Silicon slurry water washing and chlorine removal system

Abstract

The utility model discloses a kind of silicon mud water washing and removing chlorine efficiency system, including pretreatment unit, washing unit, detection unit, control unit and execution unit;By setting pretreatment unit, through-hole is opened in pretreatment tank lateral wall and installs ultrasonic transducer, high-efficiency transmission of ultrasonic energy to slurry in tank is realized, can effectively break the dense agglomerate of silicon mud, make the fully exposed chlorides of being wrapped, create favorable conditions for subsequent depth dechlorination.By setting the multistage countercurrent washing unit of N grade washing subunit series connection, fresh water is only added from last stage, washing liquid is backflowed to previous stage repeatedly, solid and liquid always maintain higher chlorine ion concentration difference, significantly improve mass transfer driving force, chlorine ion removal rate can reach more than 93%, while fresh water consumption is saved about 40% compared with traditional parallel washing mode.

Description

Technical Field

[0001] This utility model relates to the technical field of industrial solid waste resource utilization equipment, specifically to a silica mud water washing and dechlorination efficiency improvement system. Background Technology

[0002] In the production process of photovoltaic and semiconductor-grade polysilicon, processes such as chlorosilane hydrolysis and synthesis tail gas scrubbing generate large amounts of silicon-containing wastewater. This wastewater, after pressure filtration, forms a high-moisture solid waste residue, commonly known as silica sludge. Because this silica sludge originates entirely from the chlorosilane system, its dry basis chloride ion content is extremely high, typically above 10%, and in some cases exceeding 18%, making it highly corrosive. Simultaneously, its effective silicon content, which is crucial for high-value-added resource products such as silicon fertilizer and special fillers, is relatively low. Furthermore, the fine particles of silica sludge easily form dense agglomerates during stacking and pressure filtration, physically encapsulating large amounts of chloride salts within the particles and crevices, making conventional washing methods ineffective in removing them. Therefore, to achieve the resource utilization of silica sludge, the technical challenge of deep dechlorination and simultaneous improvement of effective silicon content must be addressed first. Currently, the washing treatment of this type of high-chlorine solid waste typically employs a simple combination of agitated tanks and filter presses or centrifuges, directly separating the solid and liquid after single-stage mixing, or using multiple water changes and parallel washing methods. However, this conventional treatment method relies solely on mechanical stirring, resulting in a single solid-liquid contact method, low mass transfer efficiency, and difficulty for wash water to penetrate into the aggregates. This leads to slow chloride ion elution and poor removal efficiency. Furthermore, to achieve the target of low chloride residue, repeated water changes are often required, resulting in a huge consumption of fresh water and the generation of large amounts of high-chlorine wastewater, significantly increasing the load on subsequent wastewater treatment. To further enhance the washing effect, some companies have added heating jackets or coils to the mixing tanks to accelerate ion diffusion by raising the wash water temperature to above 60°C, or have installed chemical dosing units to add acids, alkalis, or other chemical reagents to the wash water. While increasing the temperature or adding chemicals can improve dechlorination efficiency to some extent, it also leads to a significant increase in system energy consumption. Moreover, hot water or chemical reagents may cause irreversible structural changes in the active silicon components in the silica sludge, actually reducing the content of effective silicon. Furthermore, the introduction of chemical reagents not only increases operating costs but also introduces the risk of secondary pollution, significantly compromising the economic and environmental benefits of the entire process. Furthermore, in the final control stage of the washing process, current methods typically rely on experience to set fixed washing times or installing conductivity meters on the washing liquid discharge pipeline to indirectly determine the concentration by monitoring changes in the overall liquid ion concentration online. However, conductivity is a non-specific indicator. For silica mud washing liquids with complex compositions, its value is affected by the combined interference of multiple coexisting ions such as sodium, calcium, and sulfate, resulting in a very poor correlation with the target chloride ion concentration. This makes such judgment methods extremely inaccurate, often leading to insufficient washing resulting in excessive chlorine residue or excessive washing causing serious waste of water and energy. In summary, existing silica mud washing devices generally suffer from prominent drawbacks such as high water consumption, high energy and material consumption, insufficient dechlorination efficiency, easy loss of effective silicon components, and crude process control. The market urgently needs a new type of washing system that is compact in structure, highly efficient in operation, has precise and controllable processes, and can simultaneously achieve deep dechlorination and increase the effective silicon content. Utility Model Content

