Zinc-containing waste liquid treatment process

Abstract

The invention relates to the technical field of waste liquid treatment, in particular to a zinc-containing waste liquid treatment process which comprises the following steps: S1, performing primary treatment on zinc-containing waste liquid through a gravity settling device to remove large-particle impurities and suspended solids; s2, acidizing the zinc-containing solution obtained in the step S1; s3, feeding the acidified solution into an ion exchange device, and treating the solution by adopting cation exchange resin; s4, carrying out concentration treatment on the solution subjected to ion exchange treatment; s5, feeding the concentrated solution into a reduction reaction device, and carrying out reduction reaction by using a quantitative reducing agent; s6, the solution obtained after reduction treatment is subjected to precipitation treatment, and supernatant liquid is separated out; s7, filtering the separated supernatant liquid to obtain a battery-grade zinc chloride solution; through the steps of ion exchange, concentration, reduction, precipitation and filtration, alkali metal ions in the zinc-containing waste liquid are effectively removed, and the concentration and purity of the zinc solution are improved.

Description

Technical Field

[0001] The invention relates to the technical field of waste liquid treatment, and in particular to a process for treating zinc-containing waste liquid. Background Art

[0002] In the zinc smelting process, the treatment of rotary kiln flue gas and waste liquid has always been a technical challenge faced by the industry. Zinc-containing materials such as secondary zinc oxide and galvanized ash are used as raw materials, and zinc separation and purification is achieved through high-temperature roasting. However, during the roasting process, the exhaust gas contains not only a large amount of zinc, but also alkali metal ions such as sodium and potassium. These alkali metal salt impurities often cause pollution in the subsequent zinc recovery process.

[0003] At present, most traditional methods for treating zinc-containing waste liquid rely on chemical precipitation technology, usually by adding soda ash to form zinc carbonate precipitate to recover zinc; however, this method not only produces a large amount of high-salt wastewater, increases environmental protection treatment costs and the difficulty of wastewater treatment, but also makes it difficult to efficiently separate alkali metal ions in the waste liquid, resulting in excessive impurity content in battery-grade zinc chloride solution.

[0004] Therefore, how to efficiently remove these alkali metal ions from the waste liquid and produce zinc chloride solution that meets battery-grade requirements while ensuring the zinc concentration has become a technical problem that needs to be urgently solved in the current zinc smelting industry. Summary of the invention

[0005] Based on the above purpose, the present invention provides a process for treating zinc-containing waste liquid.

[0006] A zinc-containing waste liquid treatment process comprises the following steps:

[0007] S1: Preliminary treatment of the zinc-containing waste liquid through a gravity sedimentation device to remove larger particles of impurities and suspended matter to obtain a zinc-containing solution;

[0008] S2: transporting the zinc-containing solution obtained in S1 to a pickling device for acidification treatment;

[0009] S3: sending the acidified solution to an ion exchange device, treating the solution with a cation exchange resin to remove alkaline metal ions in the solution and maintain the concentration of zinc ions;

[0010] S4: concentrating the solution after the ion exchange treatment to increase the concentration of zinc;

[0011] S5: sending the concentrated solution to a reduction reaction device, and using a quantitative reducing agent to perform a reduction reaction to improve the purity of zinc;

[0012] S6: subjecting the reduced solution to precipitation treatment to separate the supernatant;

[0013] S7: filtering the separated supernatant to remove the precipitate to obtain a battery-grade zinc chloride solution.

[0014] Optionally, the S1 specifically includes:

[0015] S11: Collect the zinc-containing waste liquid from the rotary kiln dust collection system and transport it to the gravity settling device, ensuring that the initial flow rate of the waste liquid is 20 to 50 cubic meters per hour;

[0016] S12: placing the zinc-containing waste liquid in a gravity sedimentation device for a sedimentation time of 2 to 4 hours;

[0017] S13: By controlling the flow rate of the solution to 0.5 m / s to 2.0 m / s, the upper clear liquid of the zinc-containing waste liquid flows out, and a filter cloth with a filtration accuracy of 10 microns to 50 microns is used to remove large particle impurities.

