Method and system for treating nickel-containing wastewater by using composite calcium-zinc-aluminum type metal oxide

Abstract

The invention is applicable to the technical field of wastewater treatment, and particularly relates to a method and a system for treating nickel-containing wastewater by using a composite calcium-zinc-aluminum type metal oxide, the method comprises the following steps: obtaining nickel-containing wastewater of a secondary sedimentation tank, and adjusting the pH value of the nickel-containing wastewater of the secondary sedimentation tank to obtain intermediate wastewater; discharging the intermediate wastewater into a regeneration nickel removal tank, and adding a calcium-zinc-aluminum type metal oxide to obtain nickel-loaded calcium-zinc-aluminum type hydrotalcite precipitate; and recovering and drying the nickel-loaded calcium-zinc-aluminum hydrotalcite precipitate to obtain a nickel-loaded calcium-zinc-aluminum hydrotalcite product. According to the method for treating the nickel-containing wastewater by using the composite calcium-zinc-aluminum type metal oxide, the characteristics of large specific surface area and high adsorption performance of the composite calcium-zinc-aluminum type metal oxide are fully utilized, nickel ions in the wastewater are rapidly captured through physical adsorption, and meanwhile, the nickel ions are rapidly captured by using the composite calcium-zinc-aluminum type metal oxide. In the regeneration process, chemical bond combination is carried out on trapped nickel ions and calcium-zinc-aluminum hydrotalcite through chemical reaction to form nickel-loaded calcium-zinc-aluminum hydrotalcite, so that the reaction rate and the removal rate are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a method and system for treating nickel-containing wastewater by utilizing composite calcium-zinc-aluminum metal oxide. Background Art

[0002] Nickel-containing wastewater is a type of heavy metal-contaminated industrial wastewater, which is very common in the field of new energy vehicle batteries, traditional electroplating and other industries. If these nickel-containing wastewaters generated during the nickel plating process are discharged without treatment, the nickel element in them will pollute the water body, affect the survival of aquatic organisms, and even affect human health through the food chain.

[0003] Nickel is a valuable metal resource. If nickel in wastewater can be recovered through effective wastewater treatment technology, it can reduce resource waste and reduce dependence on primary nickel ore, which is conducive to sustainable development. 2+ The Ni in wastewater is mainly removed by ion exchange resin, membrane treatment, chemical precipitation and other technologies. 2+ , but these treatment processes have problems such as poor selectivity and secondary pollution. Summary of the invention

[0004] The purpose of the present invention is to provide a method for treating nickel-containing wastewater using a composite calcium-zinc-aluminum metal oxide, aiming to solve the problems of poor selectivity and secondary pollution in traditional treatment methods.

[0005] The present invention is achieved by a method for treating nickel-containing wastewater using a composite calcium-zinc-aluminum metal oxide, the method comprising:

[0006] Obtaining nickel-containing wastewater from the secondary sedimentation tank, adjusting the pH value of the nickel-containing wastewater from the secondary sedimentation tank, and obtaining intermediate wastewater;

[0007] The intermediate wastewater is discharged into a regeneration nickel removal tank and a composite calcium-zinc-aluminum metal oxide is added to obtain a nickel-loaded calcium-zinc-aluminum hydrotalcite precipitate;

[0008] The nickel-loaded calcium-zinc-aluminum hydrotalcite precipitate is recovered and dried to obtain a nickel-loaded calcium-zinc-aluminum hydrotalcite product.

[0009] Preferably, the water quality of the regenerated nickel removal pool is tested, and if the nickel content is higher than a preset value, the water is refluxed; if the nickel content is not higher than the preset value, the water is discharged.

[0010] Preferably, the composite calcium zinc aluminum type metal oxide is obtained by calcining calcium zinc aluminum type hydrotalcite.

