A type of silica and its production method

Abstract

The application discloses white carbon black and a production method thereof, and belongs to the technical field of tire materials. The method comprises the following steps: performing first oxidant activation treatment and high-temperature alkali dissolution treatment on a treatment object obtained by pretreating waste tires, performing first solid-liquid separation, and obtaining first filtrate; mixing the first filtrate with a second oxidant and a flocculating agent, performing second solid-liquid separation, and obtaining second filtrate; performing carbonization reaction on the second filtrate with CO2, performing third solid-liquid separation, and collecting solids; wherein the treatment object comprises rubber powder and / or coke residue powder. The method can effectively recycle waste tires to obtain high-purity white carbon black, has low cost, high product uniformity, easy-to-control process, environmental protection, and can be popularized in industry. The obtained white carbon black can be further recycled to prepare products such as tires.

Description

Technical Field

[0001] This invention relates to the field of tire materials technology, and more specifically, to a type of silica and its production method. Background Technology

[0002] Tire rubber powder, processed from waste tires, has a complex composition, mainly including natural or synthetic rubber, sulfur, silica, and carbon black. With the increasing requirements for green tires and tire labeling laws, the proportion of silica used in tires is gradually increasing, especially in waste passenger car tires, where silica accounts for approximately 20-35% of the tread rubber powder. The annual production capacity of silica is 2 million tons, leaving a significant shortfall. Recycling silica from tires is therefore highly significant for environmental protection and the circular economy.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a silica and its production method to solve or improve the above-mentioned technical problems.

[0005] This application can be implemented as follows:

[0006] In a first aspect, this application provides a method for producing silica, comprising the following steps:

[0007] The waste tires obtained from the pretreatment process are subjected to a first oxidant activation treatment and a high-temperature alkaline dissolution treatment, followed by a first solid-liquid separation to obtain a first liquid and a first solid.

[0008] The first liquid is mixed with the second oxidant and the flocculant, and then a second solid-liquid separation is performed to obtain the second liquid and the second solid.

[0009] The second solid is reacted with CO2 to undergo a carbonization reaction, followed by a third solid-liquid separation, and the solid is collected.

[0010] The processed materials include rubber powder and / or coke residue powder.

[0011] In an optional embodiment, the first oxidant activation treatment includes at least one of the following features:

[0012] Feature 1: The primary oxidant includes hydrogen peroxide or ozone;

[0013] Feature 2: The mass ratio of the first oxidant to the treated material is 0.1:100-10:100.

[0014] In an optional embodiment, the high-temperature alkaline dissolution treatment includes at least one of the following features:

[0015] Feature 1: The alkaline solution used in the high-temperature alkaline dissolution treatment is a sodium hydroxide solution; preferably, the solid content of the sodium hydroxide solution is 1-40%;

[0016] Feature 2: The mass ratio of alkaline solution to the treated material is 5:100-25:100;

[0017] Feature 3: The temperature for high-temperature alkali dissolution treatment is 50-200℃;

[0018] Feature 4: The pressure for high-temperature alkali dissolution treatment is 0.05-1 MPa;

[0019] Feature 5: The high-temperature alkali dissolution treatment time is 0.5-5 hours.

[0020] In an optional embodiment, the second oxidant includes hydrogen peroxide or ozone;

[0021] And / or, the mass ratio of the treated material to the second oxidant is 0.1:100-10:100.

[0022] In an optional embodiment, the flocculant includes at least one of polyaluminum chloride, polyaluminum sulfate, polyferric chloride, polyferric sulfate, and polyaluminum ferric chloride;

[0023] And / or, the mass ratio of the treated material to the flocculant is 100:0.01-100:2.

[0024] In an optional embodiment, the carbonization reaction includes at least one of the following features:

[0025] Feature 1: The carbonization reaction temperature is 50-98℃;

[0026] Feature 2: The pH value of the carbonization reaction is 7.5-10.5;

[0027] Feature 3: The carbonization reaction takes 0.1-5 hours;

[0028] Feature 4: The carbonization reaction is carried out in a centrifugal atomizing tower, a pressure atomizing tower, or a two-fluid atomizing tower.

[0029] In an optional embodiment, the pretreatment includes: crushing waste tires into rubber granules, removing the fibers and iron contained in the rubber granules, and then grinding them into rubber powder.

