Method for removing iron and aluminum ions from aluminum etching waste liquid and separation method

Abstract

The application provides a method for removing iron and aluminum ions in aluminum etching waste liquid and a separation method; the separation method comprises the following steps: S1, providing a to-be-treated liquid; the to-be-treated liquid contains iron ions and aluminum ions, and the initial pH of the to-be-treated liquid is not more than 2; S2, adjusting the pH of the to-be-treated liquid to 3-6 to obtain a first treated liquid; S3, performing heating treatment on the first treated liquid to obtain a second treated liquid; the temperature of the heating treatment is 50-100 DEG C; S4, performing cooling treatment on the second treated liquid to obtain a third treated liquid; S5, performing sedimentation treatment on the third treated liquid to obtain supernatant and iron and aluminum-containing precipitate. The application has excellent removal effect on iron and aluminum ions in the to-be-treated liquid, and solves the problem of fine particle effect in the precipitation method.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of industrial wastewater treatment, and particularly relates to a method for removing iron and aluminum ions in aluminum etching waste liquid and a separation method. BACKGROUND

[0002] A large amount of acidic etching waste liquid is generated in the etching process. The aluminum etching waste liquid is generated after wet etching of an aluminum template in the photoelectric industry. Generally, the aluminum etching waste liquid contains 50-70% of phosphoric acid, 3-20% of acetic acid and 1-5% of nitric acid, and contains a large amount of metal impurities, in which the aluminum and iron concentrations reach 1300 ppm and 500 ppm, respectively. Generally, for resource utilization of the aluminum etching waste liquid, the acetic acid, nitric acid and phosphoric acid in the aluminum etching waste liquid need to be separated by vacuum distillation, and then the separated components are further synthesized into resource products. The separated phosphoric acid bottom liquid often contains a large amount of iron and aluminum ions, which are often doped in the subsequent resource products, affecting the product purity, resulting in that the resource products are unqualified and application limited, and adversely affecting the recycling and utilization thereof. At the same time, the wastewater after direct resource treatment of the phosphoric acid bottom liquid also contains a large amount of iron and aluminum ions, and direct discharge will cause serious pollution to the water environment. Therefore, direct resource treatment of the waste liquid containing iron and aluminum will greatly reduce the recycling value, hinder the high-value utilization, and cause environmental hazards. As can be seen, efficient removal of iron and aluminum ions in the etching waste liquid has dual significance of resources and environment.

[0003] Currently, the commonly used technologies for treatment of industrial wastewater containing iron and aluminum include chemical precipitation method, oxidation-reduction method, solvent extraction method, ion exchange method, adsorption method, membrane separation technology, phytoremediation method, biological flocculation method, biological adsorption method, solvent extraction method and the like. The above treatment processes more or less have defects of poor treatment effect, high cost and easy to cause secondary pollution. Among them, the precipitation method has a wide application in the actual process due to its simple operation. However, when the precipitation method is used to treat the iron and aluminum wastewater, the fine particle effect exists, so that the fine particles of iron and aluminum are uniformly distributed in the solution, which is difficult to separate, thereby seriously affecting the separation efficiency and treatment effect. The use of flocculants has a certain effect on solving this problem, but the use of flocculants will increase the cost of reagents and increase the discharge amount of solid waste, which is not conducive to the waste reduction treatment.

[0004] Therefore, it is necessary to provide a method for removing iron and aluminum ions in aluminum etching waste liquid and a separation method, so as to solve or at least alleviate the technical problem of how to efficiently remove iron and aluminum in the waste liquid. SUMMARY

[0005] The main purpose of the present application is to provide a method for removing iron and aluminum ions in aluminum etching waste liquid and a separation method, which aims to solve or at least alleviate the technical problem of how to efficiently remove iron and aluminum in the waste liquid.

