Efficient pretreatment system for silicon material cleaning fluorine-containing wastewater

Abstract

An efficient pretreatment system for silicon material cleaning fluorine-containing wastewater comprises an automatic cleaning machine, the outlet end of the automatic cleaning machine is connected with an inlet of a waste acid pretreatment tank through a pipeline, an outlet of the waste acid pretreatment tank is connected with a plate-and-frame filter press through a pipeline, the plate-and-frame filter press is connected with a raw water pool through a pipeline, and the top of the raw water pool is connected with a high-level tank through a pipeline. The high-level tank is connected with the inlet end of the waste acid pretreatment tank through a pipeline. According to the system, wastewater with different acid concentrations can be collected in a classified manner, wastewater with different fluorine ion concentrations can be treated separately, and the treatment amount of subsequent waste residues is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of silicon material cleaning, and particularly relates to a high-efficiency pretreatment system for fluorine-containing wastewater from silicon material cleaning. Background Art

[0002] The existing treatment of fluoride-containing wastewater from raw material washing is to discharge all wastewater into the water collection and regulation tank, and then pump it into the primary coagulation and sedimentation tank for coagulation and sedimentation, add lime and flocculant PAC to remove most of the fluoride ions, SS and silicon powder, and the supernatant after sedimentation flows into the secondary coagulation and sedimentation tank for coagulation and sedimentation again, and add calcium chloride and PAC to remove fluoride ions, SS and silicon powder. The sludge produced by precipitation will be discharged into the fluoride-containing sludge tank, and then pumped into the plate and frame filter press by a pneumatic diaphragm pump for dehydration treatment. After dehydration, the sludge is transported out for treatment, and the filtrate is returned to the water collection and regulation tank for the above treatment.

[0003] A large part of the silicon materials used to produce polycrystalline ingots need to be pickled first, that is, they are cleaned with a mixed acid of hydrofluoric acid, hydrochloric acid and nitric acid in a certain proportion. The wastewater after cleaning contains a large amount of residual nitric acid, hydrochloric acid and hydrofluoric acid. These wastewaters need to be treated before they can be discharged, especially the fluoride ions in the wastewater, whose concentration needs to meet the discharge standards before they can be discharged. The existing treatment of fluorine-containing wastewater is to discharge all the wastewater into the water collection and regulating tank, and then pump it into the primary coagulation tank for coagulation and precipitation. This treatment will increase the use of reagents. The existing treatment of fluorine-containing wastewater from raw material cleaning is to discharge all the wastewater into the water collection and regulating tank, and then pump it into the primary coagulation and sedimentation tank, adding acid, alkali, lime and PAC for precipitation. Although this method can also treat residual waste acid and fluoride ions in the wastewater, a large amount of lime will not be fully reacted during the precipitation process, which will waste a lot of lime, and the subsequent waste residue treatment workload is huge, and recyclable waste acid is treated and discharged together. Summary of the invention

[0004] The technical problem to be solved by the utility model is to provide an efficient pretreatment system for fluorine-containing wastewater from silicon material cleaning. The system can classify and collect wastewater with different acid concentrations, separately treat wastewater with different fluoride ion concentrations, and reduce the subsequent treatment amount of waste residues.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0006] A high-efficiency pretreatment system for fluorine-containing wastewater from silicon material cleaning comprises an automatic cleaning machine, wherein the outlet of the automatic cleaning machine is connected to the inlet of a waste acid pretreatment tank through a pipeline, the outlet of the waste acid pretreatment tank is connected to a plate and frame filter press through a pipeline, the plate and frame filter press is connected to a raw water pool through a pipeline, the top of the raw water pool is connected to a high-position tank through a pipeline, and the high-position tank is connected to the inlet of the waste acid pretreatment tank through a pipeline.

[0007] Preferably, a first fluoride ion monitor, a first pump and a first valve are sequentially arranged on the pipeline at the outlet end of the automatic cleaning machine;

[0008] A second pump is provided on the pipeline between the waste acid pretreatment tank and the plate and frame filter press;

[0009] A fluoride ion content regulating valve is provided on the pipeline connecting the high-level tank and the automatic cleaning machine;

[0010] A pH regulating valve is provided on the pipe connecting the high-level tank and the raw water pool.

