A method for preparing composite white carbon black by wet grinding of aluminum sulfate method extraction aluminum acid residue and adding calcium

Abstract

This invention relates to the field of chemical materials technology, and particularly to a method for preparing composite silica by solid-phase wet milling of aluminate slag from the sulfuric acid process with calcium. The method involves mixing a wet sample of aluminate slag from the sulfuric acid process with calcium-containing minerals or chemical raw materials containing CaO in a molar ratio of residual acid (H₂SO₄):CaO = 1:(1-3), and then performing a solid-phase wet milling reaction. The resulting slurry is dried to obtain composite silica powder. The invention further involves composite wet milling of the aluminate slag containing residual acid and calcium-containing substances in a ball mill. The reaction between the calcium-containing substances and the sulfuric acid in the slag generates hemihydrate calcium sulfate, which coats the surface of precipitated silica particles and further grows into whiskers, forming a fibrous composite material. The invention also provides a method for manufacturing composite silica-doped rubber. The fibrous composite silica material achieves mechanical reinforcement, has tunable surface properties, and better compatibility with polymer rubber substrates.

Description

Technical Field

[0001] This invention relates to a method for treating hazardous waste from aluminate slag produced by the sulfuric acid process, and particularly to a method for preparing composite silica materials using solid-phase wet milling reaction of aluminate slag produced by the sulfuric acid process, and its application, belonging to the field of chemical materials technology. Background Technology

[0002] Aluminum-rich minerals or solid wastes such as bauxite, kaolin, boulders clay, coal gangue, and fly ash can be used as raw materials for aluminum extraction. Dissolved aluminum salts are obtained through acid dissolution, followed by precipitation and other chemical reactions to produce Al2O3 or other aluminum products. However, the acid slag remaining after aluminum extraction is a type of hazardous solid waste. The filter residue is mainly amorphous silica, referred to as "silicon slag" or "acid slag," containing a large amount of water and residual sulfuric acid. Traditional treatment methods involve washing, filtering, and drying to obtain silica powder. These methods consume extremely high amounts of water and energy, and the wastewater requires secondary treatment, making the process complex. Therefore, new technologies are urgently needed to treat this type of hazardous waste.

[0003] Taking spherical clay as an aluminum extraction raw material as an example, the mineral composition of spherical clay is mainly composed of disordered kaolinite and quartz. It can be dissolved by acid, such as sulfuric acid (H2SO4), to break down the Al-O octahedrons of the kaolinite, forming a soluble aluminum sulfate solution. After filtration, the filtrate can be processed into polyaluminum sulfate flocculant or other aluminum products. The subsequent difficulty of this type of aluminum extraction technology lies in the fact that after acid extraction of aluminum, a large amount of siliceous residue, i.e., precipitated silica, is generated. However, this colloidal substance has a pH of about 1-2, is strongly acidic, and has a high water content (>50%, wt.), making it a typical hazardous waste. To further utilize this type of aluminum extraction solid waste, traditional processes such as washing, filtering, drying, and calcination can be used to produce silica products. However, because the "acid slag" has a high water and acid content, the traditional method of producing silica consumes a great deal of materials and energy. Moreover, the silica products produced are inferior to those obtained by fumed silica or by water glass precipitation in terms of color, particle size, specific surface area, and oil absorption value, and therefore cannot be used in downstream products. In addition, there are the following difficulties in the process: (1) In order to wash away residual acid, water with a mass ratio of 4-5 times is required, resulting in a large amount of acid wastewater discharge and secondary pollution; (2) Aluminate slag is in colloidal state with fine particle size, which is difficult to filter, consumes a lot of energy, and filter cloth and other filter equipment need to be acid resistant, which is a demanding requirement; (3) In order to prepare silica powder, the filter cake after water washing and filtration needs to be dried. Because it has a very high water content, the energy consumption required for evaporation is further increased; (4) Conventional drying process causes colloidal particles to agglomerate, which cannot obtain silica powder with a small particle size, with a particle size of more than 12μm; (5) Conventional methods (announcement number CN103420386A) produce silica in spherical shape, which cannot achieve the preparation of irregular silica particles. Therefore, it is difficult to maximize the reinforcing and toughening properties of downstream products such as rubber and plastics. In view of this, the efficient use of sulfuric acid process to extract aluminate slag, digest wet slag solid waste, avoid complicated water washing, filtration and drying processes, and obtain heterogeneous or fibrous precipitated silica materials has become a technology that urgently needs to be developed.

