preferably 90℃; the crystallization precipitation time is preferably 2~4h, more preferably 2.5~3.5h, and even more preferably 3h.

[0035] In this invention, step 6) involves stirring and aging to allow the structure-directing agent to form ordered micelles in the solution; after stopping the introduction of carbon dioxide, crystallization precipitation is carried out, and the crystallized precipitation product is filtered, washed, and dried to obtain mesoporous silica. The washing reagent is preferably water, the pH value of the washed filter cake is preferably 7-8, the drying temperature is preferably 100-120℃, more preferably 110℃, and the drying time is preferably 4-6h, more preferably 4.5-5.5h, and more preferably 5h.

[0036] In this invention, the specific surface area of ​​mesoporous silica is preferably 600~1000 m². 2 / g, with a pore size preferably of 2~5nm and a purity preferably ≥98%.

[0037] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0038] In the embodiment, the main components of the coal gasification slag have the following mass contents: SiO2 52%, Al2O3 31%, Fe2O3 6%, and carbon 8%; the ball milling media in the ball milling process are alumina ceramic balls, which are composed of small balls (2~5mm in diameter) and large balls (10~20mm in diameter) with a mass ratio of 1:2.

[0039] Example 1

[0040] (1) Microwave-mechanical synergistic activation pretreatment: 100g of coal gasification slag was fed into a microwave reactor. Nitrogen gas was introduced into the microwave reactor for microwave radiation treatment under protection. The radiation was carried out for 20min at a nitrogen flow rate of 0.8L / min and a microwave power of 500W. After microwave radiation treatment, the slag was immediately transferred to a high-energy ball mill and ball-milled for 60min at a ball-to-material ratio of 15:1 and a rotation speed of 400r / min to obtain activated slag. The specific surface area was measured to be 72m². 2 / g, with a particle size of 85μm.

[0041] (2) Acid leaching for aluminum extraction: The activated slag and waste hydrochloric acid (HCl mass fraction of 15%) from steel pickling were mixed at a liquid-to-solid ratio of 8:1 and added to a reactor equipped with a stirrer. The acid leaching reaction was carried out at 85℃ and a stirring rate of 300r / min for 3 hours. The reaction product was separated into solid and liquid components using a plate and frame filter press to obtain an aluminum-containing iron leaching solution (Al). 3+ The concentration is 22 g / L, Fe 3+ (Concentration of 5g / L) and 48g of silica-rich slag.

[0042] (3) Iron-aluminum separation: A kerosene solution of TBP (20% TBP by volume) was added to the aluminum-containing iron leachate as an extractant at a ratio of 2:1. Iron ions were selectively extracted at 30°C and a stirring rate of 400 r / min for 15 min. After standing and separating, a purified aluminum chloride solution (Fe) was obtained. 3+ (Content 0.03 g / L, aluminum-iron separation rate 99.4%) and iron-rich organic phase.

[0043] (4) Preparation of polyaluminum chloride and iron resource utilization: The iron-rich organic phase was back-extracted for 25 min at 45℃ and a ratio of 3:1 using 2 mol / L hydrochloric acid as the back-extraction agent to obtain ferric chloride solution. The ferric chloride solution was evaporated and concentrated to saturation at 90℃ and then cooled to crystallize, yielding 12.8 g of ferric chloride crystals. A 15% sodium hydroxide aqueous solution was added to the purified aluminum chloride solution to adjust the pH to 3.5. The solution was then transferred to a polymerization reactor and thermally polymerized at 110℃ for 2.5 h. After cooling to room temperature, liquid polyaluminum chloride was obtained. The mass fraction of Al2O3 was 11.2% and the basicity was 65%, which met the standard of GB / T 22627-2014.

[0044] (5) Alkali leaching for silicon extraction: The silicon-rich slag is washed with deionized water until the pH value is 7, and mixed with dilute alkaline solution (sodium hydroxide mass fraction of 12%) produced by the chlor-alkali plant at a liquid-solid ratio of 10:1. The mixture is then added to the alkaline leaching reactor and stirred at 100°C for 4 hours. After the reaction is completed, the solid and liquid are separated to obtain sodium silicate solution (SiO2 concentration of 32g / L) and 5.2g of residue (moisture content of 12%).