[0030] In an optional embodiment, the rubber granules have a particle size of 1-3 mm; and / or, the rubber powder has a particle size of 30-200 mesh.

[0031] In an optional implementation, the iron removal rate is ≥99.9%.

[0032] In an optional embodiment, the silica content in the rubber powder is ≥15wt%, preferably ≥25wt%.

[0033] In an optional embodiment, the pretreatment further includes acidifying the rubber powder.

[0034] In an optional embodiment, the acid used for the acidification treatment includes at least one of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.

[0035] In an optional embodiment, the amount of acid used is 0.1-5 wt% of the rubber powder.

[0036] In an optional embodiment, the pretreatment includes: pyrolyzing waste tires to obtain coke residue; crushing and removing iron from the coke residue to obtain coke powder.

[0037] In an optional embodiment, the particle size of the coke residue powder is 300-1200 mesh.

[0038] In an optional implementation, the iron removal rate is ≥99.9%.

[0039] In an optional embodiment, the silica content in the coke residue is ≥15wt%, preferably, the silica content in the coke residue is ≥30wt%.

[0040] In an optional embodiment, the pretreatment further includes acidifying the coke residue powder.

[0041] In an optional embodiment, the acid used for the acidification treatment includes at least one of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.

[0042] In an optional embodiment, the amount of acid used is 0.1-5 wt% of the coke residue powder.

[0043] Secondly, this application provides a silica prepared by any of the methods described in the foregoing embodiments.

[0044] The beneficial effects of this application include:

[0045] The method provided in this application can effectively recycle waste tires and obtain high-purity silica. This method is low-cost, produces highly uniform products, is easy to control, and is environmentally friendly, making it suitable for industrial-scale application. The obtained silica can be further recycled for tire manufacturing, significantly reducing production costs and enabling the recycling of tire components, thus being both economical and environmentally friendly. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0047] The following provides a detailed description of the silica, its production method, and tires provided in this application.

[0048] This application discloses a method for producing silica, which includes the following steps:

[0049] The waste tires obtained from the pretreatment process are subjected to a first oxidant activation treatment and a high-temperature alkaline dissolution treatment, followed by a first solid-liquid separation to obtain a first liquid and a first solid.

[0050] The first liquid is mixed with the second oxidant and the flocculant, and then a second solid-liquid separation is performed to obtain the second liquid and the second solid.

[0051] The second solid is reacted with CO2 to undergo a carbonization reaction, followed by a third solid-liquid separation, and the solid is collected.

[0052] The processed materials include rubber powder and / or coke residue powder.

[0053] For reference, rubber powder can be obtained by pretreatment in the following way: For example, waste tires can be crushed into rubber granules, the fibers and iron contained in the rubber granules can be removed, and then the granules can be ground into rubber powder.

[0054] The silica content in the rubber powder can be ≥15wt%, preferably ≥25wt%. For example, the silica content in the rubber powder can be 15wt%, 20wt%, 25wt%, 30wt%, or 35wt%. It should be noted that if the silica content in the rubber powder is too low, the processing cost will be too high, resulting in poor economic efficiency.

[0055] In some implementations, waste tires can be first crushed into rubber blocks, and then the rubber blocks can be crushed into rubber granules and finely ground into rubber powder.

[0056] For example, waste tires can be crushed into rubber blocks of approximately 1-20 cm in size using a tire shredder or similar shredding equipment. These blocks can then be further pulverized into rubber granules of approximately 1-3 mm in diameter using a disc crusher (such as a rubber block crusher). Further, nylon fibers can be separated from the rubber granules using a fiber sorting machine, and iron can be removed from the granules a second time using an iron removal device. Finally, the rubber powder can be ground into rubber powder with a particle size of approximately 30-200 mesh using a ring roller mill, impact mill, or Raymond mill. In some preferred embodiments, the iron removal rate is ≥99.9%.

[0057] Furthermore, the rubber powder can be acidified to remove remaining metallic impurities (such as iron, manganese, copper, and other metal ions). For example, the acid used in the acidification treatment may include at least one of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. The amount of acid used can be 0.1-5 wt% of the coke residue powder, such as 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%.

[0058] For reference, coke residue powder can also be obtained through pretreatment in the following ways: For example, waste tires can be pyrolyzed to obtain coke residue material; the coke residue material can then be crushed and iron removed to obtain coke residue powder.

