A method for recovering aluminum hydroxide from aluminum ash leaching solution and a separation device

Abstract

The present invention discloses a method for recovering aluminum hydroxide from aluminum ash leachate and a separation device, and relates to the field of aluminum ash processing. The method for recovering aluminum hydroxide from aluminum ash leachate comprises the following steps: S001. Passing the aluminum ash leachate into a separation device and introducing gas from the bottom of the separation device; S002. Forming uniformly distributed floating bubbles into the gas in the separation device, and enriching the flocculent aluminum hydroxide in the aluminum ash leachate at the top of the separation device through the floating bubbles; S003. Discharging the flocculent aluminum hydroxide enriched at the top of the separation device; S004. Filtering, washing, and drying the discharged flocculent aluminum hydroxide to obtain high-purity aluminum hydroxide. The method for recovering aluminum hydroxide from aluminum ash leachate not only effectively separates aluminum hydroxide from the aluminum ash leachate, but also has low energy consumption, low operating costs, and can operate continuously and uninterruptedly.

Description

Technical Field

[0001] The invention relates to the field of aluminum ash treatment, and in particular to a method for recovering aluminum hydroxide from aluminum ash leachate and a separation device. Background Art

[0002] The aluminum profile production process produces a large amount of aluminum ash. This aluminum ash contains a large number of recyclable metal elements. It is unstable when exposed to water and releases toxic and harmful gases. Currently, the main methods for treating this aluminum ash are wet treatment and pyrolysis. Among them, wet treatment mainly uses processes such as acid or alkaline solution to first obtain an aluminum ash leaching solution, and then further adds reagents to obtain the aluminum element in the aluminum ash leaching solution. Currently, this method generally requires the addition of large amounts of reagents. In order to increase the aluminum content, it is generally necessary to go through multiple impurity removal steps to remove other metal elements. This process is complex and the reagent cost is high.

[0003] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method and separation equipment for recovering aluminum hydroxide from aluminum ash leachate, aiming to solve the technical problems of high cost and complex process in the prior art of recovering aluminum hydroxide from aluminum ash leachate.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A first aspect of the present invention provides a method for recovering aluminum hydroxide from aluminum ash leachate, comprising the following steps:

[0007] S001. The aluminum ash leaching liquid is passed into the separation device and the gas is passed from the bottom of the separation device;

[0008] S002. The gas forms a uniformly distributed floating bubble within the separation device, and the floating bubble enriches the flocculent aluminum hydroxide in the aluminum ash leachate at the top of the separation device;

[0009] S003 discharge enriched in the top of the separation equipment flocculent aluminum hydroxide;

[0010] S004. Filter, wash and dry the discharged flocculent aluminum hydroxide to obtain high-purity aluminum hydroxide.

[0011] The method for recovering aluminum hydroxide from aluminum ash leachate, wherein the residence time of the aluminum ash leachate in the separation equipment is 15 minutes to 5 hours.

[0012] In the method for recovering aluminum hydroxide from aluminum ash leachate, the rising speed of the rising bubbles is 0.1 to 3 m / s.

[0013] The method for recovering aluminum hydroxide from aluminum ash leachate, wherein, in S001, further includes circulating the aluminum ash leachate located at the bottom of the separation equipment to release the flocculent aluminum hydroxide covered by the precipitate.

[0014] The method for recovering aluminum hydroxide from aluminum ash leachate, wherein, after S003 discharges the flocculent aluminum hydroxide enriched at the top of the separation equipment, it also includes: transporting the discharged flocculent aluminum hydroxide to one or more separation equipment connected in series downstream to improve the separation purity.

[0015] The method for recovering aluminum hydroxide from aluminum ash leachate, wherein the discharged flocculent aluminum hydroxide is transported to one or more separation devices connected in series downstream to improve the separation purity, specifically also includes: refluxing the aluminum ash leachate at the bottom of the downstream separation device to the top of the previous separation device.

