Cutting fluid as well as preparation process and recycling method thereof

Abstract

The invention discloses a cutting fluid as well as a preparation process and a recycling method thereof, and the cutting fluid is prepared from the following components in parts by mass: 71.5 to 87.5 parts of water at 30 to 40 DEG C, 2 to 6 parts of polyethylene glycol, 0.5 to 3.5 parts of sodium citrate, 0.5 to 1.5 parts of polyacrylamide, 0.2 to 1 part of hydrophilic modified nano silicon dioxide, 0.3 to 1.5 parts of amino silane and 9 to 15 parts of silicon carbide micro powder. According to the cutting fluid provided by the invention, good dispersion of the silicon carbide micro powder in the cutting process is ensured, the cutting fluid has good processing performance, the silicon wafer cutting quality is improved, the silicon powder in the cutting fluid can be rapidly and effectively separated and removed after the silicon wafer is cut, effective components of the silicon powder are not influenced, rapid recovery of the silicon powder is realized, and the production cost is reduced. And the cutting fluid is convenient to recycle and reuse.

Description

Technical Field

[0001] The invention relates to the technical field of silicon material cutting, in particular to a cutting fluid and a preparation process and a recycling and regeneration method thereof. Background Art

[0002] With the development of the photovoltaic industry, photovoltaic silicon wafer slicing technology is evolving towards a larger silicon rod diameter, thinner diamond wire, and thinner silicon wafer thickness. However, as the silicon rod diameter increases and the diamond wire becomes thinner, the silicon powder excretion capacity will be significantly reduced, further causing quality problems such as line marks and uneven thickness on the silicon wafer surface; and the thinning of the diamond wire will cause the silicon powder particle size produced by cutting to become smaller, the specific surface area to increase, and the reaction activity to increase. The silicon powder reacts with water to generate hydrogen and form silicic acid and its oligomers. These colloidal substances will adhere to the steel wire, causing the risk of wire breakage; the thinning of the silicon wafer thickness means that the number of wafers output by a single knife increases, which in turn will increase the silicon powder. A large amount of silicon powder will gather and adhere to the sides and chamfers of the silicon wafer to form dirt, increasing the difficulty of subsequent cleaning, and seriously affecting the cutting effect and product quality.

[0003] Based on this, the cutting fluid, which is indispensable for silicon wafer cutting, is particularly important. High-quality cutting fluid can not only effectively lubricate the cutting wire, reduce friction resistance, and improve cutting efficiency and accuracy during the thin silicon wafer slicing process, but also provide a good cleaning effect, timely remove impurities such as debris and metal dust generated during the cutting process, extend the life of the cutting wire and protect the safety of the equipment. In addition, the cutting fluid has the function of cooling the workpiece, ensuring the cleanliness of the silicon wafer surface and simplifying the subsequent cleaning steps. Therefore, how to develop a photovoltaic silicon wafer diamond wire cutting fluid that can quickly and effectively separate and remove silicon powder in the cutting fluid without affecting its effective ingredients, and can also be easily recycled and reused is an important issue facing the photovoltaic silicon wafer cutting industry. Summary of the invention

[0004] In order to solve the above technical problems, one of the objects of the present invention is to provide a cutting fluid, which is composed of the following components in parts by mass: 71.5-87.5 parts of water at 30-40°C, 2-6 parts of polyethylene glycol, 0.5-3.5 parts of sodium citrate, 0.5-1.5 parts of polyacrylamide, 0.2-1 parts of hydrophilic modified nano-silica, 0.3-1.5 parts of aminosilane, and 9-15 parts of silicon carbide micropowder.

[0005] Preferably, the composition is composed of the following components in parts by mass: 79.5 parts of water at 30-40° C., 4 parts of polyethylene glycol, 2 parts of sodium citrate, 1 part of polyacrylamide, 0.6 parts of hydrophilic modified nano-silica, 0.9 parts of aminosilane, and 12 parts of silicon carbide micropowder.

[0006] Preferably, the polyethylene glycol is PEG 400 or PEG 600.

[0007] Preferably, the hydrophilic modified nano-silica is Hydrophilic-200.

