Method for recycling aluminum ash

Abstract

The present application belongs to the technical field of aluminum ash treatment, and particularly relates to a method for recycling aluminum ash. The method for recycling aluminum ash provided by the present application comprises the following steps: crushing secondary aluminum ash, sieving, then mixing the sieved fine material with water to obtain slurry, filtering the slurry to obtain filter cake; drying, crushing and sieving the filter cake to obtain filter cake particles; adding the filter cake particles into a roasting furnace, then introducing inert gas into the roasting furnace, heating the roasting furnace to 800-1000 DEG C to roast the filter cake particles, then introducing hydrogen fluoride gas and intermittently introducing hydrogen into the roasting furnace, and after the roasting is completed, cooling the filter cake particles to room temperature, crushing to obtain aluminum ash slag. The method for recycling aluminum ash provided by the present application can effectively reduce the silicon content in the aluminum ash slag, and does not need to add additional aluminum fluoride additive and does not need to be subjected to granulation treatment, so the process is simple.

Description

Technical Field

[0001] This invention belongs to the field of aluminum ash treatment technology, and specifically relates to a method for the resource utilization of aluminum ash. Background Technology

[0002] The processing and smelting of aluminum generates a large amount of waste residue, known as aluminum ash. Further processing of this ash, such as using physical or chemical methods to recover aluminum, also produces waste residue, known as secondary aluminum ash. Secondary aluminum ash has a complex composition, primarily containing aluminum oxide, silicon oxide, calcium oxide, iron oxide, and inorganic salts, and may also contain aluminum nitride. Therefore, the resource-based treatment of aluminum ash is receiving increasing attention and discussion.

[0003] In the field of aluminum ash resource utilization, the washing of aluminum ash is involved. After washing, a large amount of waste residue is generated, namely aluminum ash slag. Aluminum ash slag contains a high content of silicon element. Silicon element will form oxides during high temperature calcination. These oxides will affect the wear resistance and corrosion resistance of materials in the subsequent resource utilization process. Therefore, it is necessary to remove silicon from aluminum ash slag.

[0004] Existing technology discloses a method for removing silicon from water-washed aluminum ash slag, which requires the addition of aluminum fluoride additive and granulation treatment. The process is complex and requires the addition of a large amount of aluminum fluoride to achieve a good silicon removal effect. Therefore, it is necessary to study a new method for removing silicon from water-washed aluminum ash slag. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the shortcomings of the existing method for desiliconizing aluminum ash residue after water washing, which requires the addition of aluminum fluoride additives, granulation treatment, complex process, and the addition of a large amount of aluminum fluoride to achieve a good desiliconization effect, and thus provides a method for the resource utilization of aluminum ash.

[0006] To solve the above problems, the present invention provides the following solution:

[0007] A method for the resource utilization of aluminum ash includes the following steps:

[0008] 1) Crush the secondary aluminum ash, sieve it, then mix the sieved fines with water to obtain a slurry, filter the slurry to obtain a filter cake;

[0009] 2) Dry, crush, and sieve the filter cake to obtain filter cake granules;

[0010] 3) Add the filter cake particles to the roasting furnace, then introduce inert gas into the roasting furnace and heat the roasting furnace to 800-1000℃ to roast the filter cake particles. Then introduce hydrogen fluoride gas into the roasting furnace. After introducing hydrogen fluoride gas for 8-15 minutes, introduce hydrogen gas into the roasting furnace. After introducing hydrogen gas for 8-15 minutes, stop introducing hydrogen gas into the roasting furnace. After another 8-15 minutes, introduce hydrogen gas into the roasting furnace again for 8-15 minutes. During this period, continuously introduce inert gas and hydrogen fluoride gas into the roasting furnace. After roasting, cool the filter cake particles to room temperature and crush them to obtain aluminum ash slag.