[0011] Preferably, the chemical formula of calcium zinc aluminum type hydrotalcite is [Ca 2+ xZn 2+ y Al 3+ z (OH)2] x+ [CO3 2- ] z / 2 ·mH2O, where x is the molar content of Ca divalent cations, y is the molar content of Zn divalent cations, z is the molar content of Al trivalent cations, y:x is in the range of 1 to 3, (x+y):z is in the range of 2 to 4, A n- It is an n-valent anion located between the layers.

[0012] Preferably, the calcium zinc aluminum type hydrotalcite is prepared by coprecipitation of corresponding divalent and trivalent metal ion anion root salt solutions and NaOH, and the specific steps include:

[0013] Weigh 14.84*X grams of Na2CO3 and dissolve it in XL deionized water, which is recorded as solution A; weigh 32*X grams of NaOH to prepare 0.8*X liters of solution, which is recorded as solution B; take 20*Y liters of 1*M divalent metal ion anion root salt solution (wherein the molar ratio of Zn and Ca is 1-3) and 10*Y liters of 1*M trivalent metal ion anion root salt solution and mix them evenly, which is recorded as solution C, X and Y are proportional coefficients, and their values ​​are determined according to the mass of the product to be finally obtained. Solution C is added dropwise to solution A under stirring, and solution B is added dropwise to adjust the pH to be stable at 8.0-11.0. After the solution C is added dropwise, continue stirring for 2 hours, during which solution B is added to keep the pH stable at 8.0-11.0, transfer the suspension into a three-necked flask, reflux in an oil bath at 80°C for 22 hours, take out, wash with water, and filter, and dry at 80°C to obtain calcium zinc aluminum type hydrotalcite.

[0014] Preferably, in the step of adding solution B dropwise to adjust the pH to be stable at 8.0-11.0, the pH is stabilized at 9.5-10.5 by adding solution B.

[0015] Preferably, when preparing the composite calcium zinc aluminum type metal oxide, the calcium zinc aluminum type hydrotalcite is calcined at a calcination temperature between 200-400°C.

[0016] Another object of the present invention is to provide a nickel-containing wastewater treatment system using a composite calcium-zinc-aluminum metal oxide, comprising a pH regulating tank, the pH regulating tank being provided with a water inlet, a water inlet pump and a pH regulating device being provided at the water inlet, a plurality of mechanical stirring devices being arranged in the pH regulating tank, a water outlet being provided in the pH regulating tank, the water outlet being connected to a regeneration nickel removal tank, a powder dosing device being provided above the regeneration nickel removal tank, a siphon-type sludge suction machine being provided in the regeneration nickel removal tank, the siphon-type sludge suction machine being connected to a nickel-loaded calcium-zinc-aluminum hydrotalcite recovery device, the nickel-loaded calcium-zinc-aluminum hydrotalcite recovery device comprising a plate-frame dehydration device and a drying device, an online water quality monitor being provided at the water outlet of the regeneration nickel removal tank, and the regeneration nickel removal tank being connected to a discharge electric valve and a reflux electric valve.

[0017] The invention provides a method for treating nickel-containing wastewater by using a composite calcium-zinc-aluminum metal oxide. The method makes full use of the characteristics of the composite calcium-zinc-aluminum metal oxide, which has a large specific surface area and strong adsorption performance, to achieve rapid capture of nickel ions in wastewater by physical adsorption. Meanwhile, by using the memory effect, the captured nickel ions and the calcium-zinc-aluminum hydrotalcite are chemically bonded by chemical reaction during the regeneration process to form nickel-loaded calcium-zinc-aluminum hydrotalcite, thereby improving the reaction rate and removal rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A reaction flow chart of a method for treating nickel-containing wastewater using a composite calcium-zinc-aluminum metal oxide provided in an embodiment of the present invention;

[0019] Figure 2 An architectural diagram of a system for treating nickel-containing wastewater using a composite calcium-zinc-aluminum metal oxide provided in an embodiment of the present invention.