[0059] In some embodiments, pyrolysis can be carried out at 200-450°C (e.g., 200°C, 250°C, 300°C, 350°C, 400°C, or 450°C, etc.) for 6-10 hours (e.g., 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours, etc.). Exemplarily, the silica content in the coke slag can be ≥15 wt%, preferably ≥30 wt%. Exemplarily, the silica content in the coke slag can be 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%, etc.

[0060] The coke residue obtained after pyrolysis can be ultra-finely pulverized to a particle size of approximately 300-1200 mesh using fine pulverizing equipment (such as ring roller mills, impact mills, or Raymond mills). The coke residue powder is then obtained by removing the iron slag using an iron remover. In some preferred embodiments, the iron removal rate is ≥99.9%.

[0061] In some embodiments, the coke residue powder may be further subjected to acidification treatment to remove remaining metallic impurities (such as iron, manganese, copper, and other metal ions). Exemplarily, the acid used for acidification treatment may include at least one of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. The amount of acid used may be 0.1-5 wt% of the coke residue powder, such as 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%.

[0062] Continuing from the above, by pre-treating waste tires to obtain processed materials with finer particles and fewer impurities, the silica in the resulting rubber powder or coke residue powder can react more readily with alkaline solutions.

[0063] In this application, the first oxidant used in the first oxidant activation treatment of the processed material may include, for example, hydrogen peroxide or ozone.

[0064] The mass ratio of the first oxidant to the treated product can be between 0.1:100 and 10:100, such as 0.1:100, 0.5:100, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, or 10:100, or any other value within the range of 0.1:100 to 10:100. In some embodiments, the mass ratio of the first oxidant to the treated product is 0.3:100.

[0065] By performing the first oxidant activation treatment, the oxidant can be used to oxidize the organic or inorganic matter and metal ions in the treated material, which is beneficial to the pickling efficiency.

[0066] The alkaline solution used in high-temperature alkaline dissolution treatment is a sodium hydroxide solution. The solid content of the sodium hydroxide solution can be 5-40%, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%. Here, "solid content" mainly refers to the amount of solid sodium hydroxide used.

[0067] The mass ratio of alkaline solution to the treated material can be between 5:100 and 25:100, such as 5:100, 10:100, 15:100, 20:100, or 25:100, or any other value within the range of 5:100 to 25:100. In some embodiments, the mass ratio of alkaline solution to the treated material is 15:100.

[0068] If the mass ratio of alkaline solution to the treated material is less than 5:100, it is not conducive to the dissolution and extraction of silica; if the mass ratio of alkaline solution to the treated material is greater than 25:100, it is not conducive to improving the modulus of the generated sodium silicate and affecting the quality.

[0069] The temperature for high-temperature alkali dissolution treatment can be 50-200℃, such as 50℃, 80℃, 100℃, 120℃, 150℃, 180℃, or 200℃, or any other value within the range of 50-200℃. In some embodiments, the temperature for high-temperature alkali dissolution treatment is 150℃.

[0070] If the temperature of the high-temperature alkaline dissolution treatment is below 50℃, it is not conducive to the dissolution and extraction of silica; if the temperature of the high-temperature alkaline solution treatment is above 200℃, it wastes energy.

[0071] The pressure for high-temperature alkaline dissolution treatment can be 0.05-1 MPa, such as 0.05 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, or 1 MPa, or any other value within the range of 0.05-1 MPa. In some embodiments, the pressure for high-temperature alkaline dissolution treatment is 0.5 MPa.

[0072] If the pressure of the high-temperature alkaline dissolution treatment is less than 0.05 MPa, it is not conducive to the dissolution and extraction of silica; if the pressure of the high-temperature alkaline solution treatment exceeds 0.5 MPa, the dissolution treatment cost is too high.

[0073] The high-temperature alkali dissolution treatment time can be 0.5-5 hours, such as 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, or 5 hours, or any other value within the range of 0.5-5 hours. In some embodiments, the high-temperature alkali dissolution treatment time is 3 hours.

[0074] If the high-temperature alkaline dissolution treatment time is less than 0.5 hours, it is not conducive to the dissolution and extraction of silica; if the high-temperature alkaline solution treatment time exceeds 5 hours, it is not conducive to the dissolution treatment cost being too high.