[0011] Preferably, in step 3), the filter cake particles are added to the calcining furnace, and then argon gas is introduced into the calcining furnace at a flow rate of 280-350 sccm. The calcining furnace is heated to 800-1000℃ to calcinate the filter cake particles. Then, hydrogen fluoride gas is introduced into the calcining furnace at a flow rate of 20-40 sccm. After the hydrogen fluoride gas has been introduced for 8-15 minutes, hydrogen gas is introduced into the calcining furnace at a flow rate of 8-15 sccm. After the hydrogen gas has been introduced for 8-15 minutes, the hydrogen gas is stopped from being introduced into the calcining furnace. After another 8-15 minutes, hydrogen gas is introduced into the calcining furnace again for 8-15 minutes at a flow rate of 8-15 sccm. During this period, argon gas and hydrogen fluoride gas are continuously introduced into the calcining furnace. After calcination, the filter cake particles are cooled to room temperature and crushed to obtain aluminum ash slag.

[0012] Preferably, the total roasting time is 24-60 hours. It is understood that in this invention, when the roasting furnace is heated to 800-1000°C, hydrogen fluoride gas is simultaneously introduced into the furnace, and the total roasting time is calculated from the moment the furnace is heated to 800-1000°C.

[0013] Preferably, the inert gas is argon.

[0014] The present invention does not specifically limit the composition of secondary aluminum ash. Optionally, the secondary aluminum ash includes the following components by weight percentage: Al2O3 50-65%, SiO2 5-12%, Na2O 5-9%, Fe2O3 1-4%, CaO 4-7%.

[0015] Preferably, during roasting, the gas inside the roasting furnace is discharged through the furnace's outlet, collected, and kept for later use.

[0016] Preferably, in step 1), the crushed material is passed through an 80-120 mesh sieve.

[0017] Preferably, in step 1), the fine material and water are mixed at a liquid-to-solid ratio of (6-12):1.

[0018] Preferably, in step 1), the fine material and water are mixed at a liquid-to-solid ratio of 8:1.

[0019] Preferably, the drying temperature in step 2) is 90-100℃ and the drying time is 4-10h.

[0020] Preferably, the particle size of the filter cake is 1-5 mm.

[0021] The technical solution of this invention has the following advantages:

[0022] The method for resource utilization of aluminum ash provided by this invention first involves crushing and sieving secondary aluminum ash, then preparing a slurry, filtering the slurry to obtain a filter cake, drying, crushing, and sieving the filter cake to obtain filter cake particles. The filter cake particles are then added to a roasting furnace, and an inert gas is introduced into the furnace. The furnace is heated to 800-1000°C to roast the filter cake particles. Hydrogen fluoride gas is then introduced into the furnace for 8-15 minutes, followed by the introduction of hydrogen gas for another 8-15 minutes. Hydrogen gas is then stopped, and after another 8-15 minutes, hydrogen gas is introduced again for 8-15 minutes. During this process, both inert gas and hydrogen fluoride gas are continuously introduced into the furnace. After roasting, the filter cake particles are cooled to room temperature and crushed. To obtain aluminum ash slag, the process of this invention involves sequentially introducing inert gas and hydrogen fluoride gas during the roasting of filter cake particles. Under high-temperature roasting conditions, hydrogen fluoride gas reacts with silicon oxide to form silicon tetrafluoride gas. The silicon tetrafluoride gas is discharged from the roasting furnace with the inert gas, thereby achieving the silicon removal effect. Simultaneously, this invention introduces an appropriate amount of hydrogen gas intermittently while introducing inert gas and hydrogen fluoride gas. Since the filter cake is granular, when the silicon dioxide inside the particles reacts with hydrogen fluoride gas to generate silicon tetrafluoride gas, the silicon tetrafluoride gas reacts with hydrogen gas before it overflows to generate elemental silicon and hydrogen fluoride. The elemental silicon can be discharged with the inert gas, and the hydrogen fluoride can further react with the silicon dioxide inside the particles to generate silicon tetrafluoride gas. This process is repeated, greatly improving the silicon removal effect of the filter cake particles. Furthermore, the inventors discovered that continuously introducing hydrogen along with inert gas and hydrogen fluoride gas limits the silicon removal effect. They speculate this may be due to the complex composition of the filter cake particles; the addition of hydrogen reduces some of these components, which may then clog internal pathways or coat the silica surface, thus affecting the contact between silica and hydrogen fluoride. This invention employs an intermittent hydrogen introduction method, which effectively solves this problem. The aluminum ash resource utilization method provided by this invention effectively reduces the silicon content in aluminum ash slag, eliminating the need for additional aluminum fluoride additives and granulation treatment, resulting in a simple process. Detailed Implementation

