Method for recycling and reusing polishing waste liquid

Abstract

The invention discloses a recovery treatment and reutilization method of polishing waste liquid, which comprises the following steps: firstly feeding raw materials into a storage tank for storage, then taking out the raw materials in the storage tank for standing and layering, separating out lower-layer turbid liquid, adding a dispersing agent for stirring, adding the dispersing agent into the turbid liquid after uniform stirring, and then sanding to obtain the polishing waste liquid. A finished product of an aqueous solution can be directly prepared through sanding, or the solid content is measured after sanding, if the solid content is smaller than 20%, raw materials are supplemented, the solid content is increased to be not smaller than 20%, sanding continues to be conducted, homogenate is prepared, the homogenate is evenly stirred again, drying is conducted in a spray drying mode, and a finished product of powder is prepared. Stirring and sanding equipment in the steps is used for cleaning supernatant liquid separated by standing and layering, waste liquid obtained after cleaning is stirred to be uniform, then the solid content is detected, and raw materials are added to enable the solid content to be 20%-50%; and S8, complementing the solid content, and feeding into a storage tank for continuous treatment.

Description

Technical Field

[0001] This invention relates to the field of polishing waste liquid treatment technology, specifically to a method for recycling and reusing polishing waste liquid. Background Technology

[0002] With the rapid development of the global economy and the continuous advancement of industrial technology, rare earth elements, as "industrial vitamins," play an irreplaceable role in strategic emerging industries such as optoelectronics, new energy, and high-end manufacturing. my country is a major producer and consumer of rare earth resources. However, the separation, purification, and application of rare earth elements generate large amounts of industrial wastewater containing rare earth elements. The polishing wastewater used in the processing of materials such as sapphire and silicon wafers in the optoelectronic industry has a particularly high content of rare earth elements (especially cerium), which not only causes the loss of valuable rare earth resources but also poses a potential threat to the ecological environment.

[0003] Traditional rare earth recycling technologies often suffer from problems such as complex processes, high costs, low recycling efficiency, insufficient product purity, or excessively large particle size, making it difficult to meet current requirements for high-quality, low-energy-consumption, and high-value-added utilization of rare earth materials. Therefore, how to efficiently and economically recover high-value rare earths (such as cerium) from such wastewater and process them into nanomaterials with specific properties is of significant practical and strategic value for improving the utilization rate of rare earth resources, reducing environmental pollution, and promoting the development of a circular economy. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention proposes a method for the recycling and reuse of polishing waste liquid.

[0005] To achieve the above-mentioned technical effects, the present invention adopts the following solution: A method for recycling and reusing polishing waste liquid includes the following steps: S1. The raw materials are first sent into the storage tank for storage and pre-treated to remove suspended solids, heavy metals, organic matter and debris and other impurities. S2. Remove the raw materials from the storage tank and allow them to stand and separate into upper clear liquid and lower turbid liquid. S3. Separate the lower layer of turbid liquid and add a dispersant and stir to make the particles in the turbid liquid evenly distributed; S4. After stirring evenly, add dispersant again and then sand mill. The water-based product can be directly obtained by sand milling; or after sand milling, measure the solid content. If the solid content is less than 20%, add pretreated solid waste to increase the solid content to not less than 20% and continue sand milling to obtain a homogenate. S5. Stir the slurry again until it is homogeneous, and then dry it by spray drying to obtain the powder product. S6. The stirring and sand milling equipment in steps S3 and S4 above are cleaned by the supernatant separated in step S2. S7. After stirring the waste liquid obtained after cleaning evenly, test the solid content, and add raw materials to make the solid content ratio 20%~50%; S8. After replenishing the solid content, send it into the storage tank and continue to steps S2~S5.

[0006] In a preferred embodiment, the dispersant is an anionic dispersant, comprising: 40-70 parts of a main dispersant, 5-20 parts of a modified steric hindrance agent, 10-30 parts of an environmental stabilizer, 10-40 parts of an auxiliary synergist, and 100-200 parts of a solvent; wherein the main dispersant is a naphthalene sulfonate formaldehyde condensate and / or a polycarboxylate; the modified steric hindrance agent is allyl polyoxyethylene ether (APEG) with a molecular weight of 600-2000; the environmental stabilizer is an amphoteric surfactant, preferably an amino acid-type amphoteric surfactant (such as sodium lauroyl sarcosinate) or a betaine-type surfactant; the auxiliary synergist is lignin sulfonate and / or sodium carboxymethyl starch; and the solvent is water.

[0007] In a preferred embodiment, the dispersant is a composition comprising a nonionic dispersant, including: 40%-70% nonionic dispersant, 5%-15% ionic surfactant synergistic component, 1%-5% nano silica stabilizer, 5%-10% cosolvent, and the balance being water; wherein the nonionic dispersant has the general molecular structure formula R¹-(A)-(B)-(A)-R², where (A) is a polyoxyethylene segment with a degree of polymerization of 15-130, (B) is a polyoxypropylene segment with a degree of polymerization of 20-70, R¹ is an end group containing a polymerizable double bond selected from methacryloyloxy, acryloyloxy, or vinylbenzyl, and R² is an end group containing a silane coupling group selected from trimethoxysilyl, triethoxysilyl, or methyldimethoxysilyl.