[0003] In order to solve the above problems, the purpose of this utility model is to provide a system for improving the efficiency of silica mud washing and dechlorination.

[0004] This utility model is implemented by the following technical solution: A system for improving the efficiency of chlorine removal through washing of silica mud includes a pretreatment unit, a washing unit, a detection unit, a control unit, and an execution unit. The outlet of the pretreatment unit is connected to the inlet of the washing unit, and is used to mix the silica mud with the washing water and send it into the washing unit after ultrasonic dispersion pretreatment. The washing unit is equipped with a fresh water inlet, a high-chlorine wastewater outlet, and a purified silica mud outlet, which are used to perform multi-stage countercurrent washing on the pretreated silica mud slurry. The sampling end of the detection unit is connected to the liquid phase outlet of the washing unit, and is used to collect washing liquid samples and detect chloride ion concentration. The signal output end of the detection unit is electrically connected to the signal input end of the control unit. The signal output terminal of the control unit is electrically connected to the control terminal of the execution unit. The control unit is used to receive the detection signal from the detection unit and send control commands to the execution unit.

[0005] Furthermore, the pretreatment unit includes a pretreatment tank, a stirring device, an ultrasonic transducer, and an ultrasonic generator. The pretreatment tank is a sealed tank structure. An inlet and a washing water inlet are provided on the upper side wall of the pretreatment tank, and an outlet is provided at the bottom of the pretreatment tank. The stirring motor of the stirring device is located on the outside of the top of the pretreatment tank, and the rotating shaft of the stirring device passes through the top of the pretreatment tank and is located inside the pretreatment tank. An stirring impeller is provided at the lower part of the rotating shaft. At least one through hole for installing the ultrasonic transducer is provided on the side wall of the pretreatment tank. The transmitting end of the ultrasonic transducer extends into the tank body of the pretreatment tank through the through hole or is flush with the inner wall surface of the pretreatment tank, and is electrically connected to the ultrasonic generator located outside the pretreatment tank. A sealing structure is provided at the through hole.

[0006] Furthermore, a dispersant inlet is provided on the side wall of the pretreatment tank, and the dispersant inlet is connected to the dispersant dosing device through a pipeline.

[0007] Furthermore, the washing unit includes N washing sub-units connected in series, where N≥2 and N is an integer; each washing sub-unit includes a mixing tank and a solid-liquid separation device, the outlet of the mixing tank is connected to the inlet of the corresponding solid-liquid separation device, and a stirrer is provided in the mixing tank. The inlet of the mixing tank of the first-stage washing subunit is connected to the outlet of the pretreatment tank, and the liquid phase outlet of the solid-liquid separation device of the first-stage washing subunit is connected to the high-chlorine wastewater discharge pipeline. The inlet of the mixing tank of the Nth washing subunit is connected to the fresh water supply pipeline, and the solid phase outlet of the solid-liquid separation device of the Nth washing subunit is the purified silica mud discharge outlet. The solid phase outlet of the solid-liquid separation device of the i-th stage washing subunit is connected to the feed inlet of the mixing tank of the (i+1)-th stage washing subunit via a solid phase conveying device, and the liquid inlet of the mixing tank of the i-th stage washing subunit is connected to the liquid phase outlet of the solid-liquid separation device of the (i+1)-th stage washing subunit via a pipeline; where i=1,2,…,N-1.