[0023] The following embodiments are provided to further understand the present invention and are not limited to the preferred embodiments described herein, nor do they constitute a limitation on the scope of protection of the present invention.

[0024] Experimental steps or conditions not specified in the following embodiments of this invention can be implemented according to conventional experimental steps and conditions used in existing literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagents or instruments.

[0025] The secondary aluminum ash used in the following examples or comparative examples comprises the following components by weight percentage: Al2O3 64.5%, SiO2 10.8%, Na2O 7.8%, Fe2O3 2.5%, and CaO 6.4%.

[0026] Example 1

[0027] This embodiment provides a method for the resource utilization of aluminum ash, including the following steps:

[0028] 1) Crush the secondary aluminum ash and pass it through a 100-mesh sieve. Then mix the sieved fine material with water at a liquid-solid ratio of 8:1 to obtain a slurry. Filter the slurry to obtain a filter cake and filtrate.

[0029] 2) Dry the filter cake at 100℃ for 5 hours, crush it, and sieve it to obtain filter cake particles with a particle size of 1-2 mm;

[0030] 3) Add the filter cake particles to the roasting furnace, then introduce argon gas into the furnace at a flow rate of 300 sccm. Heat the furnace to 900℃ to roast the filter cake particles. Then, introduce hydrogen fluoride gas into the furnace at a flow rate of 30 sccm. After 10 minutes of hydrogen fluoride gas introduction, introduce hydrogen gas into the furnace at a flow rate of 10 sccm. After 10 minutes of hydrogen gas introduction, stop introducing hydrogen gas into the furnace. After another 10 minutes, introduce hydrogen gas into the furnace again for 10 minutes at a flow rate of 10 sccm. During this period, argon and hydrogen fluoride gases are continuously introduced into the furnace. The total roasting time is 40 minutes. During roasting, the gas in the furnace is discharged through the furnace outlet, collected, and stored for later use. After roasting, cool the filter cake particles to room temperature, crush them, and obtain aluminum ash slag. The silicon content in the aluminum ash slag is tested and found to be 0.9%.

[0031] Example 2

[0032] This embodiment provides a method for the resource utilization of aluminum ash, including the following steps:

[0033] 1) Crush the secondary aluminum ash and pass it through a 100-mesh sieve. Then mix the sieved fine material with water at a liquid-solid ratio of 8:1 to obtain a slurry. Filter the slurry to obtain a filter cake and filtrate.

[0034] 2) Dry the filter cake at 100℃ for 5 hours, crush it, and sieve it to obtain filter cake particles with a particle size of 1-2 mm;

[0035] 3) Add the filter cake particles to the roasting furnace, then introduce argon gas into the furnace at a flow rate of 280 sccm. Heat the furnace to 940℃ to roast the filter cake particles. Then, introduce hydrogen fluoride gas into the furnace at a flow rate of 32 sccm. After 12 minutes of hydrogen fluoride gas introduction, introduce hydrogen gas into the furnace at a flow rate of 15 sccm. After 12 minutes of hydrogen gas introduction, stop introducing hydrogen gas into the furnace. After another 12 minutes, introduce hydrogen gas into the furnace again for 10 minutes at a flow rate of 15 sccm. During this period, argon and hydrogen fluoride gases are continuously introduced into the furnace. The total roasting time is 46 minutes. During roasting, the gas in the furnace is discharged through the furnace outlet, collected, and stored for later use. After roasting, cool the filter cake particles to room temperature, crush them, and obtain aluminum ash slag. The silicon content in the aluminum ash slag is tested and found to be 0.5%.