[0020] Figure numerals: 1. water inlet pump; 2. water inlet; 3. pH adjustment tank; 4. mechanical stirring device; 5. pH adjustment device; 6. pH detector; 7. connecting pipe; 8. regeneration nickel removal tank; 9. powder dosing device; 10. siphon sludge suction machine; 11. online water quality monitor; 12. water outlet; 13. discharge electric valve; 14. reflux electric valve; 15. plate and frame dehydration equipment; 16. drying equipment. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but unless otherwise specified, these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first xx script may be referred to as a second xx script, and similarly, a second xx script may be referred to as a first xx script.

[0023] like Figure 1 As shown, it is a reaction flow chart of a method for treating nickel-containing wastewater using a composite calcium-zinc-aluminum metal oxide provided by an embodiment of the present invention, the method comprising:

[0024] The nickel-containing wastewater from the secondary sedimentation tank is obtained, and the pH value of the nickel-containing wastewater from the secondary sedimentation tank is adjusted to obtain intermediate wastewater.

[0025] In this step, the nickel-containing wastewater in the secondary sedimentation tank is pre-treated by adding drugs and precipitation, and mainly contains nickel ions. The nickel-containing wastewater in the secondary sedimentation tank is discharged into the pH adjustment tank (3) to adjust the pH value to between 7.0 and 8.0.

[0026] The intermediate wastewater is discharged into the regeneration nickel removal tank (8) and a composite calcium-zinc-aluminum metal oxide is added to obtain a nickel-loaded calcium-zinc-aluminum hydrotalcite precipitate.

[0027] In this step, the effluent from the pH adjustment tank is discharged into the regeneration nickel removal tank 8, and the composite calcium zinc aluminum type metal oxide is added to obtain nickel-loaded calcium zinc aluminum type hydrotalcite precipitation, and the composite calcium zinc aluminum type metal oxide is obtained by calcining calcium zinc aluminum type hydrotalcite.

[0028] The nickel-loaded calcium-zinc-aluminum hydrotalcite precipitate is recovered and dried to obtain a nickel-loaded calcium-zinc-aluminum hydrotalcite product.

[0029] The chemical expression of the calcium zinc aluminum type hydrotalcite is [Ca 2+ x Zn 2+ y Al 3+ z (OH)2] x+ [CO3 2- ] z / 2 mH2O, where A n- is an n-valent anion located between the layers, x is the molar content of Ca divalent cations, y is the molar content of Zn divalent cations, z is the molar content of Al trivalent cations, and the value of y:x in the present invention is in the range of 1 to 3, and (x+y):z is in the range of 2 to 4. After preparation and performance comparison, the treatment efficiency of calcium zinc aluminum type ternary calcium zinc aluminum type hydrotalcite on nickel-containing wastewater and the performance of nickel-loaded calcium zinc aluminum type hydrotalcite obtained after treatment are better than those of common magnesium aluminum type calcium zinc aluminum type hydrotalcite and calcium aluminum type calcium zinc aluminum type hydrotalcite.

[0030] The preparation method of the calcium zinc aluminum type hydrotalcite is as follows: the calcium zinc aluminum type hydrotalcite is prepared by coprecipitation method using corresponding divalent and trivalent metal ion anion root salt solutions and NaOH. The specific operation is as follows: weigh 14.84X g Na2CO3 and dissolve it in XL deionized water, which is recorded as solution A; weigh 32*X grams of NaOH to make 0.8*X liters of solution, which is recorded as solution B; take 20*Y liters of 1*M divalent metal ion anion root salt solution (wherein the molar ratio of Zn and Ca is 1 to 3) and 10*Y liters of 1*M trivalent metal ion anion root salt solution and mix them evenly, which is recorded as solution C. The above X and Y are proportional coefficients, which can be determined according to the final product quality to be obtained. Solution C is slowly added drop by drop to solution A under strong stirring, and solution B is added drop by drop to adjust the pH to be stable at 8.0-11.0, preferably 9.5-10.5. After the addition of solution C is completed, continue to stir vigorously for 2 hours, during which time add an appropriate amount of solution B as needed to keep the pH stable at 8.0-11.0, preferably 9.5-10.5. Finally, transfer the suspension into a three-necked flask, reflux in an oil bath at 80°C for 22 hours, take out, wash with water, filter, and dry at 80°C to obtain calcium zinc aluminum type hydrotalcite.

