Polishing slurry waste liquid recovery method and system

Abstract

To provide a method and a system for recycling a polishing slurry waste liquid.SOLUTION: There are provided a method and a system for recycling a polishing slurry waste liquid according to embodiments of the present invention. The system comprises an agitation tank and a filter. The system further comprises: a first pipeline for transporting an initial polishing slurry waste liquid to a first inlet of the agitation tank; a second pipeline for transporting the polishing slurry waste liquid from the agitation tank to the filter; and a third pipeline for transporting concentrated polishing slurry waste liquid from the filter to a second inlet of the agitation tank; a first valve for opening and closing the first pipeline; a specific gravity meter for detecting solid contents of the polishing slurry waste liquid; and a controller configured to control the first valve.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present application relates to a recovery method and system, and more particularly to a method and system for recovering polishing slurry waste liquid. [Background technology]

[0002] Panels have become an essential basic component for the screens of various electronic products. With the evolution of process technology and the continuous market demand for miniaturization, the demand for lighter and thinner panels is also increasing. For example, in the manufacturing process of liquid crystal display (LCD) panels, after the liquid crystal injection is completed and before the panel is cut, the panel substrate is subjected to grinding, polishing and thinning processes, which contributes to the thinning of the panel module.

[0003] Currently, the thinning process for panel substrates typically involves mixing powdered abrasives with water to create a polishing slurry, then combining it with a grinding pad in a grinding and polishing equipment to grind and polish the glass or sapphire substrate to remove excess thickness and remove any scratched patterns on the substrate. After the grinding or polishing process is complete, the thinned substrate must be rinsed with water so that it can be removed from the polishing pad. At the same time, the rinsing water is directly discharged and discarded along with the polishing slurry.

[0004] However, due to growing environmental awareness and concerns about the cost of grinding processes, the powder abrasives used in thinning processes involving grinding or polishing are not recycled, resulting in high manufacturing and environmental costs for the thinning process. Secondly, the usefulness of powder abrasives once used has not yet reached a level where it can be fully utilized, resulting in resource waste. However, due to the current lack of convenient and effective powder abrasive recovery equipment, most powder abrasives or polishing slurries cannot be recovered and reused. In light of the above issues, research is needed into methods for recycling polishing slurries in order to extend the lifespan of powder abrasives or polishing slurries and improve the environmental friendliness of the thinning process. Summary of the Invention [Means for solving the problem]

[0005] One embodiment of the present invention includes an agitation tank for receiving initial polishing slurry waste liquid (RS) and agitating the polishing slurry waste liquid in the tank, a filter for feeding the polishing slurry waste liquid and feeding out filtered water and concentrated polishing slurry waste liquid (FS), a first pipeline (111) connected to the agitation tank and for transferring the initial polishing slurry waste liquid to a first inlet (112) of the agitation tank, and a second pipeline (112) connected to the agitation tank and the filter (108) and for transferring the polishing slurry waste liquid from the agitation tank to the filter. a third pipeline (115) connected to the stirring tank and the filter for transferring the concentrated polishing slurry waste liquid from the filter to a second inlet of the stirring tank; a first valve (112) for opening and closing the first pipeline; a hydrometer (124) disposed in the stirring tank for detecting the solid content of the polishing slurry waste liquid; and a controller (140) electrically connected to the first valve and configured to control the first valve.

[0006] In one embodiment, the system further comprises a fourth line (131) for transferring a grinding aid to the agitation tank, and a second valve (132) for opening the fourth line.

[0007] In one embodiment, the system further comprises a water level meter (128) for detecting the level of the polishing slurry waste liquid in the agitation tank.

[0008] In one embodiment, the system comprises: 2 There is further provided a pressure pump (122) located within the path of the conduit.

[0009] In one embodiment, the system further comprises a fifth line (117) connected to the filtered water outlet of the filter for backwashing the filter.

[0010] In one embodiment, the system further comprises a sixth line (115) connected to the stirring tank and the filter and used for degassing.

[0011] In one embodiment, the controller is configured to determine a first cycle length in a filtration mode and a second cycle length in a concentration mode of the system.

[0012] In one embodiment, the controller is configured to open the first valve (112) to enter the filtration mode and maintain the level of the polishing slurry waste liquid within a predetermined range during the first cycle.

[0013] In one embodiment, in the filtration mode, the solids content of the polishing slurry waste liquid does not exceed a first solids content value.

[0014] In one embodiment, at the end of the concentration mode, the solids content of the polishing slurry waste liquid exceeds the first solids content value.

[0015] Another embodiment of the present invention provides a method for recovering polishing-slurry waste liquid, including a step of performing a filtration mode in a first cycle and a step of performing a concentration mode in a second cycle. The filtration mode includes a step of transferring an initial polishing-slurry waste liquid to an agitation tank to form a polishing-slurry waste liquid, a step of transferring the polishing-slurry waste liquid to a filter to filter the polishing-slurry waste liquid, the filter receiving the polishing-slurry waste liquid and generating filtrate water (FW) and a concentrated polishing-slurry waste liquid, and a step of transferring the concentrated polishing-slurry waste liquid to the agitation tank. The concentration mode includes a step of stopping the transfer of the initial polishing-slurry waste liquid to the agitation tank, and a step of transferring the polishing-slurry waste liquid to a filter to filter the polishing-slurry waste liquid.

[0016] In one embodiment, the ratio of the first period to the second period is 15 to 30 times.

[0017] In one embodiment, the method further includes detecting a solid content of the polishing slurry waste liquid in the agitation tank to determine the length of time of the first cycle or the second cycle.

[0018] In one embodiment, the solid content of the polishing slurry waste liquid in the stirring tank has a first solid content value at the end of the first cycle and a second solid content value at the end of the second cycle, and the ratio of the second solid content value to the first solid content value is 5 to 10 times.

[0019] In one embodiment, the change in solid content of the polishing slurry waste liquid in the stirring tank of the method has a first average speed in the first cycle and a second average speed in the second cycle, and the ratio of the second average speed to the first average speed is 15 to 30 times.

[0020] In one embodiment, the method further includes a step of maintaining the level of the polishing slurry waste liquid in the stirring tank within a predetermined height range in the filtration mode.

[0021] In one embodiment, in the filtration mode, when the solid content of the initial polishing slurry waste liquid is below a predetermined initial solid content value, the solid content value of the polishing slurry waste liquid in the stirring tank exhibits one or more increases and one or more decreases.

[0022] In one embodiment, in the concentration mode, the solids content of the polishing slurry waste liquid in the stirring tank continues to increase.

[0023] In one embodiment, the method further includes a step of executing a mixing mode in a third cycle after the concentration mode is completed, stopping the filtration of the polishing slurry waste liquid, transferring a polishing aid into the stirring tank to mix it with the polishing slurry waste liquid, and discharging the polishing slurry waste liquid at the end of the third cycle.