[0018] Optionally, the S2 specifically includes:

[0019] S21: transporting the zinc-containing solution obtained in S1 to the pickling device through a pipeline system, with a transport flow rate of 10 to 30 cubic meters per hour;

[0020] S22: in the pickling device, adding an acidic substance to the zinc-containing solution, wherein the amount of the acidic substance added is 0.5% to 3% of the total amount of the solution, so as to adjust the pH value of the solution to 1.0 to 2.5;

[0021] S23: uniformly mixing the acidic substance and the zinc-containing solution through a stirring system, controlling the stirring speed to be 100 to 300 rpm, and controlling the reaction time to be 30 to 90 minutes, so that the acidic substance reacts with impurities in the solution to promote dissolution and remove some impurities;

[0022] S24: The acidified solution is filtered to remove insoluble matter.

[0023] Optionally, the acidic substance is selected from dilute sulfuric acid, hydrochloric acid or hydrogen chloride solution.

[0024] Optionally, the S3 specifically includes:

[0025] S31: transporting the acidified solution to the ion exchange device through a pipeline, and the transport flow rate is controlled at 5 to 15 cubic meters per hour;

[0026] S32: In the ion exchange device, a cation exchange resin is selected and used, and the exchange capacity of the resin is 20 mmol / g to 50 mmol / g;

[0027] S33: By adjusting the operating conditions of the ion exchange device, the contact time between the resin and the solution is ensured to be 30 minutes to 60 minutes.

[0028] Optionally, the S4 specifically includes:

[0029] S41: transporting the solution after ion exchange treatment to an evaporation concentration device through a pipeline, with the transport flow rate controlled at 3 to 10 cubic meters per hour;

[0030] S42: in the evaporation concentration device, removing part of the water in the solution by evaporation, controlling the evaporation temperature to be between 80° C. and 120° C., and the evaporation time to be between 1 hour and 4 hours;

[0031] S43: adjusting the vacuum degree of the solution during the evaporation process to 0.08 to 0.1 MPa;

[0032] S44: The concentrated zinc-containing solution is collected into a storage container, and the zinc ion concentration after concentration is increased to 150 g / L to 300 g / L.

[0033] Optionally, the S5 specifically includes:

[0034] S51: transporting the concentrated solution to a reduction reaction device through a pipeline, with the transport flow rate controlled at 2 to 8 cubic meters per hour;

[0035] S52: adding a reducing agent to the reduction reaction device, wherein the reducing agent is selected from sodium bisulfite, sodium sulfide or sulfur dioxide solution, and the added amount is 0.2% to 1% of the total weight of the solution;

[0036] S53: controlling the reaction temperature of the solution to be between 60° C. and 90° C., and the reaction time to be between 2 hours and 4 hours;

[0037] S54: During the reduction reaction, controlling the stirring speed to be between 200 and 400 rpm;

[0038] S55: Discharge the reacted solution from the reaction device.

[0039] Optionally, the S6 specifically includes:

[0040] S61: transporting the reduced solution from the reduction reaction device to the precipitation tank, with the transport flow rate controlled at 1 to 5 cubic meters per hour;

[0041] S62: adding a precipitant to the precipitation tank in an amount of 0.5% to 2% of the total amount of the solution, and maintaining the temperature of the solution at 50° C. to 80° C.;

[0042] S63: After standing and settling for 1 to 3 hours, separate the supernatant.

[0043] Optionally, the precipitant is selected from sodium hydroxide, calcium hydroxide or magnesium hydroxide.

[0044] Optionally, the S7 specifically includes:

[0045] S71: transporting the supernatant liquid after precipitation from the sedimentation tank to the filtering device, and controlling the transport flow rate to be 1 to 3 cubic meters per hour;

[0046] S72: In the filtration device, a microfiltration membrane is used for filtration, and the pore size of the filtration membrane is controlled to be 0.1 to 1 micron;

[0047] S73: Control the filtration operating pressure to be between 0.1 and 0.5 MPa, and the filtration time to be between 2 and 6 hours;

[0048] S74: collecting the filtered zinc chloride solution into a storage container, wherein the zinc concentration of the solution is 500 g / L to 800 g / L, and the alkali metal content is less than 0.5%.