[0045] (6) Preparation of functional silicon materials: CTAB was added to a sodium silicate solution, with a molar ratio of CTAB to silicon in the sodium silicate solution of 0.2:1. The solution was stirred and aged at 50°C for 1.5 h, and the structure-directing agent formed ordered micelles in the solution. CO2 was introduced at a rate of 15 mL / min until the pH of the solution reached 7.5. After stopping the CO2 introduction, the solution was crystallized and precipitated at 90°C for 3 h. The reaction product was filtered and washed with deionized water until neutral, and then dried at 110°C for 5 h to obtain 28.5 g of mesoporous silicon dioxide. Its specific surface area was measured to be 850 m². 2 / g, pore size 3.2nm, purity 98.5%.

[0046] Example 2

[0047] (1) Microwave-mechanical synergistic activation pretreatment: 100g of coal gasification slag was fed into a microwave reactor, and argon gas was introduced into the microwave reactor for microwave radiation treatment. The irradiation was carried out for 30min at an argon flow rate of 1.2L / min and a microwave power of 300W. After microwave radiation treatment, the slag was immediately transferred to a high-energy ball mill and ball-milled for 90min at a ball-to-material ratio of 10:1 and a rotation speed of 300r / min to obtain activated slag. The specific surface area was measured to be 68m². 2 / g, with a particle size of 95μm.

[0048] (2) Acid leaching for aluminum extraction: The activated slag is mixed with hydrochloric acid (HCl mass fraction of 10%), a by-product of the chlor-alkali industry, at a liquid-solid ratio of 5:1, and added to a reactor equipped with a stirrer. The mixture is then subjected to acid leaching at 80℃ and a stirring rate of 200 r / min for 4 h. The reaction product is then subjected to solid-liquid separation using a plate and frame filter press to obtain an aluminum-containing iron leaching solution (Al). 3+ The concentration is 18 g / L, Fe 3+ (Concentration of 3g / L) and 50g of silica-rich slag.

[0049] (3) Iron-aluminum separation: A kerosene solution of primary amine N1923 (with a volume fraction of 10% in the kerosene solution) was added to the aluminum-containing iron leachate as an extractant at a ratio of 1:1. The extractant was selectively extracted for 20 min at 25°C and a stirring rate of 300 r / min. After standing and separating the layers, a purified aluminum chloride solution (Fe) was obtained. 3+ (Content 0.04 g / L, aluminum-iron separation rate 98.7%) and iron-rich organic phase.

[0050] (4) Preparation of polyaluminum chloride and iron resource utilization: The iron-rich organic phase was back-extracted for 30 min at 40℃ and a phase ratio of 2:1 using 1 mol / L hydrochloric acid as the back-extraction agent to obtain ferric chloride solution. The ferric chloride solution was evaporated and concentrated to saturation at 90℃ and then cooled to crystallize, yielding 7.6 g of ferric chloride crystals. A 10% sodium hydroxide aqueous solution was added to the purified aluminum chloride solution to adjust the pH to 3.0. The solution was then transferred to a polymerization reactor and thermally polymerized at 100℃ for 3 h. After cooling to room temperature, liquid polyaluminum chloride was obtained. The mass fraction of Al2O3 was 10.5% and the basicity was 45%, which met the GB / T 22627-2014 standard.

[0051] (5) Alkali leaching for silicon extraction: The silicon-rich slag is washed with deionized water until the pH value is 7.5, and mixed with the waste caustic alkali solution (sodium hydroxide mass fraction of 8%) generated from aluminum production at a liquid-solid ratio of 8:1. The mixture is then added to the alkali leaching reactor and stirred at 90°C for 5 hours. After the reaction, the solid and liquid are separated to obtain sodium silicate solution (SiO2 concentration of 25g / L) and 5.5g of residue (moisture content of 13%).