[0006] To achieve the above object, the present application provides a method for separating iron and aluminum, comprising the steps of:

[0007] S1, providing a to-be-treated liquid; the to-be-treated liquid contains iron ions and aluminum ions, and the initial pH of the to-be-treated liquid is not more than 2;

[0008] S2, adjusting the pH of the to-be-treated liquid to 3-6 to obtain a first treated liquid;

[0009] S3, performing a heating treatment on the first treated liquid to obtain a second treated liquid; the temperature of the heating treatment is 50-100℃;

[0010] S4, performing a cooling treatment on the second treated liquid to obtain a third treated liquid; the cooling treatment comprises: after the heating treatment is completed, the second treated liquid is cooled to not more than 35℃;

[0011] S5, performing a sedimentation treatment on the third treated liquid to obtain supernatant and iron-aluminum-containing precipitate.

[0012] Further, in the to-be-treated liquid, the concentration of iron ions is 200-800ppm, and the concentration of aluminum ions is 1000-1600ppm.

[0013] Further, the to-be-treated liquid further contains phosphoric acid.

[0014] Further, the process of adjusting the pH of the to-be-treated liquid to 3-6 comprises: mixing an alkaline precipitant into the to-be-treated liquid, and controlling the pH of the to-be-treated liquid to 3-6 by the alkaline precipitant.

[0015] Further, the alkaline precipitant comprises one or more of ammonia water and sodium hydroxide solution.

[0016] Further, the duration of the heating treatment is 2-8min.

[0017] Further, the cooling treatment is quenching treatment or normal temperature treatment; the quenching treatment comprises: after the heating treatment is completed, the second treated liquid is cooled to not more than 35℃ in liquid nitrogen or ice water; the normal temperature treatment comprises: after the heating treatment is completed, the second treated liquid is cooled to not more than 35℃ at normal temperature.

[0018] Further, the sedimentation treatment is performed at 5-35℃; the duration of the sedimentation treatment is not less than 5min or is 5-30min.

[0019] The present application also provides a method for removing iron and aluminum ions in aluminum etching waste liquid, comprising the steps of:

[0020] S01, providing an aluminum etching waste liquid containing phosphoric acid, acetic acid, nitric acid, iron ions and aluminum ions, wherein the initial pH of the aluminum etching waste liquid is not more than 2;

[0021] S02, adjusting the pH of the aluminum etching waste liquid to 3-6 to obtain a first treatment liquid;

[0022] S03, performing a heating treatment on the first treatment liquid to obtain a second treatment liquid; the temperature of the heating treatment is 50-100 DEG C;

[0023] S04, performing a cooling treatment on the second treatment liquid to obtain a third treatment liquid; the cooling treatment comprises: after the heating treatment is completed, the second treatment liquid is cooled to not more than 35 DEG C;

[0024] S05, performing a sedimentation treatment on the third treatment liquid to obtain a supernatant and an iron and aluminum containing precipitate.

[0025] Further, in the aluminum etching waste liquid, the concentration of iron ions is 200-800 ppm, and the concentration of aluminum ions is 1000-1600 ppm;

[0026] The process of adjusting the pH of the aluminum etching waste liquid to 3-6 comprises: mixing an alkaline precipitant into the aluminum etching waste liquid, and controlling the pH of the aluminum etching waste liquid to 3-6 by the alkaline precipitant; the alkaline precipitant comprises one or more of ammonia and sodium hydroxide;

[0027] The duration of the heating treatment is 2-8 min;

[0028] The cooling treatment is quenching treatment or normal temperature treatment; the quenching treatment comprises: after the heating treatment is completed, the second treatment liquid is cooled to not more than 35 DEG C in liquid nitrogen or ice water; the normal temperature treatment comprises: after the heating treatment is completed, the second treatment liquid is cooled to not more than 35 DEG C at normal temperature;

[0029] The sedimentation treatment is performed at 5-35 DEG C; the duration of the sedimentation treatment is not less than 5 min or 5-30 min.