[0008] Furthermore, the solid phase conveying device is a screw conveyor or a chute; the solid-liquid separation device is a horizontal screw centrifuge, a filter centrifuge, or a plate and frame filter press.

[0009] Furthermore, the sampling end of the detection unit is connected to the pipeline between the liquid phase outlet of the solid-liquid separation device of the Nth stage washing subunit and the liquid inlet of the mixing and stirring tank of the N-1th stage washing subunit.

[0010] Furthermore, the detection unit includes a sampling pipeline, a silver nitrate reagent storage tank, a metering pump, a mixing reaction tube, and an online turbidimeter; The inlet of the sampling pipeline is connected to the liquid phase outlet of the solid-liquid separation device of the Nth stage washing subunit, and the outlet of the sampling pipeline is connected to the first inlet of the mixing reaction tube. The silver nitrate reagent storage tank is connected to the second inlet of the mixing reaction tube via the metering pump; The outlet of the mixing reaction tube is connected to the measuring cell of the online turbidimeter; The signal output terminal of the online turbidimeter serves as the signal output terminal of the detection unit and is electrically connected to the signal input terminal of the control unit.

[0011] Furthermore, the execution unit includes a feed regulating valve located at the feed inlet of the mixing tank of the first-stage washing subunit, a water inlet regulating valve located on the fresh water supply pipeline, a stirring motor controller for driving the stirrer to operate, and a separation motor controller for driving the solid-liquid separation device to operate. The signal input terminals of the feed regulating valve, water regulating valve, stirring motor controller, and separation motor controller are all electrically connected to the signal output terminal of the control unit.

[0012] Advantages of this utility model: This invention achieves efficient transfer of ultrasonic energy to the slurry inside the tank by setting up a pretreatment unit, creating through holes in the side wall of the pretreatment tank, and installing ultrasonic transducers. This effectively breaks up dense aggregates of silica mud, fully exposing the encapsulated chloride salts and creating favorable conditions for subsequent deep dechlorination. By setting up a multi-stage counter-current washing unit consisting of N-stage washing sub-units connected in series, fresh water is added only from the last stage, and the washing liquid flows back to the previous stage for reuse. A high chloride ion concentration difference is maintained between the solid and liquid stages, significantly improving the mass transfer driving force. The chloride ion removal rate can reach over 93%, while the fresh water consumption is reduced by approximately 40% compared to traditional parallel washing methods. By setting up a detection unit, the specific precipitation reaction principle of silver nitrate and chloride ions is used to directly detect target impurities, avoiding the drawbacks of traditional conductivity methods which are affected by various ions, and achieving accurate determination of the washing endpoint. The system can automatically adjust operating parameters such as feed rate, water supply, and stirring speed based on real-time turbidity detection values, achieving intelligent and precise control of the washing process, avoiding over-washing or under-washing, and ensuring product quality stability.

[0013] This utility model system has a compact overall structure, requires no heating or addition of large amounts of chemical reagents throughout the process, has low energy consumption, does not introduce secondary pollution, and the washing wastewater can be specifically recycled and treated, making it environmentally friendly and with controllable operating costs. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the system connection in this embodiment; Figure 2 This is the control principle diagram of this embodiment.