[0075] The main reaction equations involved in the above-mentioned high-temperature alkaline dissolution process are: nSiO2 + 2NaOH = Na2O·nSiO2 + H2O.

[0076] The first solid-liquid separation can be carried out using dehydration equipment such as plate and frame separators, horizontal screw presses, or centrifuges. Accordingly, the first liquid obtained after the first solid-liquid separation is sodium silicate filtrate.

[0077] In this application, the second oxidant may also include hydrogen peroxide or ozone, etc.

[0078] The mass ratio of the second oxidant to the treated product can also be 0.1:100-10:100, such as 0.1:100, 0.5:100, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, or 10:100, or any other value within the range of 0.1:100-10:100. In some embodiments, the mass ratio of the second oxidant to the treated product is 0.3:100.

[0079] Flocculants may, by way of example but not by way of limitation, include at least one of polyaluminum chloride, polyaluminum sulfate, polyferric chloride, polyferric sulfate and polyaluminum ferric chloride.

[0080] The mass ratio of the treated material to the flocculant can be 100:0.01-100:2, such as 100:0.01, 100:0.05, 100:0.1, 100:0.5, 100:1, 100:1.5 or 100:2, or any other value within the range of 100:0.01-100:2.

[0081] By adding a flocculant, the first liquid can be clarified, for example, by flocculating impurities in the first liquid.

[0082] The second filtration and separation can be carried out using an activated carbon filtration device to obtain a high-purity second solid (sodium silicate).

[0083] In this application, the carbonization reaction temperature can be 50-98℃, such as 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 98℃, or any other value within the range of 50-98℃.

[0084] If the carbonization reaction temperature is below 50℃, it is not conducive to the formation of silica; if the carbonization reaction temperature is above 98℃, the energy consumption is too high.

[0085] The pH value of the carbonization reaction can be 7.5-10.5, such as 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.5, 9.0, 9.5, 10 or 10.5, or any other value within the range of 7.5-10.5.

[0086] If the pH value of the carbonization reaction is lower than 7.5, it is not conducive to the formation of silica; if the pH value of the carbonization reaction is higher than 9.5, it is not conducive to the quality control of silica products.

[0087] The carbonization reaction time can be 0.1-5h, such as 0.1h, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, or any other value within the range of 0.1-5h.

[0088] If the carbonization reaction time is less than 0.1 hours, it is not conducive to the formation of silica; if the carbonization reaction time is more than 5 hours, it will affect the product quality.

[0089] The carbon dioxide content in the CO2 gas during the carbonization reaction can be, for example, 30-100 wt% (e.g., 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, or 100 wt%). If the CO2 content is below 30 wt%, it is not conducive to the formation of silica.

[0090] For example, the carbonization reaction can be carried out in equipment such as a centrifugal atomizing tower, a pressure atomizing tower, or a two-fluid atomizing tower.

[0091] The chemical equations involved in the above carbonization reaction include: Na2O·nSiO2+CO2=Na2CO3+nSiO2.

[0092] After carbonization, a silica slurry is obtained, which is then filtered, washed, and dried to obtain fumed silica.

[0093] It should be noted that in the above-mentioned process of producing silica, the remaining waste coke powder, rubber or coke residue can be further processed into recycled silica as needed. The specific methods can be referred to the relevant existing technologies, which will not be elaborated here.

[0094] Accordingly, this application also provides a silica prepared by the above method. This silica has high purity, significantly improved product uniformity, and good overall performance.

[0095] The aforementioned silica can be recycled for tire manufacturing, which can greatly reduce production costs and allow the components in tires to be recycled, making it both environmentally friendly and economical.

[0096] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0097] Example 1

[0098] This embodiment provides a method for producing silica, including the following steps:

[0099] S1: Use a tire shredder to shred waste tires (from market recycling) into 1cm rubber blocks;

[0100] S2: Rubber blocks are crushed into 1mm rubber particles using a rubber block crusher, and the rubber particles are separated from the fibers (nylon fibers) using a fiber separator. The particles are then subjected to secondary iron removal using an iron removal device (iron removal rate > 99.9%).