[0008] In a preferred embodiment, the weight-average molecular weight of the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer corresponding to the general molecular structure formula R¹-(A)-(B)-(A)-R² is 4000-15000, and the total mass of the polyoxyethylene segment (A) accounts for 60%-80% of the total mass of the copolymer molecules.

[0009] In a preferred embodiment, the synergistic component of the ionic surfactant is sodium lauryl sulfate, sodium dodecylbenzene sulfonate, or hexadecyltrimethylammonium bromide.

[0010] In the preferred technical solution, in step S3, the sand grinding is carried out using a rod-pin nano-sand mill.

[0011] In the preferred embodiment, in step S5, the moisture content of the dried powder product is 0.3~0.5%.

[0012] The preferred technical solution is to use the aqueous product obtained in step S4 and the powder product obtained in step S5 as UV stabilizers.

[0013] Compared with existing technologies, the beneficial effects are: This invention innovatively transforms industrial wastewater, a pollutant, into rare earth cerium resources, realizing the transformation of waste into treasure, which aligns with the concepts of circular economy and green development.

[0014] This invention features simple operation, low energy consumption, controllable cost, and environmental friendliness, which distinguishes it from traditional complex wastewater separation and purification methods. Attached Figure Description

[0015] Figure 1 This is a flowchart of the method of the present invention.

[0016] Figure 2 This is a particle size distribution diagram of cerium nanoparticles obtained by the method of the present invention.

[0017] Figure 3 The test results show that nano-cerium obtained by the method of this invention can be used as an anti-ultraviolet agent. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] Example 1 A method for recycling and reusing polishing waste liquid includes the following steps: S1. The recovered raw material wastewater is first sent into a storage tank for storage, awaiting further treatment.

[0020] S2. Start processing: First, discharge the raw materials in the storage tank and let them stand and separate into upper clear liquid and lower turbid liquid. The nano-cerium and other particles contained in the wastewater will precipitate in the lower turbid liquid.

[0021] S3. After the stratification stabilizes, separate the lower layer of turbid liquid and add a dispersant and stir to make the particles in the turbid liquid evenly distributed. The dispersant can keep the particles in the turbid liquid stable and uniform, and it is not easy to separate into layers over a long period of time.

[0022] S4. After stirring evenly, add dispersant again and then sand mill. According to the set requirements, the water-based product can be directly obtained by sand milling; or after sand milling, measure the solid content. If the solid content is less than 20%, add pretreated solid waste to increase the solid content to not less than 20% and continue sand milling to obtain a homogenate.

[0023] S5. Stir the slurry again until it is homogeneous, and then dry it by spray drying to obtain the finished powder product.

[0024] S6. The stirring and sand milling equipment in steps S3 and S4 above are cleaned by the supernatant separated in step S2.

[0025] S7. After the waste liquid obtained after cleaning is stirred evenly, the solid content is tested, and raw material wastewater is added to increase the solid content to a ratio of 20% to 50%.

[0026] S8. After replenishing the solid content, send it into the storage tank and continue to steps S2~S5.

[0027] In a preferred embodiment, the dispersant is an anionic dispersant, comprising: 40-70 parts of a main dispersant, 5-20 parts of a modified steric hindrance agent, 10-30 parts of an environmental stabilizer, 10-40 parts of an auxiliary synergist, and 100-200 parts of a solvent; wherein the main dispersant is a naphthalene sulfonate formaldehyde condensate and / or a polycarboxylate; the modified steric hindrance agent is allyl polyoxyethylene ether (APEG) with a molecular weight of 600-2000; the environmental stabilizer is an amphoteric surfactant, preferably an amino acid-type amphoteric surfactant (such as sodium lauroyl sarcosinate) or a betaine-type surfactant; the auxiliary synergist is lignin sulfonate and / or sodium carboxymethyl starch; and the solvent is water.

[0028] In the preferred technical solution, in step S3, the sand grinding is carried out using a rod-pin nano-sand mill.

[0029] In the preferred technical solution, the spray drying conditions in step S5 are: inlet temperature 260℃, outlet temperature 100℃, and the moisture content of the resulting powder product is 0.3%~0.5%.

[0030] The preferred technical solution is to use the aqueous product obtained in step S4 and the powder product obtained in step S5 as UV stabilizers.