[0024] In one embodiment, the solid content of the polishing slurry waste liquid in the stirring tank has a third solid content value at the end of the third cycle and a second solid content value at the end of the second cycle, and the ratio of the third solid content value to the second solid content value is 1.1 times to 2 times.

[0025] Therefore, this application proposes a method and system for recovering polishing slurry waste liquid, which can properly remove excess water from the waste liquid and bring the solid content of the polishing slurry waste liquid to an ideal range for use, thereby making it possible to recycle the polishing slurry, thereby extending the life of the powder abrasive contained therein, and achieving the effects of resource reuse and cost reduction.In addition, the recovery method and system proposed in this application can effectively help the polishing slurry waste liquid recover its effectiveness, shorten the concentration time of the polishing slurry waste liquid, and effectively protect the filters in the recovery system to extend the service life of the filtration membrane, thereby improving the performance and cost advantages of the recovery system.

[0026] The foregoing has broadly outlined the technical features and advantages of embodiments of the present invention, so that the detailed embodiments of the present invention set forth below may be more readily understood. Other technical features and advantages of the subject matter of the present invention are described below. Those skilled in the art will appreciate that, by using the concepts and specific embodiments disclosed below, other structures or methods may be readily modified or designed to accomplish the same purposes of the present invention. Those skilled in the art will also appreciate that such designs, which achieve similar effects, do not depart from the spirit and scope of the present invention, as defined by the appended claims.

[0027] The disclosure of the present application can be more fully understood by referring to the embodiments and claims in conjunction with the drawings, in which like reference numerals indicate the same or similar elements. [Brief explanation of the drawings]

[0028] [Figure 1]FIG. 1 is a schematic diagram illustrating a waste liquid recovery system according to some embodiments. [Figure 2] FIG. 2 is a schematic diagram illustrating a filter according to some embodiments. [Figure 3] FIG. 3 is a flow diagram of a waste liquid recovery method according to some embodiments. [Figure 4A] 4A-4G are schematic diagrams illustrating different stages of operation of a waste fluid collection system according to some embodiments. [Figure 4B] 4A-4G are schematic diagrams illustrating different stages of operation of a waste fluid collection system according to some embodiments. [Figure 4C] 4A-4G are schematic diagrams illustrating different stages of operation of a waste fluid collection system according to some embodiments. [Figure 4D] 4A-4G are schematic diagrams illustrating different stages of operation of a waste fluid collection system according to some embodiments. [Figure 4E] 4A-4G are schematic diagrams illustrating different stages of operation of a waste fluid collection system according to some embodiments. [Figure 4F] 4A-4G are schematic diagrams illustrating different stages of operation of a waste fluid collection system according to some embodiments. [Figure 4G] 4A-4G are schematic diagrams illustrating different stages of operation of a waste fluid collection system according to some embodiments. [Figure 5] FIG. 5 is a graph showing the change in solid content of polishing slurry waste liquid at different stages of operation according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0029]

[0023] The following detailed discussion of embodiments of the present invention will be provided. However, it should be understood that the embodiments provide many usable inventive concepts that can be implemented in a wide variety of specific environments. The specific embodiments discussed are merely illustrative of specific ways to make and use the embodiments and do not limit the scope of the invention.

[0030] Throughout the drawings and exemplary embodiments, like numerals refer to like elements. The following description will focus particularly on elements that are part of, or cooperate more directly with, apparatus in accordance with embodiments of the present invention. It should be understood that elements not specifically shown or described may have different forms. The reference herein to "some embodiments" or "embodiments" means that the particular feature, structure, or characteristic associated with the depicted embodiment is included in at least one embodiment. Thus, the appearances of the phrase "some embodiments" or "in embodiments" in various places throughout the specification are not necessarily all referring to the same embodiment. It should be noted that particular features, structures, or characteristics may be present in any suitable combination in one or more embodiments.

[0031] In the drawings, the same reference numerals represent the same or similar components, and illustrate and depict exemplary embodiments of the present invention. The scales between the drawings may differ from the actual scale, and in some cases, have been exaggerated and / or simplified for the purpose of illustrating the embodiments only. Based on the following exemplary embodiments of the present invention, those skilled in the art will understand many possible applications and variations of the present invention.

[0032] Unless otherwise defined, all terms (including technical or scientific terms) used herein have the same meaning as understood by a person of ordinary skill in the art. Terms defined in commonly used dictionaries should be interpreted to have the same meaning as the context of the relevant art, and should not be interpreted as having an ideal or overly formal meaning unless they are expressly defined herein.

[0033] It should be noted that several embodiments of the present invention are provided below as examples to illustrate the core value of the present invention, but are not intended to limit the scope of protection of the present invention. For the sake of convenience of explanation and understanding, the same or similar functions or elements in different embodiments of the present invention will not be described repeatedly or shown in the drawings. New embodiments obtained by combining or substituting different elements or technical features in different embodiments, provided that they are not inconsistent with each other, still fall within the scope of protection of the present invention.

[0034] FIG. 1 is a schematic diagram illustrating a waste liquid recovery system 100 according to some embodiments. The waste liquid recovery system 100 can be used to recover slurries used in substrate processes (e.g., processes using glass or sapphire substrates), such as polishing slurries required for thinning processes. In one embodiment, the polishing slurry mainly comprises water and powdered abrasives, and may also contain additives such as dispersants, surfactants, corrosion inhibitors, and oxidizers. The actual composition and specific gravity of the additives can be adjusted depending on the grinding target. In this embodiment, the polishing slurry is used to grind display panel substrates, which may be made of glass, sapphire, or other suitable materials. The powdered abrasives in the polishing slurry can be composed of abrasive grains (e.g., cerium oxide (CeO2), lanthanum oxide (La2O3)) containing cerium (Ce), lanthanum (La), or other rare earth elements as the main elements.

[0035] In one embodiment, when a large-area panel is manufactured and not yet cut, liquid crystal is first injected into the panel during the thinning process of a display panel substrate. If the thinning process is performed later, rapid thinning can be achieved by first performing immersion etching with low-concentration hydrofluoric acid. However, this initial thinning process can result in process defects such as thickness irregularities (water ripples, dots, pits), or irregular fine pattern marks. These micro-defects can be removed by finely grinding the substrate using polishing equipment (with polishing pads) and polishing slurry to further improve the thickness uniformity of the substrate and remove pattern marks (also known as irregularities) left on the substrate due to defects in the manufacturing or transportation process between different processes, ensuring that the final substrate thickness and surface marks meet specification requirements. After the above grinding and polishing processes are completed, the substrate is washed with a clean water source (e.g., a high-purity water source such as RO water or DI water) so that the substrate can be removed from the polishing equipment. This cleaning operation removes the abrasive waste liquid remaining on the substrate, i.e., on the polishing equipment, and discharges the used abrasive waste liquid into a dedicated waste liquid pipeline or collects it in a waste liquid tank, which can be used as the raw material for producing the waste liquid recovery system 100, i.e., the initial polishing slurry waste liquid RS referred to in this specification.