[0031] The preparation method of the composite calcium zinc aluminum type metal oxide is as follows: the calcium zinc aluminum type hydrotalcite is calcined, and the calcination temperature needs to be controlled at 200-400° C. After calcination, the mixture is naturally cooled to room temperature to obtain the composite calcium zinc aluminum type metal oxide. If the temperature is too high or too low, the target product with good nickel ion removal effect cannot be obtained.

[0032] like Figure 1 As shown, in an embodiment of the present invention, a method for treating nickel-containing wastewater using a composite calcium-zinc-aluminum metal oxide is provided. The nickel-containing wastewater that can be treated comes from a wide range of sources without limitation, and may be electroplating wastewater, nickel metal ion wastewater generated by lithium battery electrode production, or nickel-containing solution discharged from a laboratory.

[0033] First, prepare the composite calcium zinc aluminum type metal oxide. Take Ca2Zn1Al1 hydrotalcite as an example. The method is as follows: weigh 7.42g Na2CO3 and dissolve it in 0.5L deionized water, which is recorded as solution A; weigh 16g NaOH to make 0.4L solution, which is recorded as solution B; take 13.33mL of 1M Ca(NO3)2 solution, 6.67mL of 1M Zn(NO3)2 solution and 10mL of 1M Al(NO3)3 solution and mix them evenly, which is recorded as solution C. Add solution C drop by drop slowly to solution A under strong stirring, and add solution B to adjust the pH to 10. After solution C is added, continue to stir vigorously for 2 hours, and add an appropriate amount of solution B as needed to keep the pH stable at 10. Finally, transfer the suspension into a three-necked flask, reflux in an oil bath at 80℃ for 22h, take out, wash with water, filter, and dry at 80℃ to obtain the Ca2Zn1Al1 hydrotalcite. Subsequently, the Ca2Zn1Al1 hydrotalcite is calcined at 200-400°C to obtain the Ca2Zn1Al1 composite metal oxide. The calcination temperature cannot exceed 500°C, otherwise the Ca2Zn1Al1 hydrotalcite will completely change into a composite oxide form of Ca, Zn and Al, and cannot be regenerated and restored to Ca2Zn1Al1 hydrotalcite. As shown in Table 1, when the Ca2Zn1Al1 composite metal oxide is regenerated into Ca2Zn1Al1 hydrotalcite at pH = 10, the final product has the largest specific surface area, the largest pore volume and pore size, and has the strongest physical adsorption characteristics. Therefore, in the synthesis process of Ca2Zn1Al1 hydrotalcite, controlling the pH between 9.5-10.5 can obtain the final product of nickel-loaded Ca2Zn1Al1 hydrotalcite with the best physical adsorption performance. The following table shows the specific surface area of ​​Ca2Zn1Al1 composite metal oxide obtained by calcining Ca2Zn1Al1 hydrotalcite prepared under different pH conditions when it is regenerated into nickel-loaded Ca2Zn1Al1 hydrotalcite in nickel-containing wastewater.

[0034]

[0035] Nickel-containing wastewater is generally acidic, H + It will react with OH in Ca2Zn1Al1 composite metal oxide and Ca2Zn1Al1 hydrotalcite. - Therefore, it is necessary to first pass through the pH adjustment tank 3 and add NaOH to control the pH of the nickel-containing wastewater to neutral. At the same time, the pH should not exceed 8.0, otherwise excessive OH in the water - Will and Ni 2+ Ni(OH)2 is formed, resulting in the presence of impurities in the final product.