[0008] Preferably, the aminosilane is γ-aminopropyltriethoxysilane or N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0009] A cutting fluid preparation process comprises the following steps:

[0010] Add 71.5-87.5 parts of 30-40°C water and 2-6 parts of polyethylene glycol (PEG) to the container in sequence, then add 0.5-3.5 parts of sodium citrate while stirring to adjust the pH to 3-4, continue to add 0.5-1.5 parts of polyacrylamide, 0.2-1 parts of hydrophilic modified nano-silicon dioxide, 0.3-1.5 parts of aminosilane, and 9-15 parts of silicon carbide powder in sequence while stirring, and continue stirring until all components are evenly mixed. 30-40°C water is more conducive to the dissolution of polyethylene glycol.

[0011] A method for recycling and reusing cutting fluid comprises the following steps:

[0012] Cutting fluid pretreatment: Collect the cutting fluid into a container, centrifuge the cutting fluid to obtain a supernatant and a precipitate, and use a silicon carbide filter membrane to perform online circulation filtration to obtain a purified liquid and a concentrated liquid. The filtration method is a large-flow cross-flow filtration, and the ratio of the purified liquid outlet speed to the concentrated liquid reflux speed is 1:3-1:6. The filter membrane pressure is 0.1-0.2Mpa, which can ensure that the filtration process is efficient and stable, and avoid damage to the filter membrane due to excessive pressure; when the solid content in the reflux concentrated liquid (solid content refers to the percentage of the mass of solid particles such as silicon carbide micropowder and silicon powder in the concentrated liquid to the total mass of the concentrated liquid) reaches 2-5%, the concentrated liquid enters the next process, and the purified liquid is deeply purified by an activated carbon column, a cation resin exchange column, and an anion resin exchange column in turn. After removing various metal ions and non-metal ions in the purified liquid, it is returned to the cutting system for recycling, saving resources;

[0013] Solid-liquid separation: The concentrated liquid with a solid content of 2-5% is passed through a filter press for solid-liquid separation to obtain silicon material and filtrate. The silicon material is sold, and the filtrate is returned to the cutting liquid pretreatment step and filtered online again using a silicon carbide filter membrane.

[0014] Preferably, the centrifugal speed is 5000-10000 rpm, and the centrifugation time is 10-20 min.

[0015] Preferably, the speed at which the purified liquid passes through the activated carbon column is 10 to 30 BV / h.

[0016] Preferably, the speed at which the purified liquid passes through the cation resin exchange column and the anion resin exchange column is 5 to 20 BV / h.

[0017] The beneficial effects are as follows: the cutting fluid formula provided in the present application uses polyethylene glycol to improve the lubrication performance of the cutting fluid, effectively reducing friction, while also preventing silicon carbide micropowder from agglomerating, making it evenly dispersed in the liquid, improving system stability, and enhancing cutting efficiency; adding aminosilane can improve the interfacial compatibility between silicon carbide micropowder and water, which can not only promote the good dispersion of silicon carbide micropowder in water, but also form a protective layer on the surface of silicon carbide micropowder, reduce the adhesion of silicon powder to other components or equipment surfaces, and facilitate subsequent recovery; aminosilane and polyethylene glycol work together to keep silicon carbide micropowder in a continuously and stably dispersed state in water; adding sodium citrate to adjust the pH value of the system can make the cutting fluid more stable, support multiple recycling of the cutting fluid, and reduce costs The invention discloses a novel method for separating silicon carbide from cutting liquid. ...

[0018] The cutting fluid preparation process provided in the present application has simple steps, strong operability, and is suitable for large-scale batch production. The prepared cutting fluid has stable performance, safety, and environmental protection.

[0019] The present application provides a method for recycling and regenerating cutting fluid. First, centrifugal separation is used to remove impurities such as metal debris and non-metallic particles generated during the cutting process. At this time, the large-flow cross-flow filtration technology of the silicon carbide filter membrane can be used to quickly purify the supernatant without easily damaging the filter membrane. Then, the purified liquid is deeply purified using an activated carbon column, a cationic resin exchange column, and an anionic resin exchange column to ensure the quality of the recovered cutting fluid. Finally, the concentrated liquid is separated into solid and liquid through a filter press. The obtained silicon material can be sold directly, and the filtrate is returned to the cutting fluid pretreatment step again. The entire process realizes the recycling of resources, reduces waste emissions, and saves the company's production costs. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand the present invention more clearly.

[0021] The following embodiments are only used to illustrate the present invention, but are not limited to the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work belong to the protection scope of the present invention.