[0101] S3: Use a fine powder mill (ring roller mill) to grind rubber granules into 200-mesh fine rubber powder (silica content is 25wt%);

[0102] S4: Add 300kg of water and 0.3kg of hydrogen peroxide to 100kg of fine rubber powder for activation, then add 15kg of caustic soda solution (solid content of 5wt%) for dissolution. The dissolution temperature is 150℃, the reaction pressure is 0.5MPa, and the reaction time is 3h. The first solid-liquid separation is carried out by plate and frame filtration to obtain the first filtrate.

[0103] S5: Add 0.3 kg of hydrogen peroxide to the first filtrate to treat the water glass, then add 0.02 kg of polyaluminum ferric chloride to flocculate the impurities. After a second filtration using an activated carbon filter, high-purity water glass is obtained.

[0104] S6: High-purity water glass is sprayed into the tower through a centrifugal atomizing reactor, and CO2 gas with a CO2 content of 30% is introduced to prepare silica. The reaction pH is controlled at 7.8 and the temperature is 90℃. The reaction is carried out for 1 hour to obtain silica slurry, which is then filtered, washed, and dried to obtain white carbon black.

[0105] Example 2

[0106] S1: Waste tires (from market recycling) are pyrolyzed at 400℃ for 8 hours to obtain coke residue (silica content of 30wt%).

[0107] S2: The coke slag is crushed to 400 mesh using a ring roller mill, and the iron slag is removed using an iron remover (iron removal rate > 99.9%) to obtain ultrafine coke slag powder.

[0108] S3: Acidification treatment of ultrafine coke residue powder is carried out using hydrochloric acid, with the amount of hydrochloric acid being 5 wt% of the ultrafine coke residue powder.

[0109] S4: Add 300 kg of water and 0.3 kg of hydrogen peroxide to 100 kg of acid-treated ultrafine coke slag powder for activation, then add 15 kg of caustic soda solution (solid content of 40 wt%) for dissolution. The dissolution temperature is 150℃, the reaction pressure is 0.5 MPa, and the reaction time is 3 h. The first solid-liquid separation is carried out by plate and frame filtration to obtain the first filtrate.

[0110] S5: Add 0.3 kg of hydrogen peroxide to the first filtrate to treat the water glass, then add 0.02 kg of polyaluminum ferric chloride to flocculate the impurities. After a second filtration using an activated carbon filter, high-purity water glass is obtained.

[0111] S6: High-purity water glass is sprayed into the carbonization tower through a centrifugal atomizing reactor, and CO2 gas with a CO2 content of 100% is introduced to prepare silica. The reaction pH is controlled at 9.5, and the resulting silica slurry is obtained. After being filtered, washed, and dried by plate and frame filter, it yields white carbon black.

[0112] Example 3

[0113] This embodiment provides a method for producing silica, including the following steps:

[0114] S1: Use a tire shredder to shred waste tires (from market recycling) into 10cm rubber blocks;

[0115] S2: Rubber blocks are crushed into 2mm rubber particles using a rubber block crusher, and the rubber particles are separated from the fibers (nylon fibers) using a fiber separator. The particles are then subjected to secondary iron removal using an iron removal device (iron removal rate > 99.9%).

[0116] S3: Use a fine powder mill (impact mill) to grind rubber granules into 50-mesh fine rubber powder (silica content is 35wt%);

[0117] S4: Activate 100kg of fine rubber powder with 300kg of water and 1kg of hydrogen peroxide, then add 5kg of caustic soda solution (solid content 30wt%) for dissolution. The dissolution temperature is 50℃, the reaction pressure is 0.25MPa, and the reaction time is 0.5h. Use a horizontal screw press for the first solid-liquid separation to obtain the first filtrate.

[0118] S5: Add 1 kg of hydrogen peroxide to the first filtrate to treat the water glass, then add 1 kg of polyaluminum sulfate to flocculate the impurities. After a second filtration using an activated carbon filter, high-purity water glass is obtained.

[0119] S6: High-purity water glass is sprayed into the tower through a centrifugal atomizing reactor, and CO2 gas with a CO2 content of 50% is introduced to prepare silica. The reaction pH is controlled at 8.8 and the temperature is 80℃. The reaction is carried out for 0.5 hours to obtain silica slurry, which is then filtered, washed, and dried to obtain white carbon black.