[0030] Compared with the prior art, the present application has at least the following advantages:

[0031] This invention proposes a rapid method for separating iron and aluminum. The process is simple, exhibits rapid and excellent removal of iron and aluminum ions from the treatment solution, and solves the fine particle effect problem in precipitation methods. This invention involves adding an alkaline precipitant to the iron- and aluminum-containing treatment solution to induce a chemical reaction, generating fine particle precipitates. The resulting treatment solution is then heated and cooled to disrupt the surface stability of the particles, causing the small particles to aggregate into larger precipitates. Crystal growth is controlled by adjusting the temperature, allowing for the simultaneous removal of iron and aluminum. This eliminates the need for additional flocculants, effectively reducing solid waste production and avoiding secondary pollution caused by flocculant addition. The method boasts high removal efficiency, stable results, a simple process, and low cost. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content shown in these drawings without creative effort.

[0033] Figure 1 This is a schematic flowchart of the method for removing iron and aluminum ions from aluminum etching waste liquid in this invention.

[0034] Figure 2 This is a graph showing the iron and aluminum removal efficiency for different settling times in Example 1 of the present invention.

[0035] Figure 3 This is a schematic diagram illustrating the effects of Example 2 (sedimentation time of 10 min), Example 5 (sedimentation time of 10 min), and Comparative Example 1 (sedimentation time of 60 min) in removing iron and aluminum from aluminum etching waste liquid in this invention.

[0036] In the figure, Example 2 corresponds to heating-rapid cooling, Example 5 corresponds to heating-room temperature, and Comparative Example 1 corresponds to room temperature precipitation; from Figure 3 It can be seen that: after adding only an alkaline precipitant and settling for 60 minutes, the supernatant is still turbid and the iron and aluminum in the supernatant are difficult to settle. After heating and cooling, the small particles quickly aggregate and grow, which makes the originally difficult-to-settle fine colloids settle quickly. The supernatant obtained is clear and transparent, and the iron and aluminum removal effect is good.

[0037] Figure 4 These are SEM images comparing the particle shapes of the iron-aluminum precipitates in Example 2 (sedimentation time 20 min) and Comparative Example 1 (sedimentation time 60 min); where (a) is the iron-aluminum precipitate in Example 2, and (b) is the iron-aluminum precipitate in Comparative Example 1; from Figure 4It can be seen that the precipitate after the heating-cooling treatment has 2-5 μm fine particles gathered, and the precipitate formed by the conventional treatment of adding only the basic precipitator has a particle size of about 50 μm; it is indicated that the heating-cooling treatment promotes the fine particles to gather and precipitate by destroying the surface stability of the particles, thereby improving the removal effect of iron and aluminum in the solution.

[0038] The implementation, functional features and advantages of the present application will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work under the premise that the present application belongs to the protection scope of the present application.

[0040] In addition, the technical solutions in each embodiment of the present application can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, and when the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope of the present application.

[0041] When the embodiments give numerical ranges, it should be understood that, unless otherwise stated by the present application, each numerical range of two endpoints and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present application are used by those skilled in the art in the prior art and the description of the present application, and any method, equipment and material of the prior art similar or equivalent to the method, equipment and material described in the embodiments of the present application can be used to realize the present application.

[0042] The present application provides a method for separating iron and aluminum, comprising the steps of:

[0043] S1, providing a liquid to be treated.

[0044] In the present application, the liquid to be treated contains iron ions (Fe 3+ ) and aluminum ions (Al 3+ ); the liquid to be treated is an acidic liquid, the initial pH of the liquid to be treated is not more than 2 or less than 1; the concentration of iron ions in the liquid to be treated is 200-800 ppm, and the concentration of aluminum ions is 1000-1600 ppm.

[0045] As a further illustration, the to-be-treated liquid can also contain phosphoric acid, and the to-be-treated liquid can be a phosphoric acid base solution containing iron ions and aluminum ions, which can be derived from aluminum etching waste liquid; as another illustration, the to-be-treated liquid can also contain phosphoric acid, acetic acid, nitric acid, and the to-be-treated liquid can be the aluminum etching waste liquid containing iron ions and aluminum ions.

[0046] S2, adjusting the pH of the to-be-treated liquid to 3-6 or 4-6 or 5-6 to obtain a first treated liquid; in the present application, the first treated liquid does not need to be left standing or stirred after the adjustment is completed; the heating treatment in step S3 is immediately performed after the adjustment is completed.

