Electrolytic aluminum hazardous waste aluminum ash treatment process

Abstract

The invention relates to the technical field of aluminum ash treatment, and discloses an electrolytic aluminum hazardous waste aluminum ash treatment process which comprises the following steps: step 1, collecting and pretreating aluminum ash; 2, physical separation; step 3, chemical leaching; step 4, ammonia water recovery and concentration; step 5, precipitation reaction; and step 6, roasting treatment. According to the method, the concentration of the aluminum ions is monitored in real time and is ensured to be within the range of 0.1-0.5 mol / L, the stable concentration of the aluminum ions in the ammonia water is kept, in the fourth step, the ammonia gas is collected by adopting a spray tower, the ammonia water is concentrated through a membrane separation technology, selection of the membrane separation technology and operation conditions are optimized, the concentration uniformity of the ammonia water is further improved, and the concentration uniformity of the ammonia water is further improved. In the third step, sodium hydroxide with the concentration of 3-5 mol / L is used for leaching, the reaction temperature is controlled to be 60-80 DEG C, the reaction lasts for 2-4 hours, the concentration of aluminum ions is kept to be 0.1-0.5 mol / L, and the beneficial effect that ammonia water enrichment is uniform and stable in the large-scale electrolytic waste aluminum denitration treatment link is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum ash treatment, and in particular to a process for treating hazardous waste aluminum ash from electrolytic aluminum. Background Art

[0002] With the development of industry and the improvement of people's living standards, aluminum alloys have been widely used in various industries. Data show that the annual waste slag produced by the aluminum profile industry in my country is about 3 million tons, and this number is expected to continue to increase with the rapid development of my country's construction industry. At present, waste aluminum ash is basically treated by landfill, which not only wastes limited land resources, but also causes environmental pollution. Calcium aluminate is mainly used in the production of water purifiers, fireproof materials, building anti-cracking and waterproofing, steel plant desulfurization and other fields. It is made by calcining bauxite and limestone. Although the production process is simple, it consumes bauxite ore. With the development of mineral resources, it will bring a series of environmental problems. If waste aluminum ash replaces bauxite and is sintered with limestone to form a refined slag containing calcium aluminate, it can replace calcium aluminate in the fields of water purifiers, steel plant desulfurizers, and quick-setting agents, which not only reduces production costs, but also makes comprehensive use of waste aluminum ash, turning waste into treasure and reducing environmental pressure.

[0003] After searching, it was found that the prior art solution publication number is CN 116871302A, which is a hazardous waste aluminum ash treatment process, and relates to the aluminum ash treatment technology field. The present invention includes step one, cracking reaction, according to the reaction of aluminum nitride with water, adding alkaline low-degree ammonia water, catalyst and water, accelerating the cracking speed, and rapidly converting ammonia gas to achieve 99% decomposition; step two, spraying ammonia collection, because a large amount of unstable ammonia gas is generated after cracking, firstly, the condenser is cooled, lactic acid water is added to spray and atomize in the tower, and water curtain cooling is achieved, and the gasification is changed into a liquefaction process, which is repeated through multiple towers until the emission standard is reached, and there is no escape. Ammonia water is reused and enriched to a 10% content concentration for commercial denitrification. The present invention reduces the use of a large number of water sources, has no secondary emission pollution, low cost, perfect management, obvious effect, high safety, low energy consumption, zero emission, high stability of the added agent, ensures good complete chlorine treatment effect, does not block the molybdenum, saves evaporation costs, and all are recycled and energy-saving.

[0004] The above technical solution mentioned in the process that after the ammonia water is treated, the concentration reaches 10%, which can be used as a commodity in the denitrification process. The enrichment process of ammonia water, especially in large-scale treatment, is difficult to ensure the stable concentration of ammonia water. If the ammonia water is not uniformly enriched or the concentration is unstable, it will affect the denitrification effect and reduce the reuse value of resources. Summary of the invention

[0005] Technical issues solved:

[0006] In view of the deficiencies in the prior art, the present invention provides a process for treating hazardous waste aluminum ash from electrolytic aluminum, which has the advantages of uniform and stable ammonia enrichment in the denitrification process of large-scale treatment of electrolytic waste aluminum, improving the denitrification effect and further enhancing the recovery efficiency of electrolytic waste aluminum, thereby solving the problems of the above-mentioned technologies.