[0036] 1 , the waste liquid collection system 100 includes a stirring tank 102, a motor 104, an agitator 106, a filter 108, a pressure pump 122, a hydrometer 124, a water pressure gauge 126, a water level gauge 128, and a controller 140. In some embodiments, the waste liquid collection system 100 may omit one or more of the components listed above. In some embodiments, the waste liquid collection system 100 may include one or more additional components, such as multiple filters. In one embodiment, the waste liquid collection system 100 further includes pipelines 111, 113, 115, 117, 119, 131, 133, and 135 and corresponding valves 112, 114, 116, 118, 120, 132, 134, and 136. In one embodiment, valves 112, 114, 116, 118, 120, 132, 134, and 136 are used to control the opening and closing of corresponding conduits 111, 113, 115, 117, 119, 131, 133, and 135.

[0037] In one embodiment, the agitation tank 102 is connected to the pipeline 111 and has a first inlet for receiving the initial polishing slurry waste liquid RS (i.e., used polishing slurry awaiting recovery processing). In this specification, various types of polishing slurry waste liquids transferred from different sources to the agitation tank 102 for mixing and / or agitation are collectively referred to as the polishing slurry waste liquid SS. The agitation tank 102 has a tank body, which may be a cylinder, a polygonal prism, or any other suitable shape, and has a pointed cone at the bottom. The agitation tank 102 can be made of stainless steel, concrete, ceramic, resin, or any other suitable material. The tank body may also include a multi-layer material, such as a corrosion-resistant layer, to prevent reaction with the components of the polishing slurry waste liquid SS in the agitation tank 102.

[0038] An agitator 106 is disposed in the stirring tank 102, and a motor 104 connected to the agitator 106 and for driving the agitator 106 is disposed in the waste liquid recovery system 100. After the initial polishing slurry waste liquid RS is transferred to the stirring tank 102 and becomes the grinding slurry waste liquid SS, the agitator 106 rotates at a predetermined rotation speed to agitate the polishing slurry waste liquid SS. In one embodiment, the motor 104 can include different types of motors, such as a servo motor, a stepping motor, a brushless motor, a DC motor, or any other suitable motor. The agitator 106 includes a stirring rod and a stirring unit. The stirring rod is connected to the motor 104 to support the stirring unit, and the stirring unit is rotated by the driving of the motor 104 to agitate the polishing slurry waste liquid SS. In one embodiment, the stirring unit can have different shapes, such as a fan blade shape, a rod shape, or any other suitable shape. In one embodiment, the stirring tank 102 also includes a bubble line, which introduces gas into the tank body, and the bubbles can help keep the solids or powder in the polishing slurry waste liquid SS in a suspended state and prevent them from settling. The introduced gas can be a clean air source (CDA) or nitrogen.

[0039] In one embodiment, the stirring tank 102 is connected to the filter 108 via pipes 113 and 115. In the recovery process, the polishing slurry waste liquid SS is transferred to the outlet of the stirring tank 102 and then transferred to the filter 108 via pipe 113, where it is separated into filtrate water FW and concentrated polishing slurry waste liquid FS. The filter 108 is connected to pipe 117, the opening and closing of which is controlled by a valve 118, and the filtrate water FW can be discharged via pipe 117. The concentrated polishing slurry waste liquid FS is returned from the filter 108 to the stirring tank 102 via pipe 115 and the second inlet of the stirring tank 102, where it is combined as the polishing slurry waste liquid SS, and the stirring-concentration circulation step continues. In this case, the valves 120 , 132 , 134 , and 136 may be closed, and the valves 114 , 116 , and 118 may be opened to circulate the polishing-slurry waste liquid SS and the concentrated polishing-slurry waste liquid FS through the pipes 113 and 115 .

[0040] In one embodiment, when the stirring tank 102 and the filter 108 perform the above-mentioned stirring-concentration circulation step, the valve 112 is controlled to maintain the pipe 111 in an open state, so that the initial polishing slurry waste liquid RS flows through the pipe 111. stirring In another embodiment, when the stirring tank 102 and the filter 108 perform the above-mentioned stirring-concentration circulation step, the valve 112 closes the line 111 to allow the initial polishing slurry waste liquid RS to be transferred to the tank 102. stirring The transfer to the tank 102 stops.

[0041] In one embodiment, a pressure pump 122 is disposed on the pipeline 113 to increase the pressure and thereby improve the transfer efficiency of the polishing slurry waste liquid SS in the pipeline 113, thereby increasing the output of the waste liquid recovery system 100. The pressure pump 122 may be configured as a different type of pump, such as a centrifugal pump, a submersible pump, an axial flow pump, a mixed flow pump, or a vortex pump. In addition, a water pressure gauge 126 may be disposed on the pipeline 113 to detect the liquid pressure of the polishing slurry waste liquid SS in the pipeline 113 and determine whether the transfer rate of the polishing slurry waste liquid SS or the liquid pressure in the pipeline 113 is within a normal range, thereby adjusting the parameters of the pressure pump 122 to control the liquid pressure in the pipeline 113.

[0042] In one embodiment, the waste liquid recovery system 100 includes a hydrometer 124 disposed in the stirring tank 102 for detecting the solids content or specific gravity value of the current polishing slurry waste liquid SS. In one embodiment, the hydrometer 124 may also include a sensing terminal extending into the stirring tank 102 for detecting the solids content of the polishing slurry waste liquid SS. The hydrometer 124 may include a display module or circuit module extending outside the stirring tank 102 for inspection and repair or for reading the detected value. The hydrometer 124 may be configured as a different type of hydrometer, such as a float type, a hydrostatic type, a vibration type, or another type of hydrometer.

[0043] In one embodiment, the waste liquid recovery system 100 is provided with a water level meter 128 disposed in the stirring tank 102 for detecting the current liquid level of the polishing-slurry waste liquid SS. The valve 112 determines whether to open or close the pipeline 111 in accordance with the liquid level of the polishing-slurry waste liquid SS detected by the water level meter 128, thereby controlling the amount of the initial polishing-slurry waste liquid RS to be transferred.