[0047] In the present application, the process of adjusting the pH of the to-be-treated liquid to 3-6 or 4-6 or 5-6 includes mixing an alkaline precipitant into the to-be-treated liquid, and controlling the pH of the to-be-treated liquid to 3-6 or 4-6 or 5-6 by the alkaline precipitant; specifically, the alkaline precipitant is added to the to-be-treated liquid to adjust the pH of the to-be-treated liquid to 3-6 or 4-6 or 5-6. The alkaline precipitant includes one or more of ammonia and sodium hydroxide solution; specifically, the ammonia or the sodium hydroxide solution, the concentration of the ammonia and the sodium hydroxide solution can be 0.1-1M.

[0048] S3, performing a heating treatment on the first treated liquid to obtain a second treated liquid.

[0049] In the present application, the temperature of the heating treatment is 50-100℃ (preferably 70-90℃ or 75-85℃ or 80-90℃), and the time length of the heating treatment is 2-8min (preferably 4-6min); for example, the first treated liquid is heated to 50-100℃ and then incubated for 2-8min.

[0050] S4, performing a cooling treatment on the second treated liquid to obtain a third treated liquid.

[0051] In the present application, the process of the cooling treatment includes immediately cooling the second treated liquid to not more than 35℃ (specifically, 5-35℃ or room temperature) after the heating treatment is completed ；The cooling treatment is quenching treatment or normal temperature treatment; the cooling time of the quenching treatment is not more than 5 minutes; the quenching treatment comprises: after the heating treatment is completed, the second treatment liquid is cooled to not more than 35 DEG C (specifically, 5-35 DEG C or normal temperature) in liquid nitrogen or ice water; the normal temperature treatment comprises: after the heating treatment is completed, the second treatment liquid is cooled to not more than 35 DEG C (specifically, 5-35 DEG C or normal temperature) at normal temperature. Preferably, the cooling treatment is the quenching treatment; specifically, the second treatment liquid is immediately subjected to the quenching treatment after the heating treatment is completed, so that the second treatment liquid is rapidly cooled. In the present application, the cooling time in liquid nitrogen can be not more than 1 minute, and the cooling time in ice water can be not more than 5 minutes.

[0052] S5, after the cooling treatment is completed, the third treatment liquid is immediately subjected to a sedimentation treatment to obtain supernatant and iron-aluminum-containing precipitate.

[0053] In the present application, the sedimentation treatment is carried out at 5-35 DEG C; the time of the sedimentation treatment is not less than 5 minutes or is 5-30 minutes or is 10-15 minutes. The sedimentation treatment is specifically carried out at normal temperature; the specific operation of the sedimentation treatment is standing.

[0054] In the present application, after the sedimentation treatment is completed, the third treatment liquid can be subjected to solid-liquid separation, so that the supernatant separation liquid and the precipitate separation product are obtained; the specific method of the solid-liquid separation is centrifugal separation.

[0055] In the present application, by adding an alkaline precipitant, heating, rapid cooling, sedimentation and other methods, iron and aluminum can be efficiently removed; specifically, a precipitant is added to the treatment liquid containing iron and aluminum ions, adjusted to a suitable pH range, then the treatment liquid after adding the precipitant is heated, rapidly cooled after being heated to a certain temperature, and after a period of sedimentation, a separation liquid with extremely low iron and aluminum concentration is obtained.

[0056] Based on the specific application scenarios of the above separation method, the present application also provides a method for removing iron and aluminum ions from aluminum etching waste liquid, and in the method for removing iron and aluminum ions from aluminum etching waste liquid and the above separation method, the same technical features can be kept consistent.

[0057] In the present application, referring to Figure 1 It is understood that the method for removing iron and aluminum ions from aluminum etching waste liquid comprises the following steps:

[0058] S01, providing aluminum etching waste liquid.

