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

Abstract

The invention 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 greater than 2; s2, adjusting the pH value of the to-be-treated liquid to 3-6 to obtain a first treated liquid; s3, heating the first treatment liquid to obtain a second treatment liquid; the temperature of the heating treatment is 50-100 DEG C; s4, cooling the second treatment liquid to obtain a third treatment liquid; and S5, the third treatment liquid is subjected to sedimentation treatment, and supernate and precipitates containing iron and aluminum are obtained. The method has an excellent removal effect on iron and aluminum ions in the to-be-treated liquid, and solves the problem of fine particle effect in a precipitation method.

Description

Technical Field

[0001] The invention belongs to the field of industrial wastewater treatment, and in particular relates to a method for removing iron and aluminum ions in aluminum etching waste liquid and a separation method. Background Art

[0002] A large amount of acidic etching waste liquid is generated during the etching process. Aluminum etching waste liquid is the waste liquid generated after wet etching of aluminum templates in the optoelectronic industry. Generally speaking, aluminum etching waste liquid contains 50-70% phosphoric acid, 3-20% acetic acid and 1-5% nitric acid, as well as a large amount of metal impurities, among which the concentrations of aluminum and iron are 1300ppm and 500ppm respectively. Generally, the resource utilization of aluminum etching waste liquid requires separating the acetic acid, nitric acid and phosphoric acid by vacuum distillation, and then further synthesizing the separated components into resource products. Products, among which, the separated phosphate base liquid often contains a large amount of iron and aluminum ions, which are often doped in subsequent resource products, affecting the purity of the products, resulting in substandard resource products and limited applications, which have an adverse impact on their recycling; at the same time, the wastewater after direct resource treatment of the phosphate base 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 waste liquid containing iron and aluminum will greatly reduce its reuse value, hinder its high-value utilization, and cause environmental damage. It can be seen that the efficient removal of iron and aluminum ions in etching waste liquid has both resource and environmental significance.

[0003] At present, the commonly used technologies for treating industrial wastewater containing iron and aluminum include chemical precipitation, oxidation-reduction, solvent extraction, ion exchange, adsorption, membrane separation technology, plant restoration, bioflocculation, biosorption, solvent extraction, etc. The above treatment processes have more or less defects such as poor treatment effect, high cost and easy to cause secondary pollution; among them, the precipitation method is widely used in actual processes due to its simple operation. However, when using the precipitation method to treat iron and aluminum wastewater, there is a fine particle effect, which makes the iron and aluminum precipitate fine particles evenly distributed in the solution and difficult to separate, thus 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 the agent and increase the discharge of solid waste, which is not conducive to the reduction of waste.

[0004] In view of this, it is necessary to provide a method for removing iron and aluminum ions in aluminum etching waste liquid and a separation method to solve or at least alleviate the technical problem of how to efficiently remove iron and aluminum in the waste liquid. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for removing iron and aluminum ions in aluminum etching waste liquid and a separation method, aiming 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 invention provides a method for separating iron and aluminum, comprising the steps of:

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

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

[0009] S3, heating the first treatment liquid to obtain a second treatment liquid; the heating temperature is 50-100° C.;

[0010] S4, cooling the second treatment liquid to obtain a third treatment liquid; the cooling process comprises: cooling the second treatment liquid to a temperature not exceeding 35° C. after completing the heating process;

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

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

[0013] Furthermore, the liquid to be treated also contains phosphoric acid.

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

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

[0016] Furthermore, the duration of the heating treatment is 2-8 minutes.

[0017] Furthermore, the cooling treatment is a quenching treatment or a normal temperature treatment; the quenching treatment includes: after completing the heating treatment, cooling the second treatment liquid in liquid nitrogen or ice water to no more than 35°C; the normal temperature treatment includes: after completing the heating treatment, cooling the second treatment liquid at normal temperature to no more than 35°C.

[0018] Furthermore, the sedimentation treatment is carried out at 5-35°C; the duration of the sedimentation treatment is not less than 5min or 5-30min.