[0044] FIG. 2 is a schematic diagram illustrating a filter 108 according to some embodiments. In one embodiment, the filter 108 is a tangential flow filter (also called a crossflow filter). In one embodiment, the filter 108 includes a passage 202, a filtration membrane 204, and a filtrate outlet 206. The passage 202 is used to rapidly pass the fed polishing slurry waste solution SS through the filter 108, separating the fed polishing slurry waste solution SS into filtrate solution FW and concentrated polishing slurry waste solution FS, which are then sent out from the filtrate outlet 206 and the outlet of the passage 202, respectively. The filtration membrane 204 can be made of a hollow fiber membrane, a spiral filtration membrane, a filter plate, or other suitable filtration membrane. The tangential flow filtration method used by the filter 108 is such that the flow direction of the material to be filtered (the polishing slurry waste solution SS) and the flow direction of the filtrate solution FW are different, for example, approximately perpendicular to each other. Therefore, when filtering the polishing slurry waste liquid SS, the polymer powder abrasive or other particles are less likely to clog the surface of the filtration membrane 204, and instead are dispersed along with the flow of the polishing slurry waste liquid SS, and do not cause colloidal reactions that would affect the fluidity when producing the concentrated polishing slurry waste liquid FS.

[0045] The filter 108 in FIG. 2 is merely an example, and other filtering methods that can be used to separate the polishing slurry waste liquid SS can also be used as filtering elements in the waste liquid recovery system 100.

[0046] 1 , the waste liquid recovery system 100 includes a pipe 135, which is controlled by a valve 136 and branches off from the path of the pipe 113 and is connected to a third inlet of the agitation tank 102. In one embodiment, before the waste liquid recovery system 100 performs a filtration or concentration mode, a degassing procedure is performed through the pipe 135 using the initial polishing slurry waste liquid RS to discharge gas accumulated in the agitation tank 102 or the pipe 113. In this case, the valves 114, 116, 118, 120, 132, and 134 are closed, and the valves 112 and 136 are opened, so that the initial polishing slurry waste liquid RS discharges gas through the pipe 135. During the degassing procedure, the initial polishing slurry waste liquid RS is circulated through the agitation tank 102 and the pipe 113, and at the same time, the accumulated gas can be discharged from the waste liquid recovery system 100 through the agitation tank 102.

[0047] In one embodiment, the stirring tank 102 and the filter 108 perform the above-mentioned stirring-concentration circulation step for a certain period of time, and after the polishing slurry waste liquid SS is concentrated, the powder abrasive concentration therein (collectively referred to as the solid content or solid content in this specification, which can be defined as the ratio of the solid content in the polishing slurry waste liquid SS to the total weight of the polishing slurry waste liquid SS) reaches a predetermined value, and then the polishing slurry waste liquid SS can be directly discharged or subjected to further processing such as the next step of mixing. In one embodiment, the waste liquid recovery system 100 includes a pipe 119 controlled by a valve 120, and the pipe 119 is connected to the pipe 113 and is used to discharge the concentrated polishing slurry waste liquid SS as the final polishing slurry CS. In this case, the valves 112, 114, 116, 118, 132, 134, and 136 are closed, and the valve 120 is opened, so that the polishing slurry waste liquid SS is discharged as the final polishing slurry CS via the pipes 113 and 119.

[0048] In one embodiment, the waste liquid collection system 100 includes a conduit 131 controlled by a valve 132, which is connected to the fourth inlet of the agitation tank 102 and delivers the polishing aid NP to the agitation tank 102 for the mixing procedure. In one embodiment, the polishing aid NP contains only abrasive grains, exists in a solid state, and does not contain water or other liquids. In this case, valves 112, 114, 116, 118, 120, 134, and 136 are closed, and valve 132 is opened to mix the polishing slurry waste liquid SS with the polishing aid NP. After the mixing process is completed, valves 112, 114, 116, 118, 132, 134, and 136 are closed, and valve 120 is opened, allowing the polishing slurry waste liquid SS to be delivered via conduits 113 and 119 as the final polishing slurry CS.

[0049] In one embodiment, the waste liquid recovery system 100 includes a conduit 133 controlled by a valve 134, which is connected to the filter 108 for performing a backwashing procedure for the filter 108. In one embodiment, after the agitation tank 102 and the filter 108 have performed the agitation-concentration circulation step for a certain period of time, some solid matter, such as abrasive particles, may still accumulate on the surface of the filtration membrane 204 in the filter 108, thereby reducing the filtration efficiency of the filter 108. Therefore, the conduit 133 can be used to send the cleaning water BW or cleaning liquid to the filter 108 to remove the solid matter adhering to the surface of the filtration membrane 204. In one embodiment, referring to FIGS. 1 and 2 , the cleaning water BW or cleaning liquid is sent back to the filtration membrane 204 through the filter water outlet 206, discharged through the passage 202 to the conduit 113, and then discharged from the waste liquid recovery system 100 via the conduit 119. During the backwashing procedure, valves 112, 116, 118, 132, and 136 are closed, and valves 114, 120, and 134 are opened, and wash water BW and solids in filtration membrane 204 are discharged via lines 113 and 119. In one embodiment, the discharge of filtered water FW during filtration or concentration mode and the introduction of wash water BW during the backwashing procedure do not overlap, so lines 117 and 133 can be shared, and the number of valves 118 and 134 can be reduced to one. During use, when filtration or concentration mode is performed, filtered water FW is discharged to the outside via this shared line through filtered water outlet 206. During the backwashing procedure, wash water BW is introduced from the outside via this shared line into filtered water outlet 206 for cleaning.

[0050] In one embodiment, the waste liquid recovery system 100 includes a controller 140 configured to control the execution of the above-described procedures, such as filtration, concentration, degassing, backwashing, mixing, and delivery. In one embodiment, the controller is connected to the hydrometer 124, the water pressure gauge 126, or the water level gauge 128 to detect the state of the polishing-slurry waste liquid SS in the stirring tank 102 and the pipeline 113. In one embodiment, the controller 140 is connected to the valves 112, 114, 116, 118, 120, 132, 134, and 136 and sends commands to open and close the valves to control the opening and closing of the pipelines 111, 113, 115, 117, 119, 131, 133, and 135. In another embodiment, the controller 140 is connected to the pressure pump 122 or the motor 104 to adjust the transfer pressure of the polishing-slurry waste liquid SS or the stirring speed of the polishing-slurry waste liquid SS. The connections between the controller 140 and each component of the waste liquid recovery system 100 described above may be physical or electrical, and may be wired or wireless, so as to perform the detection-adjustment-execution-redetection loop without interruption and to maintain the normal operation of the various procedures performed by the waste liquid recovery system 100.

[0051] The controller 140 may be configured with hardware and software, and may be configured with, for example, an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The controller 140 may also be configured with a computer, microcontroller, server, etc., and may include a processor and memory for storing, calling, and executing program code to execute various preset recovery steps of the waste liquid recovery system 100. The controller 140 may be independent of the waste liquid recovery system 100 and connected to the waste liquid recovery system 100 by wire or wirelessly, or may be integrated into a single system with the waste liquid recovery system 100.