[0049] Beneficial effects of the present invention:

[0050] The present invention can efficiently remove alkali metal ions such as sodium and potassium in zinc-containing waste liquid through the selective adsorption of cation exchange resin, while maintaining the concentration of zinc ions; this technical solution avoids the high-salt wastewater problem caused by the chemical precipitation method, effectively reduces the generation of wastewater, and significantly reduces the environmental protection cost of wastewater treatment.

[0051] The present invention can efficiently treat zinc-containing waste liquid through systematic ion exchange, concentration, reduction, precipitation and filtration processes, ensure that harmful substances in the waste liquid are effectively removed, and realize efficient recovery of zinc resources, thereby having significant environmental protection and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0053] Figure 1 A schematic diagram of a zinc-containing waste liquid treatment process according to an embodiment of the present invention;

[0054] Figure 2 Schematic diagram of the ion exchange operation process of an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. At the same time, it is explained here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art may also adopt other alternatives to implement some known technologies; and the accompanying drawings are only for more specific description of the embodiments, and are not intended to specifically limit the present invention.

[0056] It should be noted that the references to "one embodiment", "an embodiment", "an exemplary embodiment", "some embodiments" and the like in the specification indicate that the embodiments described may include specific features, structures or characteristics, but not every embodiment may include the specific features, structures or characteristics. In addition, when a specific feature, structure or characteristic is described in conjunction with an embodiment, it should be within the knowledge of a person skilled in the art to implement such feature, structure or characteristic in conjunction with other embodiments (whether or not explicitly described).

[0057] In general, a term can be understood, at least in part, from its use in context. For example, depending, at least in part, on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in the singular sense, or can be used to describe a combination of features, structures, or characteristics in the plural sense. Additionally, the term "based on" can be understood as not necessarily intended to convey an exclusive set of factors, but can instead, depending, at least in part, on the context, allow for the presence of other factors that are not necessarily explicitly described.

[0058] Example 1

[0059] like Figure 1-Figure 2 As shown, a zinc-containing waste liquid treatment process comprises the following steps:

[0060] S1: Preliminary treatment of the zinc-containing waste liquid through a gravity sedimentation device to remove larger particles of impurities and suspended matter to obtain a zinc-containing solution;

[0061] S2: The zinc-containing solution obtained in S1 is transported to a pickling device for acidification treatment. This process can effectively decompose impurities in the solution and reduce the difficulty of subsequent treatment;

[0062] S3: sending the acidified solution to an ion exchange device, treating the solution with a cation exchange resin to remove alkaline metal ions in the solution and maintain the concentration of zinc ions;

[0063] S4: concentrating the solution after the ion exchange treatment to increase the concentration of zinc;

[0064] S5: sending the concentrated solution to a reduction reaction device, using a quantitative reducing agent to perform a reduction reaction, reducing the concentration of sodium and potassium to improve the purity of zinc;

[0065] S6: subjecting the reduced solution to precipitation treatment to separate the supernatant;

[0066] S7: filtering the separated supernatant to remove the precipitate to obtain a battery-grade zinc chloride solution.

[0067] S1 specifically includes:

[0068] S11: Collect zinc-containing waste liquid from the rotary kiln dust collection system and transport it to the gravity sedimentation device, ensuring that the initial flow rate of the waste liquid is 40 cubic meters per hour to meet the needs of subsequent sedimentation treatment;

[0069] S12: The zinc-containing waste liquid is placed in a gravity sedimentation device for 3 hours to allow larger particles of impurities and suspended matter to settle to the bottom of the device;

[0070] S13: By controlling the flow rate of the solution to 1 m / s, the upper clear liquid of the zinc-containing waste liquid flows out, and a filter cloth with a filtration accuracy of 30 microns is used to remove large particle impurities.

[0071] S2 specifically includes:

[0072] S21: The zinc-containing solution obtained in S1 is transported to the pickling device through a pipeline system at a transport flow rate of 20 cubic meters per hour to ensure the processing capacity of the pickling device;

[0073] S22: in the pickling device, adding an acidic substance to the zinc-containing solution, wherein the amount of the acidic substance added is 1.5% of the total amount of the solution, so as to adjust the pH value of the solution to 1.8;

[0074] S23: uniformly mixing the acidic substance and the zinc-containing solution through a stirring system, controlling the stirring speed at 200 rpm and the reaction time at 60 minutes, so that the acidic substance reacts with impurities in the solution to promote dissolution and remove some impurities;

[0075] S24: The acidified solution is filtered to remove insoluble matter, and the treated zinc-containing solution is transported to the next treatment stage.

