Method for producing 4A zeolite by using coal gasification slag

Abstract

The invention relates to the technical field of 4A zeolite production, and discloses a method for producing 4A zeolite by using coal gasification slag, which comprises the following steps: carrying out roasting process, conversion process, refining process, primary extraction process, dissolution process, secondary extraction process, mold adjustment, slurrying, crystallization and drying on the coal gasification slag to obtain the 4A zeolite. The coal gasification slag is used as a raw material, aluminum oxide and silicon dioxide in the coal gasification slag can be fully extracted through the method, the yield of the 4A zeolite is increased, and the obtained 4A zeolite has the advantages of being high in crystallinity and whiteness, low in impurity content, large in cation exchange capacity and the like.

Description

Technical Field

[0001] The invention relates to the technical field of 4A zeolite production, and in particular to a method for producing 4A zeolite by utilizing coal gasification slag. Background Art

[0002] 4A zeolite is Na 12 Al 12 Si 12 O 48 27H2O or Na 12 [(AlO2) 12 (SiO2) 12 ]·27H2O is a three-dimensional framework structure compound composed of silicon oxygen and aluminum oxygen tetrahedron, belonging to the cubic crystal system. The center of the unit cell is a hole with a diameter of 1.14A, which is connected by an 8-membered ring and 6 similar holes. The diameter of the free hole formed by this 8-membered ring structure is 4.12A, so it is called 4A zeolite.

[0003] The traditional synthesis methods of 4A zeolite include water glass method, activated clay method, bentonite method and kaolin method. The water glass method is mature and easy to control, but the cost is high. The activated clay method and bentonite method require the addition of aluminum source, which is costly and the equipment needs to be corrosion-resistant.

[0004] The annual emission of gasification slag produced by coal gasification in my country's coal-to-liquid industry is very large. The resource utilization of gasification slag is an urgent need for the high-quality development of the ecological environment.

[0005] In the prior art, some people use coal gasification slag as raw material to prepare 4A zeolite. However, since alumina and silica cannot be fully extracted, and alumina and silica generate sodium aluminosilicate solid during the extraction process, the utilization rate of the coal gasification slag is low, and the yield of the obtained 4A zeolite is low and the quality is poor. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a method for producing 4A zeolite using coal gasification slag. The coal gasification slag is used as the raw material. The method of the present invention can fully extract the alumina and silica in the coal gasification slag, thereby increasing the yield of 4A zeolite. The obtained 4A zeolite has the advantages of high crystallinity, high whiteness, low impurity content and large cation exchange capacity.

[0007] The present invention provides a method for producing 4A zeolite by utilizing coal gasification slag, comprising the following steps: The 4A zeolite is obtained by using coal gasification slag through roasting process, conversion process, refinement process, primary extraction process, dissolution process, secondary extraction process, mold adjustment, slurrying, crystallization and drying.

[0008] Furthermore, the coal gasification slag is waste slag produced by coal decomposition during the coal gasification process in the coal-to-liquid industry.

[0009] Furthermore, the specific method of the roasting process includes: roasting the coal gasification slag.

[0010] Furthermore, the calcination temperature is 800°C-1200°C, and the calcination time is 10min-30min.

[0011] Furthermore, the specific steps of the conversion process include: uniformly mixing the coal gasification slag after the roasting process and sodium carbonate, and then heating.

[0012] Furthermore, the ratio of the coal gasification slag to sodium carbonate after the roasting process is (1:0.35-2.2) by mass.

[0013] Furthermore, the heating temperature is 1350° C.-1400° C., and the heating time is 50 min-60 min.

[0014] Furthermore, after the heating is completed, it is also necessary to ensure that the discharge temperature after heating is higher than 1050°C.

[0015] Furthermore, the specific process of the refinement process includes: quenching the product after the conversion process with water, wet grinding the product after water quenching with a dilute sodium hydroxide solution, diluting it to a liquid-solid ratio of (8:1-10:1), and finally performing solid-liquid separation.

[0016] Furthermore, the ratio of the product after the conversion process to the dilute sodium hydroxide solution during water quenching is (1:4-5) by mass.

[0017] The water quenching in the present invention refers to rapidly immersing the molten clinker obtained after the conversion process into a dilute sodium hydroxide solution at high temperature for water quenching treatment to obtain solid fine particles.