[0011] The first valve is of the same model as the fluoride ion content regulating valve, and both control the opening and closing or size of the valve by the fluoride ion content.

[0012] Preferably, the waste acid pretreatment tank comprises a box body, a motor is provided on the top of the box body, the motor is used to drive the agitator to rotate, and a calcium chloride pipeline, a sodium hydroxide pipeline, a PAC pipeline, a PAM pipeline, an acid-containing wastewater inlet pipeline, an exhaust pipeline, a recovery pipeline, a wastewater and waste residue discharge pipeline, a second fluoride ion monitor, a pH monitor and a temperature sensor are provided on the top of the box body.

[0013] The utility model can achieve the following beneficial effects:

[0014] This system can collect and classify wastewater with different acid concentrations, and treat wastewater with different fluoride ion concentrations separately, so that the lime reaction is sufficient and the amount of subsequent waste residue to be processed is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The utility model is further described below in conjunction with the accompanying drawings and embodiments:

[0016] Figure 1 This is the system structure diagram of the utility model;

[0017] Figure 2 This is the structural diagram of the waste acid pretreatment tank of the utility model.

[0018] In the figure: automatic cleaning machine 1, first fluoride ion monitor 2, first pump 3, first valve 4, waste acid pretreatment tank 5, calcium chloride pipeline 501, sodium hydroxide pipeline 502, PAC pipeline 503, PAM pipeline 504, acid wastewater inlet pipeline 505, exhaust pipeline 506, recovery pipeline 507, wastewater and waste residue discharge pipeline 508, second fluoride ion monitor 509, pH monitor 510, temperature sensor 511, motor 512, agitator 513, second pump 6, plate and frame filter press 7, raw water tank 8, pH monitor 9, fluoride ion content regulating valve 11, high-level tank 12, pH regulating valve 13, third pump 14. DETAILED DESCRIPTION

[0019] The preferred solution is Figure 1 to Figure 2As shown, a high-efficiency pretreatment system for fluorine-containing wastewater from silicon material cleaning includes an automatic cleaning machine 1, the outlet of the automatic cleaning machine 1 is connected to the inlet of a waste acid pretreatment tank 5 through a pipeline, the outlet of the waste acid pretreatment tank 5 is connected to a plate and frame filter press 7 through a pipeline, the plate and frame filter press 7 is connected to a raw water tank 8 through a pipeline, the top of the raw water tank 8 is connected to a high-level tank 12 through a pipeline, and the high-level tank 12 is connected to the inlet of the waste acid pretreatment tank 5 through a pipeline.

[0020] Specifically, a first fluoride ion monitor 2, a first pump 3 and a first valve 4 are sequentially arranged on the pipeline at the outlet end of the automatic cleaning machine 1; a second pump 6 is arranged on the pipeline between the waste acid pretreatment tank 5 and the plate and frame filter press 7; a fluoride ion content regulating valve 11 is arranged on the pipeline connecting the high-level tank 12 and the automatic cleaning machine 1; and a pH regulating valve 13 is arranged on the pipeline connecting the high-level tank 12 and the raw water tank 8.

[0021] The waste acid pretreatment tank 5 includes a box body, a motor 512 is provided on the top of the box body, and the motor 512 is used to drive the agitator 513 to rotate. The top of the box body is provided with a calcium chloride pipeline 501, a sodium hydroxide pipeline 502, a PAC pipeline 503, a PAM pipeline 504, an acid-containing wastewater inlet pipeline 505, an exhaust pipeline 506, a recovery pipeline 507, a wastewater and waste residue discharge pipeline 508, a second fluoride ion monitor 509, a pH monitor 510 and a temperature sensor 511.