[0052] 3 is a flow diagram of a waste fluid recovery method 300 according to some embodiments. The flow diagram shown in FIG. 3 is merely exemplary; in some embodiments, additional steps may be provided before, during, or after the steps illustrated by method 300. In other embodiments, one or more steps of method 300 may also be replaced or eliminated. In one embodiment, the order of the steps included in method 300 may be reversed.

[0053] 4A-4G are schematic diagrams illustrating the operation of the waste liquid recovery system 100 at different stages according to some embodiments, and each stage shown in FIG. 4A-4G may correspond to a step in the method 300. FIG. 5 is a graph illustrating the change in the solids content of the polishing slurry waste liquid SS at different stages in the waste liquid recovery method 300 according to some embodiments.

[0054] When the waste liquid recovery method 300 starts, step 302 is entered, at which time a degassing procedure is performed. The corresponding work steps can be seen in FIG. 4A, and are represented by paths F1 and F2 in FIG. 4A. When performing the degassing procedure, the initial polishing slurry waste liquid RS is transferred to the stirring tank 102, and the degassing procedure of the stirring tank 102 is performed via the pipelines 113 and 135 to discharge excess gas from the stirring tank 102 or the pipelines. In one embodiment, the execution time of the degassing procedure is from the start to time T1, and the length of the execution time is a period P0 (unit: seconds). During the degassing procedure, the pressure pump 122 operates at a low speed to promote the discharge of air from the pipelines. During the degassing procedure, the controller 140 turns on the pressure pump 122, opens the valves 112 and 136, and closes the valves 114, 116, 118, 120, 132, and 134, circulating the polishing slurry waste liquid SS and gas through the pipelines 113 and 135 while discharging the gas. During the degassing procedure, the solids content of the polishing slurry waste liquid SS in the stirring tank 102 is determined by the solids content (or corresponding specific gravity value) C1 of the initial polishing slurry waste liquid RS, and the solids content C1 is maintained at a fixed value or within a fixed range. In one embodiment, the solids content C1 is 0.01% to 5%, 0.1% to 5%, or 0.1% to 2%. In one embodiment, the solids content C1 is not higher than a predetermined initial solids content setting value CX, which may be 2% to 5%.

[0055] In step 304, the degassing procedure is stopped, and the initial polishing slurry waste liquid RS continues to be transferred to the stirring tank 102. The corresponding operation step can be seen in FIG. 4B and is represented by a path F2 in FIG. 4B. In one embodiment, the solid content value C1 of the initial polishing slurry waste liquid RS is constant or within a predetermined range lower than the initial solid content set value CX. In one embodiment, the transfer process of the initial polishing slurry waste liquid RS is performed from time T0 to time T1 during a period P1 (unit: seconds). During the transfer period P1 of the initial polishing slurry waste liquid RS, the pressure pump 122 returns to normal speed to operate in order to accelerate the transfer of the polishing slurry waste liquid SS. During the period P1, the controller 140 turns on the pressure pump 122, opens the valve 112, and closes the valves 114, 116, 118, 120, 132, 134, and 136 to allow the polishing slurry waste liquid SS to enter the stirring tank 102. In one embodiment, step 304 is performed until the polishing-slurry waste liquid SS in the stirring tank 102 reaches a predetermined level L1 or a predetermined range, for example, within a height range of 5%, 10%, or 20% above or below the water level L1, and then the valves 114, 116, and 118 are opened to enter the filtration mode. In one embodiment, during a cycle P1 in which step 304 is performed, the valves 114, 116, and 118 are opened to enter the filtration mode earlier. In the cycle P1, the controller 140 controls the amount of the initial polishing-slurry waste liquid RS to be fed by detecting the water level meter 128 and controlling the valve 112, so that the polishing-slurry waste liquid SS in the stirring tank 102 reaches the water level L1 or a predetermined range, for example, within a height range of 5%, 10%, or 20% above or below the water level L1.

[0056] In step 306, the filtration mode is executed from time T1 to time T2 during a period P2 (unit: seconds). The corresponding operation steps can be seen in FIG. 4C, and are represented by paths F2, F3, and F4 in FIG. 4C. When the filtration mode is executed, the polishing-slurry waste liquid SS is filtered along a circulation path consisting of the stirring tank 102, the filter 108, and the pipes 113, 115, and 117. In the filtration mode executed in period P2, the filter 108 discharges excess water from the polishing-slurry waste liquid SS to produce filtered water FW, so that the solid content of the concentrated polishing-slurry waste liquid FS becomes higher than that of the initial polishing-slurry waste liquid RS. When the concentrated polishing-slurry waste liquid FS circulates along the pipe 115 of path F3 and enters the stirring tank 102, the solid content of the polishing-slurry waste liquid SS in the stirring tank 102 increases. In one embodiment, in the filtration mode, the controller 140 can continuously or intermittently pump the initial polishing slurry waste liquid RS into the stirring tank 102 through detection by the water level meter 128 and control of the valve 112, and the water level of the polishing slurry waste liquid SS in the stirring tank 102 is maintained at a constant water level L1 or within a predetermined range, for example, within a height range of 5%, 10%, or 20% above or below the water level L1.

[0057] 4C and 5, as the concentrated polishing-slurry waste liquid FS is collected and re-enters the stirring tank 102, the proportion of the filtered water FW decreases, temporarily increasing the solids content of the polishing-slurry waste liquid SS in the stirring tank 102 and causing the water level to temporarily drop. At this time, the controller 140 may detect the drop in the water level via the water level meter 128 and open the valve 112 to send in more initial polishing-slurry waste liquid RS. Because the solids content of the initial polishing-slurry waste liquid RS is lower than that of the concentrated polishing-slurry waste liquid FS, the solids content of the polishing-slurry waste liquid SS in the stirring tank 102 temporarily drops, causing the water level to rise again. In one embodiment, when the controller 140 detects via the water level meter 128 that the water level has risen to a predetermined range, it partially or completely closes the valve 112 to reduce or completely stop the initial polishing-slurry waste liquid RS from entering the stirring tank 102, thereby maintaining the water level of the polishing-slurry waste liquid SS in the stirring tank 102 at a height L1 or within a predetermined range. Therefore, in the filtration mode, the solids content of the polishing slurry waste liquid SS in the stirring tank 102 may show one or more rises and one or more falls. In one embodiment, during the period P2, the solids content of the polishing slurry waste liquid SS in the stirring tank 102 shows one or more sets of alternating rises and falls.