[0018] Furthermore, the specific step of wet grinding with dilute sodium hydroxide solution includes: using dilute sodium hydroxide solution as a wet grinding agent, wet grinding the product after water quenching to a particle size between 200 meshes and 400 meshes.

[0019] In the present invention, those skilled in the art may use ball milling or other grinding methods to refine the particle size of the product after water quenching.

[0020] Furthermore, during wet grinding, the mass ratio of the dilute sodium hydroxide solution to the product after water quenching is (3-5:1).

[0021] Furthermore, the mass percentage concentration of the dilute sodium hydroxide solution is 3%-5%.

[0022] Furthermore, the preparation method of the dilute sodium hydroxide solution comprises dissolving sodium hydroxide in water.

[0023] Furthermore, the caustic Na2O in the diluted solution K The concentration is not less than 200g / L.

[0024] Furthermore, the diluted solution includes a water-quenched solution and a dilute sodium hydroxide solution.

[0025] In the present invention, it should be understood by those skilled in the art that, although the solution used for dilution is the water-quenched solution and the dilute sodium hydroxide solution, the dilute solution is mainly the dilute sodium hydroxide solution. Generally speaking, there is no strict dosage ratio between the water-quenched solution and the dilute sodium hydroxide solution. As long as the caustic Na2O in the diluted solution can be controlled, K The concentration should be no less than 200g / L.

[0026] Furthermore, the mass percentage concentration of the dilute sodium hydroxide solution is 3%-5%.

[0027] Furthermore, during the dilution process, by controlling the caustic Na2O K The concentration of sodium aluminate and sodium silicate can be completely separated, which is beneficial to the mold adjustment and slurry process. During the dilution process, stirring can be used to promote sufficient dilution and separation of sodium aluminate and sodium silicate. As an example, the stirring speed can be 20 rpm-30 rpm.

[0028] Furthermore, the specific method of the one-time extraction process includes: adding the filter residue after the refinement process to a caustic soda solution, removing water from the solution, and obtaining an intermediate product.

[0029] Furthermore, the mass percentage concentration of the caustic soda solution is 45%-50%.

[0030] Furthermore, the caustic soda solution is a sodium hydroxide solution.

[0031] Furthermore, the method for removing water from the solution is specifically: using a heating method, and the heating temperature is 320°C-550°C.

[0032] Furthermore, the molar ratio of the filter residue to the caustic soda solution is (1:2-2.4), calculated as silicon dioxide in the filter residue and calculated as sodium hydroxide in the caustic soda solution.

[0033] Furthermore, the preparation method of the caustic soda solution includes: dissolving sodium hydroxide in water.

[0034] Furthermore, the specific method of the dissolution process includes: dissolving the intermediate product obtained by the primary extraction process in a dilute sodium hydroxide solution with a mass percentage concentration of 3%-5%, and the caustic Na2O in the dissolved solution K The concentration is not less than 250g / L, filter and the filtrate is set aside.

[0035] Furthermore, the secondary extraction process specifically includes: adding the filter residue after filtering in the dissolution process to the caustic soda solution again to obtain a mixed slurry, grinding, heating reaction, diluting with a dilute sodium hydroxide solution with a mass percentage concentration of 3%-5%, filtering, and the filtrate is set aside.

[0036] Furthermore, the mass percentage concentration of sodium hydroxide in the mixed slurry is 20%-25%.

[0037] Furthermore, the particle size of the solid particles in the mixed slurry is ground to be between 200 mesh and 400 mesh.

[0038] Furthermore, the temperature of the heating reaction is 130°C-140°C, and the time of the heating reaction is 3min-5min.

[0039] Those skilled in the art should understand that during dilution, the substance can be made uniform, which is beneficial for secondary extraction. Therefore, stirring can be performed during dilution, and the stirring speed can be 60 rpm-90 rpm.

[0040] Furthermore, after dilution, the mass percentage concentration of sodium hydroxide in the diluted solution is 14%-18%.

[0041] Furthermore, the specific method for adjusting the mold includes: combining the filtrate after the refinement process, the filtrate after the dissolution process, and the filtrate after the secondary extraction, adding aluminum hydroxide to adjust the mold, and after adding aluminum hydroxide, the molar ratio of aluminum oxide to silicon dioxide in the filtrate is (1:1.52-1.65).

[0042] Furthermore, stirring is required during the mold adjustment process, and the stirring rate is 20 rpm to 30 rpm.