[0059] The aluminum etching waste liquid contains phosphoric acid, acetic acid, nitric acid, iron ions and aluminum ions, in the embodiment of the present application, the iron and aluminum in the aluminum etching waste liquid exist in the form of iron ions and aluminum ions respectively; the aluminum etching waste liquid is acidic, and the initial pH of the aluminum etching waste liquid is not more than 2 or less than 1.

[0060] In the aluminum etching waste liquid, the concentration of iron ions is 200-800 ppm, and the concentration of aluminum ions is 1000-1600 ppm; in the aluminum etching waste liquid, the mass percentage of phosphoric acid is 50-70%, the mass percentage of acetic acid is 3-20%, and the mass percentage of nitric acid is 1-5%.

[0061] S02, the pH of the aluminum etching waste liquid is adjusted to 3-6 or 4-6 or 5-6, and a first treatment liquid is obtained.

[0062] In the present application, the process of adjusting the pH of the aluminum etching waste liquid to 3-6 or 4-6 or 5-6 includes mixing an alkaline precipitant into the aluminum etching waste liquid, and controlling the pH of the aluminum etching waste liquid to 3-6 or 4-6 or 5-6 by the alkaline precipitant; the alkaline precipitant includes one or more of ammonia and sodium hydroxide solution; specifically, the ammonia or the sodium hydroxide solution, the concentration of the ammonia and the sodium hydroxide can be 0.1-1M.

[0063] S03, the first treatment liquid is subjected to a heating treatment, and a second treatment liquid is obtained.

[0064] In the present application, the temperature of the heating treatment is 50-100℃ (preferably 70-90℃ or 75-85℃), and the time of the heating treatment is 2-8min (preferably 4-6min); for example, the first treatment liquid is heated to 50-100℃ and then kept for 2-8min.

[0065] S04, the second treatment liquid is subjected to a cooling treatment, and a third treatment liquid is obtained.

[0066] In the present application, the process of the cooling treatment includes: after the heating treatment is completed, the second treatment liquid is cooled to not more than 35℃ (specifically, 5-35℃ or room temperature); the cooling treatment is quenching treatment or room temperature treatment; the cooling time of the quenching treatment is not more than 5min; the quenching treatment includes: after the heating treatment is completed, the second treatment liquid is cooled in liquid nitrogen or ice water to not more than 35℃ (specifically, 5-35℃ or room temperature); the room temperature treatment includes: after the heating treatment is completed, the second treatment liquid is cooled to not more than 35℃ (specifically, 5-35℃ or room temperature) at room temperature.

[0067] S05, immediately after the cooling treatment is completed, the third treatment liquid is subjected to a sedimentation treatment to obtain supernatant and a precipitate containing iron and aluminum.

[0068] In the present application, the sedimentation treatment is carried out at 5-35℃; the duration of the sedimentation treatment is not less than 5min or is 5-30min or is 10-15min. The sedimentation treatment is specifically carried out at room temperature; the specific operation of the sedimentation treatment is standing.

[0069] In the present application, after the sedimentation treatment is completed, the third treatment liquid can also be subjected to solid-liquid separation, so as to obtain a separated liquid of the supernatant and a separated material of the precipitate; the specific method of the solid-liquid separation is centrifugal separation. (Note: in the examples and comparative examples of the present application, when the concentration of iron and aluminum in the solution after the sedimentation treatment is tested, the supernatant is directly taken without centrifugal separation; if the precipitate needs to be separated out for analysis, centrifugal separation is adopted).

[0070] In the present application, first, an alkaline precipitant is added to the aluminum etching waste liquid and other treatment liquid; at this time, part of the iron and aluminum ions in the treatment liquid form a stable colloidal system and are difficult to precipitate; through heating-cooling, especially heating-quenching, the stability of the nanoparticles is destroyed, the fine iron and aluminum particles are quickly agglomerated into large particles and precipitate, the effect of rapid precipitation is achieved, the precipitation efficiency is improved, and the problems of high cost and secondary pollution caused by the use of flocculants and other methods are avoided, thereby providing a new method for efficiently removing high-concentration iron and aluminum wastewater.

