Continuous acid leaching production system for aluminum ash

Abstract

The utility model discloses an aluminum ash continuous acid leaching production system which comprises a slurry mixing kettle and at least two acid leaching kettles sequentially connected with the slurry mixing kettle, an aluminum ash feeding pipe and a pulping water feeding port are arranged on the slurry mixing kettle, sulfuric acid feeding pipes are arranged on the acid leaching kettles, the slurry mixing kettle and the acid leaching kettles are both provided with stirring paddles and gas outlets, and the stirring paddles and the gas outlets are communicated with each other. The gas outlet is connected with a tail gas purification device through a pipeline. According to the utility model, the continuous pickling technology is adopted to realize continuous production of aluminum ash treatment, the waiting time and the material transfer process in batch treatment can be reduced, the production efficiency is improved, the continuous pickling treatment is carried out in a closed system, the direct contact between harmful substances and operators is reduced, meanwhile, the risk of overflowing from a pot is reduced, and the production cost is reduced. And the safety of the production process is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of recycled aluminum recovery, and particularly relates to a continuous acid leaching production system for aluminum ash. Background Art

[0002] Aluminum ash is one of the main by-products of the recycled aluminum industry. According to statistics, every 1t of recycled aluminum recovered will produce 250 - 300kg of aluminum ash. Aluminum ash mainly includes metallic aluminum, aluminum oxide, aluminum nitride, magnesium aluminate spinel, salts (chloride salts and fluoride salts), etc. Its composition is complex. Long-term and large-scale accumulation is likely to cause heavy metal pollution of water bodies and soil, soil salinization, and will produce pungent ammonia gas when exposed to moisture, posing hazards to personal safety and the environment. As is well known, aluminum ash is also an important secondary resource with high comprehensive utilization value. Aluminum ash can be used to prepare flocculants to achieve high-value utilization of secondary aluminum ash and reduce environmental pollution. At the same time, when aluminum ash is utilized resourcefully, sulfuric acid or hydrochloric acid is used for acid leaching to obtain aluminum sulfate or polyaluminum chloride. Aluminum ash usually contains about 3 - 20% by mass of metallic aluminum. However, due to the active chemical properties of metallic aluminum, it can react with water to release H2 and emit a large amount of heat. Therefore, during the formation of aluminum ash, AlN is usually generated. AlN is the reaction product of molten aluminum liquid and nitrogen, and it is easily hydrolyzed by water to generate pungent and toxic gas NH3, which is also one of the main reasons for aluminum ash to affect the environment. In addition, due to the generation of a large amount of heat during the acid leaching process of aluminum ash, there is also a safety hazard of boiling over and injuring people in this reaction process. Thus, there are still certain obstacles to the resourceful utilization of aluminum ash.

[0003] In the prior art, Chinese Patent CN108950227A discloses a pressure and atmospheric pressure harmless treatment system for aluminum ash. This system consists of a pressure stirring leaching kettle, a 1# filter press, an atmospheric pressure stirring leaching tank, and a 2# filter press connected in sequence. Aluminum ash can be subjected to pressure stirring leaching and atmospheric pressure stirring leaching. The ammonia gas generated by mixing aluminum ash with water in the pressure stirring leaching kettle enters the 1# absorption tower and the 2# absorption tower for full absorption to achieve the full-automatic closed harmless treatment of aluminum ash. However, this system does not consider the influence of the large amount of heat generated during the acid leaching process of aluminum ash on the system. Especially in the pressure stirring leaching kettle, the large amount of heat generated will cause the pressure in the kettle to fluctuate, increasing the difficulty of controlling the pressure in the kettle and the difficulty of engineering implementation. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a continuous acid leaching production system for aluminum ash, which adopts continuous acid leaching technology to realize the continuous production of aluminum ash treatment, can reduce the waiting time and material transfer process in batch treatment, improve production efficiency, and the continuous acid leaching treatment is carried out in a closed system, reducing the direct contact between harmful substances and operators, and at the same time reducing the occurrence of the risk of boiling over and improving the safety of the production process.

[0005] The utility model is realized through the following technical solutions: An aluminum ash continuous acid leaching production system includes a slurry mixing kettle and at least two acid leaching kettles connected to the slurry mixing kettle in sequence. An aluminum ash feed pipe and a pulping water feeding port are arranged on the slurry mixing kettle, and a sulfuric acid feeding pipe is arranged on the acid leaching kettle. The slurry mixing kettle and the acid leaching kettle are both provided with stirring paddles and gas outlets, and the gas outlets are connected to a tail gas purification device through pipelines.