[0015] In the diagram: Pretreatment unit 100, pretreatment tank 101, stirring device 102, stirring motor 1021, rotating shaft 1022, stirring impeller 1023, ultrasonic transducer 103, ultrasonic generator 104, dispersant dosing device 105, washing unit 200, mixing tank 201, solid-liquid separation device 202, high-chlorine wastewater discharge pipeline 203, fresh water supply pipeline 204, chute 205, detection unit 300, sampling pipeline 301, silver nitrate reagent storage tank 302, metering pump 303, mixing reaction tube 304, online turbidity meter 305, control unit 400, execution unit 500, feed regulating valve 501, water inlet regulating valve 502, stirring motor controller 503, separation motor controller 504. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Example 1 like Figure 1 , 2 The system shown includes a silica mud washing and chlorine removal efficiency improvement system, comprising a pretreatment unit 100, a washing unit 200, a detection unit 300, a control unit 400, and an execution unit 500; wherein: The pretreatment unit 100 includes a pretreatment tank 101, a stirring device 102, an ultrasonic transducer 103, and an ultrasonic generator 104. The pretreatment tank 101 is a sealed tank structure. An inlet and a washing water inlet are provided on the upper side wall of the pretreatment tank 101, and an outlet is provided at the bottom of the pretreatment tank 101. The stirring motor 1021 of the stirring device 102 is located on the outside of the top of the pretreatment tank 101. The rotating shaft 1022 of the stirring device 102 passes through the top of the pretreatment tank 101 and is located inside the pretreatment tank 101. The lower part of the rotating shaft 1022... The system includes an impeller 1023; at least one through hole for mounting an ultrasonic transducer 103 is provided on the side wall of the pretreatment tank 101. The transmitting end of the ultrasonic transducer 103 extends through the through hole into the tank body of the pretreatment tank 101 or is flush with the inner wall surface of the pretreatment tank 101, and is electrically connected to an ultrasonic generator 104 located outside the pretreatment tank 101, for applying ultrasonic waves to the slurry inside the tank to break up silica mud agglomerates; a sealing structure is provided at the through hole to seal the gap between the ultrasonic transducer 103 and the through hole to prevent leakage of the slurry inside the tank. The sealing structure includes a flange seat, a gland, and a gasket; the flange seat is welded to the outer surface of the side wall of the pretreatment tank 101 and surrounds the through hole; the mounting flange of the ultrasonic transducer 103 sits on the end face of the flange seat; the gasket is provided between the end face of the mounting flange and the flange seat. A gland is fitted onto the ultrasonic transducer 103 and connected to the flange seat via fasteners to press the mounting flange and gasket against the end face of the flange seat, achieving a seal at the through-hole. A dispersant inlet is also provided on the side wall of the pretreatment tank 101, which is connected to a dispersant dosing device 105 via a pipeline. The dispersant dosing device 105 is used to quantitatively add sodium polyacrylate dispersant into the pretreatment tank 101.

[0018] The washing unit 200 includes three washing sub-units connected in series. Each washing sub-unit includes a mixing tank 201 and a solid-liquid separation device 202. The outlet of the mixing tank 201 is connected to the inlet of the corresponding solid-liquid separation device 202. A stirrer is provided in the mixing tank 201. The detection unit 300 includes a sampling pipeline 301, a silver nitrate reagent storage tank 302, a metering pump 303, a mixing reaction tube 304, and an online turbidimeter 305.

[0019] The execution unit 500 includes a feed regulating valve 501 installed at the feed inlet of the mixing tank 201 of the first-stage washing subunit, a water inlet regulating valve 502 installed on the fresh water supply pipeline 204, a stirring motor controller 503 for driving the stirrer to operate, and a separation motor controller 504 for driving the solid-liquid separation device 202 to operate.

[0020] The inlet of the mixing tank 201 of the first-stage washing subunit is connected to the outlet of the pretreatment tank 101, and the liquid outlet of the solid-liquid separation device 202 of the first-stage washing subunit is connected to the high-chlorine wastewater discharge pipeline 203. The inlet of the mixing tank 201 of the third-stage washing subunit is connected to the fresh water supply pipeline 204, and the solid outlet of the solid-liquid separation device 202 of the Nth-stage washing subunit is the purified silica sludge discharge outlet. The solid outlet of the solid-liquid separation device 202 of the second-stage washing subunit is connected to the inlet of the mixing tank 201 of the third-stage washing subunit via a chute 205, and the liquid outlet of the mixing tank 201 of the second-stage washing subunit is connected to the liquid outlet of the solid-liquid separation device 202 of the third-stage washing subunit via a pipeline. The solid-liquid separation device 202 is a plate and frame filter press.