[0036] Example 3

[0037] This embodiment provides a method for the resource utilization of aluminum ash, including the following steps:

[0038] 1) Crush the secondary aluminum ash and pass it through a 100-mesh sieve. Then mix the sieved fine material with water at a liquid-solid ratio of 8:1 to obtain a slurry. Filter the slurry to obtain a filter cake and filtrate.

[0039] 2) Dry the filter cake at 100℃ for 8 hours, crush it, and sieve it to obtain filter cake particles with a particle size of 1-2 mm;

[0040] 3) Add the filter cake particles to the roasting furnace, then introduce argon gas into the furnace at a flow rate of 350 sccm. Heat the furnace to 950℃ to roast the filter cake particles. Then, introduce hydrogen fluoride gas into the furnace at a flow rate of 40 sccm. After 15 minutes of hydrogen fluoride gas introduction, introduce hydrogen gas into the furnace at a flow rate of 15 sccm. After 15 minutes of hydrogen gas introduction, stop introducing hydrogen gas into the furnace. After another 15 minutes, introduce hydrogen gas into the furnace again for 15 minutes at a flow rate of 15 sccm. During this period, continuously introduce argon and hydrogen fluoride gas into the furnace. The total roasting time is 60 minutes. During roasting, the gas in the furnace is discharged through the furnace outlet, collected, and stored for later use. After roasting, cool the filter cake particles to room temperature, crush them, and obtain aluminum ash slag. The silicon content in the aluminum ash slag is tested and found to be 0.3%.

[0041] Example 4

[0042] This embodiment provides a method for the resource utilization of aluminum ash, including the following steps:

[0043] 1) Crush the secondary aluminum ash and pass it through a 100-mesh sieve. Then mix the sieved fine material with water at a liquid-solid ratio of 8:1 to obtain a slurry. Filter the slurry to obtain a filter cake and filtrate.

[0044] 2) Dry the filter cake at 100℃ for 5 hours, crush it, and sieve it to obtain filter cake particles with a particle size of 1-2 mm;

[0045] 3) Add the filter cake particles to the roasting furnace, then introduce argon gas into the furnace at a flow rate of 300 sccm. Heat the furnace to 950℃ to roast the filter cake particles. Then, introduce hydrogen fluoride gas into the furnace at a flow rate of 35 sccm. After 12 minutes of hydrogen fluoride gas introduction, introduce hydrogen gas into the furnace at a flow rate of 12 sccm. After 12 minutes of hydrogen gas introduction, stop introducing hydrogen gas into the furnace. After 10 minutes, introduce hydrogen gas into the furnace again for 10 minutes at a flow rate of 12 sccm. During this period, argon and hydrogen fluoride gases are continuously introduced into the furnace. The total roasting time is 44 minutes. During roasting, the gas in the furnace is discharged through the furnace outlet, collected, and stored for later use. After roasting, cool the filter cake particles to room temperature, crush them, and obtain aluminum ash slag. The silicon content in the aluminum ash slag is tested and found to be 0.7%.

[0046] Comparative Example 1

[0047] This comparative example provides a method for the resource utilization of aluminum ash. The difference between this method and Example 1 is that in step 3), filter cake particles are added to a roasting furnace, and then argon gas is introduced into the roasting furnace at a flow rate of 300 sccm. The roasting furnace is heated to 900°C to roast the filter cake particles. Then, hydrogen fluoride gas is introduced into the roasting furnace at a flow rate of 30 sccm. During this process, argon gas and hydrogen fluoride gas are continuously introduced into the roasting furnace. The total roasting time is 40 minutes. During roasting, the gas in the roasting furnace is discharged through the gas outlet of the roasting furnace, collected, and stored for later use. After roasting, the filter cake particles are cooled to room temperature and crushed to obtain aluminum ash slag. The silicon content in the aluminum ash slag is detected to be 1.8%.