[0016] A second aspect of the present invention provides a separation device for implementing the method for recovering aluminum hydroxide from aluminum ash leachate as described above, which includes at least one tower body, on which a first discharge port, a feed port, an air inlet and a second discharge port are sequentially provided from top to bottom, wherein the first discharge port is located at the top of the tower body; the second discharge port is located at the bottom of the tower body.

[0017] The separation equipment, wherein at least one distribution plate is provided in the tower body, the distribution plate is provided above the air inlet and below the feed inlet, and the distribution plate is used to evenly distribute the floating bubbles.

[0018] The separation equipment, wherein a circulation inlet is further provided at the bottom of the tower body, the circulation inlet is located above the air inlet, and is connected to the second discharge port through a circulation pipe.

[0019] The separation equipment, wherein the tower body includes multiple tower bodies, the multiple tower bodies are arranged in series, and a series reflux port is also provided on the top of the tower body, and the series reflux port is located below the first discharge port; the series reflux port of the previous tower body is connected to the second discharge port of the next tower body through a reflux pipe; the first discharge port of the previous tower body is connected to the feed port of the next tower body through a pipe.

[0020] Beneficial effects:

[0021] The first aspect of the present invention provides a method for recovering aluminum hydroxide from aluminum ash leachate, which uses floating bubbles to separate the aluminum hydroxide in the aluminum ash leachate, so that the flocculent aluminum hydroxide with a slower settling rate in the aluminum ash leachate is enriched on the surface of the leachate under the action of the floating bubbles, while other solid impurities with a faster settling rate are precipitated at the bottom of the leachate. The solid substances with different settling rates are separated by the action of the floating bubbles, thereby effectively collecting the aluminum hydroxide in the aluminum ash leachate, greatly reducing the use of reagents in wet treatment, and greatly reducing the complexity of the aluminum hydroxide recovery process.

[0022] A second aspect of the present invention provides a separation device, which is used to implement the method for recovering aluminum hydroxide from aluminum ash leachate as described above. The separation device includes one or more tower bodies, through which gas can be introduced to separate the aluminum hydroxide from the aluminum ash leachate. It has good separation effect, small footprint, and low operating cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of a separation device in one embodiment.

[0024] Figure 2 Schematic diagram of the structure of the separation device in another embodiment.

[0025] Explanation of the main component symbols: 1-tower body, 11-first discharge port, 12-feed port, 13-air inlet, 14-second discharge port, 2-gas pipeline, 21-air compressor, 3-feed pipeline, 31-delivery pump, 15-distribution plate, 16-circulation inlet, 4-circulation pipeline, 41-discharge pump, 17-series reflux port, 5-discharge pipeline, 51-discharge valve, 52-circulation valve, 6-reflux pipeline, 61-reflux pump, 18-exhaust gas outlet. DETAILED DESCRIPTION

[0026] The present invention provides a method and separation apparatus for recovering aluminum hydroxide from aluminum ash leachate. To clarify the objectives, technical solutions, and effects of the present invention, the present invention is further described below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0027] In the description of the present invention, it should be understood that the terms "up", "down", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, and a specific direction structure and operation, and therefore, cannot be understood as a limitation on the present invention. In addition, "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means more than two.

[0028] A first aspect of the present invention provides a method for recovering aluminum hydroxide from aluminum ash leachate, comprising the following steps:

[0029] S001. The aluminum ash leaching liquid is passed into the separation device and the gas is passed from the bottom of the separation device;

[0030] Specifically, the aluminum ash leaching solution generated during the wet treatment process has a salt content of 3% to 25%, and a solid content of 2% to 35%, wherein the solid components include aluminum hydroxide, α-alumina, and minerals composed of magnesium oxide, silicon oxide, aluminum oxide, etc.; preferably, the gas introduced is air;

[0031] S002. The gas forms a uniformly distributed floating bubble within the separation device, and the floating bubble enriches the flocculent aluminum hydroxide in the aluminum ash leachate at the top of the separation device;

[0032] Aluminum hydroxide is flocculent in the aluminum ash leachate. Compared with other solid components, flocculent aluminum hydroxide has the lowest settling velocity. Under the action of the rising bubbles, various solid components are separated in the separation equipment according to their different settling velocities. Among them, solid components with low settling velocity are enriched at the top of the separation equipment under the action of the upward thrust generated by the rising bubbles, while solid components with high settling velocity, such as α-alumina and mineral components composed of magnesium oxide, silicon oxide, aluminum oxide, etc., are enriched at the bottom of the separation equipment. Flocculent aluminum hydroxide has the lowest settling velocity, so it is enriched at the top of the separation equipment with a small amount of impurities.