[0043] Furthermore, the specific process of the slurrying includes: adding a directing agent to the adjusted solution for mixing; during mixing, controlling the stirring speed to 60 rpm-120 rpm and the temperature to 60°C-80°C; after the mixing is completed, controlling the stirring speed to 60 rpm-120 rpm and the stirring time to 20min-30min.

[0044] Furthermore, the guiding agent is prepared with four substances: aluminum hydroxide, sodium hydroxide, sodium hydroxide and water. When preparing the guiding agent, the aluminum hydroxide is calculated as alumina, the sodium hydroxide is calculated as silicon dioxide, and the ratio of aluminum hydroxide, sodium hydroxide, sodium hydroxide and water is (1:15:19-20:300-350) by mass.

[0045] In the present invention, the guiding agent is prepared from four substances, aluminum hydroxide, sodium hydroxide, and water, to form a 4A zeolite seed solution. The amount of seeds in the 4A zeolite seed solution is calculated and determined based on 1%-3% of the designed 4A zeolite output. After determining the amount of seeds in the 4A zeolite seed solution, the ratio of aluminum hydroxide, sodium hydroxide, sodium hydroxide, and water is (1:15:19-20:300-350) according to the weight of aluminum hydroxide, sodium hydroxide, sodium hydroxide, and water, and the specific amount of raw materials aluminum hydroxide, sodium hydroxide, sodium hydroxide, and water when preparing the guiding agent can be determined.

[0046] Furthermore, the preparation process of the directing agent includes: controlling the temperature of the solution after mixing aluminum hydroxide, sodium hydroxide, sodium hydroxide and water to 45°C-65°C, continuously stirring for 20min-30min at a stirring speed of 60 rpm-90 rpm, and then letting the solution stand for 24h-48h. The directing agent after standing is used for slurrying within 30min-60min.

[0047] Furthermore, the specific process of the crystallization includes: heating the slurried solution.

[0048] Furthermore, the heating temperature is 90° C.-98° C., the heating time is 1 h-3 h, stirring is performed during the heating process, and the stirring speed is 20 rpm-30 rpm.

[0049] Furthermore, the method also includes drying, and the specific process of drying includes: washing and drying the crystallized solid to obtain 4A zeolite.

[0050] Furthermore, the drying temperature is 95°C-105°C.

[0051] It should be understood by those skilled in the art that the washing process is to remove the impurity ions adsorbed on the surface and in the crystal lattice of 4A zeolite, and to improve the ion adsorption and exchange capacity of the 4A zeolite product. Therefore, it is necessary to use deionized water for washing, and then dry to remove the adsorbed water. The selection of the drying temperature in the present invention is based on the stability of the product structure to achieve the effect of removing the adsorbed water.

[0052] The embodiments of the present invention have the following technical effects: 1. In the method of the present invention, the coal gasification slag is first activated by a roasting process, which can not only decompose the alumina and silica in the coal gasification slag into free alumina and silica, but also facilitate the full conversion of alumina and silica in the coal gasification slag during the conversion process; the roasting process can also remove the combustible components and organic matter in the coal gasification slag, which helps to improve the whiteness and quality of the 4A zeolite obtained after crystallization; The product after the conversion process is subjected to a refinement process. In the refinement process, the product after the conversion process is water quenched, which is conducive to the product being broken into fine particles under the action of surface tension, which can not only increase the specific surface area of ​​the product, thereby facilitating the full extraction of alumina and silica in the primary extraction process and the secondary extraction process, but also lays the foundation for full wet grinding, thereby facilitating the decomposition of sodium aluminosilicate during the wet grinding process; Adding a dilute sodium hydroxide solution during wet grinding can, on the one hand, assist wet grinding and promote the decomposition of water-insoluble sodium aluminosilicate generated by alumina and silica in the conversion process, thereby facilitating the full separation of silica and alumina in the gasification slag; on the other hand, it can reduce the amount of sodium aluminosilicate residue in the filter residue after solid-liquid separation, thereby reducing the processing cost of the subsequent primary extraction process; In order to fully extract alumina and silica from the coal gasification slag, the filter residue after the refinement process needs to be processed by a primary extraction process and a secondary extraction process. During the primary extraction process, the concentration of the caustic soda solution is controlled so that all the residual sodium aluminosilicate in the filter residue is decomposed. The mutual cooperation of the primary extraction process and the secondary extraction process is conducive to improving the extraction rate of alumina and silica from the raw coal gasification slag, increasing the output of 4A zeolite, and improving the economic efficiency of the utilization of the coal gasification slag raw materials. During the dissolution process, the caustic Na2O K The concentration can improve the reaction kinetics of sodium hydroxide, prevent the regeneration of sodium aluminosilicate, and is conducive to the maximum extraction of alumina and silicon dioxide, thereby increasing the yield of 4A zeolite; During the mold adjustment process, aluminum hydroxide is added as a mold adjustment agent. On the one hand, it is to adjust the concentration of aluminum oxide so that the chemical composition ratio of aluminum oxide and silicon dioxide meets the composition of 4A zeolite, thereby laying the foundation for the formation of 4A zeolite; on the other hand, aluminum hydroxide, a mold adjustment agent, will also consume part of the sodium hydroxide, reducing the concentration of sodium hydroxide, which is conducive to the atomic arrangement of the formed crystals in the direction of the 4A zeolite crystal structure, thereby ensuring the quality of 4A zeolite; During the slurrying process, the directing agent of the present invention is prepared and used immediately, which is beneficial to further promote the atomic arrangement of the generated crystals to grow towards the 4A zeolite crystal structure; Finally, through crystallization, the 4A zeolite crystals are grown, and finally the 4A zeolite is obtained.