[0007] Technical solution:

[0008] To achieve the above object, the present invention provides the following technical solution: a process for treating hazardous waste aluminum ash from electrolytic aluminum, comprising the following steps:

[0009] Step 1: Pretreatment of aluminum ash collection: collect the aluminum ash in the aluminum ash recovery bin of the electrolytic aluminum plant, dry the collected aluminum ash at 70-100°C for 1-2 hours, and crush the dried aluminum ash;

[0010] Step 2: Physical separation: Using a gravity separator and a vibrating screen, the separation efficiency of aluminum metal and ash reaches more than 95%, and the purity of the recovered aluminum metal exceeds 90%;

[0011] Step 3, chemical leaching: adding sodium hydroxide (NaOH) with a concentration of 3-5 mol / L in a stirring tank to chemically leach the aluminum ash to extract aluminum and other metals, and monitoring the aluminum ion concentration in real time to ensure that it is within the range of 0.1-0.5 mol / L;

[0012] Step 4: Ammonia recovery and concentration: Ammonia gas is collected through a spray tower and enters an ammonia collection system. The ammonia is concentrated using membrane separation technology. The final ammonia concentration reaches 10-15% (w / v). The ammonia concentration is monitored in real time to ensure that the final concentration reaches more than 10%;

[0013] Step 5, precipitation reaction: mixing the aluminum ion-rich liquid with other metal ions to form a precipitate at a pH value of 5-7;

[0014] Step 6: Calcination: Calcinate the obtained precipitate at a temperature of 850°C-1150°C for 2-4 hours.

[0015] Preferably, in step 1, the moisture content of the aluminum ash is reduced to below 5%.

[0016] Preferably, the target particle size of the aluminum ash after drying in step 1 is 0.5-5 mm.

[0017] Preferably, in step three, the chemical leaching reaction temperature is 60-80° C., and the reaction time is 2-4 hours.

[0018] Preferably, the specific steps of membrane separation in step 4 are:

[0019] S1.1, injecting the pre-treated ammonia water into the membrane separation system;

[0020] S1.2. Under high pressure, the water in the ammonia water passes through the membrane, while the concentrated solutes in the ammonia water remain on the feed side of the membrane. Depending on the type of membrane selected, the membrane separates the ammonia molecules from the water molecules, and the ammonia concentration gradually increases;

[0021] S1.3. Monitor the pressure, flow rate and ammonia concentration during the membrane separation process. The concentrated ammonia is collected through the permeate side of the membrane and the concentration should be controlled between 10-15%.

[0022] Preferably, the precipitation reaction time in step 5 is 1-2 hours.

[0023] Preferably, the reaction of aluminum hydroxide and sodium hydroxide in step 3 is calculated as:

[0024]

[0025] The concentration of aluminum ions in step 3 is calculated as:

[0026]

[0027] in: is the concentration of aluminum ions; n is the concentration of aluminum ions; V is the total volume of the solution.

[0028] Preferably, the amount n of aluminum in step 3 is calculated as follows:

[0029]

[0030] Where: m is the mass of aluminum; M Al is the molar mass of aluminum;

[0031] The concentration control condition in step 3 is calculated as:

[0032]

[0033] This inequality constrains the concentration of aluminum ions to be maintained between 0.1 and 0.5 mol / L;

[0034] Substitute the aluminum ion concentration formula into:

[0035]

[0036] Where: This inequality ensures that under different conditions of the amount of aluminum substance n and the solution volume V, the concentration of aluminum ions Keep between 0.1 and 0.5 mol / L.

[0037] Preferably, the ammonia concentration in step 4 is defined and calculated as:

[0038]

[0039] Where: C is the concentration of ammonia water, is the mass of ammonia, V solution is the total volume of ammonia solution;

[0040] The target calculation of concentrated ammonia water is:

[0041] C ≥ 10%

[0042] The relationship between the mass and volume of ammonia collected in step 4 is:

[0043]

[0044] in: is the molar mass of ammonia.