[0022] All valves and pumps are controlled by PLC programming. In the waste acid pretreatment tank: the valves on the calcium chloride pipeline, PAC pipeline and PAM pipeline are controlled by the fluoride ion monitor. When the fluoride ion concentration is lower than 20 mg / L, the valve will automatically close. The valve on the sodium hydroxide pipeline is controlled by the pH monitor and the temperature sensor. The temperature sensor controls the valve opening. When the reaction temperature exceeds 70°C, the valve opening is automatically reduced to slow down the reaction speed and make the reaction temperature lower than 70°C. The pH monitor controls the start and stop of the valve. When the monitored pH value is greater than 7, the valve automatically closes. When the valve is closed, the temperature sensor no longer controls the valve opening, and the exhaust pipe is connected to the automatic elution tower.

[0023] The processing flow of this system is:

[0024] Acidic wastewater is discharged from the waste acid outlet of the automatic cleaning machine into a pipeline with a fluoride ion monitor on it. When the fluoride ion concentration is higher than 1000 mg / L, it passes through the first valve and enters the waste acid pretreatment tank. The treated wastewater and waste residue are pumped into the plate and frame filter press through the second pump. After filtration, the clear liquid flows into the raw water tank by gravity. Some high-concentration fluoride-containing wastewater can also be stored in the waste acid pretreatment tank for recycling. When the fluoride ion concentration monitored by the fluoride ion monitor is lower than 1000 mg / L, it passes through the fluoride ion content regulating valve and enters the high-level tank, and then directly enters the raw water tank through the PH regulating valve. There is a pH monitor in the raw water tank. When the monitored pH value is lower than 1000 mg / L, it enters the high-level tank through the fluoride ion content regulating valve, and then directly enters the raw water tank through the PH regulating valve. The pH regulating valve is closed at 7 o'clock; the waste acid pretreatment tank includes calcium chloride pipeline, sodium hydroxide pipeline, PAC pipeline, PAM pipeline, acid wastewater inlet pipeline, exhaust pipeline, recovery pipeline, treated wastewater and waste residue discharge pipeline, fluoride ion monitor, pH monitor, temperature sensor, motor, agitator, and system process pipeline materials are all acid-resistant and alkali-resistant materials; the waste acid pretreatment tank is made of PP material, the wall thickness is 20mm, and the tank body size is 1.6m×1.6×1.6m. The size should not be too large to avoid the acid-base neutralization reaction to release a large amount of heat violently and make the temperature too high; the number of waste acid pretreatment tanks can be increased according to actual needs;

[0025] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A high-efficiency pretreatment system for fluorine-containing wastewater from silicon material cleaning, comprising an automatic cleaning machine (1), characterized in that: The outlet of the automatic cleaning machine (1) is connected to the inlet of the waste acid pretreatment tank (5) through a pipeline, the outlet of the waste acid pretreatment tank (5) is connected to the plate and frame filter press (7) through a pipeline, the plate and frame filter press (7) is connected to the raw water tank (8) through a pipeline, the top of the raw water tank (8) is connected to the high-level tank (12) through a pipeline, and the high-level tank (12) is connected to the inlet of the waste acid pretreatment tank (5) through a pipeline.

2. The high-efficiency pretreatment system for fluorine-containing wastewater from silicon material cleaning according to claim 1, characterized in that: A first fluoride ion monitor (2), a first pump (3) and a first valve (4) are sequentially arranged on the pipeline at the outlet end of the automatic cleaning machine (1); A second pump (6) is provided on the pipeline between the waste acid pretreatment tank (5) and the plate and frame filter press (7); A fluoride ion content regulating valve (11) is provided on the pipeline connecting the high-level tank (12) and the automatic cleaning machine (1); A pH regulating valve (13) is provided on the pipeline connecting the high-level tank (12) and the raw water pool (8).

3. The high-efficiency pretreatment system for fluorine-containing wastewater from silicon material cleaning according to claim 1, characterized in that: The waste acid pretreatment tank (5) comprises a box body, a motor (512) is provided on the top of the box body, the motor (512) is used to drive the agitator (513) to rotate, and a calcium chloride pipeline (501), a sodium hydroxide pipeline (502), a PAC pipeline (503), a PAM pipeline (504), an acid-containing wastewater inlet pipeline (505), an exhaust pipeline (506), a recovery pipeline (507), a wastewater and waste residue discharge pipeline (508), a second fluoride ion monitor (509), a pH monitor (510) and a temperature sensor (511) are provided on the top of the box body.

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