[0022] In the examples of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the examples of the present invention, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art.

[0023] Source of raw materials:

[0024] Polyethylene glycol PEG 400 and polyethylene glycol PEG 600 were purchased from Shandong Feihong New Materials Co., Ltd.;

[0025] Sodium citrate was purchased from Shenzhen Love Biotechnology Co., Ltd.;

[0026] Polyacrylamide, APAM-HP, was purchased from Zibo Lanerqing Polymer Materials Co., Ltd.;

[0027] Hydrophilic modified nano-silica, Hydrophilic-200, was purchased from Nanjing Quanlong Biotechnology Co., Ltd.;

[0028] Hydrophobic modified nanosilica, MGS-2, was purchased from Nanjing Baoket New Materials Co., Ltd.;

[0029] γ-Aminopropyltriethoxysilane was purchased from Wuhan Shuer Biotechnology Co., Ltd.;

[0030] N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane was purchased from Hangzhou Jessica Chemical Co., Ltd.;

[0031] Silicon carbide powder, GC#800, GC#1000, GC#1200, were purchased from Zibo Daoxin New Material Technology Co., Ltd.;

[0032] Silicon carbide filter membrane was purchased from Shandong Huaen New Materials Technology Co., Ltd.;

[0033] Activated carbon column, purchased from Ningxia Shengmei Huarui Activated Carbon Manufacturing Co., Ltd.;

[0034] Cationic resin exchange column, GQ-04, purchased from Xinxiang Haihengnuo Purification Equipment Co., Ltd.;

[0035] Anion resin exchange column, RL-16-1, was purchased from Henan Jiashuo Environmental Protection Technology Co., Ltd.;

[0036] Filter press, XZ30 / 870-30U, purchased from Henan Beibang Intelligent Environmental Protection Engineering Technology Co., Ltd.;

[0037] The remaining reagents and equipment are commercially available.

[0038] Example 1

[0039] The present embodiment provides a cutting fluid, which is composed of the following components in parts by mass: 71.5 parts of 30° C. water, 6 parts of polyethylene glycol, 3.5 parts of sodium citrate, 1.5 parts of polyacrylamide, 1 part of hydrophilic modified nano-silica, 1.5 parts of aminosilane, and 15 parts of silicon carbide micropowder (GC#800); wherein the polyethylene glycol is PEG 400; and the aminosilane is γ-aminopropyltriethoxysilane.

[0040] A cutting fluid preparation process comprises the following steps:

[0041] Add 71.5 parts of 30°C water and 6 parts of polyethylene glycol to the container in sequence, then add 3.5 parts of sodium citrate while stirring to adjust the pH to 3, continue to add 1.5 parts of polyacrylamide, 1 part of hydrophilic modified nano-silica, 1.5 parts of aminosilane, and 15 parts of silicon carbide powder in sequence while stirring, and continue stirring until all components are evenly mixed.

[0042] A method for recycling and reusing cutting fluid comprises the following steps:

[0043] Cutting fluid pretreatment: collect the cutting fluid into a container, centrifuge the cutting fluid at a centrifugal speed of 5000rpm for 20min; obtain supernatant and precipitate, and use silicon carbide filter membrane to perform online circulation filtration to obtain purified liquid and concentrated liquid. The filtration method is large-flow cross-flow filtration, the ratio of the purified liquid outlet speed to the concentrated liquid reflux speed is 1:3, the filter membrane pressure is 0.1Mpa, and when the solid content in the reflux concentrated liquid reaches 2%, the concentrated liquid enters the next process for treatment, and the purified liquid passes through the activated carbon column, the cation resin exchange column, and the anion resin exchange column for deep purification in turn. After removing various metal ions and non-metal ions in the purified liquid, it is returned to the cutting system for recycling; the speed of the purified liquid passing through the activated carbon column is 10BV / h; the speed of the purified liquid passing through the cation resin exchange column and the anion resin exchange column is 5BV / h;

[0044] Solid-liquid separation: The concentrated liquid with a solid content of 2% is passed through a filter press for solid-liquid separation to obtain silicon material and filtrate. The silicon material is sold, and the filtrate is returned to the cutting liquid pretreatment step and is again filtered online using a silicon carbide filter membrane.