[0004] Patents CN103058239A and CN101844770A disclose a technology for extracting alumina and silica from fly ash. While this method successfully utilizes Al2O3 and SiO2 in fly ash, the process requires repeated acid leaching, alkali leaching, and calcination, making it complex and lengthy. The product is difficult to causticize and sinter, and it generates a large amount of CO2, resulting in excessively high energy consumption and costs, hindering industrial production. Patent CN101125656B discloses a method for extracting silicon and aluminum from fly ash. Although this method generates no waste, it uses a 40% causticizing alkali solution, and the costs of water washing and filtration remain high. Furthermore, the large amount of silicon-containing slag generated after aluminum extraction, after neutralization and drying, results in a powder used in cement, which has very low product value and is economically unfeasible. Patent CN103121700A provides an alkaline desilication and quicklime sintering method. This method emphasizes product purity but neglects the high energy consumption required for alkali leaching and high-temperature calcination. Publicly available patents CN103145161B and CN114014329A utilize coal gangue to prepare pseudoboehmite and co-produce precipitated silica. This method employs carbonization and acidification for silicon-aluminum separation, and the alkaline leaching residue is sintered with sodium carbonate and limestone to recover CO2. However, this method places extremely high demands on equipment for gas recovery, and repeated acid-alkali leaching not only results in excessive residue but also in extremely high energy consumption during drying. In summary, existing technologies mostly target aluminum-containing solid waste, involving acid and alkali dissolution, or multiple processes, followed by surface treatment to obtain modified siliceous fillers. These processes are lengthy and do not consider how to directly utilize the residual acid in the wet residue, failing to avoid the high costs associated with filtration and drying. Taking the "one-step acid dissolution method" for producing polyaluminum sulfate from low-grade clay as an example, the aluminate slag from clay extraction is a typical high-silica slag, with SiO2 as its main chemical component, and also containing small amounts of Al2O3, Fe2O3, and other residues. Because wet slag has a high acid content and extremely high water content, colloidal wet slag is difficult to filter. If a large amount of water is used to wash the waste slag to neutrality before filtration, it will lead to high energy consumption, high cost of equipment investment and secondary pollution. Therefore, new technologies to achieve harmless treatment of aluminate slag and obtain high-value siliceous materials still need to be developed.

[0005] Silica is a general term for amorphous silica products, mainly referring to precipitated silica, fumed silica, and ultrafine silica gel, and also including powdered aluminum silicate and calcium silicate as admixtures. Its composition can be represented as SiO2·nH2O, where nH2O exists in the form of surface hydroxyl groups. Silica is lightweight, non-toxic, and odorless, and possesses advantages such as large specific surface area, high dispersibility, good chemical stability, high temperature resistance, and good electrical insulation. It is used in many fields including rubber industry, animal feed, catalysis, food, medicine, dental care, nursing, papermaking, coatings, inks, and agrochemicals. As a rubber reinforcing agent, silica is used in large quantities, accounting for more than 35% of the total usage. To achieve good reinforcing effects, silica particles should have as many interaction points with rubber as possible. In particular, designing irregularly shaped or surface-functionalized silica powders can achieve reinforcing and toughening effects on rubber composites. Regarding silica composite technology, patent CN103881420A discloses a method of preparing highly dispersible rubber fillers by combining starch and silica. While this method solves the dispersibility issue, the use of starch leads to high costs and hinders industrialization. Patent CN105504345A discloses a method of wet milling silica and graphite sheets in an ethanol environment using precipitation. Although this achieves functionalization, it completely ignores the cost and environmental impact of ethanol. Patent CN113149070A discloses a method of obtaining photocatalytic silica composite materials by co-precipitating titanium tetrachloride and sodium silicate. The silicon tetrachloride used in this method is extremely expensive, and the treatment of the generated sodium chloride brine wastewater is also a bottleneck for this technology. Patent CN101293656B discloses a method of mixing microsilica powder and water glass and adjusting the pH to obtain a core-shell structured composite silica material. This method also requires a large amount of water and surfactants, making wastewater treatment difficult.