[0048] Comparative Example 2

[0049] This comparative example provides a method for the resource utilization of aluminum ash. The difference from Example 1 is that in step 3), filter cake particles are added to a roasting furnace, and argon gas is introduced into the furnace at a flow rate of 300 sccm. The furnace is heated to 900°C to roast the filter cake particles. Then, hydrogen fluoride gas is introduced into the furnace at a flow rate of 30 sccm. After 10 minutes of hydrogen fluoride gas introduction, hydrogen gas is introduced into the furnace at a flow rate of 10 sccm. Argon, hydrogen fluoride, and hydrogen are continuously introduced into the furnace during this period. The total roasting time is 40 minutes. During roasting, the gas inside the furnace is discharged through the furnace outlet, collected, and stored for later use. After roasting, the filter cake particles are cooled to room temperature and crushed to obtain aluminum ash slag. The silicon content in the aluminum ash slag is detected to be 1.4%.

[0050] Obviously, those skilled in the art can make other modifications based on the above embodiments, and the obvious modifications therefrom are still within the protection scope of this invention.

Claims

1. A method for the resource utilization of aluminum ash, characterized in that, Includes the following steps: 1) Crush the secondary aluminum ash, sieve it, then mix the sieved fines with water to obtain a slurry, filter the slurry to obtain a filter cake; 2) Dry, crush, and sieve the filter cake to obtain filter cake granules; 3) Add the filter cake particles to the calcining furnace, then introduce inert gas into the furnace and heat it to 800-1000℃ to calcine the filter cake particles. Then, introduce hydrogen fluoride gas into the furnace for 8-15 minutes, followed by hydrogen gas. After another 8-15 minutes of hydrogen gas introduction, stop introducing hydrogen gas and then introduce it again for 8-15 minutes. During this period, continuously introduce inert gas and hydrogen fluoride gas into the furnace. After calcination, cool the filter cake particles to room temperature and crush them to obtain aluminum ash slag. The continuous introduction of inert gas and hydrogen fluoride gas into the furnace during this period refers to the continuous introduction of inert gas and hydrogen fluoride gas from the start of hydrogen fluoride gas introduction until the end of calcination.

2. The method for resource utilization of aluminum ash according to claim 1, characterized in that, In step 3), the filter cake particles are added to the calcining furnace, and argon gas is introduced into the furnace at a flow rate of 280-350 sccm. The furnace is heated to 800-1000℃ to calcine the filter cake particles. Then, hydrogen fluoride gas is introduced into the furnace at a flow rate of 20-40 sccm. After 8-15 minutes of hydrogen fluoride gas introduction, hydrogen gas is introduced into the furnace at a flow rate of 8-15 sccm. After 8-15 minutes of hydrogen gas introduction, the hydrogen gas introduction is stopped. After another 8-15 minutes, hydrogen gas is introduced into the furnace again at a flow rate of 8-15 sccm. During this period, argon and hydrogen fluoride gases are continuously introduced into the furnace. After calcination, the filter cake particles are cooled to room temperature and crushed to obtain aluminum ash slag.

3. The method for resource utilization of aluminum ash according to claim 1, characterized in that, The inert gas is argon.

4. The method for resource utilization of aluminum ash according to claim 1 or 2, characterized in that, During roasting, the gas inside the roasting furnace is discharged through the furnace's outlet, collected, and kept for later use.

5. The method for resource utilization of aluminum ash according to claim 1 or 2, characterized in that, After crushing in step 1), the material is passed through an 80-120 mesh sieve.

6. The method for resource utilization of aluminum ash according to claim 1 or 2, characterized in that, In step 1), the fine materials and water are mixed at a liquid-solid ratio of (6-12):

1.

7. The method for resource utilization of aluminum ash according to claim 1 or 2, characterized in that, In step 1), the fine materials and water are mixed at a liquid-to-solid ratio of 8:

1.

8. The method for resource utilization of aluminum ash according to claim 1 or 2, characterized in that, In step 2), the drying temperature is 90-100℃ and the drying time is 4-10h.

9. The method for resource utilization of aluminum ash according to claim 1 or 2, characterized in that, The particle size of the filter cake is 1-5 mm.