[0045] Example 2

[0046] The present embodiment provides a cutting fluid, which is composed of the following components in parts by mass: 79.5 parts of 35° C. water, 4 parts of polyethylene glycol, 2 parts of sodium citrate, 1 part of polyacrylamide, 0.6 parts of hydrophilic modified nano-silica, 0.9 parts of aminosilane, and 12 parts of silicon carbide micropowder (GC#1000); wherein the polyethylene glycol is PEG 600; and the aminosilane is N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0047] A cutting fluid preparation process comprises the following steps:

[0048] Add 79.5 parts of 35°C water and 4 parts of polyethylene glycol to the container in sequence, then add 2 parts of sodium citrate while stirring to adjust the pH to 3.5, continue to add 1 part of polyacrylamide, 0.6 parts of hydrophilic modified nano-silica, 0.9 parts of aminosilane, and 12 parts of silicon carbide powder in sequence while stirring, and continue stirring until all components are evenly mixed.

[0049] A method for recycling and reusing cutting fluid comprises the following steps:

[0050] Cutting fluid pretreatment: collect the cutting fluid into a container, centrifuge the cutting fluid at a centrifugal speed of 7500rpm for 15min; obtain supernatant and precipitate, and use silicon carbide filter membrane to perform online circulation filtration to obtain purified liquid and concentrated liquid. The filtration method is large-flow cross-flow filtration, the ratio of the outlet speed of the purified liquid to the reflux speed of the concentrated liquid is 1:5, the filter membrane pressure is 0.16Mpa, and when the solid content in the reflux concentrated liquid reaches 4%, the concentrated liquid enters the next process for treatment, and the purified liquid passes through the activated carbon column, the cation resin exchange column, and the anion resin exchange column for deep purification in turn. After removing various metal ions and non-metal ions in the purified liquid, it is returned to the cutting system for recycling; the speed of the purified liquid passing through the activated carbon column is 20BV / h; the speed of the purified liquid passing through the cation resin exchange column and the anion resin exchange column is 13BV / h;

[0051] Solid-liquid separation: The concentrated liquid with a solid content of 4% is passed through a filter press for solid-liquid separation to obtain silicon material and filtrate. The silicon material is sold, and the filtrate is returned to the cutting liquid pretreatment step and is again filtered online using a silicon carbide filter membrane.

[0052] Example 3

[0053] The present embodiment provides a cutting fluid, which is composed of the following components in parts by mass: 87.5 parts of 40°C water, 2 parts of polyethylene glycol, 0.5 parts of sodium citrate, 0.5 parts of polyacrylamide, 0.2 parts of hydrophilic modified nano-silica, 0.3 parts of aminosilane, and 9 parts of silicon carbide micropowder (GC#1200); wherein the polyethylene glycol is PEG 400; and the aminosilane is γ-aminopropyltriethoxysilane.

[0054] A cutting fluid preparation process comprises the following steps:

[0055] Add 87.5 parts of 40°C water and 2 parts of polyethylene glycol to the container in sequence, then add 0.5 parts of sodium citrate while stirring to adjust the pH to 4.5, continue to add 0.5 parts of polyacrylamide, 0.2 parts of hydrophilic modified nano-silica, 0.3 parts of aminosilane, and 9 parts of silicon carbide powder in sequence while stirring, and continue stirring until all components are evenly mixed.

[0056] A method for recycling and reusing cutting fluid comprises the following steps:

[0057] Cutting fluid pretreatment: collect the cutting fluid into a container, centrifuge the cutting fluid at a centrifugal speed of 10,000 rpm for 10 minutes; obtain supernatant and precipitate, and use a silicon carbide filter membrane to perform online circulation filtration to obtain purified liquid and concentrated liquid. The filtration method is large-flow cross-flow filtration, and the ratio of the purified liquid outlet speed to the concentrated liquid reflux speed is 1:6. The filter membrane pressure is 0.2Mpa. When the solid content in the reflux concentrated liquid reaches 5%, the concentrated liquid enters the next process for treatment. The purified liquid passes through an activated carbon column, a cation resin exchange column, and an anion resin exchange column for deep purification in turn. After removing various metal ions and non-metal ions in the purified liquid, it is returned to the cutting system for recycling; the speed of the purified liquid passing through the activated carbon column is 30BV / h; the speed of the purified liquid passing through the cation resin exchange column and the anion resin exchange column is 20BV / h;

[0058] Solid-liquid separation: The concentrated liquid with a solid content of 5% is passed through a filter press for solid-liquid separation to obtain silicon material and filtrate. The silicon material is sold, and the filtrate is returned to the cutting liquid pretreatment step and filtered online again using a silicon carbide filter membrane.

