Silicon powder recovery treatment system for silicon wafer wastewater in semiconductor industry and silicon powder recovery process thereof

Abstract

The invention relates to the technical field of silicon powder recovery, and discloses a silicon wafer wastewater treatment system in the semiconductor industry and a silicon powder recovery process thereof.According to the silicon wafer wastewater treatment system in the semiconductor industry and the silicon powder recovery process and method thereof, after wastewater is filtered through a grid, the PH is adjusted by adding acid, on one hand, alkaline substances in the wastewater can be neutralized and the PH can be reduced by adding the acid, and on the other hand, the pH of the wastewater can be reduced; acid is added, so that the wastewater temperature is reduced; the wastewater is directly subjected to filter pressing, so that a traditional coagulating sedimentation process is replaced, and a reaction tank, a sedimentation tank, a dosing system and the like required by a traditional coagulating reaction are omitted, so that the investment cost of equipment in the early stage is reduced; coagulant and flocculant do not need to be added, so that the medicament operation cost required by coagulating sedimentation is saved; the grinding wastewater containing silicon powder is directly subjected to overpressure filtration, so that the silicon sludge subjected to pressure filtration can be recycled and sold as a valuable article to replace industrial solid waste formed after dosing, and the sludge treatment cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon powder recovery, and in particular to a semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and a silicon powder recovery process thereof. Background Art

[0002] Silicon wafers are materials used to manufacture semiconductor components. Generally, after remelting, pulling, slicing, chamfering, grinding, polishing, and cleaning, polysilicon can be obtained into chip-level silicon wafers with smooth and flat surfaces and neat edges. As the diameter of silicon wafers increases and the feature size of integrated circuits decreases, higher requirements are placed on the flatness of the wafer surface and the degree of cleanliness and damage of the surface. In semiconductor process technology, surface flattening is an important technology for processing high-density lithography, because a flat surface without ups and downs can avoid scattering during exposure.

[0003] In combination with the production process and pollution-generating links of silicon wafers in the semiconductor and photovoltaic industries, a large amount of clean water is used to clean silicon wafers during the cleaning process of silicon wafer production, resulting in a large amount of silicon slag powder and the like entering with the wastewater, especially silicon wafer cleaning wastewater. The main substances in the wastewater are silicon powder and some cleaning liquid agents used in production. If the silicon powder in the silicon wafer cleaning wastewater can be recovered, it will not only reduce the amount of sludge disposal for the enterprise, but also reduce the burden of subsequent treatment of silicon wafer wastewater. The silicon powder in silicon wafer cleaning wastewater mainly exists in the form of suspended matter, and the key is to explore effective silicon powder recovery methods. The research on this part in the existing technology mainly focuses on the recovery of silicon in cutting waste and photovoltaic modules, and it is impossible to achieve the recovery of silicon powder in cleaning wastewater; in view of this, we propose a silicon powder recovery and treatment system for silicon wafer wastewater in the semiconductor industry and a silicon powder recovery process. Summary of the invention

[0004] The purpose of the present invention is to provide a semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and silicon powder recovery process, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and silicon powder recovery process, comprising the following steps: S1. Collecting the raw wastewater from the workshop; S2. Wastewater flows to the wastewater station through a lifting pump or workshop trench; S3. A screen pool is set up at the wastewater station to intercept large particles and garbage in the water; S4, wastewater flows into the wastewater pH adjustment tank by gravity after passing through the screen tank; S5. Add chemical agents into the wastewater pH adjustment tank to initially adjust the pH of the wastewater to a weakly acidic range; S6, wastewater flows by gravity through the pH adjustment tank into the wastewater collection tank; S7. Add chemical agents again into the wastewater collection tank; S8. The treated water in the wastewater collection tank is pumped to the transfer tank; S9. Set up a pre-coating system; the filter cloth for the filter press should be a combined filter cloth suitable for the water quality; S10. A single filter press is equipped with a junction box, and a monitoring instrument is installed in the junction box to monitor the water quality parameters of the pre-coating effluent; S11. If the pre-coating water is clear and the water quality monitoring is within the set range, it will flow back to the pre-coating water tank. If it is not within the set range and is judged to be unqualified, it will flow back to the wastewater pH adjustment tank; S12. After the pre-coating liquid of the filter press is clear and the water quality is qualified, the filter press feed pump is turned on to pump the wastewater from the transfer tank into the filter press for filtration; the filtrate from the filter press is collected and flows into the junction box, and is monitored by the turbidity meter. If it is within the set range, the clear liquid automatic valve opens to flow to the next structure. If it exceeds the set range, the dirty liquid automatic valve opens and the filtrate flows back to the wastewater collection tank.