[0036] The nickel-containing wastewater after pH adjustment enters the regeneration nickel removal pool 8, and the prepared composite calcium zinc aluminum type metal oxide is added at this time. At normal temperature and pressure, after 3-5 hours of reaction, the Ca2Zn1Al1 composite metal oxide is restored to Ca2Zn1Al1 hydrotalcite. In this process, the initial stage of the reaction is relatively rapid, mainly utilizing the strong physical adsorption characteristics of the Ca2Zn1Al1 composite metal oxide to adsorb the nickel ions in the water. Subsequently, it enters the middle and late stages of the reaction, which is relatively slow, mainly because the Ca2Zn1Al1 composite metal oxide gradually recovers to Ca2Zn1Al1 hydrotalcite under the effect of the memory effect. In the recovery process, nickel ions will be loaded on the surface of the Ca2Zn1Al1 hydrotalcite in the form of chemical bond connection, and some nickel ions will enter the interlayer of the Ca2Zn1Al1 hydrotalcite. Finally, a nickel-loaded Ca2Zn1Al1 hydrotalcite product with a stable structure will be formed.

[0037] The nickel-loaded Ca2Zn1Al1 hydrotalcite precipitate is recovered and fully dried to obtain a commercially available nickel-loaded Ca2Zn1Al1 hydrotalcite product.

[0038] The water quality should be tested at the outlet of the regenerated nickel removal pool 8 to detect the nickel content therein. It can only be discharged after meeting the standards, and then other pollutants can be removed. If it does not meet the standards, it should be returned to the entrance of the regenerated nickel removal pool 8 for reprocessing. The process of regenerating Ca2Zn1Al1 composite metal oxide into Ca2Zn1Al1 hydrotalcite usually takes about 4-6 hours. The regeneration speed is faster in high temperatures in summer and slower in low temperatures in winter. If it is found in actual application that the nickel content at the outlet of the regenerated nickel removal pool 8 continues to exceed the standard, the flow rate of the entire system should be reduced, and the hydraulic retention time of the regenerated nickel removal pool 8 should be extended to ensure complete regeneration, and the Ca2Zn1Al1 composite metal oxide should be replenished in time to ensure the removal efficiency of nickel ions.

[0039] In the laboratory test bench test environment, the inlet water temperature is 30℃, pH=3.0, the total nickel content is 0.500mg / L, the total wastewater volume is 1000L, and the Figure 1 The process shown in the figure is used for treatment. The final effluent water quality test results are shown in Table 2. When the regeneration nickel removal process lasts for 4 hours, the total nickel removal rate has reached 99.20%, and the final nickel-loaded Ca2Zn1Al1 hydrotalcite product output reaches 21.69g. When the reaction time is increased to 5 hours, the total nickel removal rate and the final nickel-loaded Ca2Zn1Al1 hydrotalcite product output have not been significantly improved. In actual application, the duration of regeneration nickel removal can be dynamically adjusted according to the changes in effluent water quality to ensure a better nickel removal effect. The following table shows the effluent water quality and nickel-loaded Ca2Zn1Al1 hydrotalcite output under different regeneration nickel removal process times.

[0040]

[0041] As a comparison, commercial Mg2Al1 hydrotalcite was used to synthesize Mg2Al1 composite metal oxide under the same conditions, and the test was carried out under the same laboratory bench test environment. The results are shown below. From the data, it can be seen that the Ca2Zn1Al1 composite metal oxide can remove a higher proportion of nickel ions in a shorter time than the composite metal oxide prepared from the common Mg2Al1 hydrotalcite.

[0042]

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] The method and system provided by the present invention make full use of the characteristics of large specific surface area and strong adsorption performance of composite calcium-zinc-aluminum metal oxide, and realize rapid capture of nickel ions in sewage through physical adsorption. At the same time, by utilizing the memory effect, the captured nickel ions and calcium-zinc-aluminum hydrotalcite are chemically bonded to form nickel-loaded calcium-zinc-aluminum hydrotalcite through chemical reaction during the regeneration process. The method has a faster reaction rate and a higher removal rate.

[0045] The method and system provided by the present invention reduce the process flow of nickel-containing wastewater treatment, are easy to operate, and have strong adaptability. They can be applied to nickel-containing wastewater treatment in different regions and of different scales, and do not require the addition of excessive chemical agents during the treatment process, thereby ensuring the stable operation of the system.