[0058] In one embodiment, through the filtration mode performed within the period P2, the solid content (or equivalent specific gravity value) of the polishing-slurry waste solution SS in the stirring tank 102 changes from a solid content value C1 at time T1 to a solid content value C2 at time T2, and the solid content value C2 is greater than the solid content value C1. In one embodiment, the solid content value C2 is 2% to 12%, 5% to 12%, or 5% to 8%. In one embodiment, the ratio of the solid content value C1 to the solid content value C2 is 10 to 400, 20 to 200, or 20 to 80.

[0059] In one embodiment, step 304 is omitted, and after the degassing procedure of step 302, the process directly enters the filtration mode of step 306. In other words, at the end of the cycle P0, the controller 140 increases the speed of the pressure pump 122, opens the valves 112, 114, 116, and 118, and closes the valves 132, 134, and 136, so that the initial polishing slurry waste liquid RS continues to be transferred to the stirring tank 102 and the polishing slurry waste liquid SS can enter the filter 108 for filtration circulation.

[0060] In step 308, the concentration mode is executed from time T2 to time T3 with a period P3 (unit: seconds). The corresponding operation steps can be seen in FIG. 4D, represented by paths F3 and F4 in FIG. 4D. When the filtration mode is executed up to one stage and a condition for the concentration mode is triggered, the filtration mode is terminated and the process proceeds to the concentration mode. The trigger condition for the concentration mode can be a predetermined time period P2 or a predetermined solids content value C2. When either condition is met, the process is deemed to be able to proceed to the concentration mode. In the concentration mode, the polishing slurry waste liquid SS is concentrated along the stirring tank 102, the filter 108, and the pipelines 113, 115, and 117. The similarity between the concentration mode and the filtration mode is that the filter 108 removes excess water from the polishing slurry waste liquid SS to produce filtrate FW, resulting in a higher solids content in the concentrated polishing slurry waste liquid FS than in the initial polishing slurry waste liquid RS.

[0061] The biggest difference between the concentration mode and the filtration mode is that the concentration mode is stopped and the initial polishing slurry waste liquid RS is transferred to the stirring tank 102, so in the concentration mode, the total amount of solids in the polishing slurry waste liquid SS in the waste liquid recovery system 100 does not basically increase, but the filter 108 continues to circulate and concentrate the polishing slurry waste liquid SS, filtering out excess water in the polishing slurry waste liquid SS and discharging it as filtered water FW, so that the solid content of the polishing slurry waste liquid SS in the stirring tank 102 continues to rise, but the height of the water level continues to drop from level L1 or from the original predetermined range. In one embodiment, in the concentration mode, the controller 140 stops the initial polishing slurry waste liquid RS from entering the stirring tank 102 through control of the valve 112, and monitors the water level meter 128 to ensure that the height of the polishing slurry waste liquid SS in the stirring tank 102 is above level L2 or within a predetermined range, for example, within 5% or 10% above or below level L2.

[0062] 4D and 5, when the concentrated polishing slurry waste liquid FS is returned to the stirring tank 102, the proportion of the filtrate FW decreases, so that the solid content of the polishing slurry waste liquid SS in the stirring tank 102 rises and the water level drops. At this time, since the initial polishing slurry waste liquid RS is not replenished, the solid content of the polishing slurry waste liquid SS in the stirring tank 102 continues to rise but does not drop. On the other hand, in the concentration mode, the water level in the stirring tank 102 continues to drop but does not rise. In one embodiment, in the filtration mode, the solid content of the polishing slurry waste liquid SS in the stirring tank 102 continues to rise while the water level continues to drop. This phenomenon is clearly different from the phenomenon in which the solid content or water level of the polishing slurry waste liquid SS in the stirring tank 102 in the filtration mode show one or more pairs of alternating rises and falls.

[0063] In one embodiment, through the concentration mode executed within the period P3, the solid content (or equivalent specific gravity value) of the polishing-slurry waste solution SS in the stirring tank 102 changes from a solid content value C2 at time T2 to a solid content value C3 at time T3, and the solid content value C3 is greater than the solid content value C2. In one embodiment, the solid content value C3 is 6% to 20%, 8% to 20%, or 8% to 15%. In one embodiment, the ratio of the solid content value C3 to the solid content value C2 is 1.01 to 4, 1.01 to 2, or 1.1 to 2. In one embodiment, the period P2 is greater than the period P3. In one embodiment, the ratio of the period P2 to the period P3 is 10 to 45, 15 to 45, or 15 to 30.

[0064] 4C, 4D, and 5, the filtration and concentration modes proposed in the present application can achieve the highest productivity for recovering the initial polishing slurry waste liquid RS. In one embodiment, the filtration mode can cooperate with the filter 108 to perform gradual circulation filtration and concentration of the polishing slurry waste liquid SS. In one embodiment, because the initial polishing slurry waste liquid RS has a low solids content, only the tangential flow filter 108 is used for filtration and concentration. If the solids content range of the polishing slurry waste liquid SS fed to the filter 108 is not properly adjusted and the desired solids content required for the final polishing slurry CS cannot be reached within the short period P1, the length of the period P1 must be extended, which can have a negative impact on the filter 108. For example, the filter membrane 204 is prone to clogging, shortening the life of the filter membrane 204 or requiring more frequent backwashing to restore the filter's filtration function. Therefore, in the filtration mode, the rate of change in the solid content of the polishing slurry waste liquid SS is continuously monitored, and the initial polishing slurry waste liquid RS is appropriately replenished to steadily increase the solid content of the polishing slurry waste liquid SS, thereby protecting the filter 108 and ensuring its longest life.

[0065] On the other hand, after the filtration mode is performed for a certain period of time (e.g., period P2), the solid content of the polishing slurry waste liquid SS reaches a solid content value C2, and the proportion of excess water therein significantly decreases. At this time, the concentration mode is performed to filter and concentrate the polishing slurry waste liquid SS without replenishing the initial slurry waste liquid RS, thereby accelerating the removal of residual water from the polishing slurry waste liquid SS. Furthermore, compared with the filtration mode, the excess water can be removed in a shorter time, shortening the filtration and concentration time of the filter 108 for highly concentrated polishing slurry waste liquid SS. That is, the length of period P3 is shorter than period P2, which prevents clogging of the filter 108 and reduces the frequency of backwashing the filtration membrane 204, thereby extending the life of the filter 108. In one embodiment, when deciding to switch to the concentration mode, the initial solid content value C2 at the start of the concentration mode, the target solid content value C3 at the end of the concentration mode, and the period length P3 at which the filter 108 can effectively operate, assuming that the solid content of the feed continues to increase, must be taken into consideration. The ranges of ideal values ​​for the above parameters must be considered together to determine the optimal initial solids content value C2, the target final solids content value C3, and the concentration mode cycle P3. This allows the concentration mode to rapidly increase the solids content of the polishing slurry waste liquid SS without impairing the life of the filter 108, thereby improving the recovery efficiency and maintenance costs of the waste liquid recovery system 100. In one embodiment, the operation cycle P2 or P3 of the filtration mode or concentration mode is not predetermined, but the controller 140 determines the length of the cycle P2 or P3 based on the solids content value of the polishing slurry waste liquid SS in the filtration mode or concentration mode and its change amount, and determines to stop the filtration mode or concentration mode when the solids content value of the polishing slurry waste liquid SS reaches a predetermined value, such as the solids content value C2 or C3.