[0006] S13. After the wastewater feeding of the filter press is completed, the mud unloading operation is carried out.

[0007] S14. The filtrate after wastewater filtration enters the subsequent biochemical treatment system for deep treatment and meets the discharge standards after treatment.

[0008] Optionally, the weak acidity range of S5 is 6.4-7.6.

[0009] Optionally, the pre-coating system includes a pre-coating transfer pump, a pre-coating dissolution tank, and a pre-coating water tank.

[0010] Optionally, the S9 further includes: S91. Before the wastewater is filtered by the filter press, pre-coat the filter press in advance; S92, the pre-coating agent is stirred and dissolved in the pre-coating dissolving water tank to obtain the pre-coating liquid, which is then lifted to the pre-coating water tank by the pre-coating transfer pump.

[0011] Optionally, the S10 further includes: S101, the liquid from both sides of the filter press enters the junction box; S102. A turbidity meter is installed in the junction box to monitor the turbidity of the filter press outlet liquid and to control the automatic valve and water flow direction on the outlet pipe of the junction box.

[0012] Optionally, the S11 further includes: If the pre-coating water is turbid, it will flow back to the wastewater collection tank; If the outgoing water is clear liquid, it will flow back to the pre-coating water tank.

[0013] Optionally, the chemical agents in S7 are H2SO4, hydrochloric acid, and citric acid, which are used to improve the solubility and fluidity of the sludge and adjust the pH value of the wastewater.

[0014] Optionally, the biochemical treatment system includes secondary pH adjustment treatment and relay treatment.

[0015] Compared with the prior art, the present invention provides a system for recovering silicon powder from wastewater from semiconductor wafers and a silicon powder recovery process thereof, which has the following beneficial effects: 1. The semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and its silicon powder recovery process, after the wastewater is filtered through the grid, acid is added to adjust the pH. On the one hand, acid can neutralize the alkaline substances in the wastewater and lower the pH. At the same time, acid is conducive to reducing the temperature of the wastewater; the wastewater is directly pressure filtered, replacing the traditional coagulation sedimentation process, without the need to add a large amount of coagulants and flocculants, thereby greatly reducing the reaction tanks, sedimentation tanks and dosing systems required for the traditional coagulation reaction, thereby reducing the initial equipment investment cost.

[0016] 2. The semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and its silicon powder recovery process directly filter the grinding wastewater containing silicon powder, so the silicon mud after filtration can be recovered and sold as valuable goods, replacing the industrial solid waste formed after adding drugs; at the same time, it saves the cost of coagulation and precipitation agents, and only needs to add a small amount of acid at the front end, that is, add one agent to adjust the pH. The traditional coagulation and precipitation process requires the addition of more than three agents, and the amount of agents used is also very large.

[0017] 3. The silicon powder recovery and treatment system for silicon wafer wastewater in the semiconductor industry and its silicon powder recovery process are different from the traditional coagulation and sedimentation process. Due to the large amount of reagents added, the physical and chemical sludge is also large. The amount of wet sludge that the enterprise needs to treat every day and the sludge transportation and disposal fee are also high. The silicon powder resource recycling is realized, and the enterprise does not produce physical and chemical sludge, and the enterprise physical and chemical sludge disposal fee is zero; at the same time, by selling recycled silicon sludge, it creates added value for the enterprise.

[0018] 4. The semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and its silicon powder recovery process can be made into an integrated system engineering project, or can be used as a transformation project in existing semiconductor and photovoltaic industry grinding wastewater treatment projects. In addition, it can also be made into a vehicle-mounted integrated device for complete small flow treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0021] like Figure 1 As shown, the present invention provides a technical solution: a semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and a silicon powder recovery process, comprising the following steps: S1. Collecting the raw wastewater from the workshop; S2. Wastewater flows to the wastewater station through a lifting pump or workshop trench; S3. A screen pool is set up at the wastewater station to intercept large particles and garbage in the water; S4, wastewater flows into the wastewater pH adjustment tank by gravity after passing through the screen tank; S5. Add chemical agents into the wastewater pH adjustment tank to initially adjust the pH of the wastewater to the weak acid range of 6.4-7.6; S6, wastewater flows by gravity through the pH adjustment tank into the wastewater collection tank; S7, adding chemical agents again into the wastewater collection tank. In this embodiment, the chemical agent is H2SO4, which is used to improve the solubility and fluidity of the sludge; S8. The treated water in the wastewater collection tank is pumped to the transfer tank; S9. Set up a pre-coating system; the filter cloth of the filter press shall be a combined filter cloth suitable for the water quality, and the pre-coating system shall include a pre-coating transfer pump, a pre-coating dissolution tank, and a pre-coating water tank; S91. Before the wastewater is filtered by the filter press, pre-coat the filter press in advance; S92, the pre-coating agent is stirred and dissolved in the pre-coating dissolving water tank to obtain the pre-coating liquid, which is then lifted to the pre-coating water tank by the pre-coating transfer pump.