[0006] Silica itself has some drawbacks, such as strong hydrophilicity, poor dispersibility, high surface energy, and poor compatibility with rubber. In order to overcome these drawbacks, its surface needs to be coated. The process includes: (1) organosilane coupling agent coating: silane coupling agent is a substance that can chemically react with inorganic and organic materials. By chemically bonding with the surface of silica, it can effectively improve the dispersibility, oleophilicity and compatibility with organic materials of silica; (2) polymer coating: using polymers to coat silica can change its surface properties, such as improving its hydrophobicity, antifouling and anti-friction properties; (3) metal oxide coating: coating metal oxides can improve the high temperature resistance, oxidation resistance and catalytic activity of silica; (4) nanomaterial coating: by coating nanomaterials, silica can be endowed with new functions, such as conductivity, magnetism and optical properties. Therefore, developing coated precipitated silica to form composite powder is of great significance for the technological improvement of new chemical products.

[0007] Existing research focuses on the composite coating of inorganic microparticles such as SiO2 with organic polymer emulsions to form inorganic-organic composite particle dispersion systems. While electrostatic attraction can achieve this coating, the resulting composite particle systems exhibit varying performance characteristics, hindering the development of a universal technology. Another method involves synthesizing an ethanol solution of silica particles, surface-modifying it, and then using dispersion polymerization to achieve SiO2 coating with polystyrene. However, the ethanol solution is extremely expensive, making industrialization impractical. Current technologies all employ organic coating modification, but no feasible technical solution has been presented. Research on the inorganic modification of silica is relatively limited. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a method for preparing composite silica materials by solid-phase wet milling of aluminate slag obtained through sulfuric acid extraction with calcium, comprising the following steps:

[0009] Wet samples of aluminate residue from the sulfuric acid process are mixed with calcium minerals or chemical raw materials containing CaO in a molar ratio of residual acid H2SO4:CaO = 1:(1~3), and solid-phase wet milling is carried out. The resulting mixed slurry is dried or air-dried to obtain composite silica powder.

[0010] The wet sample of aluminate slag obtained by the sulfuric acid process has a water content in the range of 40% to 60% and a pH value of 0.5 to 2. The mass ratio of silicon slag solid, water, and sulfuric acid in the wet sample of aluminate slag obtained by the sulfuric acid process is 3:2:1. The mass content of SiO2 in the silicon slag solid is in the range of 93% to 95%, the mass content of Al2O3 is in the range of 4% to 5%, the mass content of Fe2O3 is in the range of 0.5% to 0.8%, and the total content of other impurities such as CaO, MnO, TiO2, K2O, Na2O, P2O5, etc. is less than 1.0%.

[0011] The solid-phase wet grinding reaction is carried out in a ball mill, and the preferred process parameters are: ball mill slurry filling rate of 28.0±1.0%, ball-to-material mass ratio of 8.0±0.5%, ball-to-small ball mass ratio of 2:1, and grinding time of 4.0±0.5h.

[0012] The sulfuric acid process for extracting aluminate slag is a silicate slag obtained by leaching one of the following aluminum- and silicon-containing minerals or solid wastes: bauxite, kaolin, ball clay, coal gangue, or fly ash, with sulfuric acid as the main component.

[0013] The calcium minerals or chemical raw materials mentioned are one or more of the following: calcite, dolomite, stalactite, seashell, calcium oxide, light calcium carbonate, heavy calcium carbonate, or dolomite.

[0014] The ball milling equipment is one of the following: zirconia grinding jar and grinding balls, agate grinding jar and grinding balls, polytetrafluoroethylene grinding jar and grinding balls, nylon grinding jar and grinding balls, acid-resistant ceramic grinding jar and grinding balls, and polyurethane grinding jar and grinding balls.

[0015] The composite silica material prepared by the above method can be used in the manufacture of rubber.

[0016] This invention further provides a method for manufacturing composite silica-doped rubber, comprising the following steps:

[0017] Take 50 parts of the composite silica powder prepared by the above method, 100 parts of styrene-butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 3 parts of polyethylene glycol (4000), 1.2 parts of accelerator DM, 0.7 parts of accelerator M, 0.5 parts of accelerator DPG, and 2 parts of sulfur. Put them into an open mill and plasticize at 40°C. Let it stand for more than 16 hours, then vulcanize and cool for more than 10 hours to obtain composite silica material toughened styrene-butadiene rubber products.

[0018] The working principle of the method for preparing composite silica materials by adding calcium to aluminate residue obtained by sulfuric acid extraction in this invention is as follows:

[0019] This invention involves composite wet milling of aluminized slag containing residual acid and calcium-containing substances in a ball mill. The calcium-containing substances react with sulfuric acid in the slag to generate calcium sulfate hemihydrate. This calcium sulfate hemihydrate coats the surface of precipitated silica particles and further grows into whiskers, forming a fibrous composite material. The specific surface area and whiteness are higher than those of the original dry slag powder.