[0006] The slurry mixing kettle and the acid leaching kettle are connected by an overflow pipe, and the outlet height of the kettle body at the upper level of the overflow pipe is lower than the height of the kettle body at the lower level of the overflow pipe, and an overflow valve is arranged on the overflow pipe.

[0007] Baffle plates are arranged on the side walls of the slurry mixing kettle and the acid leaching kettle.

[0008] The slurry mixing kettle and the acid leaching kettle are both provided with liquid level gauges, and the liquid level gauges are interlocked and controlled with the overflow valves between their respective kettle bodies and the lower-level kettle bodies.

[0009] The overflow pipes are all provided with slurry flow meters, and the sulfuric acid feeding pipes are all provided with acid adding valves. The slurry flow meters are interlocked and controlled with the acid adding valves on the lower-level kettle bodies connected to their respective overflow pipes.

[0010] The number of the acid leaching kettles is three, and a material outlet connecting to the next process is arranged on the acid leaching kettle at the last stage.

[0011] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0012] (1) The utility model uses a slurry mixing kettle connected in sequence and multiple-stage acid leaching kettles to continuously acid leach aluminum ash, enabling aluminum compounds (such as metallic aluminum, aluminum oxide, aluminum nitride, etc.) in the aluminum ash to be more efficiently converted into soluble aluminum ions and enter the leaching solution, thereby improving the leaching rate of aluminum.

[0013] (2) Through the continuous acid leaching production of aluminum ash treatment, the utility model can reduce the waiting time in batch processing and the material transfer process, and improve production efficiency.

[0014] (3) The utility model conducts continuous acid leaching treatment in a closed system, collects and treats harmful gases generated by the system through a tail gas purification device, can reduce the direct contact between harmful substances and operators, and at the same time reduces the occurrence of the risk of boiling over, improving the safety of the production process.

[0015] (4) The utility model can achieve automatic control, such as a PLC control system, which can accurately control various parameters in the acid leaching process, such as acid concentration, temperature, stirring rate, etc., to ensure the stability and consistency of the process.

[0016] (5) The utility model can reduce waste gas emissions. By combining the continuous acid leaching technology with a tail gas purification device, it can effectively treat the acid liquid waste gas generated, reduce waste gas emissions, and reduce environmental pollution.

[0017] In summary, the utility model provides an aluminum ash multi-stage acid leaching production device, which adopts a multi-stage overflow method for continuous production. At the same time, the device can operate stably and continuously, and has significant advantages in improving the leaching rate and purity of aluminum, optimizing the process flow, environmental protection benefits, economy and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a process schematic diagram of the utility model.

[0019] Among them, 1 - slurry mixing kettle, 2 - acid leaching kettle, 3 - aluminum ash feed pipe, 4 - pulping water feeding port, 5 - sulfuric acid feed pipe, 6 - stirring paddle, 7 - gas outlet, 8 - tail gas purification device, 9 - overflow pipe, 10 - overflow valve, 11 - baffle plate, 12 - liquid level gauge, 13 - slurry flowmeter, 14 - acid adding valve, 15 - material outlet, 16 - induced draft fan. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The following further details the utility model in conjunction with embodiments, but the embodiments of the utility model are not limited thereto.

[0021] Embodiment 1:

[0022] This embodiment relates to an aluminum ash continuous acid leaching production system. The system combines a slurry mixing kettle 1 and a multi-stage acid leaching kettle 2 to achieve the continuous acid leaching process of aluminum ash. Since the existing conventional aluminum ash acid leaching process generally adds enough sulfuric acid and aluminum ash at one time for reaction, as the reaction progresses, the sulfuric acid concentration gradually decreases and the reaction temperature also gradually decreases, which is very likely to cause a decrease in reaction efficiency. Therefore, by adopting the continuous acid leaching process, the required sulfuric acid can be added in multiple times during the aluminum ash acid leaching process to ensure that all the aluminum ash in the reaction kettle can react with high-concentration sulfuric acid. The unreacted aluminum ash in each stage can be transferred to the next stage for reaction, and at the same time, the next stage of reaction replenishes the corresponding proportion of high-concentration sulfuric acid to further react the unreacted aluminum oxide in the aluminum ash, thereby improving the leaching rate of the reaction.