[0031] Example 2 Compared with Example 1, the difference lies in the dispersant used, which is a composition containing a nonionic dispersant, comprising: 40%-70% nonionic dispersant, 5%-15% ionic surfactant synergistic component, 1%-5% nano silica stabilizer, 5%-10% cosolvent, and the balance being water; wherein, the general molecular structure of the nonionic dispersant is R¹-(A)-(B)-(A)-R², where (A) is a polyoxyethylene segment with a degree of polymerization of 15-130, (B) is a polyoxypropylene segment with a degree of polymerization of 20-70, R¹ is an end group containing a polymerizable double bond selected from methacryloyloxy, acryloyloxy, or vinylbenzyl, and R² is an end group containing a silane coupling group selected from trimethoxysilyl, triethoxysilyl, or methyldimethoxysilyl.

[0032] In a preferred embodiment, the weight-average molecular weight of the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer corresponding to the general molecular structure formula R¹-(A)-(B)-(A)-R² is 4000-15000, and the total mass of the polyoxyethylene segment (A) accounts for 60%-80% of the total mass of the copolymer molecules.

[0033] In a preferred embodiment, the synergistic component of the ionic surfactant is sodium lauryl sulfate, sodium dodecylbenzene sulfonate, or hexadecyltrimethylammonium bromide.

[0034] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0036] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

Claims

1. A method for recycling and reusing polishing waste liquid, characterized in that, Includes the following steps: S1. The raw materials are first sent into the storage tank for storage and pre-treated to remove suspended solids, heavy metals, organic matter and debris and other impurities. S2. Take out the raw materials from the storage tank and let them stand to separate into an upper clear liquid and a lower turbid liquid. S3. Separate the lower layer of turbid liquid and add a dispersant and stir to make the particles in the turbid liquid evenly distributed; S4. After stirring the turbid liquid evenly, add the dispersant again and then sand mill it. The water-based product can be directly obtained by sand milling; or after sand milling, measure the solid content. If the solid content is less than 20%, add the pretreated solid waste to increase the solid content to not less than 20% and continue sand milling to obtain a homogenate. S5. Stir the mixture again until homogeneous, and then dry it by spray drying to obtain the finished powder product. S6. The stirring and sand milling equipment in steps S3 and S4 above are cleaned by the supernatant separated in step S2. S7. After stirring the waste liquid obtained after cleaning evenly, test the solid content, and add raw materials to make the solid content ratio 20%~50%; S8. After replenishing the solid content, send it into the storage tank and continue to steps S2~S5.

2. The method for recycling and reusing polishing waste liquid as described in claim 1, characterized in that, The dispersant is an anionic dispersant, comprising: 40-70 parts of a main dispersant, 5-20 parts of a modified steric hindrance agent, 10-30 parts of an environmental stabilizer, 10-40 parts of an auxiliary synergist, and 100-200 parts of a solvent; wherein, the main dispersant is naphthalene sulfonate formaldehyde condensate and / or polycarboxylate; the modified steric hindrance agent is allyl polyoxyethylene ether (APEG) with a molecular weight of 600-2000; the environmental stabilizer is an amphoteric surfactant, using an amino acid-type amphoteric surfactant (such as sodium lauroyl sarcosinate) or a betaine-type surfactant; the auxiliary synergist is lignin sulfonate and / or sodium carboxymethyl starch; and the solvent is water.

3. The method for recycling and reusing polishing waste liquid as described in claim 1, characterized in that, The dispersant is a composition containing a nonionic dispersant, comprising: 40%-70% nonionic dispersant, 5%-15% ionic surfactant synergistic component, 1%-5% nano-silica stabilizer, 5%-10% cosolvent, and the balance being water; wherein the general molecular formula of the nonionic dispersant is R. ¹ -(A)-(B)-(A)-R ² The corresponding (A) is a polyoxyethylene segment with a degree of polymerization of 15-130, and the corresponding (B) is a polyoxypropylene segment with a degree of polymerization of 20-70. The corresponding R... ¹ It is an end group containing a polymerizable double bond, selected from methacryloyloxy, acryloyloxy, or vinylbenzyl and the corresponding R. ² The terminal group is a silane coupling group, selected from trimethoxysilane, triethoxysilane or methyldimethoxysilane.

4. The method for recycling and reusing polishing waste liquid as described in claim 3, characterized in that, The general molecular structural formula is R ¹ -(A)-(B)-(A)-R ² The corresponding modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer has a weight-average molecular weight of 4,000-15,000, and the total mass of the polyoxyethylene segment (A) accounts for 60%-80% of the total molecular mass of the copolymer.

5. The method for recycling and reusing polishing waste liquid as described in claim 3, characterized in that, The synergistic component of the ionic surfactant is sodium lauryl sulfate, sodium dodecylbenzenesulfonate, or hexadecyltrimethylammonium bromide.

6. The method for recycling and reusing polishing waste liquid as described in claim 3, characterized in that, In step S3, the sand milling is performed using a pin-type nano-sand mill.

7. The method for recycling and reusing polishing waste liquid as described in claim 1, characterized in that, In step S5, the moisture content of the dried powder product is 0.3~0.5%.

8. The method for recycling and reusing polishing waste liquid as described in claim 1, characterized in that, The aqueous solution obtained in step S4 and the powdered product obtained in step S5 are used as UV stabilizers.

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