[0053] 2. The method of the present invention is for coal gasification slag with an Al2O3 mass percentage of 16.59% and a SiO2 mass percentage of 53.8%. The extraction rate of Al2O3 in the coal gasification slag raw material reaches 97%, and the extraction rate of SiO2 reaches 95.91%; the extracted Al2O3 and SiO2 together account for 96.17% of the total amount of Al2O3 and SiO2 in the coal gasification slag raw material, and account for more than 67% of the total amount of the coal gasification slag raw material.

[0054] 3. The calcium exchange capacity, whiteness, crystallinity, particle size and pH value of the 4A zeolite produced by the method of the present invention from coal gasification slag all meet the product quality standards of 4A zeolite for detergent additives. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0056] In a first aspect, some embodiments of the present invention provide a method for producing 4A zeolite using coal gasification slag, comprising the following steps: The 4A zeolite is obtained by using coal gasification slag through roasting process, conversion process, refinement process, primary extraction process, dissolution process, secondary extraction process, mold adjustment, slurrying, crystallization and drying.

[0057] In some embodiments, the coal gasification slag is waste slag produced by coal decomposition during the coal gasification process in the coal-to-liquids industry.

[0058] In some embodiments, the specific method of the roasting process includes: roasting the coal gasification slag.

[0059] In some embodiments, the calcination temperature is 800° C.-1200° C., and the calcination time is 10 min-30 min.

[0060] In some embodiments, the specific steps of the conversion process include: uniformly mixing the coal gasification slag after the roasting process and sodium carbonate, and then heating.

[0061] In some embodiments, the ratio of coal gasification slag to sodium carbonate after the roasting process is (1:0.35-2.2) by mass.

[0062] In some embodiments, the heating temperature is 1350° C.-1400° C., and the heating time is 50 min-60 min.

[0063] In some embodiments, after heating, it is also necessary to ensure that the discharge temperature after heating is higher than 1050°C.

[0064] In the present invention, by controlling the temperature of the conversion process, it is ensured that the aluminum oxide and silicon dioxide in the coal gasification slag are fully converted into sodium aluminate and sodium silicate, and the sodium aluminosilicate solid formed between the aluminum oxide and silicon dioxide is reduced, which is conducive to maximally extracting aluminum oxide and silicon dioxide from the coal gasification slag.

[0065] In some embodiments, the specific process of the refinement process includes: quenching the product after the conversion process with a dilute sodium hydroxide solution, wet grinding the product after the water quenching with a dilute sodium hydroxide solution, diluting it to a liquid-solid ratio of (8:1-10:1), and finally performing solid-liquid separation.

[0066] In some embodiments, the ratio of the product after the conversion process to the dilute sodium hydroxide solution during water quenching is (1:4-5) by mass.

[0067] In some embodiments, the specific step of wet grinding with dilute sodium hydroxide solution includes: using dilute sodium hydroxide solution as a wet grinding agent, wet grinding the product after water quenching to a particle size between 200 mesh and 400 mesh.

