A method for removing aluminum nitride from secondary aluminum dross
By adding additives such as calcium oxide and sucrose to secondary aluminum ash, a low-temperature hydrolysis reaction is promoted to remove aluminum nitride, solving the problem of high energy consumption in secondary aluminum ash treatment and achieving low-cost, high-efficiency aluminum nitride removal, which is suitable for the preparation of building materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF RESOURCES UTILIZATION & RARE EARTH DEV GUANGDONG ACAD OF SCI
- Filing Date
- 2024-03-13
- Publication Date
- 2026-07-14
AI Technical Summary
Existing technologies for treating aluminum nitride in secondary aluminum ash suffer from high energy consumption and high costs, making it difficult to achieve efficient and low-cost harmless treatment.
Calcium oxide and/or calcium hydroxide are used as catalysts, and sucrose and/or glucose are used as retarder. They are mixed with secondary aluminum ash to form a reaction slurry. Aluminum nitride is removed through low-temperature hydrolysis reaction, generating ammonia and calcium hydroxide, which promotes the rapid hydrolysis of aluminum nitride.
It achieves low-cost and efficient removal of aluminum nitride from secondary aluminum ash, reduces processing energy consumption, improves reaction efficiency, and is suitable for the production of building materials.
Abstract
Description
Technical Field
[0001] This invention relates to the field of aluminum ash treatment technology, and in particular to a method for removing aluminum nitride from secondary aluminum ash. Background Technology
[0002] Aluminum ash is an industrial solid waste, consisting of slag produced during the high-temperature melting of aluminum in electrolytic aluminum plants and various aluminum profile factories, as well as ash residue generated during subsequent processing. In the "National Hazardous Waste List" promulgated and implemented on January 1, 2021, aluminum ash was explicitly included for the first time. Aluminum ash can be classified into primary aluminum ash and secondary aluminum ash based on its composition. Primary aluminum ash typically contains a high concentration of metallic aluminum; the fine aluminum ash remaining after methods such as ash extraction are usually called secondary aluminum ash. Secondary aluminum ash has a complex composition, containing various impurities such as aluminum oxides, chlorides, metallic aluminum, and aluminum nitride, making it more difficult to process.
[0003] The potential hazards of aluminum ash stem primarily from its high reactivity of metallic aluminum and aluminum nitride. Metallic aluminum reacts with water to produce hydrogen gas, which can easily cause explosions and fires; aluminum nitride reacts with water to produce irritating ammonia gas, which can easily cause environmental pollution. Furthermore, the ammonia and soluble salts contained in aluminum ash can also harm air, water, and soil.
[0004] Secondary aluminum ash, as a toxic and hazardous solid waste, cannot be disposed of using conventional methods such as storage or landfill. These methods not only occupy large amounts of land but also pose a risk of secondary pollution due to leaks, leading to serious environmental and public health problems. Therefore, there is an urgent need to develop harmless treatment technologies for secondary aluminum ash. Currently, there are research reports on the harmless treatment of secondary aluminum ash both domestically and internationally, with treatment methods mainly divided into pyrometallurgical and hydrometallurgical processes. The pyrometallurgical process uses high-temperature roasting with the addition of roasting aids such as sulfates and cryolite to remove active substances such as aluminum nitride and metallic aluminum from the secondary aluminum ash, offering advantages such as a short process flow and simple operation. However, pyrometallurgical treatment of secondary aluminum ash suffers from problems such as high roasting temperatures, high energy consumption, and incomplete oxidation of aluminum nitride. The hydrometallurgical process is an effective method for removing active substances from secondary aluminum ash, denitrifying it through hydrolysis. Existing hydrometallurgical processes suffer from high energy consumption due to high hydrolysis temperatures and long hydrolysis times. Current research also explores methods to promote the hydrolytic removal of aluminum nitride from secondary aluminum ash by adding readily soluble alkaline additives such as sodium hydroxide and sodium carbonate to wet processes. However, these methods still suffer from long reaction times and high temperatures, resulting in high energy consumption. Furthermore, the high cost and large quantities of readily soluble alkaline additives like sodium hydroxide and sodium carbonate limit the application of these methods.
[0005] Therefore, the present invention aims to provide a new method for removing aluminum nitride from secondary aluminum ash, so as to effectively reduce processing energy consumption, reduce processing costs, and promote the economical treatment of secondary aluminum ash. Summary of the Invention
[0006] The main technical problem solved by this invention is to provide a method for removing aluminum nitride from secondary aluminum ash, which can achieve low-cost and effective removal of aluminum nitride from secondary aluminum ash.
[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for removing aluminum nitride from secondary aluminum ash, comprising the following steps:
[0008] S1: Mix secondary aluminum ash, catalyst aid and retarder, add water to make a reaction slurry;
[0009] S2: Stir the reaction slurry to carry out the aluminum nitride hydrolysis reaction to obtain denitrified aluminum ash.