[0071] The following are specific examples of the present application:

[0072] Example 1

[0073] A method for removing iron and aluminum ions in aluminum etching waste liquid, comprising the following steps:

[0074] 1. Take the aluminum etching waste liquid of a company, Al 3+ and Fe 3+ concentrations are 1300ppm and 500ppm respectively, and pH<1. The aluminum etching waste liquid is labeled with the content of phosphoric acid of 50-70%, the content of acetic acid of 3-20%, and the content of nitric acid of 1-5%.

[0075] 2. At room temperature, ammonia water is added to the aluminum etching waste liquid (high-concentration ammonia water is added first for coarse adjustment, and low-concentration ammonia water is added for fine adjustment, and the concentration of ammonia water is in the range of 0.1-1M), the pH of the waste liquid is adjusted to 5, and a first treatment liquid is obtained.

[0076] 3. The first treatment liquid is heated to 75℃ and kept for 5min to obtain a second treatment liquid.

[0077] 4. The second treatment liquid is rapidly cooled to room temperature within 5 minutes by ice water cooling to obtain a third treatment liquid.

[0078] 5. The third treatment liquid is allowed to settle at room temperature to separate into supernatant and iron-aluminum precipitate.

[0079] In this example, when the settling time is 10 minutes, the Fe and Al concentrations in the supernatant are 6.75 ppm and 23.79 ppm, respectively.

[0080] In this example, when the settling time is 15 minutes, the Fe and Al concentrations in the supernatant are 2.41 ppm and 11.46 ppm, respectively.

[0081] Example 2

[0082] A method for removing iron and aluminum ions from aluminum etching waste liquid, comprising the following steps:

[0083] 1. Take aluminum etching waste liquid from a company (same as in Example 1).

[0084] 2. At room temperature, add ammonia water (first add high-concentration ammonia water for coarse adjustment, then add low-concentration ammonia water for fine adjustment, and the ammonia water concentration is in the range of 0.1-1 M) to the aluminum etching waste liquid to adjust the pH of the waste liquid to 5 to obtain a first treatment liquid.

[0085] 3. Heat the first treatment liquid to 85°C and maintain for 5 minutes to obtain a second treatment liquid.

[0086] 4. Rapidly cool the second treatment liquid to room temperature within 5 minutes by ice water cooling to obtain a third treatment liquid.

[0087] 5. Allow the third treatment liquid to settle at room temperature to separate into supernatant and iron-aluminum precipitate.

[0088] In this example, when the settling time is 10 minutes, the Fe and Al concentrations in the supernatant are 1.07 ppm and 5.52 ppm, respectively.

[0089] Example 3

[0090] A method for removing iron and aluminum ions from aluminum etching waste liquid, comprising the following steps:

[0091] 1. Take aluminum etching waste liquid from a company (same as in Example 1).

[0092] 2. At room temperature, add ammonia water (first add high-concentration ammonia water for coarse adjustment, then add low-concentration ammonia water for fine adjustment, and the ammonia water concentration is in the range of 0.1-1 M) to the aluminum etching waste liquid to adjust the pH of the waste liquid to 5 to obtain a first treatment liquid.

[0093] 3. The first treatment solution is heated to 85°C and kept for 5 minutes to obtain a second treatment solution.

[0094] 4. The second treatment solution is rapidly cooled to room temperature within 1 minute by liquid nitrogen cooling to obtain a third treatment solution.

[0095] 5. The third treatment solution is allowed to settle at room temperature to separate into supernatant and iron-aluminum precipitate.

[0096] In this example, when the settling time is 10 minutes, the Fe and Al concentrations in the supernatant are 1.41 ppm and 5.07 ppm, respectively.

[0097] Example 4

[0098] A method for removing iron and aluminum ions from aluminum etching waste solution, comprising the following steps:

[0099] 1. Take aluminum etching waste solution from a company (same as in Example 1).

[0100] 2. At room temperature, add ammonia water (first add high-concentration ammonia water for coarse adjustment, then add low-concentration ammonia water for fine adjustment, and the ammonia water concentration is in the range of 0.1-1 M) to the aluminum etching waste solution to adjust the pH of the waste solution to 5 to obtain a first treatment solution.