[0076] The acidic substance is selected from hydrochloric acid.

[0077] S3 specifically includes:

[0078] S31: transporting the acidified solution to the ion exchange device through a pipeline, and the transport flow rate is controlled at 10 cubic meters per hour to meet the needs of the ion exchange process;

[0079] S32: In the ion exchange device, a cation exchange resin is selected, the exchange capacity of the resin is 30 mmol / g, and the sodium (Na+) or potassium (K+) alkali metal ions in the solution are selectively removed while maintaining the concentration of zinc ions (Zn2+);

[0080] S33: By adjusting the operating conditions of the ion exchange device, the contact time between the resin and the solution is ensured to be 45 minutes to ensure sufficient exchange and removal of alkali metal ions.

[0081] S4 specifically includes:

[0082] S41: The solution after ion exchange treatment is transported to the evaporation concentration device through a pipeline, and the transport flow rate is controlled at 5 cubic meters per hour to ensure the normal processing load of the concentration device;

[0083] S42: in the evaporation concentration device, removing part of the water in the solution by evaporation, controlling the evaporation temperature at 100° C. and the evaporation time at 2 hours to increase the concentration of zinc ions in the solution;

[0084] S43: adjusting the vacuum degree of the solution during the evaporation process to 0.09 MPa to accelerate the evaporation rate of water and ensure a stable concentration effect;

[0085] S44: The concentrated zinc-containing solution is collected into a storage container, and the zinc ion concentration after concentration is increased to 200 g / L, providing the required zinc concentration basis for subsequent processes.

[0086] S5 specifically includes:

[0087] S51: The concentrated solution is transported to the reduction reaction device through a pipeline, and the transport flow rate is controlled at 4 cubic meters per hour to ensure stable operation of the device;

[0088] S52: adding a reducing agent to the reduction reaction device, wherein the reducing agent is selected from sodium sulfide and the added amount is 0.5% of the total weight of the solution;

[0089] S53: controlling the reaction temperature of the solution to 80° C. and the reaction time to 3 hours to ensure that the reducing agent reacts completely with the target component in the solution;

[0090] S54: During the reduction reaction, the stirring speed is controlled at 300 rpm to ensure uniformity of the solution and sufficient distribution of the reducing agent during the reduction reaction;

[0091] S55: The reacted solution is discharged from the reaction device for use in subsequent precipitation and filtration steps.

[0092] S6 specifically includes:

[0093] S61: transporting the reduced solution from the reduction reaction device to the precipitation tank, and controlling the transport flow rate at 3 cubic meters per hour to ensure that the solution enters the precipitation device smoothly;

[0094] S62: adding a precipitant to the precipitation tank in an amount of 1% of the total solution, and maintaining the temperature of the solution at 60° C.;

[0095] S63: After standing and settling for 2 hours, the supernatant is separated and the supernatant is used for subsequent filtration steps.

[0096] The precipitating agent is selected from calcium hydroxide.

[0097] S7 specifically includes:

[0098] S71: transporting the supernatant liquid after precipitation from the sedimentation tank to the filtering device, and controlling the transport flow rate to 2 cubic meters per hour so as to be evenly distributed into the filtering device;

[0099] S72: In the filtration device, a microfiltration membrane is used for filtration, and the pore size of the filtration membrane is controlled at 0.5 microns to ensure effective retention of sediment;

[0100] S73: Control the filtration operating pressure at 0.3 MPa and the filtration time at 4 hours to ensure that the sediment is completely retained on the filter medium;

[0101] S74: collecting the filtered zinc chloride solution into a storage container, wherein the zinc concentration of the solution is 500 g / L to 800 g / L, and the alkali metal content is less than 0.5%.