[0068] In some embodiments, during wet grinding, the mass ratio of the dilute sodium hydroxide solution to the product after water quenching is (3-5:1).

[0069] In some embodiments, the mass percentage concentration of the dilute sodium hydroxide solution is 3%-5%.

[0070] In some embodiments, the method for preparing the dilute sodium hydroxide solution comprises dissolving sodium hydroxide in water.

[0071] In some embodiments, the caustic Na2O in the diluted solution K The concentration is not less than 200g / L.

[0072] In some embodiments, the mass percentage concentration of the dilute sodium hydroxide solution is 3%-5%.

[0073] In some embodiments, during the dilution process, by controlling the caustic Na2O K The concentration of sodium aluminate and sodium silicate can be completely separated, which is beneficial to the mold adjustment and slurry process. During the dilution process, stirring can be used to promote sufficient dilution and separation of sodium aluminate and sodium silicate. As an example, the stirring speed can be 20 rpm-30 rpm.

[0074] In some embodiments, the specific method of the one-time extraction process includes: adding the filter residue after the refinement process to a caustic soda solution, removing water from the solution, and obtaining an intermediate product.

[0075] In some embodiments, the mass percent concentration of the caustic soda solution is 45%-50%.

[0076] In some embodiments, the method for removing water from the solution is specifically: using a heating method, and the heating temperature is 320°C-550°C.

[0077] In some embodiments, the molar ratio of the filter residue to the caustic soda solution is (1:2-2.4) based on silicon dioxide and the molar ratio of the caustic soda solution to sodium hydroxide.

[0078] In some embodiments, the method for preparing the caustic soda solution includes: dissolving sodium hydroxide in water.

[0079] In some embodiments, the specific method of the dissolution process includes: dissolving the intermediate product obtained by the primary extraction process in a dilute sodium hydroxide solution with a mass percentage concentration of 3%-5%, and the caustic Na2O in the dissolved solution K The concentration is not less than 250g / L, filter and the filtrate is set aside.

[0080] In some embodiments, the secondary extraction process specifically includes: adding the filter residue after filtering in the dissolution process to the caustic soda solution again to obtain a mixed slurry, grinding, heating to react, diluting with a dilute sodium hydroxide solution with a mass percentage concentration of 3%-5%, filtering, and setting the filtrate aside.

[0081] In some embodiments, the mass percentage concentration of sodium hydroxide in the mixed slurry is 20%-25%.

[0082] In some embodiments, the particle size of the solid particles in the mixed slurry is ground to be between 200 mesh and 400 mesh.

[0083] In some embodiments, the temperature of the heating reaction is 130° C.-140° C., and the time of the heating reaction is 3 min-5 min.

[0084] In some embodiments, after dilution, the mass percentage concentration of sodium hydroxide in the diluted solution is 14%-18%.

[0085] In some embodiments, the specific method of adjusting the mold includes: combining the filtrate after the refinement process, the filtrate after the dissolution process, and the filtrate after the secondary extraction, adding aluminum hydroxide to adjust the mold, and after adding aluminum hydroxide, the molar ratio of alumina to silicon dioxide in the filtrate is (1:1.52-1.65).

[0086] In some embodiments, stirring is required during the mold adjustment process, and the stirring rate is 20 rpm to 30 rpm.

[0087] In some embodiments, the specific process of the slurrying includes: adding a directing agent to the solution after mold adjustment for mixing; during mixing, controlling the stirring speed to 60 rpm-120 rpm and the temperature to 60°C-80°C; after mixing, controlling the stirring speed to 60 rpm-120 rpm and the stirring time to 20min-30min.

[0088] In some embodiments, the guiding agent is prepared with four substances: aluminum hydroxide, sodium hydroxide, sodium hydroxide, and water; when preparing the guiding agent, the aluminum hydroxide is calculated as alumina, the sodium hydroxide is calculated as silicon dioxide, and the ratio of aluminum hydroxide, sodium hydroxide, sodium hydroxide, and water is (1:15:19-20:300-350) by mass.

[0089] In some embodiments, the preparation process of the directing agent includes: controlling the temperature of the solution after mixing aluminum hydroxide, sodium hydroxide, sodium hydroxide and water to 45°C-65°C, continuously stirring for 20min-30min at a stirring speed of 60 rpm-90 rpm, and then letting the solution stand for 24h-48h. The directing agent after standing is used for slurrying within 30min-60min.