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

[0020] S01, providing aluminum etching waste liquid, wherein 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 greater than 2;

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

[0022] S03, heating the first treatment liquid to obtain a second treatment liquid; the heating temperature is 50-100° C.;

[0023] S04, cooling the second treatment liquid to obtain a third treatment liquid; the cooling process comprises: cooling the second treatment liquid to a temperature not exceeding 35° C. after completing the heating process;

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

[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 value of the aluminum etching waste liquid to 3-6 comprises: mixing an alkaline precipitant into the aluminum etching waste liquid, and controlling the pH value of the aluminum etching waste liquid to be 3-6 by the alkaline precipitant; the alkaline precipitant comprises one or more of ammonia water and sodium hydroxide;

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

[0028] The cooling treatment is a quenching treatment or a normal temperature treatment; the quenching treatment includes: cooling the second treatment liquid in liquid nitrogen or ice water to no more than 35°C after the heating treatment is completed; the normal temperature treatment includes: cooling the second treatment liquid at normal temperature to no more than 35°C after the heating treatment is completed;

[0029] The sedimentation treatment is carried out at 5-35° 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 invention has at least the following advantages:

[0031] The present invention proposes a method for quickly separating iron and aluminum, which has a simple process, has a rapid and excellent removal effect on iron and aluminum ions in a treated liquid, and solves the problem of fine particle effect in the precipitation method. The present invention adds an alkaline precipitant to the treated liquid containing iron and aluminum ions to carry out a chemical reaction to generate fine particle precipitation, and then heats and cools the resulting treated liquid to destroy the surface stability of the particles, so that the original small particles aggregate into large particle precipitation, and regulates the crystal growth by changing the temperature, and removes iron and aluminum at the same time, so that there is no need to add additional flocculants, effectively reducing the output of solid waste, and avoiding the problem of secondary pollution caused by the addition of flocculants. The removal efficiency is high, the effect is stable, the process method is simple, and the process cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in 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 described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents shown in these drawings without paying creative work.

[0033] Figure 1 The present invention is a schematic flow chart of a method for removing iron and aluminum ions from aluminum etching waste liquid;

[0034] Figure 2 This is a diagram of iron and aluminum removal efficiency corresponding to different settling times in Example 1 of the present invention;

[0035] Figure 3 It is a schematic diagram of the effect of removing iron and aluminum in aluminum etching waste liquid in Example 2 (settling time is 10 min), Example 5 (settling time is 10 min) and Comparative Example 1 (settling time is 60 min) of the present invention;

[0036] In the figure, Example 2 corresponds to heating-quenching, Example 5 corresponds to heating-normal temperature, and Comparative Example 1 corresponds to normal temperature precipitation; Figure 3 It can be seen that: conventionally, after only adding alkaline precipitant and settling for 60 minutes, the supernatant is still turbid, and the iron and aluminum in the clear liquid are difficult to settle. After the heating-cooling treatment, the small particles quickly agglomerate and grow, making the fine colloids that were originally difficult to settle quickly settle down, and the final supernatant is clear and transparent, with good iron and aluminum removal effect;

[0037] Figure 4 The SEM images of the particle shapes of the iron-aluminum precipitate in Example 2 (settling time is 20 min) and the iron-aluminum precipitate in Comparative Example 1 (settling time is 60 min) of the present invention are compared; wherein (a) is the iron-aluminum precipitate in Example 2, and (b) is the iron-aluminum precipitate in Comparative Example 1; Figure 4It can be seen that the precipitate after the heating-cooling treatment is composed of fine particles of 2 to 5 μm, while the particle size of the precipitated particles formed by the conventional addition of only alkaline precipitant is about 50 μm. This shows that the heating-cooling treatment destroys the surface stability of the particles, promotes the aggregation and precipitation of fine particles, and thus improves the removal effect of iron and aluminum in the solution.

[0038] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0041] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are familiar to those skilled in the art and the description of the present invention, and any methods, equipment and materials of the prior art similar or equivalent to the methods, equipment and materials described in the embodiments of the present invention can also be used to implement the present invention.

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

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

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

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

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

[0047] In the present invention, the process of adjusting the pH of the liquid to be treated to 3-6, 4-6 or 5-6 comprises: mixing an alkaline precipitant into the liquid to be treated, and controlling the pH of the liquid to be treated to 3-6, 4-6 or 5-6 by the alkaline precipitant; specifically, the present invention adds the alkaline precipitant into the liquid to be treated, and adjusts the pH of the liquid to be treated to 3-6, 4-6 or 5-6. The alkaline precipitant comprises one or more of ammonia water and sodium hydroxide solution; specifically, the ammonia water or the sodium hydroxide solution, and the concentrations of the ammonia water and the sodium hydroxide solution can be 0.1-1M.