[0023] Refer to Figure 1 As shown in the structure, the system structure of this embodiment can be specifically summarized as follows:

[0024] It consists of a slurry mixing kettle 1, acid leaching kettles 2 with multiple levels, and a tail gas purification device 8. The acid leaching kettles 2 with multiple levels are successively connected to the slurry mixing kettle 1. The slurry mixing kettle 1 and the acid leaching kettles 2, as well as adjacent acid leaching kettles 2, are connected through overflow pipes 9. An aluminum ash feed pipe 3, a pulping water feeding port 4, and a gas outlet 7 are respectively arranged on the slurry mixing kettle 1, and a sulfuric acid feed pipe 5 and a gas outlet 7 are arranged on the acid leaching kettle 2. At the same time, the gas outlets 7 on the slurry mixing kettle 1 and the acid leaching kettles 2 are connected to the tail gas purification device 8 through pipelines and controlled by a blower 16, so that the tail gas (hydrogen, sulfuric acid mist, sulfur dioxide, ammonia) generated in the kettle can be drawn into the tail gas purification device 8 for treatment. During treatment, the hydrogen in the tail gas can be directly discharged at high altitude after purification, and the sulfuric acid mist, sulfur dioxide, and ammonia can be jointly treated by means of water absorption and alkali solution spraying.

[0025] In this embodiment, stirring paddles 6 and baffle plates 11 are provided in both the slurry mixing kettle 1 and the acid leaching kettles 2. The stirring paddles 6 and the baffle plates 11 are used in combination to improve the uniformity of the material mixing in the kettle. The baffle plate 11 is a baffle provided on the side wall of the kettle body and can be fixed to the inner wall of the kettle body in an inclined or vertical manner along the axial direction of the kettle body. In the continuous acid leaching process, the design of the baffle plate 11 can adjust and control the flow rate and flow direction of the acid leaching solution, ensure that the acid leaching solution flows through the aluminum ash layer evenly and stably, enable the aluminum ash to fully contact and react with the acid leaching solution, and improve the acid leaching efficiency. At the same time, the baffle plate 11 can also promote the bubbles generated in the kettle to dissipate as soon as possible and reduce the risk of boiling over. In the specific implementation process, the reasonable design of the position and shape of the baffle plate 11 can also be utilized. For example, by reasonably designing the length, width, and / or inclination angle of the baffle plate 11 according to the fluid in the kettle, the flow field distribution in the acid leaching kettle 2 can be further optimized, making the aluminum ash particles more dispersed and uniform in the acid leaching solution, which is conducive to the full reaction between the aluminum ash and the acid leaching solution and also helps to improve the leaching efficiency of aluminum and the purity of the leaching solution.

[0026] In this embodiment, the conveying of materials between the kettle bodies is realized through the overflow pipe 9, as Figure 1 shown in the structure. An overflow valve 10 is arranged on the overflow pipe 9, and the control of the overflow valve 10 can be controlled according to the liquid level height in the kettle. The overflow pipe 9 is respectively connected to the discharge port and the feed port of two adjacent kettle bodies. The discharge port of the upper-level kettle body is arranged at the lower part of the kettle body, and the feed port of the lower-level kettle body is arranged at the upper part of the kettle body. When the liquid level of the upper-level kettle body reaches the overflow liquid level, the overflow valve 10 can be opened, and the materials in the kettle can flow into the lower-level kettle body through the overflow pipe 9. For example, between the slurry mixing kettle 1 and the multi-level acid leaching kettles 2 in this embodiment, through the interlocking control of the overflow liquid level and the overflow valve 10, the continuous feeding and discharging of materials can be realized, and the continuous operation of the acid leaching process can be achieved.

[0027] Example 2:

[0028] This embodiment relates to an automatic control system for a continuous acid leaching process, that is, adding automated interlock control to the aluminum ash continuous acid leaching production system in Embodiment 1, including but not limited to: connecting the aluminum ash feed pipe 3 to the aluminum ash feeder, installing a pulp water valve on the pipe connecting the pulp water feeding port 4, and interlock controlling the aluminum ash feeder and the pulp water valve, so that the opening, closing or opening degree of the pulp water valve can be adjusted according to the aluminum ash feeding amount; installing a pulp flowmeter 13 on the overflow pipe 9 and an acid adding valve 14 on the sulfuric acid feed pipe 5, and interlock controlling the pulp flowmeter 13 and the acid adding valve 14 on the lower-stage kettle body connected to the overflow pipe 9 where it is located, so that the opening, closing or opening degree of the acid adding valve 14 can be adjusted according to the pulp flow; installing a liquid level gauge 12 on the pulp mixing kettle 1 and the acid leaching kettle 2, measuring the liquid level in the corresponding kettle body through the liquid level gauge 12, and interlock controlling the preset overflow liquid level and the overflow valve 10 between the kettle body where it is located and the lower-stage kettle body, so that the opening or closing of the overflow valve 10 can be adjusted according to the overflow liquid level. And these interlock controls can all be realized by a PLC automatic control system.