[0059] Comparative Example 1

[0060] Commercially available photovoltaic silicon wafer diamond wire cutting fluid was purchased from Dongguan Hill Metal Materials Co., Ltd.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 3 is that the amount of 40° C. water is increased from 87.5 parts to 87.8 parts, and aminosilane is not added. The other components and experimental steps are the same as those in Example 3.

[0063] Comparative Example 3

[0064] The difference between this comparative example and Example 3 is that the amount of 40° C. water is increased from 87.5 parts to 88 parts, and polyacrylamide is not added. The other components and experimental steps are the same as those in Example 3.

[0065] Comparative Example 4

[0066] The difference between this comparative example and Example 3 is that 0.2 parts of hydrophobic modified nano-silica are used to replace 0.2 parts of hydrophilic modified nano-silica, and the other components and experimental steps are the same as those in Example 3.

[0067] Test method:

[0068] The performance of the cutting fluids prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was tested in accordance with T / QGCML 3974-2024 “Silicon Wafer Cutting Fluids”; the test results are shown in Table 1 below.

[0069] Table 1 Cutting fluid test performance index results obtained in each embodiment and comparative example

[0070]

[0071]

[0072] On the one hand, too high viscosity will limit the fluidity of the cutting fluid and the suspension of silicon carbide powder, resulting in a decrease in cutting efficiency. On the other hand, it will affect the chip removal performance of the cutting fluid, so that the silicon powder cannot be taken away in time, affecting the cutting quality; if the viscosity is too low, the silicon carbide powder cannot be effectively kept suspended, and the rapid precipitation of the silicon carbide powder will affect the cutting effect. In addition, it will also affect the lubrication and cooling performance of the cutting fluid, resulting in poor surface quality of the silicon wafer; It can be seen from Table 1 that the viscosity of the cutting fluid in Examples 1 to 3 is within a suitable range, and compared with Comparative Example 1, the viscosity is lower. This viscosity can not only ensure that the silicon carbide powder is well dispersed in the cutting fluid during the cutting process, but also It can quickly and effectively separate and remove silicon powder in the cutting liquid after silicon wafer cutting; this conclusion can be mutually supported by the sedimentation velocity value. If the sedimentation velocity is too fast, it is not conducive to the silicon carbide powder to maintain a good suspension state in the cutting liquid, and if the sedimentation velocity is too slow, it is not conducive to the silicon powder to be quickly and effectively separated and removed from the cutting liquid. It can be seen from Table 1 that the sedimentation velocity of the cutting liquid in Examples 1 to 3 is within a suitable range, and compared with Comparative Example 1, the sedimentation velocity is slower, which further confirms the characteristics that the cutting liquid of the present application can not only ensure that the silicon carbide powder is well dispersed in the cutting liquid during the cutting process, but also can quickly and effectively separate and remove the silicon powder in the cutting liquid after the silicon wafer is cut.

[0073] In the lubrication performance (PB / N), the larger the PB value, i.e., the maximum no-seizure load, the better the extreme pressure performance of the cutting fluid, and the smaller the N value, the more it can reduce the wear generated during the cutting process. It can be seen from Table 1 that compared with Comparative Example 1, Examples 1 to 3 have better lubrication performance, and this conclusion can also be confirmed from the surface roughness values ​​of the silicon wafer products obtained by cutting after cleaning. It can be seen from Table 1 that compared with Comparative Example 1, the surface roughness values ​​of the silicon wafer products obtained by cutting in Examples 1 to 3 are also smaller after cleaning, indicating that the surfaces of the silicon wafer products obtained by cutting in Examples 1 to 3 are smoother.