[0033] S003 discharge enriched in the top of the separation equipment flocculent aluminum hydroxide;

[0034] S004. The discharged flocculent aluminum hydroxide is filtered, washed, and dried to obtain high-purity aluminum hydroxide. Specifically, after the liquid at the top of the separation equipment is discharged, it is filtered to complete solid-liquid separation to obtain high-purity aluminum hydroxide. After washing, the soluble impurities remaining on the surface of the aluminum hydroxide can be removed, thereby further improving the purity of the aluminum hydroxide.

[0035] Preferably, the residence time of the aluminum ash leaching solution in the separation device is 15 minutes to 5 hours. The residence time of the aluminum ash leaching solution in the separation device should not be too short, otherwise the various solid components in the aluminum ash leaching solution will not be completely separated, and too many impurities will be enriched at the top of the separation device.

[0036] Preferably, the rising velocity of the rising bubbles is 0.1 to 3 m / s. The rising velocity of the rising bubbles should not be too low, otherwise it will not generate sufficient upward thrust to enrich the aluminum hydroxide at the top of the separation device. The rising velocity of the rising bubbles should not be too high, otherwise it will generate excessive upward thrust, resulting in excessive impurities.

[0037] Preferably, S001 further includes circulating the aluminum ash leaching solution located at the bottom of the separation device to release the flocculent aluminum hydroxide covered by the precipitate. During the separation process, the aluminum ash leaching solution continuously flows into the separation device, and some of the settling solid components cover the aluminum hydroxide below, causing some of the aluminum hydroxide to settle at the bottom of the separation device. By circulating the aluminum ash leaching solution located at the bottom of the separation device, the precipitated aluminum hydroxide can be separated from other solid components, releasing the aluminum hydroxide from the precipitate, thereby improving the recovery rate of the aluminum hydroxide.

[0038] Preferably, when the aluminum ash leaching liquid located at the lower part of the separation equipment circulates, the aluminum ash leaching liquid circulates to above the floating bubbles, and the aluminum hydroxide is fully separated from other solid components through the circulation effect and the floating bubbles.

[0039] Preferably, after discharging the flocculent aluminum hydroxide accumulated at the top of the separation device in step S003, the step further includes: transporting the discharged flocculent aluminum hydroxide to one or more separation devices connected in series downstream to improve separation purity. The purity of the aluminum hydroxide can be further improved through multiple separations.

[0040] Preferably, the method of conveying the discharged flocculent aluminum hydroxide to one or more downstream separation devices connected in series to improve separation purity further includes: recirculating the aluminum ash leachate at the bottom of the downstream separation device to the top of the previous separation device. This step can transfer solid sediment in the downstream separation device to the upstream, preventing the gradual accumulation of solid sediment in the downstream separation device during continuous operation, thereby reducing the effectiveness of the series operation of multiple separation devices.

[0041] See also Figure 1In a second aspect, the present invention provides a separation device for implementing the above-mentioned method for recovering aluminum hydroxide from aluminum ash leachate, comprising at least one tower body 1, on which a first discharge port 11, a feed port 12, an air inlet 13, and a second discharge port 14 are sequentially provided from top to bottom. The first discharge port 11 is located at the top of the tower body 1; the second discharge port 14 is located at the bottom of the tower body 1. The first discharge port 11 is used to discharge the enriched aluminum hydroxide mixed solution at the top of the tower body 1. The second discharge port 14 is used to discharge the sediment at the bottom of the tower body 1.