[0045] Preferably, the equilibrium calculation of the ammonia concentration process in step 4 is:

[0046]

[0047] in: is the mass of ammonia in the initial ammonia solution; is the mass of ammonia in the concentrated ammonia water; m loss is the mass of ammonia lost during the concentration process;

[0048] The real-time monitoring concentration is calculated as: 10% ≤ C actual ≤15%.

[0049] Compared with the prior art, the present invention provides a process for treating hazardous waste aluminum ash from electrolytic aluminum, which has the following beneficial effects:

[0050] 1. The present invention maintains a stable concentration of aluminum ions in ammonia water by real-time monitoring of aluminum ion concentration and ensuring that it is within the range of 0.1-0.5 mol / L. In step 4, a spray tower is used to collect ammonia gas, and ammonia water is concentrated by membrane separation technology. The method can effectively separate ammonia gas and water, ensure that the enrichment process of ammonia gas is uniform and efficient, and the selection and operation conditions of membrane separation technology are optimized to further improve the concentration uniformity of ammonia water. During the ammonia water concentration process, the concentration, pressure and flow rate of ammonia water are monitored in real time, so that the operator can adjust the operation parameters in time to ensure that the ammonia water concentration is stable between 10-15%. The dynamic adjustment capability is particularly important for large-scale processing and helps to cope with changes in different batches of aluminum ash. In the precipitation reaction step, the pH value is maintained within the range of 5-7, which helps the uniform reaction of aluminum ions with other metal ions to form a stable precipitate. The uniform reaction conditions reduce the concentration of gold ions in ammonia water. The fluctuation of metal ion concentration can be reduced, thereby improving the overall quality of ammonia water. The design of the entire process flow takes into account the connection and coordination between each step, so that the output of each step can provide a stable input for the next step. For example, the drying and crushing steps of aluminum ash ensure the efficiency of subsequent physical separation, which in turn affects the effect of chemical leaching and ammonia water recovery. Through the above measures, the treatment process of hazardous waste aluminum ash from electrolytic aluminum can achieve uniform and stable ammonia water enrichment, ensuring that the quality and concentration of ammonia water can meet production requirements during large-scale treatment. This not only improves the resource recovery efficiency, but also reduces the risk of environmental pollution. In step three, sodium hydroxide with a concentration of 3-5 mol / L is used for leaching, and the reaction temperature is controlled at 60-80℃ for 2-4 hours to keep the aluminum ion concentration at 0.1-0.5 mol / L, achieving the beneficial effect of uniform and stable ammonia water enrichment in the large-scale treatment of electrolytic waste aluminum destocking.

[0051] 2. The present invention monitors the pressure, flow rate and ammonia concentration during the membrane separation process to ensure that each parameter is within the optimal range, thereby maximizing the ammonia recovery effect, dynamically adjusting these operating parameters to cope with changes in raw material characteristics, and continuously optimizing the ammonia recovery efficiency. By strictly controlling the concentration of aluminum ions at 0.1-0.5 mol / L, the efficiency of aluminum dissolution reaction is improved, ensuring that a larger proportion of aluminum enters the ammonia recovery process. This control directly affects the subsequent precipitation reaction and ammonia enrichment effect, and is crucial to improving the aluminum recovery rate. By controlling the pH value (5-7) under alkaline conditions and conducting a precipitation reaction for 1-2 hours, a stable precipitate is formed, and aluminum is efficiently separated from other metals, which not only improves the aluminum recovery rate, but also ensures the quality of the precipitate, which is convenient for subsequent processing, thereby achieving the beneficial effect of improving the de-metallization effect and further enhancing the recovery efficiency of electrolytic waste aluminum. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of the steps of the present invention; DETAILED DESCRIPTION

[0053] 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.