[0120] Example 4

[0121] This embodiment provides a method for producing silica, including the following steps:

[0122] S1: Use a tire shredder to shred waste tires (from market recycling) into 20cm rubber blocks;

[0123] S2: The rubber block is crushed into 3mm rubber particles using a rubber block crusher, and the rubber particles are separated from the fibers (nylon fibers) using a fiber separator. The particles are then subjected to two iron removal processes (iron removal rate > 99.9%).

[0124] S3: Use a fine powder mill (Raymond mill) to grind rubber granules into 100-mesh fine rubber powder (silica content is 40wt%).

[0125] S4: Activate 100kg of fine rubber powder with 300kg of water and 10kg of hydrogen peroxide, then add 25kg of caustic soda solution (solid content 20wt%) for dissolution at 200℃, reaction pressure 0.05MPa, and reaction time 5h. Use a centrifuge for the first solid-liquid separation to obtain the first filtrate.

[0126] S5: Add 10 kg of hydrogen peroxide to the first filtrate to treat the water glass, then add 2 kg of polyferric chloride to flocculate the impurities. After a second filtration using an activated carbon filter, high-purity water glass is obtained.

[0127] S6: High-purity water glass is sprayed into the tower through a centrifugal atomizing reactor, and CO2 gas with a CO2 content of 80% is introduced to prepare silica. The reaction pH is controlled at 7.8 and the temperature is 98℃. The reaction is carried out for 0.5 hours to obtain silica slurry, which is then filtered, washed and dried to obtain white carbon black.

[0128] Example 5

[0129] The difference between this embodiment and Embodiment 1 is that both the first oxidant and the second oxidant are ozone.

[0130] Comparative Example 1

[0131] The difference between this comparative example and Example 1 is that the waste tires were not pretreated and were directly subjected to the first oxidant activator treatment and subsequent steps.

[0132] Comparative Example 2

[0133] The difference between this comparative example and Example 1 is that the mass ratio of the first oxidant to the treated product is 0.05:100.

[0134] Comparative Example 3

[0135] The difference between this comparative example and Example 1 is that the mass ratio of the first oxidant to the treated product is 15:100.

[0136] Comparative Example 4

[0137] The difference between this comparative example and Example 1 is that the mass ratio of alkaline solution to the treated material is 2:100.

[0138] Comparative Example 5

[0139] The difference between this comparative example and Example 1 is that the mass ratio of alkaline solution to the treated material is 30:100.

[0140] Comparative Example 6

[0141] The difference between this comparative example and Example 1 is that the temperature of the high-temperature alkali dissolution treatment is 40°C.

[0142] Comparative Example 7

[0143] The difference between this comparative example and Example 1 is that the temperature of the high-temperature alkali dissolution treatment is 250°C.

[0144] Comparative Example 8

[0145] The difference between this comparative example and Example 1 is that the pressure of the high-temperature alkaline dissolution treatment is 1.2 MPa.

[0146] Comparative Example 9

[0147] The difference between this comparative example and Example 1 is that the high-temperature alkaline dissolution treatment time is 8 hours.

[0148] Comparative Example 10

[0149] The difference between this comparative example and Example 1 is that the solid treated with high-temperature alkaline solution is directly subjected to a carbonization reaction.

[0150] Comparative Example 11

[0151] The difference between this comparative example and Example 1 is that the carbonization reaction temperature is 40°C.

[0152] Comparative Example 12

[0153] The difference between this comparative example and Example 1 is that the carbonization reaction temperature is 100°C.

[0154] Comparative Example 13

[0155] The difference between this comparative example and Example 1 is that the pH value of the carbonization reaction is 7.0.

[0156] Comparative Example 14

[0157] The difference between this comparative example and Example 1 is that the pH value of the carbonization reaction is 11.

[0158] Comparative Example 15

[0159] The difference between this comparative example and Example 1 is that the carbonization reaction time is 6 hours.

[0160] Test case

[0161] The silica obtained in Examples 1-5 and Comparative Examples 1-15 were compared, and the results are shown in Table 1.

[0162] Table 1 Comparison Results

[0163]

[0164]

[0165] As can be seen from Table 1, the method provided in this application can obtain silica with high recovery rate and purity by recycling waste tires.