[0021] The inlet of sampling pipeline 301 is connected to the liquid phase outlet of the solid-liquid separation device 202 of the third-stage washing subunit, and the outlet of sampling pipeline 301 is connected to the first inlet of mixing reaction tube 304. Silver nitrate reagent storage tank 302 is connected to the second inlet of mixing reaction tube 304 via metering pump 303, which quantitatively injects silver nitrate reagent into mixing reaction tube 304. The outlet of mixing reaction tube 304 is connected to the measuring cell of online turbidimeter 305, allowing the washing liquid sample and silver nitrate reagent to mix and react inside the tube before entering the measuring cell. The signal output terminal of online turbidimeter 305 serves as the signal output terminal of detection unit 300 and is electrically connected to the signal input terminal of control unit 400. The signal input terminals of feed regulating valve 501, water regulating valve 502, stirring motor controller 503, and separation motor controller 504 are all electrically connected to the signal output terminal of control unit 400, used to adjust the feed rate, water supply, or start / stop the equipment according to control commands.

[0022] The control unit 400 has a preset turbidity threshold. The control unit 400 is used to compare the turbidity value measured by the detection unit 300 with the turbidity threshold. When the turbidity value is lower than the turbidity threshold, it is determined that the washing end point has been reached, and the corresponding control signal is output.

[0023] Job Description: The system in this embodiment includes the following stages during its operation: (a) Preprocessing stage First, the silica mud raw material to be treated is added into the pretreatment tank 101 through the feed inlet, and at the same time, washing water is injected into the tank through the washing water inlet at a preset liquid-to-solid ratio of 10:1. The stirring device 102 is started, and the stirring motor 1021 drives the rotating shaft 1022 and the stirring impeller 1023 to rotate, mechanically stirring the slurry in the tank, so that the silica mud and washing water are initially mixed evenly.

[0024] Simultaneously, the ultrasonic generator 104 is activated, providing electrical power to the ultrasonic transducer 103 installed on the side wall of the pretreatment tank 101. The transmitting end of the ultrasonic transducer 103 extends into the tank through the through-hole, emitting ultrasonic waves into the slurry. Under the combined action of ultrasonic cavitation and mechanical effects, the dense agglomerates of silica mud particles are broken up, and the chloride salts originally physically trapped inside the particles and in the gaps are fully exposed to the washing water. During this process, the sealing structure at the through-hole, through the cooperation of the flange seat, gland, and gasket, ensures the tank's airtightness and prevents slurry leakage.

[0025] Sodium polyacrylate dispersant can also be quantitatively added into the tank through the dispersant inlet via the dispersant dosing device 105 to further enhance the dispersion effect of the particles and prevent secondary agglomeration.

[0026] (ii) Multi-stage countercurrent washing stage After pretreatment is completed, open the discharge port at the bottom of the pretreatment tank 101 and send the pretreated silica mud slurry into the washing unit 200.

[0027] Washing unit 200 adopts a three-stage counter-current washing mode, and the specific process is as follows: First-stage washing: The pretreated slurry first enters the first-stage mixing tank 201, where it is mixed and stirred with the washing liquid from the second-stage solid-liquid separation device 202, which already contains a certain concentration of chloride ions. After a certain period of contact, the slurry enters the first-stage solid-liquid separation device 202 for solid-liquid separation. The separated liquid phase, due to its highest chloride ion concentration, is discharged from the system through the high-chlorine wastewater discharge pipeline 203 and enters the subsequent wastewater treatment process. The separated silica sludge filter cake is then sent to the second-stage mixing tank 201 via chute 205.

[0028] Second-stage washing: The silica filter cake from the first stage is mixed and stirred in the second-stage mixing and stirring tank 201 with a washing liquid with a low chloride ion concentration from the third-stage solid-liquid separation device 202. After stirring, it enters the second-stage solid-liquid separation device 202 for solid-liquid separation. The separated liquid phase is pumped back to the first-stage mixing and stirring tank 201 through a liquid phase return pipe for use as washing liquid, and the separated solid phase is sent to the third-stage mixing and stirring tank 201 through a chute 205.