[0020] The reaction between calcium-containing substances and sulfuric acid is an exothermic reaction, which can make full use of the heat energy generated by itself to accelerate the reaction and powder drying.

[0021] Solid-phase wet milling overcomes the high energy consumption problem caused by filtration, washing, and drying through particle collision.

[0022] If calcium carbonate-containing materials are used as raw materials for solid-phase wet milling, carbon dioxide is released during the reaction, and some water vapor is generated during the wet milling process. This reaction can keep the material loose, effectively avoid particle aggregation, and help reduce the size of powder particles to obtain powder with a large specific surface area.

[0023] This invention provides a method for manufacturing composite silica-doped rubber. The fibrous composite silica material achieves mechanical reinforcement, has tunable surface properties, and exhibits better compatibility with substrate materials such as polymer rubber and plastics. The composite silica-doped styrene-butadiene rubber obtained by this invention meets the HG / T 2404 standard for its tensile properties and other mechanical properties.

[0024] The beneficial effects of this invention are:

[0025] This invention solves the filtration problem of aluminate slag from the colloidal sulfuric acid extraction process by using a wet milling method. Utilizing residual acid and water from the wet slag, hemihydrate calcium sulfate whiskers are generated, which coat the surface of precipitated silica particles, preparing CaSO4∙0.5H2O@SiO2∙nH2O or gypsum@fumed silica composite powders. The aluminate slag obtained in this invention can be used directly without water washing or drying. The wet milling process is simple, energy-efficient, and produces products with excellent performance. The hemihydrate calcium sulfate CaSO4∙0.5H2O obtained by this invention, also known as gypsum whiskers, possesses excellent mechanical properties. The product is a white, loose, needle-like substance with a complete and smooth shape and a good aspect ratio. The hemihydrate calcium sulfate whisker-coated precipitated silica composite powder obtained by this method has advantages such as high temperature resistance, good toughness, acid and alkali corrosion resistance, high strength, and high modulus. Furthermore, CaSO4∙0.5H2O has good oleophilicity, thus exhibiting good compatibility with polymer materials. Gypsum-carbon black composites possess excellent reinforcing and toughening properties, as well as being non-toxic. Adding them to polymer materials such as rubber and plastics can significantly improve the mechanical properties of rubber. Furthermore, calcium sulfate whiskers coat the surface of SiO2 particles, masking any remaining non-ferrous metals and achieving a whitening effect.

[0026] This invention provides a method that not only effectively utilizes the siliceous waste residue from the aluminate extraction process using sulfuric acid, but also utilizes the residual acid and water in the residue to form coated calcium sulfate whiskers, thus solving the thorny problem of acidic hazardous waste. This method simplifies the process, requiring only wet grinding, followed by drying to remove a small amount of water from the wet-milled product, yielding the powder. This invention avoids high-energy-consuming steps such as washing, filtering, and drying of the aluminate extraction residue, simplifying the process, maximizing material utilization, achieving low-energy conversion, and realizing the green conversion of solid hazardous waste. Through optimized solid-phase wet grinding reaction process parameters such as ball mill slurry filling rate, ball-to-material ratio, and grinding time, a high-performance fibrous composite silica powder is obtained, with whisker lengths of 16.47-35.79 μm, an average length of 27.96 μm, and an aspect ratio of 13.6. Its specific surface area and particle size meet the standards for ultrafine silica, and its dispersibility is better. The aforementioned fibrous composite silica morphology cannot be achieved if the solid-phase wet grinding reaction process parameters are too high or too low. The resulting fibrous composite silica, when applied to rubber fillers, exhibits significant reinforcing effects and demonstrates excellent economic and environmental benefits. It generates no waste, truly realizing the transformation of waste into treasure. Attached Figure Description

[0027] Figure 1 This is an X-ray diffraction pattern of aluminum extraction waste residue from clay in Example 1 of the present invention.

[0028] Figure 2 This is a SEM image of aluminum extraction waste residue from ball clay after acid leaching in Example 1 of the present invention. As can be seen from the image, after acid leaching, the lamellar structure of the ball clay is destroyed, and a large number of pores and gaps appear. The surface becomes rough and irregular, and the average particle size is 50 μm.