[0010] In one embodiment of the present invention, the catalyst promoter comprises calcium oxide and / or calcium hydroxide. Specifically, the catalyst promoter can be calcium oxide and / or calcium hydroxide, or it can be a material rich in calcium oxide and / or calcium hydroxide, such as waste carbide slag.
[0011] In one embodiment of the present invention, the retarder comprises sucrose and / or glucose. Specifically, the retarder can be sucrose and / or glucose, or it can be waste molasses, sugary wastewater, etc., containing sucrose and / or glucose.
[0012] In one embodiment of the present invention, the catalyst is calcium oxide.
[0013] In one embodiment of the present invention, the retarder is sucrose or glucose.
[0014] In one embodiment of the present invention, the amount of the catalyst additive is 2-20% of the mass of the secondary aluminum ash. Further, the amount of the catalyst additive is 10-20% of the mass of the secondary aluminum ash.
[0015] In one embodiment of the present invention, the amount of the retarder is 0.2-5% of the mass of the secondary aluminum ash. Further, the amount of the retarder is 0.5-5% of the mass of the secondary aluminum ash.
[0016] In one embodiment of the present invention, in step S1, the liquid-to-solid ratio of the reaction slurry is 5–35 ml / g. Further, the liquid-to-solid ratio of the reaction slurry is 5–30 ml / g. Herein, the liquid-to-solid ratio refers to the ratio of the volume of water to the total mass of secondary aluminum ash, catalyst aid, and retarder. For example, if the liquid-to-solid ratio of the reaction slurry is 10 ml / g, then the ratio of the volume of water (in ml) used in preparing the reaction slurry to the total mass (in g) of secondary aluminum ash, catalyst aid, and retarder is 10 ml / g.
[0017] In one embodiment of the present invention, in step S2, the reaction temperature of the hydrolysis reaction is 20–99°C and the reaction time is 0.5–10 h.
[0018] Preferably, in step S2, the hydrolysis reaction is carried out at a temperature of 20–90°C for 1–10 hours.
[0019] More preferably, in step S2, the reaction temperature of the hydrolysis reaction is 20-40°C and the reaction time is 0.5-6h; more preferably, in step S2, the reaction temperature of the hydrolysis reaction is 40°C and the reaction time is 2-6h.
[0020] In one embodiment of the present invention, in step S2, after the aluminum nitride hydrolysis reaction is completed, solid-liquid separation is performed, and the separated solid is denitrified aluminum ash. The solid-liquid separation can be carried out using one or more methods such as sedimentation separation, centrifugation separation, and filtration separation. The liquid wastewater obtained from the solid-liquid separation can be reused after treatment. The obtained denitrified aluminum ash can be used to manufacture building materials.
[0021] As one embodiment of the present invention, the secondary aluminum ash is aluminum ash obtained after primary aluminum ash is extracted with metallic aluminum; or it is desalinated aluminum ash obtained after primary aluminum ash is extracted with metallic aluminum and then washed with water.
[0022] The method for removing aluminum nitride from secondary aluminum ash provided by this invention involves mixing the secondary aluminum ash with a catalyst and a retarder, adding water to form a reaction slurry, and then stirring the mixture to allow the aluminum nitride in the secondary aluminum ash to undergo a hydrolysis reaction for removal. This method, through the combined use of the catalyst and retarder, lowers the hydrolysis reaction temperature of the secondary aluminum ash, shortens the reaction time, and improves the efficiency of the hydrolysis reaction, effectively reducing energy consumption and achieving highly efficient removal of aluminum nitride from the secondary aluminum ash. The method for removing aluminum nitride from secondary aluminum ash provided by this invention uses calcium oxide and / or calcium hydroxide as catalysts, combined with a small amount of sucrose and / or glucose as retarders. The reagents used are low-cost, reducing processing costs and promoting the economical treatment of secondary aluminum ash.
[0023] The method for removing aluminum nitride from secondary aluminum ash provided by this invention involves a hydrolysis reaction system in which aluminum nitride reacts with water to generate ammonia gas, which then dissolves in water to form ammonia water. Added calcium oxide reacts with water to generate calcium hydroxide, or calcium hydroxide is added directly. The presence of calcium hydroxide promotes the release of ammonia gas, thus driving the reaction between aluminum nitride and water. Sucrose and / or glucose are used as retarder to prevent the formation of a coating layer of calcium aluminate on the surface of aluminum nitride particles, allowing the aluminum nitride hydrolysis reaction to continue. Through hydrolysis treatment using a water-calcium hydroxide-sucrose and / or glucose system, rapid and efficient removal of aluminum nitride from secondary aluminum ash can be achieved at relatively low temperatures.
[0024] The method of this invention provides a new approach for the low-cost and harmless treatment of secondary aluminum ash, and has great potential for industrial application. Detailed Implementation
[0025] The technical solution of the present invention will be described in detail below through specific embodiments. These embodiments are intended to further illustrate the content of the present invention, but are not intended to limit the scope of protection of the claims of the present invention.