[0054] See also Figure 1 , a process for treating hazardous waste aluminum ash from electrolytic aluminum, comprising the following steps:

[0055] Step 1: Pretreatment of aluminum ash collection: collect the aluminum ash in the aluminum ash recovery bin of the electrolytic aluminum plant, dry the collected aluminum ash at 70-100°C for 1-2 hours, and crush the dried aluminum ash;

[0056] Step 2: Physical separation: Using a gravity separator and a vibrating screen, the separation efficiency of aluminum metal and ash reaches more than 95%, and the purity of the recovered aluminum metal exceeds 90%;

[0057] Step 3, chemical leaching: adding sodium hydroxide (NaOH) with a concentration of 3-5 mol / L in a stirring tank to chemically leach the aluminum ash to extract aluminum and other metals, and monitoring the aluminum ion concentration in real time to ensure that it is within the range of 0.1-0.5 mol / L;

[0058] Step 4: Ammonia recovery and concentration: Ammonia gas is collected through a spray tower and enters an ammonia collection system. The ammonia is concentrated using membrane separation technology. The final ammonia concentration reaches 10-15% (w / v). The ammonia concentration is monitored in real time to ensure that the final concentration reaches more than 10%;

[0059] Step 5, precipitation reaction: mixing the aluminum ion-rich liquid with other metal ions to form a precipitate at a pH value of 5-7;

[0060] Step 6: Calcination: Calcinate the obtained precipitate at a temperature of 850°C-1150°C for 2-4 hours.

[0061] High physical separation efficiency: Through gravity separator and vibrating screen, the separation efficiency of aluminum metal and ash exceeds 95%, and the purity of recycled aluminum metal exceeds 90%. This means that most of the aluminum metal can be effectively recycled, reducing resource waste.

[0062] Low energy consumption drying: The drying process of aluminum ash is carried out at 70-100℃. The relatively low temperature reduces energy consumption while effectively removing moisture and reducing the risk of contamination in subsequent processing.

[0063] Ammonia recovery and utilization: Ammonia is collected and recovered through a spray tower, which reduces ammonia emissions and reduces the impact on the environment.

[0064] Aluminum ion concentration monitoring: During the chemical leaching process, the aluminum ion concentration is monitored in real time to ensure that it is within the range of 0.1-0.5 mol / L, which helps to optimize the aluminum extraction efficiency and avoid resource waste.

[0065] Membrane separation technology: Using membrane separation technology to concentrate ammonia water can effectively increase the concentration of ammonia water, reduce the cost and complexity of subsequent treatment, and ensure the quality of ammonia water.

[0066] Controlling pH: Carrying out precipitation reaction at a pH of 5-7 helps to effectively separate aluminum from other metals, form a stable precipitate, and further improve metal recovery rate.

[0067] High temperature roasting: Through the roasting treatment at 850℃-1150℃, aluminum and other metals can be effectively separated, the purity of the final product can be improved, and the maximum utilization of resources can be ensured.

[0068] Resource recovery and utilization: This process not only effectively recovers aluminum metal, but also can extract other valuable metals, increasing economic benefits and reducing waste disposal costs.

[0069] Coordination of the entire process: Good connection and coordination between various steps improves the overall processing efficiency, reduces resource loss in the intermediate links, and forms an efficient closed-loop processing system.

[0070] Specifically, in step 1, the moisture content of the aluminum ash is reduced to below 5%.

[0071] Specifically, the target particle size of the aluminum ash after drying in step 1 is 0.5-5 mm.

[0072] Specifically, in step three, the chemical leaching reaction temperature is 60-80° C., and the reaction time is 2-4 hours.

[0073] Moisture content reduced to below 5%:

[0074] Improve the efficiency of subsequent treatment: Reducing the moisture content helps to reduce the dilution effect in subsequent chemical reactions and improve the leaching efficiency of aluminum.

[0075] Reduced energy consumption: Drying to less than 5% moisture reduces energy consumption during roasting and leaching, improving overall energy efficiency.

[0076] Anti-caking: Low moisture content reduces the cohesiveness of aluminum ash, facilitating subsequent physical separation and handling.

[0077] The target particle size of the aluminum ash after drying is 0.5-5mm:

[0078] Optimize separation effect: The appropriate particle size range helps to improve the separation efficiency of aluminum metal during the physical separation process and ensure the best separation effect of aluminum slag.