[0029] Specifically, the continuous acid leaching production system includes the following steps:

[0030] Step 1, pulping:

[0031] Through the PLC automatic control system, the aluminum ash feeder and the pulp water valve are simultaneously opened, and the aluminum ash is added into the pulp mixing kettle 1 through the feeder for pulping. At the same time, the induced draft fan 16 is started to absorb the generated tail gas.

[0032] Step 2, mixing:

[0033] The pulp mixing kettle 1 mixes the aluminum ash and water for pulping. When the pulp reaches the overflow liquid level, the PLC automatic control system opens the overflow valve 10, and the pulp enters the acid leaching kettle 2 through the overflow pipe 9.

[0034] Step 3, primary acid leaching:

[0035] After the pulp enters the acid leaching kettle 2, the acid adding valve 14 is opened through the PLC automatic control system, sulfuric acid is added into the acid leaching kettle 2, the acid adding amount is controlled according to the pulp amount, and the tail gas treatment system is kept open during the acid leaching process.

[0036] Step 4, continuous acid leaching:

[0037] When the primary acid leaching is completed, through the PLC automatic control system for automatic control, the control method of the primary acid leaching is repeated in the lower-stage acid leaching kettle 2, and the acid leaching operation is continuously carried out multiple (three) times;

[0038] Step 5, product transfer:

[0039] The aluminum ash after continuous multiple (three) times of acid leaching is transferred from the material outlet 15 of the acid leaching kettle 2 at the last stage to the next process for filtering and washing of aluminum sulfate.

[0040] The above are only the preferred embodiments of the present utility model, and do not impose any form of limitation on the present utility model. Any simple modification or equivalent change made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A continuous acid leaching production system for aluminum ash, characterized in that: It includes a slurry mixing kettle (1) and at least two acid leaching kettles (2) connected in sequence to the slurry mixing kettle (1). An aluminum ash feed pipe (3) and a pulping water feeding port (4) are provided on the slurry mixing kettle (1), and a sulfuric acid feed pipe (5) is provided on the acid leaching kettle (2). Both the slurry mixing kettle (1) and the acid leaching kettle (2) are provided with stirring paddles (6) and gas outlets (7), and the gas outlets (7) are connected to a tail gas purification device (8) through pipelines.

2. The aluminum ash continuous acid leaching production system according to claim 1, wherein: The slurry mixing kettle (1) and the acid leaching kettle (2) are connected by an overflow pipe (9) between them, and between adjacent acid leaching kettles (2). The height of the kettle body outlet above the overflow pipe (9) is lower than the height of the kettle body below the overflow pipe (9), and an overflow valve (10) is provided on the overflow pipe (9).

3. The aluminum ash continuous acid leaching production system according to claim 1, characterized in that: Choke plates (11) are provided on the side walls of the slurry mixing kettle (1) and the acid leaching kettle (2).

4. The aluminum ash continuous acid leaching production system according to claim 2, wherein: Both the slurry mixing kettle (1) and the acid leaching kettle (2) are provided with liquid level gauges (12), and the liquid level gauges (12) are interlocked and controlled with the overflow valves (10) between their respective kettle bodies and the lower-level kettle bodies.

5. The aluminum ash continuous acid leaching production system according to claim 2, wherein: Each overflow pipe (9) is provided with a slurry flowmeter (13), and each sulfuric acid feed pipe (5) is provided with an acid addition valve (14). The slurry flowmeter (13) is interlocked and controlled with the acid addition valve (14) on the lower-level kettle body connected to its respective overflow pipe (9).

6. The aluminum ash continuous acid leaching production system according to claim 1, characterized in that: The number of the acid leaching kettles (2) is three, and a material outlet (15) connecting to the next process is provided on the acid leaching kettle (2) at the last stage.

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