[0052] (6) Preparation of functional silicon materials: Polyethylene glycol 400 was added to a sodium silicate solution, with a molar ratio of 0.1:1 between polyethylene glycol 400 and silicon in the sodium silicate solution. The mixture was stirred and aged at 40°C for 2 hours, and the structure-directing agent formed ordered micelles in the solution. CO2 was introduced at a rate of 10 mL / min until the pH of the solution reached 7. After stopping the CO2 introduction, the mixture was crystallized and precipitated at 80°C for 4 hours. The reaction product was filtered and washed with deionized water until neutral, and then dried at 105°C for 5.5 hours to obtain 26.3 g of mesoporous silica, with a specific surface area of ​​620 m². 2 / g, pore size 2.5nm, purity 98.2%.

[0053] Example 3

[0054] (1) Microwave-mechanical synergistic activation pretreatment: 100g of coal gasification slag was fed into a microwave reactor. Nitrogen gas was introduced into the microwave reactor for microwave radiation treatment under protection. The radiation was carried out for 10 minutes at a nitrogen flow rate of 0.5L / min and a microwave power of 800W. Immediately after the microwave radiation treatment, the slag was transferred to a high-energy ball mill and ball-milled for 30 minutes at a ball-to-material ratio of 20:1 and a rotation speed of 500r / min to obtain activated slag. The specific surface area was measured to be 95m². 2 / g, with a particle size of 70μm.

[0055] (2) Acid leaching for aluminum extraction: The activated slag and waste hydrochloric acid (HCl mass fraction of 20%) from steel pickling were mixed at a liquid-to-solid ratio of 10:1 and added to a reactor equipped with a stirrer. The acid leaching reaction was carried out at 100℃ and a stirring rate of 400r / min for 2 hours. The reaction product was separated into solid and liquid components using a plate and frame filter press to obtain an aluminum-containing iron leaching solution (Al). 3+ The concentration is 28 g / L, Fe 3+ (Concentration of 7g / L) and 45g of silica-rich slag.

[0056] (3) Iron-aluminum separation: A kerosene solution of TBP (30% TBP by volume) was added to the aluminum-containing iron leachate as an extractant at a ratio of 3:1. Iron ions were selectively extracted at 40°C and a stirring rate of 500 r / min for 10 min. After standing and separating, a purified aluminum chloride solution (Fe) was obtained. 3+ (Content 0.02 g / L, aluminum-iron separation rate 99.7%) and iron-rich organic phase.

[0057] (4) Preparation of polyaluminum chloride and iron resource utilization: The iron-rich organic phase was back-extracted for 20 min at 50 °C and a ratio of 4:1 using 3 mol / L hydrochloric acid solution as the back-extraction agent to obtain ferric chloride solution. The ferric chloride solution was evaporated and concentrated to saturation at 90 °C and then cooled to crystallize, yielding 18.2 g of ferric chloride crystals. A 20% sodium hydroxide aqueous solution was added to the purified aluminum chloride solution to adjust the pH to 4.0. The solution was then transferred to a polymerization reactor and thermally polymerized at 120 °C for 2 h. After cooling to room temperature, liquid polyaluminum chloride was obtained. The mass fraction of Al2O3 was 12.1% and the basicity was 85%, which met the standard of GB / T 22627-2014.

[0058] (5) Alkali leaching for silicon extraction: The silicon-rich slag is washed with deionized water until the pH value is 8, and mixed with dilute alkaline solution (sodium hydroxide mass fraction of 15%) produced by the chlor-alkali plant at a liquid-solid ratio of 12:1. The mixture is then added to the alkaline leaching reactor and stirred at 120°C for 3 hours. After the reaction, the solid and liquid are separated to obtain sodium silicate solution (SiO2 concentration of 38g / L) and 4.8g of residue (moisture content of 12%).