[0022] S10. A single filter press is equipped with a junction box, and a monitoring instrument is installed in the junction box to monitor the water quality parameters of the pre-coating effluent; S101, the liquid from both sides of the filter press enters the junction box; S102. A turbidity meter is installed in the junction box to monitor the turbidity of the filter press outlet liquid and to control the automatic valve and water flow direction on the outlet pipe of the junction box.

[0023] S11. If the pre-coating water is clear and the water quality monitoring is within the set range, it will flow back to the pre-coating water tank. If it is not within the set range and is judged to be unqualified, it will flow back to the wastewater pH adjustment tank; If the pre-coating water is turbid, it will flow back to the wastewater collection tank; If the outgoing water is clear liquid, it will flow back to the pre-coating water tank.

[0024] S12. When the pre-coating liquid of the filter press is clear and the water quality is qualified, the feed pump of the filter press is turned on to pump the wastewater from the transfer tank into the filter press for filtration; the filtrate of the filter press is collected and flows into the junction box, and is monitored by the turbidity meter. If it is within the set range, the clear liquid automatic valve opens to flow to the next structure. If it exceeds the set range, the dirty liquid automatic valve opens and the filtrate flows back to the wastewater collection tank.

[0025] S13. After the wastewater feeding of the filter press is completed, the mud unloading operation is carried out.

[0026] S14: The filtrate after the wastewater filter press enters the subsequent biochemical treatment system for deep treatment and is discharged after being treated to meet the standards. The biochemical treatment system includes secondary pH adjustment treatment and relay treatment.

[0027] As an application of this embodiment: After the wastewater is filtered through the screen, the pH is adjusted by adding acid. On the one hand, adding acid can neutralize the alkaline substances in the wastewater and lower the pH. At the same time, adding acid is conducive to reducing the temperature of the wastewater. Direct pressure filtration of the wastewater replaces the traditional coagulation and sedimentation process. There is no need to add a large amount of coagulants and flocculants, thereby greatly reducing the reaction tanks, sedimentation tanks and dosing systems required for traditional coagulation reactions, thereby reducing the initial equipment investment cost.

[0028] The present invention directly performs filter press on the grinding wastewater containing silicon powder, so the silicon mud after filter press can be recycled and sold as valuable goods, replacing the industrial solid waste formed after adding drugs; at the same time, the cost of coagulation and precipitation agents is saved, and only a small amount of acid needs to be added at the front end, that is, one agent is added to adjust the pH. The traditional coagulation and precipitation process requires the addition of more than three agents, and the amount of agents used is also large.

[0029] The present invention is different from the traditional coagulation and sedimentation process. Due to the large amount of reagents added, the amount of physical and chemical sludge is also large. The amount of wet sludge that the enterprise needs to treat every day and the sludge transportation and disposal fee are also high. The silicon powder resource recycling is realized, and the enterprise does not produce physical and chemical sludge, and the enterprise physical and chemical sludge disposal fee is zero; at the same time, by selling the recycled silicon sludge, it creates added value for the enterprise.

[0030] The present invention can be made into an integrated system engineering project, or can be applied as a modification project to existing semiconductor and photovoltaic industry grinding wastewater treatment projects. In addition, it can also be made into a vehicle-mounted integrated device for complete set of small flow treatment. Example

[0031] The new semiconductor industry silicon wafer wastewater silicon powder resource recovery treatment process technology provided by this solution is used to treat the wastewater of a silicon wafer wastewater plant in Yangzhou. When the influent SS is about 1000mg / L and the wastewater volume is 10000m3 / d, 21 tons of silicon sludge can be unloaded every day, which is sold at the market average price of 800 yuan per ton. Compared with the traditional coagulation and sedimentation process, which produces physical and chemical sludge, according to the outsourcing disposal fee of about 500 yuan per ton, the company can make a net profit of 1,300 yuan per ton of sludge, that is, a net profit of 2.73 yuan per ton of wastewater for the cost of sludge per ton of water. Example