[0090] In some embodiments, the specific process of the crystallization includes: heating the slurried solution.

[0091] In some embodiments, the heating temperature is 90° C.-98° C., the heating time is 1 h-3 h, stirring is performed during the heating process, and the stirring speed is 20 rpm-30 rpm.

[0092] In some embodiments, the specific process of drying includes: washing and drying the crystallized solid to obtain 4A zeolite.

[0093] In some embodiments, the drying temperature is 95°C-105°C.

[0094] The following is described in conjunction with some specific embodiments: Embodiment 1:

[0095] A coal gasification slag with an Al2O3 mass percentage of 16.59% and an SiO2 mass percentage of 53.80% is calcined at 1000°C for 20 minutes to complete the calcination process.

[0096] Conversion process: The coal gasification slag after the roasting process is mixed with sodium carbonate, heated for alkali melting treatment to obtain molten clinker. The coal gasification slag after the roasting process and sodium carbonate are mixed according to the mass ratio of coal gasification slag: sodium carbonate = 1:2, reacted at a heating temperature of 1400°C for 55 minutes, and the discharge temperature is maintained above 1050°C to obtain molten clinker.

[0097] Refining process: The molten clinker obtained by the conversion process is quickly quenched with a dilute sodium hydroxide solution with a mass percentage concentration of 4% while at high temperature. During the water quenching, the ratio of the product after the soda ash melt to the dilute sodium hydroxide solution is 1:5 by mass to obtain solid fine particles; the solid fine particles are input into the next wet grinding process; wet grinding is performed with a dilute sodium hydroxide solution with a mass percentage concentration of 4%, and the wet grinding is completed when the fineness is 300 mesh. The mass ratio of the dilute sodium hydroxide solution and the product after water quenching is 4:1. The slurry obtained by wet grinding is diluted with the water quenched solution and a dilute sodium hydroxide solution with a mass percentage concentration of 4%, and diluted to a liquid-solid ratio of 8:1-10:1. In this range, the caustic Na2O in the solution is controlled. K ≥200g / L, stir continuously at 25 rpm during dilution; filter immediately after dilution and keep the filtrate for later use; Primary extraction process: add caustic soda solution with a mass percentage concentration of 47% to the filter cake after the refinement process, the filter residue is calculated as silicon dioxide, the caustic soda solution is calculated as sodium hydroxide, the molar ratio of the filter residue to the caustic soda solution is 1:2.2, and heat the reaction at 350°C until the material becomes dry powder; Dissolution process: The dry powder obtained from the first extraction process is dissolved in a dilute sodium hydroxide solution with a mass percentage concentration of 4%; during the dissolution, the caustic Na2O in the solution after dissolution is controlled. K ≥250g / L; After dissolving, filter immediately and set the filtrate aside; The filter cake obtained by filtration is subjected to secondary extraction process; Secondary extraction process: add the filter cake obtained by the primary extraction process to a caustic soda solution with a mass percentage concentration of 47%, and the mass percentage concentration of sodium hydroxide in the mixed slurry after adding the caustic soda solution is 25%; grind the mixed slurry after adding the caustic soda solution to 300 mesh solid particles in the slurry, and heat at 135°C for reaction for 3 minutes; dilute the slurry after the reaction with a dilute sodium hydroxide solution, and stir evenly at 80 rpm, and the amount of the dilute sodium hydroxide solution added is 16% of the mass percentage concentration of sodium hydroxide in the dilute slurry after adding the dilute sodium hydroxide solution; filter immediately after dilution; the filtrate is set aside, and the filter cake obtained by filtration is washed with 95°C hot water until the pH is ≤11; Mold adjustment: The filtrates after the refinement process, dissolution process and secondary extraction process are combined, and aluminum hydroxide is added for mold adjustment. The molar ratio of Al2O3 and SiO2 in the solution is adjusted, and solid aluminum hydroxide is added under continuous stirring at a stirring speed of 25 rpm to dissolve all the added aluminum hydroxide. After adding aluminum hydroxide, the molar ratio of alumina to silicon dioxide in the filtrate is 1:1.6.