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

[0049] In the present invention, the temperature of the heating treatment is 50-100°C (preferably 70-90°C or 75-85°C or 80-90°C), and the duration of the heating treatment is 2-8min (preferably 4-6min); for example, the present invention heats the first treatment liquid to 50-100°C and then keeps it warm for 2-8min.

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

[0051] In the present invention, the cooling process includes: immediately cooling the second treatment liquid to a temperature not exceeding 35°C (specifically 5-35°C or room temperature) after the heating process is completed. ；The cooling treatment is a quenching treatment or a normal temperature treatment; the cooling time of the quenching treatment does not exceed 5 minutes; the quenching treatment includes: after completing the heating treatment, cooling the second treatment liquid in liquid nitrogen or ice water to no more than 35°C (specifically, 5-35°C or normal temperature); the normal temperature treatment includes: after completing the heating treatment, cooling the second treatment liquid at normal temperature to no more than 35°C (specifically, 5-35°C or normal temperature). Preferably, the cooling treatment is the quenching treatment; specifically, the present invention immediately performs the quenching treatment on the second treatment liquid after completing the heating treatment, thereby rapidly cooling the second treatment liquid. In the present invention, the cooling time in liquid nitrogen may be no more than 1 minute, and the cooling time in ice water may be no more than 5 minutes.

[0052] S5, after completing the cooling treatment, immediately subjecting the third treatment liquid to a sedimentation treatment to obtain a supernatant and a precipitate containing iron and aluminum.

[0053] In the present invention, the sedimentation treatment is carried out at 5-35°C; the duration of the sedimentation treatment is not less than 5min or 5-30min or 10-15min. The sedimentation treatment is specifically carried out at room temperature; the specific operation of the sedimentation treatment is standing.

[0054] In the present invention, after the sedimentation treatment is completed, the third treatment liquid can be subjected to solid-liquid separation to obtain the separated liquid of the supernatant and the separated material of the precipitate; the specific method of the solid-liquid separation is centrifugal separation.

[0055] The present invention can efficiently remove iron and aluminum by adding an alkaline precipitant, heating, rapid cooling, sedimentation and the like. Specifically, the present invention adds a precipitant to a liquid to be treated containing iron and aluminum ions, adjusts the pH value to a suitable pH range, heats the treated liquid after the precipitant is added, rapidly cools the liquid after heating to a certain temperature, and sediments the liquid for a period of time, and obtains a separated liquid with extremely low iron and aluminum concentrations after solid-liquid separation.

[0056] Based on the specific application scenarios of the above-mentioned separation method, the present invention also provides a method for removing iron and aluminum ions from aluminum etching waste liquid. In the method for removing iron and aluminum ions from aluminum etching waste liquid and the above-mentioned separation method, the limitations on the same technical features can remain consistent.

[0057] In the present invention, see Figure 1 It is understood that the method for removing iron and aluminum ions in aluminum etching waste liquid includes the steps of:

[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 an embodiment of the present invention, 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 greater than 2 or less than 1.

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

[0061] S02, adjusting the pH of the aluminum etching waste liquid to 3-6 or 4-6 or 5-6 to obtain a first treatment liquid.

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

[0063] S03, heating the first treatment liquid to obtain a second treatment liquid.

[0064] In the present invention, the temperature of the heating treatment is 50-100°C (preferably 70-90°C or 75-85°C), and the duration of the heating treatment is 2-8min (preferably 4-6min); for example, the present invention heats the first treatment liquid to 50-100°C and then keeps it warm for 2-8min.

[0065] S04, cooling the second treatment liquid to obtain a third treatment liquid.

[0066] In the present invention, the cooling treatment process includes: after completing the heating treatment, cooling the second treatment liquid to no more than 35°C (specifically, 5-35°C or room temperature); the cooling treatment is a quenching treatment or a room temperature treatment; the cooling time of the quenching treatment does not exceed 5 minutes; the quenching treatment includes: after completing the heating treatment, cooling the second treatment liquid in liquid nitrogen or ice water to no more than 35°C (specifically, 5-35°C or room temperature); the room temperature treatment includes: after completing the heating treatment, cooling the second treatment liquid at room temperature to no more than 35°C (specifically, 5-35°C or room temperature).

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

[0068] In the present invention, the sedimentation treatment is carried out at 5-35°C; the duration of the sedimentation treatment is not less than 5min or 5-30min or 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 invention, after the sedimentation treatment is completed, the third treatment liquid can also be subjected to solid-liquid separation to obtain the separated liquid of the supernatant and the separated product of the precipitate; the specific method of the solid-liquid separation is centrifugal separation. (Note: In the embodiments and comparative examples of the present invention, when the iron and aluminum concentrations in the solution after the sedimentation treatment are tested, the supernatant is directly aspirated without centrifugal separation. If the precipitate needs to be separated for analysis, centrifugal separation is used).