[0101] 3. The first treatment solution is heated to 95°C and kept for 5 minutes to obtain a second treatment solution.

[0102] 4. The second treatment solution is rapidly cooled to room temperature within 5 minutes by ice water cooling to obtain a third treatment solution.

[0103] 5. The third treatment solution is allowed to settle at room temperature to separate into supernatant and iron-aluminum precipitate.

[0104] In this example, when the settling time is 30 minutes, the Fe and Al concentrations in the supernatant are 80.65 ppm and 158.47 ppm, respectively.

[0105] Example 5

[0106] A method for removing iron and aluminum ions from aluminum etching waste solution, comprising the following steps:

[0107] 1. Take aluminum etching waste solution from a company (same as in Example 1).

[0108] 2. At room temperature, add sodium hydroxide solution (first add high concentration sodium hydroxide solution for coarse adjustment, then add low concentration sodium hydroxide solution for fine adjustment, the concentration of sodium hydroxide solution is in the range of 0.1-1M) to the aluminum etching waste liquid, adjust the pH of the waste liquid to 5, and obtain a first treatment liquid.

[0109] 3. Heat the first treatment liquid to 85°C and keep for 5 min, and obtain a second treatment liquid.

[0110] 4. Cool the second treatment liquid to room temperature (about 40 min) at room temperature, and obtain a third treatment liquid.

[0111] 5. Allow the third treatment liquid to settle at room temperature in a static manner, so that the third treatment liquid is layered into supernatant and iron-aluminum precipitate.

[0112] In this embodiment, when the settling time is 15 min, the concentrations of Fe and Al in the supernatant are 7.68 ppm and 16.73 ppm, respectively.

[0113] In this embodiment, when the settling time is 30 min, the concentrations of Fe and Al in the supernatant are 3.34 ppm and 9.93 ppm, respectively.

[0114] Example 6

[0115] A method for removing iron and aluminum ions in aluminum etching waste liquid, comprising the following steps:

[0116] 1. Take the aluminum etching waste liquid of a certain company (same as in Example 1).

[0117] 2. At room temperature, add ammonia water (first add high concentration ammonia water for coarse adjustment, then add low concentration ammonia water for fine adjustment, the concentration of ammonia water is in the range of 0.1-1M) to the aluminum etching waste liquid, adjust the pH of the waste liquid to 5, and obtain a first treatment liquid.

[0118] 3. Heat the first treatment liquid to 85°C and keep for 5 min, and obtain a second treatment liquid.

[0119] 4. Cool the second treatment liquid to room temperature (about 40 min) at room temperature, and obtain a third treatment liquid.

[0120] 5. Allow the third treatment liquid to settle at room temperature in a static manner, so that the third treatment liquid is layered into supernatant and iron-aluminum precipitate.

[0121] In this embodiment, when the settling time is 15 min, the concentrations of Fe and Al in the supernatant are 12.90 ppm and 25.35 ppm, respectively.

[0122] In this embodiment, when the settling time is 30 min, the Fe and Al concentrations in the supernatant are 2.94 ppm and 10.79 ppm, respectively.

[0123] Comparative Example 1

[0124] A method for removing iron and aluminum ions in aluminum etching waste liquid, comprising the following steps:

[0125] 1. Take aluminum etching waste liquid of a company (same as in Example 1).

[0126] 2. At room temperature, add ammonia water (first add high-concentration ammonia water for coarse adjustment, then add low-concentration ammonia water for fine adjustment, and the ammonia water concentration is in the range of 0.1-1M) to the aluminum etching waste liquid, adjust the pH of the waste liquid to 5, and obtain a treatment liquid.

[0127] 3. The treatment liquid is settled at room temperature in a static manner, so that the treatment liquid is layered into supernatant and iron and aluminum precipitate.

[0128] In this comparative example, when the settling time is 15 min, the Fe and Al concentrations in the supernatant are 193.55 ppm and 714.61 ppm, respectively.