[0059] (6) Preparation of functional silicon materials: CTAB was added to a sodium silicate solution, with a molar ratio of CTAB to silicon in the sodium silicate solution of 0.3:1. The solution was stirred and aged at 60°C for 1 h, and the structure-directing agent formed ordered micelles in the solution. CO2 was introduced at a rate of 20 mL / min until the pH of the solution reached 8. After stopping the CO2 introduction, the solution was crystallized and precipitated at 100°C for 2 h. The reaction product was filtered and washed with deionized water until neutral, and then dried at 115°C for 4.5 h to obtain 30.1 g of mesoporous silicon dioxide, with a specific surface area of ​​980 m². 2 / g, pore size 4.8nm, purity 98.8%.

[0060] Comparative Example 1

[0061] The microwave radiation treatment step is omitted, and the coal gasification slag is directly put into a high-energy ball mill for ball milling. Other process steps and parameters are the same as in Example 1.

[0062] The specific surface area of ​​the activated slag obtained in Comparative Example 1 was 52 m². 2 / g; the final aluminum leaching rate was 68%, the silicon leaching rate was 82%, the mass fraction of Al2O3 in the polyaluminum chloride was 9.8%, the yield of mesoporous silica was 20.3g, and the specific surface area was 550m². 2 / g, all indicators are lower than those in Example 1.

[0063] This invention first pre-treats coal gasification slag with microwave radiation, utilizing the thermal and non-thermal effects of microwaves to initially open silicon-aluminum bonds. This is then combined with mechanical activation to further enhance the reactivity of the slag. Subsequently, aluminum is extracted by acid leaching with industrial waste hydrochloric acid. The resulting aluminum-iron leachate is then solvent-extracted to achieve highly selective separation and resource recovery of iron. The purified aluminum chloride solution is adjusted for pH and thermally polymerized to prepare high-quality polyaluminum chloride. The silica-rich slag produced by acid leaching is washed and then leached with industrial waste alkaline solution to extract silicon. The resulting sodium silicate solution, under the action of a structure-directing agent, is carbonized and precipitated to prepare high-value-added mesoporous silica. This invention significantly improves the aluminum-silicon leaching rate through microwave-mechanical synergistic activation, achieving the synergistic and efficient treatment of three wastes: coal gasification slag, waste hydrochloric acid, and waste alkaline solution. The process is closed-loop, the product has high added value, and the environmental and economic benefits are significant.

[0064] The process of this invention is mature and reliable, and the equipment used is all commonly used industrial equipment, which is easy to scale up for production. Based on the annual processing of 10,000 tons of coal gasification slag, it can produce more than 8,000 tons of polyaluminum chloride, more than 3,000 tons of mesoporous silica, and more than 1,000 tons of ferric chloride crystals. At the same time, it can dispose of more than 15,000 tons of waste hydrochloric acid and more than 12,000 tons of waste alkali solution, significantly improving the annual economic benefits. It can also effectively solve the environmental pollution problems of coal gasification slag and waste acid and alkali, and has broad industrial application prospects.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle 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 preparing polyaluminum and functional silicon materials from coal gasification slag and waste hydrochloric acid by microwave-assisted mechanical force activation, characterized in that, The method comprises the following steps: 1) sequentially performing microwave irradiation treatment and ball milling on coal gasification slag to obtain activated slag; 2) performing acid leaching reaction on the activated slag and waste hydrochloric acid, and then performing solid-liquid separation to obtain aluminum-iron-containing leaching solution and silicon-rich slag; 3) adding an extractant solution to the aluminum-iron-containing leaching solution to perform extraction, thereby obtaining iron-rich organic phase and purified aluminum chloride solution; 4) mixing the iron-rich organic phase and hydrochloric acid to perform back extraction, and then performing evaporation concentration and cooling crystallization to obtain iron chloride crystals; adjusting the pH value of the purified aluminum chloride solution to perform thermal polymerization reaction, thereby obtaining polymerized aluminum chloride; 5) performing alkali leaching reaction on the silicon-rich slag and waste lye, and then performing solid-liquid separation to obtain sodium silicate solution and residue; 6) sequentially performing aging and carbon dioxide introduction to adjust the pH value of the solution, and then performing crystallization and precipitation to obtain mesoporous silicon dioxide.