[0042] Specifically, the air inlet 13 is connected to a gas pipeline 2 , and an air compressor 21 is provided on the gas pipeline 2 for controlling the air intake speed. The air inlet 13 is located at the bottom of the tower body 1 .

[0043] The feed port 12 is used to input aluminum ash leaching liquid into the tower body 1. Preferably, the feed port 12 is arranged in the middle of the tower body 1 to be away from the sediment at the bottom of the tower body 1.

[0044] Specifically, the feed port 12 is connected to a feed pipe 3 , and a delivery pump 31 is provided on the feed pipe 3 . The delivery pump 31 is used to control the feeding speed of the aluminum ash immersion liquid.

[0045] Preferably, at least one distribution plate 15 is provided within the tower body 1. The distribution plate 15 is positioned above the air inlet 13 and below the feed port 12. The distribution plate 15 is configured to uniformly distribute rising bubbles. Specifically, the distribution plate 15 has multiple evenly distributed through-holes. When passing through the distribution plate 15, both rising bubbles and the aluminum ash solution can only pass through the through-holes, dispersing large bubbles into smaller ones and achieving a more uniform flow rate within the tower. Maintaining a uniform flow rate for both the gas and aluminum ash solution within the tower helps improve the separation of aluminum hydroxide.

[0046] Preferably, the feed port 12 is provided above at least one distribution plate 15 , and when the aluminum ash leaching liquid enters the tower from the feed port 12 , it can be mixed with the evenly distributed floating bubbles.

[0047] Preferably, a circulation inlet 16 is further provided at the bottom of the tower body 1 . The circulation inlet 16 is located above the air inlet 13 and is connected to the second discharge port 14 through a circulation pipe 4 .

[0048] Specifically, the second discharge port 14 is connected to a discharge pipe 5, which is equipped with a discharge pump 41. The discharge end of the discharge pump 41 is connected to a tee. The two discharge ends of the tee are respectively equipped with a discharge valve 51 and a circulation valve 52. The discharge end equipped with the circulation valve 52 is connected to the circulation pipe 4. During use, the discharge valve 51 or the circulation valve 52 is opened as needed. When the sediment at the bottom of the tower body 1 reaches a certain height, the discharge valve 51 is opened to discharge the sediment.

[0049] Specifically, the circulation inlet 16 is located above the distribution plate 15. Through the circulation action of the discharge pump 41, the sediment at the bottom can be rolled at the bottom of the tower, thereby separating the aluminum hydroxide at the bottom from other solid sediments, so that the aluminum hydroxide buried at the bottom can be re-enriched to the top of the tower body 1 under the action of the floating bubbles.

[0050] Preferably, the tower body 1 includes a plurality of tower bodies 1, which are arranged in series. Figure 2 The top of the tower body 1 is also provided with a series reflux port 17, and the series reflux port 17 is located below the first discharge port 11; the series reflux port 17 of the previous tower body 1 is connected to the second discharge port 14 of the next tower body 1 through a reflux pipe 6, and the reflux pipe 6 is provided with a reflux pump 61; the first discharge port 11 of the previous tower body 1 is connected to the feed port 12 of the next tower body 1 through a pipe, and the pipe is provided with a delivery pump 31.

[0051] The following example is used for illustration. In a separation device, two tower bodies 1 are connected in series, namely tower body No. 1 and tower body No. 2; the series reflux port 17 of tower body No. 1 is connected to the second discharge port 14 of tower body No. 2; and the first discharge port 11 of tower body No. 1 is connected to the feed port 12 of tower body No. 2. In this embodiment, if the series reflux port 17 is not provided, the sediment at the bottom of tower body No. 2 will increase rapidly during operation, and these gradually accumulated sediments will affect the separation effect of tower body No. 2. Compared with the sediment in tower body No. 1, the sediment in tower body No. 2 contains more aluminum hydroxide, so it is not suitable to be discharged directly. Instead, it can be refluxed to the top of tower body No. 1, so that the separation function of tower body No. 1 can be exerted again without losing aluminum hydroxide, and the problem of increased sediment in tower body No. 2 can also be avoided. Specifically, tower body No. 1 and tower body No. 2 can use the same air compressor 21 to provide gas.