[0079] Increase the surface area for leaching reaction: Smaller particle size increases the surface area of ​​aluminum ash, promotes the rate of chemical leaching reaction, and improves the extraction rate of aluminum.

[0080] The reaction temperature is 60-80°C:

[0081] Accelerated reaction rates: Within this temperature range, the rate of chemical reactions increases significantly, helping to extract aluminum and other metals faster and improving overall recycling efficiency.

[0082] Reduced energy consumption: Relatively low reaction temperatures (compared to high temperature reactions) can reduce energy consumption and lower overall processing costs.

[0083] Reaction time is 2-4 hours:

[0084] Optimize aluminum dissolution rate: Appropriate reaction time ensures sufficient dissolution of aluminum and other metals, avoiding insufficient aluminum extraction due to too short a time.

[0085] Improve operational flexibility: Within the 2-4 hours reaction time, the operation can be adjusted according to the actual situation to ensure the optimization of reaction conditions.

[0086] Specifically, the membrane separation steps in step 4 are as follows:

[0087] S1.1, injecting the pre-treated ammonia water into the membrane separation system;

[0088] S1.2. Under high pressure, the water in the ammonia water passes through the membrane, while the concentrated solutes in the ammonia water remain on the feed side of the membrane. Depending on the type of membrane selected, the membrane separates the ammonia molecules from the water molecules, and the ammonia concentration gradually increases;

[0089] S1.3. Monitor the pressure, flow rate and ammonia concentration during the membrane separation process. The concentrated ammonia is collected through the permeate side of the membrane and the concentration should be controlled between 10-15%.

[0090] Specifically, the precipitation reaction time in step 5 is 1-2 hours.

[0091] Specifically, the reaction of aluminum hydroxide and sodium hydroxide in step 3 is calculated as:

[0092]

[0093] The concentration of aluminum ions in step 3 is calculated as:

[0094]

[0095] in: is the concentration of aluminum ions; n is the concentration of aluminum ions; V is the total volume of the solution.

[0096] Specifically, the amount of aluminum in step 3 is calculated as follows:

[0097]

[0098] Where: m is the mass of aluminum; M Al is the molar mass of aluminum;

[0099] The concentration control condition in step 3 is calculated as:

[0100]

[0101] This inequality constrains the concentration of aluminum ions to be maintained between 0.1 and 0.5 mol / L;

[0102] Substitute the aluminum ion concentration formula into:

[0103]

[0104] Where: This inequality ensures that under different conditions of the amount of aluminum substance n and the solution volume V, the concentration of aluminum ions Keep between 0.1 and 0.5 mol / L.

[0105] Specifically, the definition and calculation of the ammonia concentration in step 4 is:

[0106]

[0107] Where: C is the concentration of ammonia water, is the mass of ammonia, V solution is the total volume of ammonia solution;

[0108] The target calculation for concentrated ammonia is:

[0109] C ≥ 10%

[0110] The relationship between the mass and volume of ammonia collected in step 4 is:

[0111]

[0112] in: is the molar mass of ammonia.

[0113] Specifically, the equilibrium calculation of the ammonia concentration process in step 4 is:

[0114]

[0115] in: is the mass of ammonia in the initial ammonia solution; is the mass of ammonia in the concentrated ammonia water; m loss is the mass of ammonia lost during the concentration process;

[0116] Real-time monitoring concentration is calculated as: 10% ≤ C actual ≤15%.