[0046] The product obtained by the method provided by the present invention is nickel-loaded calcium-zinc-aluminum hydrotalcite, which has improved physical and chemical properties compared with pure calcium-zinc-aluminum hydrotalcite, and can be used as a building material additive, a plastic industry reinforcing agent, a preparation of drug controlled-release agents and sustained-release agents, a rubber industry filler, an industrial catalytic material, etc., and has a wide range of applications in the industrial field. The recycling and reuse of metallic nickel is fully realized, which is conducive to sustainable development.

[0047] like Figure 2As shown, the present invention also provides a nickel-containing wastewater treatment system using a composite calcium-zinc-aluminum metal oxide, comprising a pH regulating tank 3, wherein the pH regulating tank 3 is provided with a water inlet 2, wherein a water inlet pump 1 and a pH regulating device 5 are provided at the water inlet 2, wherein a plurality of mechanical stirring devices 4 are arranged in the pH regulating tank 3, wherein the pH regulating tank 3 is provided with a water outlet 12, wherein the water outlet 12 is connected to a regeneration nickel removal tank 8, wherein a powder dosing device 9 is provided above the regeneration nickel removal tank 8, wherein a siphon-type sludge suction machine 10 is provided in the regeneration nickel removal tank 8, wherein the siphon-type sludge suction machine 10 is connected to a nickel-loaded calcium-zinc-aluminum hydrotalcite recovery device, wherein the nickel-loaded calcium-zinc-aluminum hydrotalcite recovery device comprises a plate-frame dehydration device 15 and a drying device 16, wherein an online water quality monitor 11 is provided at the water outlet of the regeneration nickel removal tank 8, and wherein the regeneration nickel removal tank 8 is connected to a discharge electric valve 13 and a reflux electric valve 14.

[0048] In this embodiment, the pH adjusting device 5 is used to add a pH adjusting agent, the mechanical stirring device 4 is used to mix the wastewater and NaOH evenly, the plate-frame dehydration device 15 is used to dehydrate the nickel-loaded calcium-zinc-aluminum hydrotalcite precipitate, the drying device 16 is used to further dry the dehydrated nickel-loaded calcium-zinc-aluminum hydrotalcite to obtain commercially available nickel-loaded calcium-zinc-aluminum hydrotalcite, the siphon suction mud machine 10 is used to collect the nickel-loaded calcium-zinc-aluminum hydrotalcite precipitate and discharge it into the nickel-loaded calcium-zinc-aluminum hydrotalcite recovery device through a pipeline, and an online water quality monitor 11 is provided at the outlet of the regeneration nickel removal tank 8 for concentration detection of the nickel content in the water, and discharge it through a pipeline after meeting the standard; if it does not meet the standard, the valve is opened through the linkage control of the automatic control system, and the effluent is led back to the inlet of the regeneration nickel removal tank 8 by the bypass pipeline for reprocessing. The pH adjusting tank 3 and the regeneration nickel removal tank 8 are used to process large flow (>300m 3 / d) nickel-containing wastewater is constructed by civil engineering. 3 / d) When the wastewater contains nickel, it is a metal sheet shell, which can be combined into an integrated equipment.

[0049] pH adjustment tank 3 and regeneration nickel removal tank 8 are used to treat large flow (>300m 3 / d) nickel-containing wastewater, in order to meet the hydraulic retention time, the pool volume is large and is usually built by civil engineering; when treating small flow (≤300m 3 / d) When treating wastewater containing nickel, metal sheet shells can be used to combine into an integrated device, which is convenient for quick installation and shortens the construction period.

[0050] In actual application, nickel-containing wastewater is transported by the water inlet pump 1 and enters the pH adjustment tank 3 through the water inlet 2. The pH adjustment device 5 will add a 10% concentration of NaOH solution according to the amount of water. The pH value of the nickel-containing wastewater will be detected in real time by the pH detector 6 at the outlet of the pH adjustment tank 3, and the measured pH value will be transmitted to the pH adjustment device 5, and then the pH value at the outlet will be stabilized between 7.0-8.0 through PID control. The mechanical stirring device 4 can fully stir and mix the NaOH solution and the nickel-containing wastewater.