[0052] Preferably, a plurality of distribution plates 15 are vertically arranged in the tower body 1. Properly increasing the number of distribution plates 15 can not only effectively increase the distribution uniformity of the floating bubbles and control the particle size of the floating bubbles, but also maintain a uniform flow rate of the aluminum ash leaching liquid in the tower body 1.

[0053] In a preferred embodiment, a distribution plate 15 is disposed between the series reflux port 17 and the first discharge port 11; at least one distribution plate 15 is disposed above and below the feed port 12; at least one distribution plate 15 is disposed between the gas inlet 13 and the circulation inlet 16; and at least one distribution plate 15 is disposed above the circulation inlet 16. Distributor plates 15 are disposed above the points where the gas and aluminum ash liquid enter the tower body 1, allowing for rapid and uniform distribution of the gas or liquid, thereby improving the overall separation effect.

[0054] Preferably, a tail gas outlet 18 is provided at the top of the tower body 1, and the tail gas outlet 18 is located above the first discharge port 11. After passing through the aluminum ash immersion liquid, the upwardly floating bubbles finally gather at the top of the tower body 1 and are discharged through the tail gas outlet 18.

[0055] Specifically, a filtering device and a drying device may be provided downstream of the separation device, wherein the filtering device may be a filter press and the filtering device may be connected to a water flushing pipeline to complete the washing process.

[0056] The separation equipment of the present invention can continuously take in and out water, and efficiently recover aluminum hydroxide in the aluminum ash leaching solution.

[0057] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for recovering aluminum hydroxide from aluminum ash leaching solution, characterized in that: The steps include: S001. The aluminum ash leachate is passed into the separation device, and the gas is passed from the bottom of the separation device to circulate the aluminum ash leachate at the lower part of the separation device to release the flocculent aluminum hydroxide covered by the precipitate; S002. The gas forms uniformly distributed floating bubbles in the separation device, the floating bubbles having a floating velocity of 0.1 to 3 m / s, and the flocculent aluminum hydroxide in the aluminum ash leachate is enriched at the top of the separation device by the floating bubbles; S003 discharge enriched in the top of the separation device flocculent aluminum hydroxide, the discharge of flocculent aluminum hydroxide is transported to one or more separation devices in series located downstream to improve separation purity; S004. The discharged flocculent aluminum hydroxide is filtered, washed, and dried to obtain high-purity aluminum hydroxide; The separation device comprises at least one tower body, on which a first discharge port, a feed port, an air inlet, and a second discharge port are sequentially provided from top to bottom, wherein the first discharge port is located at the top of the tower body; and the second discharge port is located at the bottom of the tower body; At least one distribution plate is provided in the tower body, and the distribution plate is provided above the air inlet and below the feed inlet, and the distribution plate is used to evenly distribute the floating bubbles; A circulation inlet is also provided at the bottom of the tower body. The circulation inlet is located above the air inlet and is connected to the second discharge port through a circulation pipeline.

2. The method for recovering aluminum hydroxide from aluminum ash leaching solution according to claim 1, wherein: The residence time of the aluminum ash leaching solution in the separation equipment is 15 minutes to 5 hours.

3. The method for recovering aluminum hydroxide from aluminum ash leaching solution according to claim 1, wherein: The method of transporting the discharged flocculent aluminum hydroxide to one or more separation devices connected in series downstream to improve the separation purity specifically includes: refluxing the aluminum ash leaching liquid at the bottom of the downstream separation device to the top of the previous separation device.

4. The method for recovering aluminum hydroxide from aluminum ash leaching solution according to claim 1, wherein: The tower body includes multiple tower bodies, and the multiple tower bodies are arranged in series. The top of the tower body is also provided with a series reflux port, and the series reflux port is located below the first discharge port; the series reflux port of the previous tower body is connected to the second discharge port of the next tower body through a reflux pipe; the first discharge port of the previous tower body is connected to the feed port of the next tower body through a pipe.

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