[0129] In this comparative example, when the settling time is 30 min, the Fe and Al concentrations in the supernatant are 118.62 ppm and 287.69 ppm, respectively.

[0130] In this comparative example, when the settling time is 60 min, the Fe and Al concentrations in the supernatant are 116.56 ppm and 283.84 ppm, respectively.

[0131] In the above technical solution of the present application, the above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation made under the technical concept of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A method for separating iron from aluminum, characterized in that, The method comprises the steps of: S1, providing a to-be-treated liquid; the to-be-treated liquid contains iron ions and aluminum ions, and the initial pH of the to-be-treated liquid is not more than 2; S2, adjusting the pH of the to-be-treated liquid to 4-5 to obtain a first treated liquid; S3, performing a heating treatment on the first treated liquid to obtain a second treated liquid; the temperature of the heating treatment is 75-85 DEG C, and the time length of the heating treatment is 2-8 min; S4, performing a cooling treatment on the second treated liquid to obtain a third treated liquid; The cooling treatment process comprises: after the heating treatment is completed, the second treated liquid is cooled to not more than 35 DEG C; the cooling treatment is a quenching treatment; S5, performing a sedimentation treatment on the third treated liquid to obtain supernatant and iron-aluminum-containing precipitate.

2. The separation method of claim 1, wherein, The concentration of iron ions in the to-be-treated liquid is 200-800 ppm, and the concentration of aluminum ions is 1000-1600 ppm.

3. The separation method of claim 1, wherein, The to-be-treated liquid also contains phosphoric acid.

4. The separation method of claim 1, wherein, The process of adjusting the pH of the to-be-treated liquid to 4-5 comprises: mixing an alkaline precipitant into the to-be-treated liquid, and controlling the pH of the to-be-treated liquid to 4-5 by the alkaline precipitant.

5. The separation method of claim 4, wherein, The alkaline precipitant comprises one or more of ammonia and sodium hydroxide solution.

6. The separation method of claim 1, wherein, The quenching treatment comprises: after the heating treatment is completed, the second treated liquid is cooled to not more than 35 DEG C in liquid nitrogen or ice water.

7. The separation method of claim 1, wherein, The sedimentation treatment is performed at 5-35 DEG C; the time length of the sedimentation treatment is 5-30 min.

8. A method for removing iron and aluminum ions from aluminum etching waste solution, characterized by, The method comprises the steps of: S01, providing an aluminum etching waste liquid; the aluminum etching waste liquid contains phosphoric acid, acetic acid, nitric acid, iron ions and aluminum ions, and the initial pH of the aluminum etching waste liquid is not more than 2; S02, adjusting the pH of the aluminum etching waste liquid to 4-5 to obtain a first treated liquid; S03, performing a heating treatment on the first treated liquid to obtain a second treated liquid; the temperature of the heating treatment is 75-85 DEG C, and the time length of the heating treatment is 2-8 min; S04, performing a cooling treatment on the second treated liquid to obtain a third treated liquid; The cooling treatment process comprises: after the heating treatment is completed, the second treated liquid is cooled to not more than 35 DEG C; the cooling treatment is a quenching treatment; S05, performing a sedimentation treatment on the third treated liquid to obtain supernatant and iron-aluminum-containing precipitate.

9. The method for removing iron and aluminum ions from aluminum etching waste solution according to claim 8, characterized in that, The concentration of iron ions in the aluminum etching waste liquid is 200-800 ppm, and the concentration of aluminum ions is 1000-1600 ppm; The process of adjusting the pH of the aluminum etching waste liquid to 4-5 comprises: mixing an alkaline precipitant into the aluminum etching waste liquid, and controlling the pH of the aluminum etching waste liquid to 4-5 by the alkaline precipitant; the alkaline precipitant comprises one or more of ammonia and sodium hydroxide; The quenching treatment comprises: after the heating treatment is completed, the second treated liquid is cooled to not more than 35 DEG C in liquid nitrogen or ice water; The sedimentation treatment is performed at 5-35 DEG C; the time length of the sedimentation treatment is 5-30 min.

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