[0029] Third-stage washing: The silica sludge filter cake from stage 2 is mixed and stirred in the third-stage mixing and stirring tank 201 with fresh washing water added through the fresh water supply pipeline 204. After stirring, it enters the third-stage solid-liquid separation device 202 for final solid-liquid separation. The separated liquid phase is pumped back to the second-stage mixing and stirring tank 201 through the return pipeline for use as washing liquid, and the separated solid phase is the purified silica sludge product, which is discharged from the outlet.

[0030] In the aforementioned countercurrent process, fresh washing water is added only from the last stage, while silica sludge solids move from the first stage to the next. The solids and washing liquid flow in opposite directions, maintaining a high chloride ion concentration difference, which provides a continuous mass transfer driving force for deep dechlorination, while significantly saving the amount of fresh water used.

[0031] (III) Detection and Control Stage At the liquid phase outlet of the third-stage solid-liquid separation device 202, sampling pipeline 301 continuously or periodically collects small amounts of washing liquid samples. This sample enters the first inlet of the mixing reaction tube 304. Simultaneously, silver nitrate solution from the silver nitrate reagent storage tank 302 is quantitatively injected into the second inlet of the mixing reaction tube 304 via metering pump 303 at a preset ratio. The two mix and react within the tube: if the washing liquid still contains a high concentration of chloride ions, a white precipitate of silver chloride is formed, increasing the liquid turbidity; conversely, if chloride ions have been largely removed, very little precipitation occurs, resulting in very low turbidity.

[0032] The mixture then flows into the measuring cell of the online turbidimeter 305, which measures the turbidity value of the liquid in real time and transmits the detection signal to the control unit 400.

[0033] Before system operation, the following key control parameters need to be preset in the control unit 400: the turbidity threshold is set to 50 NTU, corresponding to the turbidity level when the chloride ion concentration in the washing liquid drops below 50 mg / L; reaching this value indicates a preliminary determination of the washing endpoint; the turbidity warning threshold is set to 200 NTU, indicating that the washing effect is close to but not yet fully met; the turbidity severely exceeding the standard threshold is set to 800 NTU, indicating extremely poor washing effect, requiring strong intervention measures. In addition, the rated feed rate needs to be set to 10 m³ / min. 3 / h, minimum feed rate is 3m 3 / h, rated water supply capacity is 5m3 / h, maximum water supply is 10m 3 The system has a stirring speed of 60 r / min, a maximum stirring speed of 100 r / min, and a system stability determination time of 5 minutes.

[0034] During system operation, the online turbidity meter 305 detects the turbidity value of the final stage washing liquid in real time and transmits the signal to the control unit 400. The control unit 400 executes the corresponding control strategy according to the range of the turbidity value.

[0035] When the real-time turbidity value exceeds the warning threshold of 200 NTU, it indicates that the chloride ion concentration in the washing liquid remains at a high level, the dechlorination effect is not ideal, and the washing intensity needs to be increased. At this time, the control unit 400 sends an adjustment command to the execution unit 500: the feed regulating valve 501 reduces its opening, gradually lowering the feed rate from the rated value, down to a minimum of 3m³. 3 / h, to reduce the amount of silica sludge entering the washing unit per unit time and extend the residence and contact time of materials in each washing unit; the water inlet regulating valve 502 increases the opening, gradually increasing the fresh water supply from the rated value, up to a maximum of 10m 3 The system adjusts its speed by increasing the liquid-to-solid ratio in the final washing stage to enhance the driving force of the chloride ion concentration gradient. The stirring motor controller 503 increases the output frequency, gradually raising the stirring speed of each mixing tank from the rated value, up to a maximum of 100 r / min, to improve the contact and mass transfer efficiency between the solid and liquid phases. The separation motor controller 504 maintains the normal operation of the solid-liquid separation device. These adjustments continue until the turbidity value measured by the online turbidity meter 305 begins to decrease continuously and falls below the warning threshold of 200 NTU, indicating that the intervention measures have taken effect and the system gradually returns to normal operating parameters.