[0166] In summary, the method provided in this application has at least the following advantages:

[0167] ① The equipment requirements are simple and easy to industrialize;

[0168] ② The finer adhesive powder obtained by using a pulverizing process (preferably multiple pulverizations) makes it easier for the alkaline solution to react with the silica in the adhesive powder.

[0169] ③ Using flocculants, activated carbon, and other treatment methods to clarify the filtrate makes it easier to obtain high-purity silica;

[0170] ④ The raw materials are widely available, and the process is environmentally friendly;

[0171] ⑤ The resulting product has higher purity, significantly improved product uniformity, and higher overall performance.

[0172] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing white carbon black, characterized by, The method comprises the following steps: a first oxidant activation treatment and a high-temperature alkali dissolution treatment are performed on a treatment product obtained by pretreating waste tires, a first solid-liquid separation is performed, and a first liquid and a first solid are obtained; the first liquid is mixed with a second oxidant and a flocculant, a second solid-liquid separation is performed, and a second liquid and a second solid are obtained; the second liquid is subjected to a carbonization reaction with CO2, a third solid-liquid separation is performed, and a solid is collected; the treatment product comprises rubber powder and / or coke residue powder; the first oxidant used in the first oxidant activation treatment comprises hydrogen peroxide or ozone; the mass ratio of the first oxidant to the treatment product is 0.1:100-10:100; the alkali solution used in the high-temperature alkali dissolution treatment is a sodium hydroxide solution; the mass ratio of the alkali solution to the treatment product is 5:100-25:100; the temperature of the high-temperature alkali dissolution treatment is 50-200 ℃; the pressure of the high-temperature alkali dissolution treatment is 0.05-1 MPa; and the time of the high-temperature alkali dissolution treatment is 0.5-5 h; the second oxidant comprises hydrogen peroxide or ozone; the mass ratio of the treatment product to the second oxidant is 0.1:100-10:100; the flocculant comprises at least one of polyaluminum chloride, polyaluminum sulfate, polyferric chloride, polyferric sulfate and polyaluminum ferric sulfate; and the mass ratio of the treatment product to the flocculant is 100:0.01-100:2; the temperature of the carbonization reaction is 50-98 ℃; the pH value of the carbonization reaction is 7.5-10.5; and the time of the carbonization reaction is 0.1-5 h.

2. The method of claim 1, wherein, The solid content of the sodium hydroxide solution is 1-40%.

3. The method of claim 1, wherein, The carbonization reaction is performed in a centrifugal atomization tower, a pressure atomization tower or a two-fluid atomization tower.

4. The method of claim 1, wherein, The pretreatment comprises: the waste tires are crushed into rubber particles, fibers and iron contained in the rubber particles are removed, and the rubber particles are finely ground into rubber powder.

5. The method of claim 4, wherein, The particle size of the rubber particles is 1-3 mm; and / or the particle size of the rubber powder is 30-200 mesh.

6. The method of claim 4, wherein, The iron removal rate is ≥99.9%.

7. The method of claim 4, wherein, The content of silicon dioxide in the rubber powder is ≥15 wt%.

8. The method of claim 7, wherein, The content of silicon dioxide in the rubber powder is ≥25 wt%.

9. The method of claim 4, wherein, The pretreatment further comprises:

10. The method of claim 9, wherein, the rubber powder is subjected to acidification treatment.

11. The method of claim 10, wherein, The acid used in the acidification treatment comprises at least one of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.

12. The method of claim 1, wherein, The amount of the acid is 0.1-5 wt% of the rubber powder. The pretreatment comprises: the waste tires are subjected to pyrolysis, and coke residue material is obtained; 13. The method of claim 12, wherein, the coke residue material is crushed and iron is removed, and coke residue powder is obtained.

14. The method of claim 12, wherein, The particle size of the coke residue powder is 300-1200 mesh.

15. The method of claim 12, wherein, The iron removal rate is ≥99.9%.

16. The method of claim 15, wherein, The content of silicon dioxide in the coke residue material is ≥15 wt%.

17. The method of claim 12, wherein, The content of silicon dioxide in the coke residue material is ≥30 wt%.

18. The method of claim 17, wherein, The pretreatment further comprises:

19. The method of claim 18, wherein, the coke residue powder is subjected to acidification treatment. The acid used in the acidification treatment comprises at least one of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid. The amount of the acid is 0.1-5 wt% of the coke residue powder.

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