[0098] Preparation of guiding agent: The dosage of guiding agent is determined by calculation based on 2% of the designed 4A zeolite output; the guiding agent is prepared with aluminum hydroxide, sodium hydroxide, sodium hydroxide and water, with aluminum hydroxide being calculated as alumina and sodium hydroxide being calculated as silicon dioxide; the ratio of aluminum hydroxide, sodium hydroxide, sodium hydroxide and water is 1:15:19:300 by mass, and the temperature of the mixed solution is controlled to be 55°C. After continuous stirring at a stirring speed of 75 rpm for 25 minutes, the solution is allowed to stand for 40 hours. The guiding agent after standing is used in the slurrying stage within 30 minutes.

[0099] Slurrying: The prepared 4A zeolite directing agent is slowly added to the solution adjusted with aluminum hydroxide under continuous stirring to obtain a dilute gel solution; during slurrying, the stirring speed of the two solutions is controlled at 100 rpm and the temperature after mixing is 70°C; after the two solutions are mixed, the stirring speed is maintained at 100 rpm for continuous stirring for 25 minutes.

[0100] Crystallization: After slurrying, the temperature of the solution was rapidly raised to 95°C, the stirring speed was reduced to 25 rpm, and stirring was continued for 2 hours to complete crystallization.

[0101] Drying: The 4A zeolite filter cake obtained by filtering and washing after crystallization is dried at a temperature of 100° C. to obtain a 4A zeolite product.

[0102] In this embodiment, the mass percentage concentration of the caustic soda solution is 47%, and the mass percentage concentration of the dilute sodium hydroxide solution is 4%.

[0103] Comparative Example 1: The preparation method of Comparative Example 1 is the same as that of Example 1, but Comparative Example 1 does not have a calcination process step.

[0104] Comparative Example 2: The preparation method of Comparative Example 2 is the same as that of Example 1, but in the conversion process of Comparative Example 2, the heating temperature is 1200° C. and the heating time is 30 minutes.

[0105] Comparative Example 3: The preparation method of Comparative Example 3 is the same as that of Example 1, but in Comparative Example 3, no dilute sodium hydroxide solution is added during wet grinding.

[0106] Comparative Example 4: The preparation method of Comparative Example 4 is the same as that of Example 1, but Comparative Example 4 does not have a roasting process, and in the conversion process, the heating temperature is 1200° C. and the heating time is 30 minutes.

[0107] The products obtained from the embodiments and comparative examples of the present invention were tested.

[0108] Calcium exchange capacity detection method: loss on ignition method.

[0109] Whiteness detection method: color difference method.

[0110] Method for detecting crystallinity: X-ray diffraction method.

[0111] Particle size detection method: sedimentation method.

[0112] pH value detection method: potentiometric method.

[0113] Results and Analysis: Table 1 Test results of products obtained from the examples and comparative examples — <![CDATA[Calcium exchange capacity (mgCaCO3 / g dry basis)]]> Particle size (≤4μm,%) Whiteness (%) Crystallinity (%) pH Alumina extraction rate (%) Silica extraction rate (%) Example 1 302 92 96 85 10.8 97.00% 95.91% Comparative Example 1 253 82 74 71 11.0 95.03% 93.46% Comparative Example 2 296 88 95 83 10.7 89.57% 87.81% Comparative Example 3 295 86 94 81 11.0 95.81% 93.62% Comparative Example 4 250 83 73 70 10.9 88.46% 87.24% It can be found in Table 1 that the 4A zeolite product obtained by the present invention meets the quality standards of 4A zeolite products for detergent builders in terms of calcium exchange capacity, whiteness, particle size, and pH value, and the product of the present invention is significantly better than Comparative Examples 1 to 4 in terms of calcium exchange capacity, whiteness, and crystallinity. It can be seen that through the interaction between the steps of the method of the present invention, not only the extraction rate of alumina and silica is improved, but also a 4A zeolite with better quality is obtained.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing 4A zeolite using coal gasification slag, characterized in that: The steps include: The 4A zeolite is obtained by using coal gasification slag through roasting process, conversion process, refinement process, primary extraction process, dissolution process, secondary extraction process, mold adjustment, slurrying, crystallization and drying.

2. The method according to claim 1, characterized in that The coal gasification slag is waste residue generated by coal decomposition during the coal gasification process in the coal-to-liquids industry.

3. The method according to claim 1, characterized in that The specific method of the roasting process includes: roasting the coal gasification slag; The temperature of the calcination treatment is 800° C.-1200° C., and the time of the calcination treatment is 10 min-30 min.