[0032] The new semiconductor industry silicon wafer wastewater silicon powder resource recovery treatment process technology provided by this solution is used to treat the grinding wastewater of a semiconductor wastewater plant in Nanjing. When the inlet SS is about 400mg / L and the wastewater volume is 1000m3 / d, 1 ton of silicon sludge can be unloaded every day and sold at the market average price of 800 yuan per ton. Compared with the traditional coagulation and sedimentation process, which produces physical and chemical sludge, the company can make a net profit of 1,300 yuan per ton of sludge according to the outsourcing disposal fee of about 500 yuan per ton, that is, a net profit of 1.3 yuan per ton of wastewater for the cost of sludge per ton of water.

[0033] The above generally describes the present invention in detail, but it is obvious to a person skilled in the art that some modifications or improvements can be made to the present invention. Therefore, modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A semiconductor industry silicon wafer wastewater treatment system and silicon powder recovery process, characterized by: The steps include: S1. Collecting the raw wastewater from the workshop; S2. Wastewater flows to the wastewater station through a lifting pump or workshop trench; S3. A screen pool is set up at the wastewater station to intercept large particles and garbage in the water; S4, wastewater flows into the wastewater pH adjustment tank by gravity after passing through the screen tank; S5. Add chemical agents into the wastewater pH adjustment tank to initially adjust the pH of the wastewater to a weakly acidic range; S6, wastewater flows by gravity through the pH adjustment tank into the wastewater collection tank; S7. Add chemical agents again into the wastewater collection tank; S8. The treated water in the wastewater collection tank is pumped to the transfer tank; S9. Set up a pre-coating system; the filter cloth for the filter press should be a combined filter cloth suitable for the water quality; S10. A single filter press is equipped with a junction box, and a monitoring instrument is installed in the junction box to monitor the water quality parameters of the pre-coating effluent; S11. If the pre-coating water is clear and the water quality monitoring is within the set range, it will flow back to the pre-coating water tank. If it is not within the set range and is judged to be unqualified, it will flow back to the wastewater pH adjustment tank; S12. When the pre-coating liquid of the filter press is clear and the water quality is qualified, the feed pump of the filter press is turned on to pump the wastewater from the transfer tank into the filter press for filtration; the filtrate of the filter press is collected and flows into the junction box, and is monitored by the turbidity meter. If it is within the set range, the clear liquid automatic valve opens to flow to the next structure. If it exceeds the set range, the dirty liquid automatic valve opens and the filtrate flows back to the wastewater collection tank. 2.S13, after the wastewater feeding of the filter press is completed, the mud unloading operation is carried out. 3.S14. The filtrate after wastewater filtration enters the subsequent biochemical treatment system for deep treatment and meets the discharge standards after treatment.

4. According to claim 1, a semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and silicon powder recovery process, characterized in that: The weak acidity range of S5 is 6.4-7.

6.

5. According to claim 1, a semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and silicon powder recovery process, characterized in that: The pre-coating system comprises a pre-coating transfer pump, a pre-coating dissolution tank and a pre-coating water tank.

6. The semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and silicon powder recovery process according to claim 1, characterized in that: The S9 further comprises: S91. Before the wastewater is filtered by the filter press, pre-coat the filter press in advance; S92, the pre-coating agent is stirred and dissolved in the pre-coating dissolving water tank to obtain the pre-coating liquid, which is then lifted to the pre-coating water tank by the pre-coating transfer pump.

7. The semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and silicon powder recovery process according to claim 1, characterized in that: The S10 further comprises: S101, the liquid from both sides of the filter press enters the junction box; S102. A turbidity meter is installed in the junction box to monitor the turbidity of the filter press outlet liquid and to control the automatic valve and water flow direction on the outlet pipe of the junction box.

8. The semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and silicon powder recovery process according to claim 1, characterized in that: The S11 further comprises: If the pre-coating water is turbid, it will flow back to the wastewater collection tank; If the outgoing water is clear liquid, it will flow back to the pre-coating water tank.

9. The semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and silicon powder recovery process according to claim 1, characterized in that: The chemical agents in S7 are H2SO4, hydrochloric acid and citric acid, which are used to improve the solubility and fluidity of sludge and adjust the pH value of wastewater.

10. The semiconductor industry silicon wafer wastewater silicon powder recovery treatment system and silicon powder recovery process according to claim 1, characterized in that: The biochemical treatment system includes secondary pH adjustment treatment and relay treatment.

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