[0036] When the real-time turbidity value is between the acceptable threshold of 50 NTU and the warning threshold of 200 NTU, it indicates that the washing is nearing completion, but the chloride ion concentration has not yet stabilized and reached the standard. Fine-tuning is required to avoid over-washing and resource waste. At this time, the control unit 400 gradually restores the opening of the feed regulating valve 501 and the water regulating valve 502 to near their rated values, returning the feed rate and water supply to normal design conditions. The stirring motor controller 503 gradually restores the stirring speed to the rated value of 60 r / min to avoid unnecessary energy consumption. The separation motor controller 504 maintains the normal operation of the solid-liquid separation device. The system continues to operate under this condition until the turbidity value further decreases and falls below the acceptable threshold of 50 NTU, at which point it enters the endpoint determination process.

[0037] When the real-time turbidity value drops below the acceptable threshold of 50 NTU, it indicates that the chloride ion concentration in the washing liquid has initially reached the acceptable level. To prevent misjudgment due to instantaneous system fluctuations, the control unit 400 does not immediately shut down, but maintains the current working state of all actuators and starts timing. Within the 5-minute system stabilization period, if the turbidity value remains below the acceptable threshold of 50 NTU, the control unit 400 determines that the washing endpoint has been stably reached; if the turbidity value rebounds and exceeds the acceptable threshold of 50 NTU within this period, the timing is reset to zero, and the system automatically returns to the previous control interval to continue the washing operation.

[0038] Once the washing endpoint is confirmed, the control unit 400 outputs a shutdown command: the feed regulating valve 501 is fully closed, stopping the supply of silica mud slurry to the washing unit; the water inlet regulating valve 502 is fully closed, stopping the supply of fresh water; after the material in each mixing tank is emptied, the stirring motor controller 503 sequentially stops each stirring motor; after the material in each solid-liquid separation device is processed, the separation motor controller 504 sequentially stops each separation motor. Simultaneously, the control unit 400 outputs an audible and visual alert signal to notify the operator to unload the material or prepare for the next batch of material.

[0039] After being treated by this system, the dry basis chloride ion content of the silica mud can be stably reduced from more than 18% to less than 2%, and the effective silica content can be increased from about 14.6% to more than 20%. Moreover, the overall water consumption is reduced by about 40% compared with the traditional parallel multiple washing method.

[0040] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A system for improving the efficiency of silica mud washing and dechlorination, characterized in that, It includes a pretreatment unit, a washing unit, a detection unit, a control unit, and an execution unit; The outlet of the pretreatment unit is connected to the inlet of the washing unit, and is used to mix the silica mud with the washing water and send it into the washing unit after ultrasonic dispersion pretreatment. The washing unit is equipped with a fresh water inlet, a high-chlorine wastewater outlet, and a purified silica mud outlet, which are used to perform multi-stage countercurrent washing on the pretreated silica mud slurry. The sampling end of the detection unit is connected to the liquid phase outlet of the washing unit, and is used to collect washing liquid samples and detect chloride ion concentration. The signal output end of the detection unit is electrically connected to the signal input end of the control unit. The signal output terminal of the control unit is electrically connected to the control terminal of the execution unit. The control unit is used to receive the detection signal from the detection unit and send control commands to the execution unit.