[0029] Figure 3 This is a particle size distribution diagram of aluminum extraction waste residue from Embodiment 1 of the present invention.

[0030] Figure 4 This is a SEM image of the composite silica material in Example 1 of the present invention. Detailed Implementation

[0031] The present invention is further illustrated by the following embodiments, which are not intended to limit the invention in any way. Any modifications or alterations made to the present invention that are easily implemented by those skilled in the art without departing from the technical solutions of the present invention shall fall within the scope of the claims of the present invention.

[0032] Example 1:

[0033] a: Activated clay balls (containing 53.08% SiO2, 33.31% Al2O3 and other small amounts of metal oxides) were acid-leached with 35% sulfuric acid at a mass ratio of 1:2.18. The reaction temperature was 90℃ and the reaction time was 4 hours.

[0034] b: After filtering the suspension obtained in step a at 20 MPa, aluminum sulfate residue is obtained. Figure 1-3 As shown, the water content in the acid residue was 45%, and the concentration of the residual acid, sulfuric acid, was 2.5 mol / L.

[0035] c: The acid residue obtained in step b is mixed with light calcium carbonate solid at a molar ratio of H2SO4:CaO of 1:2. The mixture is then wet-milled in a high-speed ball mill for 4 hours to obtain a composite filler. The ball mill jar is a zirconia ball mill jar, and the milling media are zirconia balls with ϕ=5mm and ϕ=10mm, with a material-to-ball mass ratio of 1:12 and a slurry filling rate of 28%.

[0036] e: The composite filler is dried at 105℃, and then ground to obtain the composite silica material. For example... Figure 4 As shown, the product contains a large number of slender whiskers, at which point the calcium sulfate hemihydrate whiskers are coated with silicon dioxide crystals.

[0037] f: Take 50 parts of the composite silica material obtained in step e, 100 parts of styrene-butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 3 parts of polyethylene glycol (4000), 1.2 parts of accelerator DM, 0.7 parts of accelerator M, 0.5 parts of accelerator DPG, and 2 parts of sulfur. Put them into an open mill and plasticize at 40°C. Let it stand for 16 hours, then vulcanize and cool for 10 hours to obtain the composite silica material toughened styrene-butadiene rubber product.

[0038] The test results of composite silica materials and toughened styrene-butadiene rubber products are shown in the table below:

[0039] Loss on ignition (dry weight) % ≦7.0 1.0 5μm sieve residue % ≦0.5 0.12 Water-soluble matter % ≦2.5 1.0 color% Not lower than the standard sample Not lower than the standard sample (SRS1) Reduction in heating % 4.0-8.0 4.1 pH value 5.0-8.0 6.5 <![CDATA[Specific surface area m 2 / g]]> Class E 112 300% constant tensile stress (MPa) ≥5.5 5.6 500% constant tensile stress (MPa) ≥13.0 14.2 Tensile strength (MPa) ≥19.0 19.1 Elongation at break % ≥550% 980%

[0040] Example 2:

[0041] a: Acid leaching of bauxite with 35% sulfuric acid at a molar ratio of 1:3, reaction temperature 70℃, reaction time 3 hours;

[0042] b: The suspension obtained in step a was filtered by pressure to obtain aluminum sulfate slag. The water content in the slag was determined to be 56%, and the concentration of residual acid (H₂SO₄) was 1.05 mol / L.

[0043] c: The acid residue obtained in step b is mixed with calcite at a molar ratio of H2SO4:CaO of 1:1.2. The mixture is then wet-milled in a high-speed ball mill for 5 hours to obtain a composite powder. The ball mill jar is a polyurethane ball mill jar, and the milling media are alumina balls with ϕ=5mm and ϕ=10mm, with a material-to-ball mass ratio of 1:12 and a slurry filling rate of 28%.

[0044] e: Dry the composite filler at 105℃, and then grind it to obtain the composite silica material.

[0045] f: Take 50 parts of the composite silica material obtained in step e, 100 parts of styrene-butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 3 parts of polyethylene glycol (4000), 1.2 parts of accelerator DM, 0.7 parts of accelerator M, 0.5 parts of accelerator DPG, and 2 parts of sulfur. Put them into an open mill and plasticize at 40°C. Let it stand for 16 hours, then vulcanize and cool for 10 hours to obtain the composite silica material toughened styrene-butadiene rubber product.