[0102] Example 2

[0103] S1: The zinc-containing waste liquid from the rotary kiln dust collection system is sent to the gravity sedimentation device at a flow rate of 20 cubic meters per hour, and the solution flow rate is controlled to be 0.5m / s. The upper clear liquid flows out through the filter cloth with a filtration accuracy of 10 microns to obtain a zinc-containing solution;

[0104] S2: The zinc-containing solution obtained in S1 is transported to a pickling device at a flow rate of 10 cubic meters per hour, and dilute sulfuric acid is added at a rate of 0.5% of the total amount of the solution, the pH of the solution is adjusted to 1.0, the stirring speed is controlled to 100 rpm, the mixing reaction is carried out for 30 minutes, and the insoluble matter is removed by filtration to obtain an acidified solution;

[0105] S3: The acidified solution is fed into an ion exchange device at a flow rate of 5 cubic meters per hour, using a cation exchange resin (exchange capacity 20 mmol / g), the solution is in contact with the resin for 30 minutes, and the zinc concentration is kept unchanged after the alkali metal ions are removed;

[0106] S4: sending the solution after ion exchange treatment to an evaporation concentration device at a flow rate of 3 cubic meters per hour, controlling the evaporation temperature to 80°C, evaporating for 1 hour, concentrating under a vacuum degree of 0.08MPa, and finally increasing the zinc ion concentration to 150g / L;

[0107] S5: The concentrated solution is fed into a reduction reaction device at a flow rate of 2 cubic meters per hour, sodium bisulfite is added in an amount of 0.2% of the total weight of the solution, the reaction is carried out at 60° C. for 2 hours, the stirring speed is 200 rpm, and the solution is discharged after reduction;

[0108] S6: sending the reduced solution into a precipitation tank at a flow rate of 1 cubic meter per hour, adding sodium hydroxide in an amount of 0.5% of the total solution, maintaining the solution temperature at 50°C, settling for 1 hour, and separating the supernatant;

[0109] S7: The supernatant is sent to a microfiltration device at a flow rate of 1 cubic meter per hour, the pore size of the filter membrane is 0.1 micron, the operating pressure is 0.1 MPa, and the filtration is performed for 2 hours to obtain a battery-grade zinc chloride solution with a zinc concentration of 500 g / L and an alkali metal content of less than 0.4%.

[0110] Example 3

[0111] S1: The zinc-containing waste liquid from the rotary kiln dust collection system is sent to the gravity sedimentation device at a flow rate of 50 cubic meters per hour, and the solution flow rate is controlled to be 2.0 m / s. The upper clear liquid flows out through the filter cloth with a filtration accuracy of 50 microns to obtain a zinc-containing solution;

[0112] S2: The zinc-containing solution obtained in S1 is transported to a pickling device at a flow rate of 30 cubic meters per hour, and a hydrogen chloride solution is added at the same time, and the addition amount is 3% of the total solution. The pH of the solution is adjusted to 2.5, the stirring speed is controlled to 300 rpm, and the mixing reaction is carried out for 90 minutes. After filtering to remove insoluble matter, an acidified solution is obtained;

[0113] S3: The acidified solution is fed into an ion exchange device at a flow rate of 15 cubic meters per hour, using a cation exchange resin (exchange capacity 50 mmol / g), the solution is in contact with the resin for 60 minutes, and the zinc concentration is kept unchanged after the alkali metal ions are removed;

[0114] S4: sending the solution after ion exchange treatment to an evaporation concentration device at a flow rate of 10 cubic meters per hour, controlling the evaporation temperature at 120°C, evaporating for 4 hours, concentrating under a vacuum degree of 0.1MPa, and finally increasing the zinc ion concentration to 300g / L;

[0115] S5: The concentrated solution is fed into a reduction reaction device at a flow rate of 8 cubic meters per hour, sulfur dioxide solution is added, the addition amount is 1% of the total weight of the solution, the reaction is carried out at 90° C. for 4 hours, the stirring speed is 400 rpm, and the solution is discharged after reduction;

[0116] S6: sending the reduced solution into a precipitation tank at a flow rate of 5 cubic meters per hour, adding magnesium hydroxide in an amount of 2% of the total solution, maintaining the solution temperature at 80°C, settling for 3 hours, and separating the supernatant;

[0117] S7: The supernatant is sent to a microfiltration device at a flow rate of 3 cubic meters per hour, the pore size of the filter membrane is 1 micron, the operating pressure is 0.5 MPa, and the filtration is performed for 6 hours to obtain a battery-grade zinc chloride solution with a zinc concentration of 800 g / L and an alkali metal content of less than 0.5%.