2. The silica mud washing and dechlorination efficiency improvement system according to claim 1, characterized in that, The pretreatment unit includes a pretreatment tank, a stirring device, an ultrasonic transducer, and an ultrasonic generator. The pretreatment tank is a sealed tank structure. An inlet and a washing water inlet are provided on the upper side wall of the pretreatment tank, and an outlet is provided at the bottom of the pretreatment tank. The stirring motor of the stirring device is located on the outside of the top of the pretreatment tank, and the rotating shaft of the stirring device passes through the top of the pretreatment tank and is located inside the pretreatment tank. An stirring impeller is provided at the lower part of the rotating shaft. At least one through hole for installing the ultrasonic transducer is provided on the side wall of the pretreatment tank. The transmitting end of the ultrasonic transducer extends into the tank body of the pretreatment tank through the through hole or is flush with the inner wall surface of the pretreatment tank, and is electrically connected to the ultrasonic generator located outside the pretreatment tank. A sealing structure is provided at the through hole.

3. The silica mud washing and dechlorination efficiency improvement system according to claim 2, characterized in that, A dispersant inlet is also provided on the side wall of the pretreatment tank, and the dispersant inlet is connected to the dispersant dosing device through a pipeline.

4. The silica mud washing and dechlorination efficiency improvement system according to claim 1, characterized in that, The washing unit includes N washing sub-units connected in series, where N≥2 and N is an integer; each washing sub-unit includes a mixing tank and a solid-liquid separation device, the outlet of the mixing tank is connected to the inlet of the corresponding solid-liquid separation device, and a stirrer is provided in the mixing tank. The inlet of the mixing tank of the first-stage washing subunit is connected to the outlet of the pretreatment tank of the pretreatment unit, and the liquid phase outlet of the solid-liquid separation device of the first-stage washing subunit is connected to the high-chlorine wastewater discharge pipeline. The inlet of the mixing tank of the Nth washing subunit is connected to the fresh water supply pipeline, and the solid phase outlet of the solid-liquid separation device of the Nth washing subunit is the purified silica mud discharge outlet. The solid phase outlet of the solid-liquid separation device of the i-th stage washing sub-unit is connected to the feed inlet of the mixing tank of the i+1-th stage washing sub-unit through a solid phase conveying device, and the liquid inlet of the mixing tank of the i-th stage washing sub-unit is connected to the liquid phase outlet of the solid-liquid separation device of the i+1-th stage washing sub-unit through a pipeline. Where i = 1, 2, ..., N-1.

5. The silica mud washing and dechlorination efficiency improvement system according to claim 4, characterized in that, The solid phase conveying device is a screw conveyor or a chute; the solid-liquid separation device is a horizontal screw centrifuge, a filter centrifuge, or a plate and frame filter press.

6. The silica mud washing and dechlorination efficiency improvement system according to claim 4, characterized in that, The sampling end of the detection unit is connected to the pipeline between the liquid phase outlet of the solid-liquid separation device of the Nth stage washing subunit and the liquid inlet of the mixing and stirring tank of the N-1th stage washing subunit.

7. The silica mud washing and dechlorination efficiency improvement system according to claim 4, characterized in that, The detection unit includes a sampling pipeline, a silver nitrate reagent storage tank, a metering pump, a mixing reaction tube, and an online turbidimeter; The inlet of the sampling pipeline is connected to the liquid phase outlet of the solid-liquid separation device of the Nth stage washing subunit, and the outlet of the sampling pipeline is connected to the first inlet of the mixing reaction tube. The silver nitrate reagent storage tank is connected to the second inlet of the mixing reaction tube via the metering pump; The outlet of the mixing reaction tube is connected to the measuring cell of the online turbidimeter; The signal output terminal of the online turbidimeter serves as the signal output terminal of the detection unit and is electrically connected to the signal input terminal of the control unit.

8. The silica mud washing and dechlorination efficiency improvement system according to claim 4, characterized in that, The execution unit includes a feed regulating valve located at the feed inlet of the mixing tank of the first-stage washing subunit, a water regulating valve located on the fresh water supply pipeline, a stirring motor controller for driving the stirrer, and a separation motor controller for driving the solid-liquid separation device. The signal input terminals of the feed regulating valve, water regulating valve, stirring motor controller, and separation motor controller are all electrically connected to the signal output terminal of the control unit.

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