[0046] The test results of composite silica materials and toughened styrene-butadiene rubber products are shown in the table below:

[0047] Loss on ignition (dry weight) % ≦7.0 1.5 % of residue on 45μm sieve ≦0.5 0.2 Water-soluble matter % ≦2.5 1.0 color Not lower than the standard sample Not lower than the standard sample (SRS1) heating loss % 4.0-8.0 3.8 pH value 5.0-8.0 6.8 <![CDATA[Specific surface area m 2 / g]]> Class E 108 300% constant tensile stress (MPa) ≥5.5 5.7 500% constant tensile stress (MPa) ≥13.0 13.2 Tensile strength (MPa) ≥19.0 19.2 Elongation at break % ≥550% 1080%

[0048] Example 3:

[0049] a: Calcined activated kaolin was acid-leached with 35% sulfuric acid at a mass ratio of 1:2.18, at a reaction temperature of 85℃ and a reaction time of 4 hours;

[0050] b: The suspension obtained in step a was filtered by pressure to obtain aluminum slag from sulfuric acid extraction. The water content in the slag was determined to be 45%, and the concentration of the residual sulfuric acid was 2.5 mol / L.

[0051] c: The acid residue obtained in step b is mixed with calcite at a molar ratio of H2SO4:CaO of 1:1.5. The mixture is then wet-milled in a high-speed ball mill for 4 hours to obtain a composite powder. The ball mill jar is an agate ball mill jar, and the milling media are agate balls with ϕ=5mm and ϕ=10mm, with a material-to-ball mass ratio of 1:12 and a slurry filling rate of 28%.

[0052] e: Dry the composite filler at 105℃, and then grind it to obtain the composite silica material.

[0053] f: Take 50 parts of the composite silica material obtained in step e, 100 parts of styrene-butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 3 parts of polyethylene glycol (4000), 1.2 parts of accelerator DM, 0.7 parts of accelerator M, 0.5 parts of accelerator DPG, and 2 parts of sulfur. Put them into an open mill and plasticize at 40°C. Let it stand for 16 hours, then vulcanize and cool for 10 hours to obtain the composite silica material toughened styrene-butadiene rubber product.

[0054] The test results of composite silica materials and toughened styrene-butadiene rubber products are shown in the table below.

[0055] Loss on ignition (dry weight) % ≦7.0 1.8 % of residue on 45μm sieve ≦0.5 0.5 Water-soluble matter % ≦2.5 1.5 color% Not lower than the standard sample Not lower than the standard sample (SRS1) Reduction in heating % 4.0-8.0 4.0 pH value 5.0-8.0 7.0 <![CDATA[Specific surface area m 2 / g]]> Class E 75 300% constant tensile stress (MPa) ≥5.5 5.8 500% constant tensile stress (MPa) ≥13.0 13.4 Tensile strength (MPa) ≥19.0 20.5 Elongation at break % ≥550% 870%

[0056] Example 4:

[0057] a: Calcined coal gangue was acid-leached with 35% sulfuric acid at a mass ratio of 1:3.0, at a reaction temperature of 80℃ and a reaction time of 4 hours;

[0058] b: The suspension obtained in step a was filtered by pressure to obtain aluminum slag from sulfuric acid extraction. The water content in the slag was determined to be 55%, and the concentration of the residual sulfuric acid was 1.5 mol / L.

[0059] c: The acid residue obtained in step b is mixed with heavy calcium carbonate at a molar ratio of H2SO4:CaO of 1:1.5. The mixture is then wet-milled in a high-speed ball mill for 4 hours to obtain a composite powder. The ball mill jar is an acid-resistant ceramic ball mill jar, and the milling media are acid-resistant ceramic balls with ϕ=5mm and ϕ=10mm, with a material-to-ball mass ratio of 1:12 and a slurry filling rate of 28%.

[0060] e: Dry the composite filler at 105℃, and then grind it to obtain the composite silica material.

[0061] f: Take 50 parts of the composite silica material obtained in step e, 100 parts of styrene-butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 3 parts of polyethylene glycol (4000), 1.2 parts of accelerator DM, 0.7 parts of accelerator M, 0.5 parts of accelerator DPG, and 2 parts of sulfur. Put them into an open mill and plasticize at 40°C. Let it stand for 16 hours, then vulcanize and cool for 10 hours to obtain the composite silica material toughened styrene-butadiene rubber product.

[0062] The test results of composite silica materials and toughened styrene-butadiene rubber products are shown in the table below.