[0066] In the filtration mode, the average rate V2 of change in the solid content or specific gravity of the polishing-slurry waste liquid SS can be determined by the length of the period P2 and the amount of change in the solid content. For example, the average rate V2 can be defined as V2 = (C2 - C1) / P2 (unit: % / second). Similarly, in the concentration mode, the average rate V3 of change in the solid content or specific gravity of the polishing-slurry waste liquid SS can be determined by the length of the period P3 and the amount of change in the solid content. For example, the average rate V3 can be defined as V3 = (C3 - C2) / P3 (unit: % / second). From the above description of the filtration mode and the concentration mode, it can be seen that the excess water removal efficiency is higher in the concentration mode than in the filtration mode, and therefore the relationship V3 > V2 holds. In one embodiment, the average rate V2 is 0.1 to 0.8, 0.2 to 0.8, or 0.2 to 0.5. In another embodiment, the average rate V3 is 1 to 20, 3 to 20, or 3 to 10. In one embodiment, the ratio of the average velocity V2 to the average velocity V3 is 5 to 100 times, 5 to 50 times, or 10 to 50 times.

[0067] In step 310, a backwashing procedure for the filter 108 is performed. The corresponding operational steps can be seen in FIG. 4E and are represented by path F5 in FIG. 4E. In one embodiment, the backwashing procedure can be performed at the end or during the filtration or concentration mode. In the example shown in FIG. 4E, if the controller 140 finds that the filtering effect of the filter 108 is lower than a predetermined value, for example, that the discharge rate of the filtered water FW is lower than a predetermined value, it can be determined that the filter's filtration membrane 204 is likely clogged to some extent, and therefore a backwashing procedure needs to be performed. When performing the backwashing procedure, the controller 140 closes valves 112, 116, 118, 132, and 136 and opens valves 114, 120, and 134 to allow the wash water BW to flow back through line 133 to the filter membrane 204 of the filter 108 to remove solids adhering to the membrane 204, and then discharges wastewater containing the clogged material and wash water through lines 113 and 119. When the controller 140 detects that the backwash procedure has run for a predetermined time or that the solids content of the discharged wastewater is below a predetermined value, the backwash procedure can be stopped and the system can return to the previous filtration or concentration mode or proceed to the next stage. In one embodiment, the cycle length of the backwash procedure is between 300 seconds and 900 seconds.

[0068] In step 312, the mixing mode is executed in a period P4 (unit: seconds). The period P4 is executed from time T3 to time T4. The corresponding operation stage can be seen in FIG. 4F, represented by path F6 in FIG. 4F. When the concentration mode advances to a certain stage, triggering the completion condition of the concentration mode, the concentration mode ends, and the concentrated polishing-slurry waste solution SS is discharged as is, or the system advances to the mixing mode. The end condition of the concentration mode is the end of a predetermined time period P3 or the solid content of the polishing-slurry waste solution SS reaches a predetermined solid content value C3. When either of these conditions is met, the concentration mode is considered to have ended. To enter the mixing mode, the controller 140 closes valves 112, 114, 116, 118, 120, 134, and 136, turns off the pressure pump 122, and opens valve 132, allowing the polishing aid NP to enter the stirring tank 102 via the pipeline 131 and mix with the polishing-slurry waste solution SS. In one embodiment, in the mixing mode, the controller 140 adjusts the amount of polishing aid NP fed through control of the valve 132, and monitors whether the solid content in the polishing slurry waste solution SS in the stirring tank 102 reaches a predetermined solid content value C4 through detection by the hydrometer 124. In the mixing mode, the addition of the polishing aid NP may cause the water level in the stirring tank 102 to rise from the water level L2 to the height of the water level L3.

[0069] In one embodiment, through the mixing mode executed within the period P4, the solids content (or equivalent specific gravity value) of the polishing-slurry waste solution SS in the stirring tank 102 changes from a solids content value C3 at time T3 to a solids content value C4 at time T4, and the solids content value C4 is greater than the solids content value C3. In one embodiment, the solids content value C4 is 6% to 30%, 6% to 20%, or 8% to 20%. In one embodiment, the ratio of the solids content value C4 to the solids content value C3 is 1.01 to 2, 1.1 to 2, or 1.1 to 1.3.

[0070] In step 314, the final polishing slurry CS is discharged. The corresponding operation steps can be seen in FIG. 4G and are represented by path F7 in FIG. 4G. After the polishing slurry waste liquid SS completes the concentration mode in step 308 or the mixing mode in step 312, the concentrated polishing slurry waste liquid SS is discharged to become the final polishing slurry CS. In one embodiment, after the polishing slurry waste liquid SS completes the concentration mode in step 308, the polishing slurry waste liquid SS is directly discharged to become the final polishing slurry CS, which can be mixed with the polishing aid NP or other steps in another facility or another execution stage in the waste liquid recovery system 100. When the final polishing slurry CS is discharged, the controller 140 closes the valves 112, 114, 116, 118, 132, 134, and 136 and opens the pressure pump 122 and the valve 120 to allow the final polishing slurry CS to be discharged via the pipelines 113 and 119.

[0071] Although the content and advantages of the embodiments of the present invention have been described in detail above, it should be understood that numerous modifications, substitutions, and alternatives can be made thereto without departing from the spirit and scope of the present invention as defined by the appended claims. Furthermore, the scope of the present application is not limited to the specific embodiments of the processes, machines, manufacture, compositions of matter, means, methods, and steps described in the specification. Based on this disclosure, one skilled in the art can understand that existing or future-developed processes, machines, manufacture, compositions of matter, means, methods, and steps can be used that have the same function or achieve substantially the same results as the embodiments described herein. Therefore, these processes, machines, manufacture, compositions of matter, means, methods, and steps are also included within the scope of the appended claims. [Explanation of symbols]