[0051] The nickel-containing wastewater in the pH adjustment tank 3 is overflowed and enters the regeneration nickel removal tank 8 through the connecting pipe 7. The Ca2Zn1Al1 composite metal oxide is loaded into the powder dosing device 9, and then controlled by the automatic control program, and is added to the water inlet of the regeneration nickel removal tank 8, and the regeneration nickel removal tank 8 is filled with water. Based on the large specific surface area of ​​the Ca2Zn1Al1 composite metal oxide, the nickel ions in the wastewater will be physically adsorbed by the composite metal oxide in a short time and gradually precipitated at the bottom of the regeneration nickel removal tank 8. After that, under the action of the memory effect, through chemical action, nickel-loaded Ca2Zn1Al1 hydrotalcite is regenerated after 3-5h. At this time, the siphon suction mud machine 10 is started to collect the nickel-loaded Ca2Zn1Al1 hydrotalcite at the bottom of the regeneration nickel removal tank and transport it to the plate and frame dehydration equipment 15 through a pipeline. After dehydration into dry mud, it enters the drying equipment 16 and is further processed into a fluffy, dry nickel-loaded Ca2Zn1Al1 hydrotalcite product.

[0052] An online water quality monitor 11 is installed at the water outlet of the regeneration nickel removal tank 8 to detect parameters such as the pH and total nickel content of the upper clear liquid in real time. When the total nickel content is lower than 0.05 mg / L or the limit value set according to project needs, the reflux electric valve 14 is closed and the discharge electric valve 13 is opened, and the upper clear liquid of the regeneration nickel removal tank 8 meets the discharge standards; when the total nickel content is higher than 0.05 mg / L or the limit value set according to project needs, the reflux electric valve 14 is opened and the discharge electric valve 13 is closed, and the upper clear liquid of the regeneration nickel removal tank 8 returns to the water inlet of the regeneration nickel removal tank 8 through the reflux pipe for reprocessing.

[0053] In the actual test, the processing scale was set to 1200m 3 / d, running time 24 hours a day, temperature 30℃, pH=4.50, total nickel content of influent water 1.00mg / L, using Figure 2 The treatment system shown in the figure was used for treatment. After testing, the effluent quality was 0.01 mg / L of total nickel and pH = 7.42, which met the national standards. The total nickel removal rate was 99.00%. After drying treatment, 48 kg of nickel-loaded Ca2Zn1Al1 hydrotalcite was finally recovered after 24 hours of operation.

[0054] It should be understood that, although each step in the flow chart of each embodiment of the present invention is shown in sequence according to the indication of the arrow, these steps are not necessarily performed in sequence according to the order indicated by the arrow. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be performed in other orders. Moreover, at least a portion of the steps in each embodiment may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily performed at the same time, but can be performed at different times, and the execution order of these sub-steps or stages is not necessarily performed in sequence, but can be performed in turn or alternately with at least a portion of other steps or sub-steps or stages of other steps.

[0055] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0056] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for treating nickel-containing wastewater using a composite calcium-zinc-aluminum metal oxide, characterized in that: The method comprises: Obtaining nickel-containing wastewater from the secondary sedimentation tank, adjusting the pH value of the nickel-containing wastewater from the secondary sedimentation tank, and obtaining intermediate wastewater; The intermediate wastewater is discharged into a regeneration nickel removal tank (8) and a composite calcium-zinc-aluminum metal oxide is added to obtain a nickel-loaded calcium-zinc-aluminum hydrotalcite precipitate; The nickel-loaded calcium-zinc-aluminum hydrotalcite precipitate is recovered and dried to obtain a nickel-loaded calcium-zinc-aluminum hydrotalcite product.

2. The method for treating nickel-containing wastewater using a composite calcium-zinc-aluminum metal oxide according to claim 1, characterized in that: The water quality of the regeneration nickel removal pool (8) is tested. If the nickel content is higher than a preset value, the water is refluxed. If the nickel content is not higher than the preset value, the water is discharged.