[0063] Loss on ignition (dry weight) % ≦7.0 1.0 % of residue on 45μm sieve ≦0.5 0.5 Water-soluble matter % ≦2.5 1.8 color% Not lower than the standard sample Not lower than the standard sample (SRS1) Reduction in heating % 4.0-8.0 4.1 pH value 5.0-8.0 7.1 <![CDATA[Specific surface area m 2 / g]]> Class E 73 300% constant tensile stress (MPa) ≥5.5 5.9 500% constant tensile stress (MPa) ≥13.0 13.7 Tensile strength (MPa) ≥19.0 19.5 Elongation at break % ≥550% 680%

[0064] Example 5:

[0065] a: 20 parts of activated clay balls (SiO2 53%, Al2O3 33% and other small amounts of metal oxides) were acid-leached with 35% sulfuric acid at a mass ratio of 1:2.2. The reaction temperature was 90℃ and the reaction time was 3.5 hours.

[0066] b: The suspension obtained in step a was filtered by pressure to obtain aluminum slag from sulfuric acid extraction. The water content in the slag was determined to be 45%, and the concentration of the residual sulfuric acid was 2.5 mol / L.

[0067] c: Add dolomite solid to the acid residue obtained in step b, with a molar ratio of H2SO4:CaO of 1:2. The mixture is then wet-milled in a high-speed ball mill for 4 hours to obtain a composite powder. The milling jar is a polytetrafluoroethylene (PTFE) jar, and the milling media are zirconium silicate balls with ϕ=5mm and ϕ=10mm, with a material-to-ball mass ratio of 1:12 and a slurry filling rate of 28%.

[0068] e: Dry the composite filler at 105℃, and then grind it to obtain the composite silica material.

[0069] f: Take 50 parts of the composite silica material obtained in step e, 100 parts of styrene-butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 3 parts of polyethylene glycol (4000), 1.2 parts of accelerator DM, 0.7 parts of accelerator M, 0.5 parts of accelerator DPG, and 2 parts of sulfur. Put them into an open mill and plasticize at 40°C. Let it stand for 16 hours, then vulcanize and cool for 10 hours to obtain the composite silica material toughened styrene-butadiene rubber product.

[0070] The test results of composite silica materials and toughened styrene-butadiene rubber products are shown in the table below.

[0071] Loss on ignition (dry weight) % ≦7.0 2.5 % of residue on 45μm sieve ≦0.5 0.6 Water-soluble matter % ≦2.5 2.4 color% Not lower than the standard sample Not lower than the standard sample (SRS1) Reduction in heating % 4.0-8.0 4.1 pH value 5.0-8.0 7.0 <![CDATA[Specific surface area m 2 / g]]> Class E 71.8 300% constant tensile stress (MPa) ≥5.5 6.0 500% constant tensile stress (MPa) ≥13.0 14.5 Tensile strength (MPa) ≥19.0 19.4 Elongation at break % ≥550% 850%

[0072] Example 6:

[0073] a: Acid leaching of fly ash and concentrated sulfuric acid at a molar ratio of 1:3, reaction temperature 85℃, reaction time 5.5 hours;

[0074] b: The suspension obtained in step a was diluted with water and then filtered under pressure to obtain aluminum sulfate residue. The water content in the residue was determined to be 45%, and the concentration of residual sulfuric acid was 6.5 mol / L.

[0075] c: The acid residue obtained in step b is mixed with solid shell powder at a molar ratio of H2SO4:CaO of 1:2. The mixture is then wet-milled in a high-speed ball mill for 4 hours to obtain a composite powder. The ball mill jar is made of nylon, and the milling media are zirconia balls with ϕ=5mm and ϕ=10mm, with a material-to-ball mass ratio of 1:12 and a slurry filling rate of 28%.

[0076] e: Dry the composite filler at 105℃, and then grind it to obtain the composite silica material.

[0077] f: Take 50 parts of the composite silica material obtained in step e, 100 parts of styrene-butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 3 parts of polyethylene glycol (4000), 1.2 parts of accelerator DM, 0.7 parts of accelerator M, 0.5 parts of accelerator DPG, and 2 parts of sulfur. Put them into an open mill and plasticize at 40°C. Let it stand for 16 hours, then vulcanize and cool for 10 hours to obtain the composite silica material toughened styrene-butadiene rubber product.

[0078] The test results of composite silica materials and toughened styrene-butadiene rubber products are shown in the table below.