4. The method according to claim 1, characterized in that: The specific steps of the conversion process include: uniformly mixing the coal gasification slag after the roasting process and sodium carbonate, and heating them; The ratio of coal gasification slag to sodium carbonate after the roasting process is (1:0.35-2.2) by mass; The heating temperature is 1350°C-1400°C, and the heating time is 50min-60min; After heating, it is also necessary to ensure that the discharge temperature after heating is higher than 1050°C.

5. The method according to claim 4, characterized in that The specific process of the refinement process includes: quenching the product after the conversion process with water, wet grinding the quenched product with a dilute sodium hydroxide solution, diluting it to a liquid-solid ratio of (8:1-10:1), and finally performing solid-liquid separation; The product after the conversion process and the dilute sodium hydroxide solution during water quenching, by mass, the ratio of the product after the conversion process to the dilute sodium hydroxide solution is (1:4-5); The specific steps of wet grinding with dilute sodium hydroxide solution include: using dilute sodium hydroxide solution as a wet grinding agent to wet grind the product after water quenching to a particle size of 200-400 mesh; During wet grinding, the mass ratio of dilute sodium hydroxide solution to the product after water quenching is (3-5:1); The mass percentage concentration of the dilute sodium hydroxide solution is 3%-5%; The caustic Na2O in the diluted solution K The concentration is not less than 200g / L.

6. The method according to claim 1, characterized in that The specific method of the one-time extraction process includes: adding the filter residue after the refinement process to a caustic soda solution, removing water from the solution, and obtaining an intermediate product; The mass percentage concentration of the caustic soda solution is 45%-50%; The method for removing water from the solution is specifically: using a heating method, the heating temperature is 320°C-550°C; The filter residue is calculated as silicon dioxide, and the caustic soda solution is calculated as sodium hydroxide. The molar ratio of the filter residue to the caustic soda solution is (1:2-2.4).

7. The method according to claim 1, characterized in that The specific method of the dissolution process comprises: dissolving the intermediate product obtained from the primary extraction process in a dilute sodium hydroxide solution with a mass percentage concentration of 3%-5%, and the caustic Na2O K The concentration is not less than 250g / L, filter and the filtrate is set aside.

8. The method according to claim 1, characterized in that The secondary extraction process specifically includes: adding the filter residue after the dissolution process to the caustic soda solution again to obtain a mixed slurry, grinding, heating for reaction, diluting with a dilute sodium hydroxide solution with a mass percentage concentration of 3%-5%, filtering, and the filtrate is set aside; The mass percentage concentration of sodium hydroxide in the mixed slurry is 20%-25%; The grinding process is performed until the particle size of the solid particles in the mixed slurry is between 200 mesh and 400 mesh; The temperature of the heating reaction is 130°C-140°C, and the heating reaction time is 3min-5min; After dilution, the mass percentage concentration of sodium hydroxide in the diluted solution is 14%-18%.

9. The method according to claim 1, characterized in that: The specific method of adjusting the mold includes: combining the filtrate after the refinement process, the filtrate after the dissolution process, and the filtrate after the secondary extraction, adding aluminum hydroxide to adjust the mold, and after adding aluminum hydroxide, the molar ratio of aluminum oxide to silicon dioxide in the filtrate is (1:1.52-1.65); Stirring is also required during the mold adjustment process, and the stirring rate is 20 rpm-30 rpm.

10. The method according to claim 1, characterized in that The specific process of the slurrying includes: adding a directing agent to the solution after mold adjustment for mixing; during mixing, controlling the stirring speed to 60 rpm-120 rpm and the temperature to 60° C.-80° C.; after the mixing is completed, controlling the stirring speed to 60 rpm-120 rpm and the stirring time to 20 min-30 min; The guiding agent is prepared by using aluminum hydroxide, sodium hydroxide, sodium hydroxide and water. When preparing the guiding agent, the aluminum hydroxide is calculated as alumina, the sodium hydroxide is calculated as silicon dioxide, and the weight ratio of the aluminum hydroxide, sodium hydroxide, sodium hydroxide and water is (1:15:19-20:300-350). The specific process of the crystallization includes: heating the slurried solution; The heating temperature is 90°C-98°C, the heating time is 1h-3h, stirring is performed during the heating process, and the stirring speed is 20 rpm-30 rpm; The specific drying process includes: washing and drying the crystallized solid to obtain 4A zeolite; The drying temperature is 95°C-105°C.