[0074] It can also be seen from Table 1 that in Comparative Example 2, after no aminosilane is added, the cutting fluid prepared has a very small amount of precipitation at the bottom and the viscosity is reduced. This may be due to the poor interfacial compatibility between silicon carbide micropowder and water after the lack of aminosilane; while in Comparative Example 3, without the addition of polyacrylamide, the deposition rate of the cutting fluid prepared is significantly reduced. This may be due to the reduced rate of mutual attraction and aggregation of silicon powders after the lack of polyacrylamide; and looking at Comparative Example 4, it can be found that after replacing the hydrophilic modified nano-silica with the hydrophobic modified nano-silica, there is a very small amount of precipitation at the bottom of the prepared cutting fluid and the deposition rate is significantly reduced. This may be due to the poor compatibility of the hydrophobic modified nano-silica with other components and the inability to synergize with the polyacrylamide.

[0075] In summary, the cutting fluid provided in the present application not only ensures the good dispersion of silicon carbide micropowder during the cutting process, so that the cutting fluid has good processing performance and improves the quality of silicon wafer cutting, but also can quickly and effectively separate and remove silicon powder in the cutting fluid after silicon wafer cutting without affecting its effective ingredients. It not only realizes the rapid recovery of silicon powder, but also facilitates the recycling and reuse of the cutting fluid.

[0076] The above is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A cutting fluid, characterized in that: The composition is composed of the following components in parts by mass: 71.5-87.5 parts of water at 30-40° C., 2-6 parts of polyethylene glycol, 0.5-3.5 parts of sodium citrate, 0.5-1.5 parts of polyacrylamide, 0.2-1 parts of hydrophilic modified nano-silica, 0.3-1.5 parts of aminosilane, and 9-15 parts of silicon carbide micropowder.

2. The cutting fluid according to claim 1, characterized in that: The invention is composed of the following components in parts by mass: 79.5 parts of water at 30-40° C., 4 parts of polyethylene glycol, 2 parts of sodium citrate, 1 part of polyacrylamide, 0.6 parts of hydrophilic modified nano-silicon dioxide, 0.9 parts of aminosilane and 12 parts of silicon carbide micropowder.

3. The cutting fluid according to claim 1, characterized in that: The polyethylene glycol is selected from PEG 400 or PEG 600.

4. The cutting fluid according to claim 1, characterized in that The hydrophilic modified nano-silica is Hydrophilic-200.

5. The cutting fluid according to claim 1, characterized in that: The aminosilane is selected from γ-aminopropyltriethoxysilane (APTES) or N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (AEAPTES).

6. A process for preparing a cutting fluid, characterized in that: The following steps are involved: Add 71.5-87.5 parts of 30-40°C water and 2-6 parts of polyethylene glycol to the container in sequence, then add 0.5-3.5 parts of sodium citrate while stirring to adjust the pH to 3-4, continue to add 0.5-1.5 parts of polyacrylamide, 0.2-1 parts of hydrophilic modified nano-silica, 0.3-1.5 parts of aminosilane, and 9-15 parts of silicon carbide powder in sequence while stirring, and continue stirring until all components are evenly mixed.

7. A method for recycling cutting fluid, characterized in that: The following steps are involved: Cutting fluid pretreatment: Collect the cutting fluid into a container, centrifuge the cutting fluid to obtain a supernatant and a precipitate, and use a silicon carbide filter membrane to perform online circulation filtration to obtain a purified liquid and a concentrated liquid. The filtration method is a large-flow cross-flow filtration, and the ratio of the purified liquid outlet speed to the concentrated liquid reflux speed is 1:3-1:

6. The filter membrane pressure is 0.1-0.2Mpa. When the solid content in the refluxed concentrated liquid reaches 2-5%, the concentrated liquid enters the next process. The purified liquid is deeply purified by an activated carbon column, a cation resin exchange column, and an anion resin exchange column in turn. After removing various metal ions and non-metal ions in the purified liquid, it is returned to the cutting system for recycling; Solid-liquid separation: The concentrated liquid with a solid content of 2-5% is separated into silicon material and filtrate by a filter press. The silicon material is sold, and the filtrate is returned to the cutting liquid pretreatment step and filtered online again by the silicon carbide filter membrane.

8. The cutting fluid recycling method according to claim 7, characterized in that: The centrifugal speed is 5000-10000 rpm, and the centrifugation is 10-20 minutes.

9. The cutting fluid recycling method according to claim 7, characterized in that: The speed at which the purified liquid passes through the activated carbon column is 10 to 30 BV / h.

10. The cutting fluid recycling method according to claim 7, characterized in that: The speed at which the purified liquid passes through the cation resin exchange column and the anion resin exchange column is 5-20 BV / h.

Images