[0070] The invention firstly adds an alkaline precipitant to the aluminum etching waste liquid waiting for treatment. At this time, part of the iron and aluminum ions in the treatment liquid form a stable colloidal system, which is difficult to precipitate. The invention also uses a heating-cooling, especially a heating-quenching method to destroy the stability of the nanoparticles, so that the fine iron and aluminum particles are quickly agglomerated into large particles and precipitated, thereby achieving a rapid precipitation effect. While improving the precipitation efficiency, it avoids the environmental problems such as high cost and secondary pollution caused by the use of flocculants and other methods, thereby providing a new method for efficiently removing high-concentration iron and aluminum wastewater.

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

[0072] Example 1

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

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

[0075] 2. At room temperature, add ammonia water to the aluminum etching waste liquid (first add high-concentration ammonia water for rough adjustment, then add low-concentration ammonia water for fine adjustment, the ammonia concentration is in the range of 0.1-1M), adjust the pH of the waste liquid to 5, and obtain the first treatment liquid.

[0076] 3. Heat the first treatment liquid to 75°C and keep it warm for 5 minutes to obtain the second treatment liquid.

[0077] 4. Use ice water cooling to cool the second treatment liquid to room temperature within 5 minutes to obtain the third treatment liquid.

[0078] 5. Allow the third treatment liquid to settle at room temperature in a static manner, so that the third treatment liquid is separated into a supernatant and iron-aluminum precipitates.

[0079] In this embodiment, when the sedimentation time is 10 min, the concentrations of Fe and Al in the supernatant are 6.75 ppm and 23.79 ppm, respectively.

[0080] In this embodiment, when the sedimentation time is 15 min, the concentrations of Fe and Al 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 certain company (same as Example 1).

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

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

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

[0087] 5. Allow the third treatment liquid to settle at room temperature in a static manner, so that the third treatment liquid is separated into a supernatant and iron-aluminum precipitates.

[0088] In this embodiment, when the sedimentation time is 10 min, the concentrations of Fe and Al 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 certain company (same as Example 1).

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

[0093] 3. Heat the first treatment liquid to 85°C and keep it warm for 5 minutes to obtain the second treatment liquid.

[0094] 4. Use liquid nitrogen cooling to cool the second treatment liquid to room temperature within 1 minute to obtain the third treatment liquid.

[0095] 5. Allow the third treatment liquid to settle at room temperature in a static manner, so that the third treatment liquid is separated into a supernatant and iron-aluminum precipitates.

[0096] In this embodiment, when the sedimentation time is 10 min, the concentrations of Fe and Al 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 liquid, comprising the following steps:

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

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

[0101] 3. Heat the first treatment liquid to 95°C and keep it warm for 5 minutes to obtain the second treatment liquid.

[0102] 4. Use ice water cooling to cool the second treatment liquid to room temperature within 5 minutes to obtain the third treatment liquid.

[0103] 5. Allow the third treatment liquid to settle at room temperature in a static manner, so that the third treatment liquid is separated into a supernatant and iron-aluminum precipitates.

[0104] In this embodiment, when the sedimentation time is 30 min, the concentrations of Fe and Al 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 liquid, comprising the following steps:

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

[0108] 2. At room temperature, add sodium hydroxide solution to the aluminum etching waste liquid (first add high concentration sodium hydroxide solution for rough 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), adjust the pH of the waste liquid to 5, and obtain the first treatment liquid.

[0109] 3. Heat the first treatment liquid to 85°C and keep it warm for 5 minutes to obtain the second treatment liquid.

[0110] 4. Cool the second treatment liquid to room temperature (about 40 minutes) under normal temperature conditions to 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 separated into a supernatant and iron-aluminum precipitates.

[0112] In this embodiment, when the sedimentation 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 sedimentation 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 from aluminum etching waste liquid, comprising the following steps:

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

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

[0118] 3. Heat the first treatment liquid to 85°C and keep it warm for 5 minutes to obtain the second treatment liquid.

[0119] 4. Cool the second treatment liquid to room temperature (about 40 minutes) under normal temperature conditions to 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 separated into a supernatant and iron-aluminum precipitates.