[0118] Table 1 Comparison of performance parameters of finished zinc chloride solution

[0119] Compare Projects Example 1 Example 2 Example 3 Zinc concentration (g / L) 600 500 800 Alkali metal content (%) 0.2 0.4 0.5 Solution purity (%) 99.8 99.5 99.3 Processing time (hours) 12 10 16 Energy consumption (kWh) 300 250 400 Impurity content (ppm) 50 80 100 Stability (days) 180 150 200

[0120] As can be seen from Table 1 above, Example 1 performs well in zinc concentration, alkali metal content, solution purity and stability, while having a moderate processing time and low energy consumption; although Example 3 has a higher zinc concentration, its alkali metal content and impurity content are slightly higher, and its energy consumption is relatively large; Example 2 has the lowest energy consumption, but its zinc concentration and solution purity are not as good as Example 1; therefore, taking all performance indicators into consideration, Example 1 is the best example.

[0121] Table 2 Comparison of other performance parameters

[0122] Compare Projects Example 1 Example 2 Example 3 pH stability range 6.5±0.1 6.3±0.2 6.4±0.3 Electrical conductivity (mS / cm) 70 68 69 Heavy metal impurities (ppm) 0.1 0.2 0.15 Treatment equipment operation and maintenance cost (yuan / ton) 150 180 170 Equipment area (square meters) 200 210 205 Operator requirements (persons) 2 3 2 Production cycle (days) 10 11 12

[0123] As can be seen from Table 2 above, Example 1 shows the best values ​​in all comparison items, including a more stable pH range, lower heavy metal impurity content and maintenance cost, and moderate equipment footprint and production cycle; in contrast, Example 2 has a higher maintenance cost, and Example 3 has a slightly higher heavy metal impurity content; therefore, taking all indicators into consideration, Example 1 is considered to be the best embodiment.

[0124] The present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention. In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without the description of these details. In addition, in order to avoid unnecessary confusion about the essence of the present invention, well-known methods, processes, procedures, components and circuits are not described in detail.

[0125] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A process for treating zinc-containing waste liquid, characterized in that: The following steps are involved: S1: Preliminary treatment of the zinc-containing waste liquid through a gravity sedimentation device to remove larger particles of impurities and suspended matter to obtain a zinc-containing solution; S2: transporting the zinc-containing solution obtained in S1 to a pickling device for acidification treatment; S3: sending the acidified solution to an ion exchange device, treating the solution with a cation exchange resin to remove alkaline metal ions in the solution and maintain the concentration of zinc ions; S4: concentrating the solution after the ion exchange treatment to increase the concentration of zinc; S5: sending the concentrated solution to a reduction reaction device, and using a quantitative reducing agent to perform a reduction reaction to improve the purity of zinc; S6: subjecting the reduced solution to precipitation treatment to separate the supernatant; S7: filtering the separated supernatant to remove the precipitate to obtain a battery-grade zinc chloride solution.

2. A zinc-containing waste liquid treatment process according to claim 1, characterized in that: The S1 specifically includes: S11: Collect the zinc-containing waste liquid from the rotary kiln dust collection system and transport it to the gravity settling device, ensuring that the initial flow rate of the waste liquid is 20 to 50 cubic meters per hour; S12: placing the zinc-containing waste liquid in a gravity sedimentation device for a sedimentation time of 2 to 4 hours; S13: By controlling the flow rate of the solution to 0.5 m / s to 2.0 m / s, the upper clear liquid of the zinc-containing waste liquid flows out, and a filter cloth with a filtration accuracy of 10 microns to 50 microns is used to remove large particle impurities.