3. The method for treating nickel-containing wastewater using a composite calcium-zinc-aluminum metal oxide according to claim 1, characterized in that: The composite calcium zinc aluminum type metal oxide is obtained by calcining calcium zinc aluminum type hydrotalcite.

4. The method for treating nickel-containing wastewater using a composite calcium-zinc-aluminum metal oxide according to claim 1, characterized in that: The chemical formula of calcium zinc aluminum hydrotalcite is [Ca 2+ x Zn 2+ y Al 3+ z (OH)2] x+ [CO3 2- ] z / 2 ·mH2O, where x is the molar content of Ca divalent cations, y is the molar content of Zn divalent cations, z is the molar content of Al trivalent cations, y:x is in the range of 1 to 3, (x+y):z is in the range of 2 to 4, A n- It is an n-valent anion located between the layers.

5. The method for treating nickel-containing wastewater using a composite calcium-zinc-aluminum metal oxide according to claim 1, characterized in that: Calcium zinc aluminum type hydrotalcite is prepared by co-precipitation method with corresponding divalent and trivalent metal ion anion root salt solution and NaOH, and the specific steps include: Weigh 14.84*X grams of Na2CO3 and dissolve it in XL deionized water, which is recorded as solution A; weigh 32*X grams of NaOH to prepare 0.8*X liters of solution, which is recorded as solution B; take 20*Y liters of 1*M divalent metal ion anion root salt solution (wherein the molar ratio of Zn and Ca is 1-3) and 10*Y liters of 1*M trivalent metal ion anion root salt solution and mix them evenly, which is recorded as solution C, X and Y are proportional coefficients, and their values ​​are determined according to the mass of the product to be finally obtained. Solution C is added dropwise to solution A under stirring, and solution B is added dropwise to adjust the pH to be stable at 8.0-11.

0. After the solution C is added dropwise, continue stirring for 2 hours, during which solution B is added to keep the pH stable at 8.0-11.0, transfer the suspension into a three-necked flask, reflux in an oil bath at 80°C for 22 hours, take out, wash with water, and filter, and dry at 80°C to obtain calcium zinc aluminum type hydrotalcite.

6. The method for treating nickel-containing wastewater using composite calcium-zinc-aluminum metal oxide according to claim 5, characterized in that: In the step of adding solution B dropwise to stabilize the pH at 8.0-11.0, the pH is stabilized at 9.5-10.5 by adding solution B.

7. The method for treating nickel-containing wastewater using composite calcium-zinc-aluminum metal oxide according to claim 3, characterized in that: When preparing the composite calcium-zinc-aluminum metal oxide, the calcium-zinc-aluminum hydrotalcite is calcined at a temperature between 200 and 400°C.

8. A nickel-containing wastewater treatment system using a composite calcium-zinc-aluminum metal oxide, characterized in that: The invention comprises a pH regulating tank (3), wherein the pH regulating tank (3) is provided with a water inlet (2), wherein a water inlet pump (1) and a pH regulating device (5) are provided at the water inlet (2), wherein a plurality of mechanical stirring devices (4) are arranged in the pH regulating tank (3), wherein a water outlet (12) is provided in the pH regulating tank (3), wherein the water outlet (12) is connected to a regeneration nickel removal tank (8), wherein a powder dosing device (9) is provided above the regeneration nickel removal tank (8), wherein a siphon-type sludge suction machine (10) is provided in the regeneration nickel removal tank (8), wherein the siphon-type sludge suction machine (10) is connected to a nickel-loaded calcium-zinc-aluminum hydrotalcite recovery device, wherein the nickel-loaded calcium-zinc-aluminum hydrotalcite recovery device comprises a plate-frame dehydration device (15) and a drying device (16), wherein an online water quality monitor (11) is provided at the water outlet of the regeneration nickel removal tank (8), and wherein the regeneration nickel removal tank (8) is connected to a discharge electric valve (13) and a reflux electric valve (14).

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