[0121] In this embodiment, when the sedimentation 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 sedimentation time is 30 min, the concentrations of Fe and Al 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 from aluminum etching waste liquid, comprising the following steps:

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

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

[0127] 3. Allow the treated liquid to settle at room temperature in a static manner, so that the treated liquid is separated into supernatant and iron-aluminum precipitate.

[0128] In this comparative example, when the sedimentation time was 15 min, the concentrations of Fe and Al in the supernatant were 193.55 ppm and 714.61 ppm, respectively.

[0129] In this comparative example, when the sedimentation time was 30 min, the concentrations of Fe and Al in the supernatant were 118.62 ppm and 287.69 ppm, respectively.

[0130] In this comparative example, when the sedimentation time was 60 min, the concentrations of Fe and Al in the supernatant were 116.56 ppm and 283.84 ppm, respectively.

[0131] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for separating iron and aluminum, characterized in that: Includes steps: S1, providing a liquid to be treated; the liquid to be treated contains iron ions and aluminum ions, and the initial pH of the liquid to be treated is not greater than 2; S2, adjusting the pH of the liquid to be treated to 3-6 to obtain a first treated liquid; S3, heating the first treatment liquid to obtain a second treatment liquid; the heating temperature is 50-100° C.; S4, cooling the second treatment liquid to obtain a third treatment liquid; The cooling treatment process includes: cooling the second treatment liquid to no more than 35° C. after completing the heating treatment; S5, subjecting the third treatment liquid to sedimentation treatment to obtain a supernatant and a precipitate containing iron and aluminum.

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

3. The separation method according to claim 1, characterized in that The liquid to be treated also contains phosphoric acid.

4. The separation method according to claim 1, characterized in that The process of adjusting the pH value of the liquid to be treated to 3-6 comprises: mixing an alkaline precipitant into the liquid to be treated, and controlling the pH value of the liquid to be treated to 3-6 by the alkaline precipitant.

5. The separation method according to claim 4, characterized in that The alkaline precipitant includes one or more of ammonia water and sodium hydroxide solution.

6. The separation method according to claim 1, characterized in that The duration of the heating treatment is 2-8 minutes.

7. The separation method according to claim 1, characterized in that The cooling treatment is a quenching treatment or a normal temperature treatment; the quenching treatment includes: after completing the heating treatment, cooling the second treatment liquid in liquid nitrogen or ice water to no more than 35°C; the normal temperature treatment includes: after completing the heating treatment, cooling the second treatment liquid at normal temperature to no more than 35°C.

8. The separation method according to claim 1, characterized in that The sedimentation treatment is carried out at 5-35° C.; the duration of the sedimentation treatment is not less than 5 min or 5-30 min.

9. A method for removing iron and aluminum ions from aluminum etching waste liquid, characterized in that: Includes steps: S01, providing aluminum etching waste liquid, wherein 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 greater than 2; S02, adjusting the pH of the aluminum etching waste liquid to 3-6 to obtain a first treatment liquid; S03, heating the first treatment liquid to obtain a second treatment liquid; the heating temperature is 50-100° C.; S04, cooling the second treatment liquid to obtain a third treatment liquid; The cooling treatment process includes: cooling the second treatment liquid to no more than 35° C. after completing the heating treatment; S05, subjecting the third treatment liquid to sedimentation treatment to obtain a supernatant and a precipitate containing iron and aluminum.

10. The method for removing iron and aluminum ions from aluminum etching waste liquid according to claim 9, characterized in that: In the aluminum etching waste liquid, the concentration of iron ions is 200-800ppm, and the concentration of aluminum ions is 1000-1600ppm; The process of adjusting the pH value of the aluminum etching waste liquid to 3-6 comprises: mixing an alkaline precipitant into the aluminum etching waste liquid, and controlling the pH value of the aluminum etching waste liquid to be 3-6 by the alkaline precipitant; the alkaline precipitant comprises one or more of ammonia water and sodium hydroxide; The duration of the heating treatment is 2-8 minutes; The cooling treatment is a quenching treatment or a normal temperature treatment; the quenching treatment includes: cooling the second treatment liquid in liquid nitrogen or ice water to no more than 35°C after the heating treatment is completed; the normal temperature treatment includes: cooling the second treatment liquid at normal temperature to no more than 35°C after the heating treatment is completed; The sedimentation treatment is carried out at 5-35° C.; the duration of the sedimentation treatment is not less than 5 min or 5-30 min.

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