2. The method for preparing polyaluminum and functional silicon materials by microwave-assisted mechanical activation of coal gasification slag and waste hydrochloric acid according to claim 1, characterized in that, In step 1), the microwave irradiation treatment is performed at a power of 300-800 W for 10-30 min in a protective gas, and the flow rate of the protective gas is 0.5-1.5 L / min.

3. The method for preparing polyaluminum and functional silicon material by microwave synergistic mechanical force activation of coal gasification slag and waste hydrochloric acid according to claim 1 or 2, characterized in that, Step 1) during the ball milling, the ball-to-material ratio is 10-20:1, the rotation speed of the ball mill is 300-500 r / min, the ball milling time is 30-90 min, and the specific surface area of the activated slag is ≥65 m 2 / g and the particle size is ≤100 μm.

4. The method according to claim 3, wherein the microwave synergic mechanical force activated coal gasification slag and waste hydrochloric acid are used to prepare polyaluminum and functional silicon materials. In step 2), the mass fraction of the waste hydrochloric acid is 10-20%, the liquid-solid ratio of the activated slag and waste hydrochloric acid is 5-10:1, the acid leaching reaction is performed at a temperature of 80-100 ℃ for 2-4 h, and stirring is performed during the acid leaching reaction at a stirring rate of 200-400 r / min.

5. The method for preparing polyaluminum and functional silicon materials by microwave-assisted mechanical activation of coal gasification slag and waste hydrochloric acid according to claim 4, characterized in that, In step 3), the extraction is performed at a temperature of 25-40 ℃, a phase ratio of 1-3:1 and a stirring rate of 300-500 r / min for 10-20 min. The solvent of the extractant solution is kerosene, the extractant is tributyl phosphate or primary amine N1923, and the volume fraction of the extractant in the extractant solution is 10-30%.

6. The method for preparing polyaluminum and functional silicon material by microwave synergistic mechanical force activation of coal gasification slag and waste hydrochloric acid according to claim 4 or 5, characterized in that, In step 4), the concentration of the hydrochloric acid is 1-3 mol / L, the back extraction is performed at a temperature of 40-50 ℃, a phase ratio of 2-4:1 and a stirring rate of 300-500 r / min for 20-30 min. In step 4), the pH value of the purified aluminum chloride solution is adjusted to 3.0-4.0 by using a sodium hydroxide solution with a mass fraction of 10-20%, and the thermal polymerization reaction is performed at a temperature of 100-120 ℃ for 2-3 h.

7. The method according to claim 6, wherein the microwave synergic mechanical force activation is carried out at a temperature of 300-400°C, a pressure of 0.1-0.5 MPa, and a microwave power of 300-500 W. In step 5), the silicon-rich slag is washed to neutral, and then mixed with the waste lye, and the liquid-solid ratio of the silicon-rich slag and waste lye is 8-12:1, and the mass fraction of sodium hydroxide in the waste lye is 8-15%. In step 5), the alkali leaching reaction is performed at a temperature of 90-120 ℃ for 3-5 h, the water content of the residue is less than or equal to 15%, and the concentration of SiO2 in the sodium silicate solution is 20-40 g / L.

8. The method for preparing polyaluminum and functional silicon materials by microwave-assisted mechanical activation of coal gasification slag and waste hydrochloric acid according to claim 7, characterized in that, In step 6), the structure directing agent is cetyltrimethylammonium bromide or polyethylene glycol, and the molar ratio of the structure directing agent to silicon in the sodium silicate solution is 0.1-0.3:

1.

9. The method for preparing polyaluminum and functional silicon materials by microwave-assisted mechanical activation of coal gasification slag and waste hydrochloric acid according to claim 8, characterized in that, In step 6), the aging is performed at a temperature of 40-60 ℃ for 1-2 h, the carbon dioxide is introduced at a rate of 10-20 mL / min, the pH value of the solution is adjusted to 7-8 by introducing carbon dioxide, and the crystallization and precipitation are performed at a temperature of 80-100 ℃ for 2-4 h.