[0117] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for treating hazardous waste aluminum ash from electrolytic aluminum, characterized in that: The following steps are involved: Step 1: Pretreatment of aluminum ash collection: collect the aluminum ash in the aluminum ash recovery bin of the electrolytic aluminum plant, dry the collected aluminum ash at 70-100°C for 1-2 hours, and crush the dried aluminum ash; Step 2: Physical separation: Using a gravity separator and a vibrating screen, the separation efficiency of aluminum metal and ash reaches more than 95%, and the purity of the recovered aluminum metal exceeds 90%; Step 3, chemical leaching: adding sodium hydroxide (NaOH) with a concentration of 3-5 mol / L in a stirring tank to chemically leach the aluminum ash to extract aluminum and other metals, and monitoring the aluminum ion concentration in real time to ensure that it is within the range of 0.1-0.5 mol / L; Step 4: Ammonia recovery and concentration: Ammonia gas is collected through a spray tower and enters an ammonia collection system. The ammonia is concentrated using membrane separation technology. The final ammonia concentration reaches 10-15% (w / v). The ammonia concentration is monitored in real time to ensure that the final concentration reaches more than 10%; Step 5, precipitation reaction: mixing the aluminum ion-rich liquid with other metal ions to form a precipitate at a pH value of 5-7; Step 6: Calcination: Calcinate the obtained precipitate at a temperature of 850°C-1150°C for 2-4 hours.

2. The process for treating hazardous waste aluminum ash from electrolytic aluminum according to claim 1, characterized in that: In the step 1, the moisture content of the aluminum ash is reduced to below 5%.

3. The process for treating hazardous waste aluminum ash from electrolytic aluminum according to claim 1, characterized in that: The target particle size of the aluminum ash after drying in the step 1 is 0.5-5 mm.

4. The process for treating hazardous waste aluminum ash from electrolytic aluminum according to claim 1, characterized in that: In the step 3, the chemical leaching reaction temperature is 60-80° C., and the reaction time is 2-4 hours.

5. The process for treating hazardous waste aluminum ash from electrolytic aluminum according to claim 1, characterized in that: The specific steps of membrane separation in step 4 are: S1.1, injecting the pre-treated ammonia water into the membrane separation system; S1.

2. Under high pressure, the water in the ammonia water passes through the membrane, while the concentrated solutes in the ammonia water remain on the feed side of the membrane. Depending on the type of membrane selected, the membrane separates the ammonia molecules from the water molecules, and the ammonia concentration gradually increases; S1.

3. Monitor the pressure, flow rate and ammonia concentration during the membrane separation process. The concentrated ammonia is collected through the permeate side of the membrane and the concentration should be controlled between 10-15%.

6. The process for treating hazardous aluminum ash from electrolytic aluminum according to claim 1, characterized in that: The precipitation reaction time in step 5 is 1-2 hours.

7. The process for treating hazardous waste aluminum ash from electrolytic aluminum according to claim 1, characterized in that: The reaction of aluminum hydroxide and sodium hydroxide in step 3 is calculated as follows: The concentration of aluminum ions in step 3 is calculated as: in: is the concentration of aluminum ions; n is the concentration of aluminum ions; V is the total volume of the solution.

8. The process for treating hazardous waste aluminum ash from electrolytic aluminum according to claim 1, characterized in that: The amount n of aluminum in step 3 is calculated as follows: Where: m is the mass of aluminum; M Al is the molar mass of aluminum; The concentration control condition in step 3 is calculated as: This inequality constrains the concentration of aluminum ions to be maintained between 0.1 and 0.5 mol / L; Substitute the aluminum ion concentration formula into: Where: This inequality ensures that under different conditions of the amount of aluminum substance n and the solution volume V, the concentration of aluminum ions Keep between 0.1 and 0.5 mol / L.

9. The process for treating hazardous waste aluminum ash from electrolytic aluminum according to claim 1, characterized in that: The definition and calculation of the ammonia concentration in step 4 is: Where: C is the concentration of ammonia water, is the mass of ammonia, V solution is the total volume of ammonia solution; The target calculation of concentrated ammonia water is: C≥10％ The relationship between the mass and volume of ammonia collected in step 4 is: in: is the molar mass of ammonia.

10. The process for treating hazardous aluminum ash from electrolytic aluminum according to claim 1, characterized in that: The equilibrium calculation of the ammonia concentration process in step 4 is: in: is the mass of ammonia in the initial ammonia solution; is the mass of ammonia in the concentrated ammonia water; m loss is the mass of ammonia lost during the concentration process; The real-time monitoring concentration is calculated as: 10% ≤ C actual ≤15%.

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