3. A zinc-containing waste liquid treatment process according to claim 1, characterized in that: The S2 specifically includes: S21: transporting the zinc-containing solution obtained in S1 to the pickling device through a pipeline system, with a transport flow rate of 10 to 30 cubic meters per hour; S22: in the pickling device, adding an acidic substance to the zinc-containing solution, wherein the amount of the acidic substance added is 0.5% to 3% of the total amount of the solution, so as to adjust the pH value of the solution to 1.0 to 2.5; S23: uniformly mixing the acidic substance and the zinc-containing solution through a stirring system, controlling the stirring speed to be 100 to 300 rpm, and controlling the reaction time to be 30 to 90 minutes, so that the acidic substance reacts with impurities in the solution to promote dissolution and remove some impurities; S24: The acidified solution is filtered to remove insoluble matter.

4. A zinc-containing waste liquid treatment process according to claim 3, characterized in that: The acidic substance is selected from dilute sulfuric acid, hydrochloric acid or hydrogen chloride solution.

5. A zinc-containing waste liquid treatment process according to claim 1, characterized in that: The S3 specifically includes: S31: transporting the acidified solution to the ion exchange device through a pipeline, and the transport flow rate is controlled at 5 to 15 cubic meters per hour; S32: In the ion exchange device, a cation exchange resin is selected and used, and the exchange capacity of the resin is 20 mmol / g to 50 mmol / g; S33: By adjusting the operating conditions of the ion exchange device, the contact time between the resin and the solution is ensured to be 30 minutes to 60 minutes.

6. A zinc-containing waste liquid treatment process according to claim 1, characterized in that: The S4 specifically includes: S41: transporting the solution after ion exchange treatment to an evaporation concentration device through a pipeline, with the transport flow rate controlled at 3 to 10 cubic meters per hour; S42: in the evaporation concentration device, removing part of the water in the solution by evaporation, controlling the evaporation temperature to be between 80° C. and 120° C., and the evaporation time to be between 1 hour and 4 hours; S43: adjusting the vacuum degree of the solution during the evaporation process to 0.08 to 0.1 MPa; S44: The concentrated zinc-containing solution is collected into a storage container, and the zinc ion concentration after concentration is increased to 150 g / L to 300 g / L.

7. A zinc-containing waste liquid treatment process according to claim 1, characterized in that: The S5 specifically includes: S51: transporting the concentrated solution to a reduction reaction device through a pipeline, with the transport flow rate controlled at 2 to 8 cubic meters per hour; S52: adding a reducing agent to the reduction reaction device, wherein the reducing agent is selected from sodium bisulfite, sodium sulfide or sulfur dioxide solution, and the added amount is 0.2% to 1% of the total weight of the solution; S53: controlling the reaction temperature of the solution to be between 60° C. and 90° C., and the reaction time to be between 2 hours and 4 hours; S54: During the reduction reaction, controlling the stirring speed to be between 200 and 400 rpm; S55: Discharge the reacted solution from the reaction device.

8. A zinc-containing waste liquid treatment process according to claim 1, characterized in that: The S6 specifically includes: S61: transporting the reduced solution from the reduction reaction device to the precipitation tank, with the transport flow rate controlled at 1 to 5 cubic meters per hour; S62: adding a precipitant to the precipitation tank in an amount of 0.5% to 2% of the total amount of the solution, and maintaining the temperature of the solution at 50° C. to 80° C.; S63: After standing and settling for 1 to 3 hours, separate the supernatant.

9. A zinc-containing waste liquid treatment process according to claim 8, characterized in that: The precipitating agent is selected from sodium hydroxide, calcium hydroxide or magnesium hydroxide.

10. A zinc-containing waste liquid treatment process according to claim 1, characterized in that: The S7 specifically includes: S71: transporting the supernatant liquid after precipitation from the sedimentation tank to the filtering device, and controlling the transport flow rate to be 1 to 3 cubic meters per hour; S72: In the filtration device, a microfiltration membrane is used for filtration, and the pore size of the filtration membrane is controlled to be 0.1 to 1 micron; S73: Control the filtration operating pressure to be between 0.1 and 0.5 MPa, and the filtration time to be between 2 and 6 hours; S74: collecting the filtered zinc chloride solution into a storage container, wherein the zinc concentration of the solution is 500 g / L to 800 g / L, and the alkali metal content is less than 0.5%.

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