[0079] Loss on ignition (dry weight) % ≦7.0 3.2 % of residue on 45μm sieve ≦0.5 0.6 Water-soluble matter % ≦2.5 1.8 color% Not lower than the standard sample Not lower than the standard sample (SRS1) Reduction in heating % 4.0-8.0 4.5 pH value 5.0-8.0 7.0 <![CDATA[Specific surface area m 2 / g]]> Class E 70.0 300% constant tensile stress (MPa) ≥5.5 6.5 500% constant tensile stress (MPa) ≥13.0 14.8 Tensile strength (MPa) ≥19.0 20.3 Elongation at break % ≥550% 580%

Claims

1. A method for preparing composite white carbon black by wet grinding of alumina residue from sulfuric acid process with calcium in solid phase, characterized by: Includes the following steps: A wet sample of aluminate slag from the sulfuric acid extraction process is mixed with calcareous minerals or chemical raw materials containing CaO in a molar ratio of residual acid H2SO4:CaO = 1:(1~3). A solid-phase wet milling reaction is then carried out. The reaction between the calcareous material and the sulfuric acid in the slag produces hemihydrate calcium sulfate. This hemihydrate calcium sulfate coats the surface of precipitated silica particles and grows into whiskers, forming a fibrous composite material. The resulting slurry is dried or air-dried to obtain composite silica powder coated with hemihydrate calcium sulfate. The water content of the wet sample of aluminate slag from the sulfuric acid extraction process is in the range of 40%~60%. The calcareous minerals or chemical raw materials containing CaO are one or more of the following: calcite, stalactite, shell, light calcium carbonate, heavy calcium carbonate, or dolomite. The sulfuric acid extraction slag is a silicate slag obtained by leaching aluminum-silicon-containing minerals or solid waste with sulfuric acid. The solid-phase wet grinding reaction is carried out in a ball mill with a slurry filling rate of 28.0±1.0%, a ball-to-material mass ratio of 8.0±0.5%, a ball-to-small ball mass ratio of 2:1, and a grinding time of 4.0±0.5 h.

2. The method for preparing composite white carbon black by wet grinding of aluminate residue with calcium in solid phase in sulfuric acid process according to claim 1, characterized in that: The pH value of the wet sample of aluminate slag extracted by the sulfuric acid process is 0.5~2; the mass ratio of silica slag solid, water and sulfuric acid in the wet sample of aluminate slag extracted by the sulfuric acid process is 3:2:

1.

3. The method for preparing composite silica by solid-phase wet milling of aluminate slag obtained by sulfuric acid extraction according to claim 2, characterized in that: The SiO2 content in the silicon slag solid is in the range of 93% to 95%, the Al2O3 content is in the range of 4% to 5%, the Fe2O3 content is in the range of 0.5% to 0.8%, and the total content of other impurities is less than 1.0%.

4. The method for preparing composite white carbon black by wet grinding of aluminate residue with calcium in solid phase according to claim 1, characterized in that: The aluminum-silicon-containing main mineral or solid waste mentioned is one of bauxite, kaolin, ball clay, coal gangue or fly ash.

5. The method for preparing composite white carbon black by wet grinding of aluminate residue with calcium in solid phase according to claim 1, characterized in that: The ball mill is one of the following: zirconia grinding jar and grinding balls, agate grinding jar and grinding balls, polytetrafluoroethylene grinding jar and grinding balls, nylon grinding jar and grinding balls, acid-resistant ceramic grinding jar and grinding balls, and polyurethane grinding jar and grinding balls.

6. A composite silica material, characterized by: The composite silica is prepared by the method of preparing composite silica by adding calcium solid-phase wet milling to the aluminate residue extracted by the sulfuric acid process according to any one of claims 1-5, wherein the composite silica material is a fibrous composite material formed by coating the surface of precipitated silica particles with hemihydrate calcium sulfate.

7. A method for manufacturing a composite silica-doped rubber, characterized by comprising the following steps: Take 50 parts of the composite silica material as described in claim 6, 100 parts of styrene-butadiene rubber, 1 part of stearic acid, 5 parts of zinc oxide, 3 parts of polyethylene glycol, 1.2 parts of accelerator DM, 0.7 parts of accelerator M, 0.5 parts of accelerator DPG, and 2 parts of sulfur, load them into an open mill and plasticize them at 40°C. Let them stand for more than 16 hours, then vulcanize them and cool them for more than 10 hours to obtain a composite silica material-toughened styrene-butadiene rubber product.

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