[0072] 100 Waste liquid recovery system 102 Stirring tank 104 Motor 106 Stirrer 108 filters 111 Pipeline 112 Valve 113 Pipeline 114 Valve 115 Pipeline 116 Valve 117 Pipeline 118 Valve 119 Pipeline 120 valve 122 Pressure pump 124 Hydrometer 126 Water pressure gauge 128 Water level gauge 131 Pipeline 132 Valve 133 Pipeline 134 Valve 135 Pipeline 136 Valve 140 Controller Aisle 202 204 Filtration Membrane 206 Filtrate water outlet 300 ways 302 steps 304 steps 306 steps 308 steps 310 steps 312 steps 314 steps C1 Solid content value / specific gravity value C2 Solid content value / specific gravity value C3 Solid content value / specific gravity value C4 Solid content value / specific gravity value F1 Route F2 pathway F3 Route F4 route F5 Route F6 Route F7 Route P0 period P1 period P2 period P3 period P4 period T0 time T1 time T2 time T3 time T4 time BW Backwash water CS Final Polishing Slurry FW filtered water FS Concentrated Polishing Slurry Wastewater NP Polishing Aid RS Initial Polishing Slurry Waste SS Polishing slurry waste liquid

Claims

1. 1. A system for recovering polishing slurry waste liquid, the system comprising: an agitation tank for receiving an initial polishing slurry waste liquid containing a rinse liquid and polishing debris and agitating the polishing slurry waste liquid in the tank, wherein the initial polishing slurry waste liquid becomes the polishing slurry waste liquid of the system when received in the agitation tank; a filter for receiving the polishing slurry waste liquid, filtering the polishing slurry waste liquid, separating the polishing slurry waste liquid into filtrate and concentrated polishing slurry waste liquid, and sending the filtered water and concentrated polishing slurry waste liquid out; a first conduit connected to the stirring tank, the first conduit being opened during a filtering mode to transfer the initial polishing slurry waste liquid to a first inlet of the stirring tank, and the first conduit being closed during a concentration mode to stop the transfer of the initial polishing slurry waste liquid to the first inlet; a second pipeline connected to the stirring tank and the filter, the second pipeline being opened during the filtering mode and the concentration mode to transfer the polishing slurry waste liquid from the stirring tank to the filter; a third conduit connected to the stirring tank and the filter, the third conduit being opened during the filtering mode and the concentration mode to transfer the concentrated polishing slurry waste liquid from the filter to the second inlet of the stirring tank; a first valve for opening and closing the first pipeline; a hydrometer disposed in the stirring tank for detecting a solid content of the polishing slurry waste liquid in the stirring tank, the solid content being defined as a concentration of an abrasive; a controller electrically connected to the first valve and configured to control the first valve; Equipped with In the filtration mode, the filtration of the polishing slurry waste liquid and the transfer of the initial polishing slurry waste liquid are simultaneously performed, and in the concentration mode, only the filtration of the polishing slurry waste liquid is performed; The system, wherein the controller is configured to define a length of a first period of the system during which the filtration mode is performed and a length of a second period during which the concentration mode is performed.

2. a fourth pipeline for transferring a polishing aid to the stirring tank so that the amount of the abrasive in the concentrated polishing slurry waste liquid reaches a predetermined value and the concentrated polishing slurry waste liquid can function as a final polishing slurry; a second valve for opening the fourth conduit during mixing to allow the polishing aid to enter the stirring tank, and for closing the fourth conduit to stop the polishing aid from entering the stirring tank when the mixing stops; The system of claim 1 further comprising:

3. The system according to claim 1 , further comprising a water level meter for detecting the level of the polishing slurry waste liquid in the stirring tank.

4. The system of claim 1 further comprising a pressure pump located in the path of the second conduit.

5. 10. The system of claim 1, further comprising a fifth line connected to the filtered water outlet of the filter for backwashing the filter.

6. The system according to claim 1 , further comprising a sixth pipe line connected to the stirring tank and the filter and used for degassing to remove air or bubbles from the stirring tank.

7. 2. The system of claim 1, wherein in the filtering mode, the solids content of the polishing slurry waste liquid does not exceed a first solids content value defined as a threshold at which the system initiates the concentration mode.

8. 8. The system of claim 7, wherein upon completion of the concentration mode, the solids content of the polishing slurry effluent exceeds the first solids content value.

9. The system of claim 1 , wherein the controller is configured to open the first valve to enter the filtration mode and maintain the level of the polishing slurry waste liquid within a predetermined range during the first cycle.

10. 10. A method for recovering polishing slurry waste using the system of claim 1, comprising: the first cycle in which the filtration mode is performed; the second cycle in which the concentration mode is performed; Equipped with The first period is transferring the initial polishing slurry waste liquid to the stirring tank to produce the polishing slurry waste liquid; transferring the polishing slurry waste liquid to the filter for filtering, the filter receiving the polishing slurry waste liquid and generating filtrate and concentrated polishing slurry waste liquid; transferring the concentrated polishing slurry waste liquid to the stirring tank; Including, The second period is stopping the transfer of the initial polishing slurry waste liquid to the stirring tank; transferring the polishing slurry waste liquid to the filter and filtering it; A method comprising:

11. The method of claim 10, wherein the ratio of the first period to the second period is 15 to 30 times.

12. The method of claim 10 , further comprising detecting a solid content of the polishing slurry waste liquid in the agitation tank to determine the length of time of the first cycle or the length of time of the second cycle.

13. The method according to claim 10, wherein the solid content of the polishing slurry waste liquid in the stirring tank has a first solid content value at the end of the first cycle and a second solid content value at the end of the second cycle, and the ratio of the second solid content value to the first solid content value is 5 to 10 times.

14. The method according to claim 10, wherein the change in the solid content of the polishing slurry waste liquid in the stirring tank has a first average velocity in the first cycle and a second average velocity in the second cycle, and the ratio of the second average velocity to the first average velocity is 15 to 30 times.

15. The method according to claim 10 , further comprising the step of maintaining the level of the polishing slurry waste liquid in the stirring tank within a predetermined height range in the filtration mode.

16. The solid content of the initial polishing slurry waste liquid is equal to or less than a predetermined initial solid content value, The method according to claim 10, wherein in the filtering mode, the solids content of the polishing slurry waste liquid in the stirring tank exhibits one or more rises and one or more falls.

17. The method of claim 10, wherein in the concentration mode, the solids value of the polishing slurry waste liquid in the agitation tank continues to increase.

18. 11. The method of claim 10, further comprising the steps of: after the concentration mode is completed, executing a mixing mode in a third cycle to stop filtering the polishing slurry waste liquid, transferring a polishing aid into the stirring tank to mix it with the polishing slurry waste liquid, and discharging the polishing slurry waste liquid at the end of the third cycle.

19. The method according to claim 18, wherein the solid content of the polishing slurry waste liquid in the stirring tank has a third solid content value at the end of the third cycle and a second solid content value at the end of the second cycle, and the ratio of the third solid content value to the second solid content value is 1.1 times to 2 times.

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