[0026] In the following examples, all pharmaceutical agents used are commercially available products. Unless otherwise specified, all percentages in the examples are by mass.
[0027] Example 1
[0028] This embodiment provides a method for removing aluminum nitride from secondary aluminum ash. The secondary aluminum ash being treated is aluminum ash obtained after extracting metallic aluminum from primary aluminum ash, wherein the mass percentage content of aluminum nitride is 10.63%. The treatment method includes the following steps:
[0029] (1) Put 40g of secondary aluminum ash, 4g of catalytic aid calcium oxide (CaO) and 1g of retarder sucrose into the reaction tank, add water to the reaction tank until the liquid-solid ratio of the reaction slurry is 20mL / g, stir continuously to carry out the hydrolysis reaction of aluminum nitride, the reaction temperature is 40℃ and the reaction time is 2h.
[0030] (2) After the reaction is completed, the denitrified aluminum ash and wastewater are obtained by filtration and separation.
[0031] The dried aluminum ash weighed 39.61 g. A sample was taken and the aluminum nitride content was determined by the Kjeldahl method to be 1.43%. The denitrification rate of the hydrolysis process was calculated to be 86.7%.
[0032] Example 2
[0033] This embodiment provides a method for removing aluminum nitride from secondary aluminum ash. The secondary aluminum ash being treated is aluminum ash obtained after extracting metallic aluminum from primary aluminum ash, wherein the mass percentage content of aluminum nitride is 10.63%. The treatment method includes the following steps:
[0034] (1) Put 40g of secondary aluminum ash, 4g of catalytic aid calcium oxide (CaO) and 0.3g of retarder glucose into the reaction tank, add water to the reaction tank until the liquid-solid ratio of the reaction slurry is 30mL / g, and stir continuously to carry out the hydrolysis reaction of aluminum nitride. The reaction temperature is 90℃ and the reaction time is 1h.
[0035] (2) After the reaction is completed, the denitrified aluminum ash and wastewater are obtained by filtration and separation.
[0036] The dried aluminum ash weighed 40.35g. A sample was taken and the aluminum nitride content was determined by the Kjeldahl method to be 0.31%. The denitrification rate of the hydrolysis process was calculated to be 97.1%.
[0037] In this embodiment, the hydrolysis temperature is increased to 90°C, and the denitrification rate can reach 97.1% after 1 hour of reaction. It can be seen that although the hydrolysis temperature is high, the efficient removal of aluminum nitride from secondary aluminum ash can be achieved in a short time, and therefore the energy consumption is also low.
[0038] Example 3
[0039] This embodiment provides a method for removing aluminum nitride from secondary aluminum ash. The secondary aluminum ash being treated is aluminum ash obtained after extracting metallic aluminum from primary aluminum ash, wherein the mass percentage content of aluminum nitride is 10.63%. The treatment method includes the following steps:
[0040] (1) Put 40g of secondary aluminum ash, 6g of catalytic aid calcium oxide (CaO) and 1g of retarder sucrose into the reaction tank, add water to the reaction tank until the liquid-solid ratio of the reaction slurry is 10mL / g, stir continuously to carry out the hydrolysis reaction of aluminum nitride, the reaction temperature is 40℃ and the reaction time is 4h.
[0041] (2) After the reaction is completed, the denitrified aluminum ash and wastewater are obtained by filtration and separation.
[0042] The dried aluminum ash weighed 42.89 g. A sample was taken and the aluminum nitride content was determined by the Kjeldahl method to be 0.66%. The denitrification rate of the hydrolysis process was calculated to be 93.3%.
[0043] Example 4
[0044] This embodiment provides a method for removing aluminum nitride from secondary aluminum ash. The secondary aluminum ash being treated is aluminum ash obtained after extracting metallic aluminum from primary aluminum ash, wherein the mass percentage content of aluminum nitride is 10.63%. The treatment method includes the following steps:
[0045] (1) Put 40g of secondary aluminum ash, 4g of catalytic aid calcium oxide (CaO) and 0.32g of retarder glucose into the reaction tank, add water to the reaction tank until the liquid-solid ratio of the reaction slurry is 30mL / g, and stir continuously to carry out the hydrolysis reaction of aluminum nitride. The reaction temperature is 40℃ and the reaction time is 6h.
[0046] (2) After the reaction is completed, the denitrified aluminum ash and wastewater are obtained by filtration and separation.
[0047] The dried aluminum ash weighed 40.30 g. A sample was taken and the aluminum nitride content was determined by the Kjeldahl method to be 0.49%. The denitrification rate of the hydrolysis process was calculated to be 95.4%.
[0048] Example 5
[0049] This embodiment provides a method for removing aluminum nitride from secondary aluminum ash. The secondary aluminum ash being treated is desalinated aluminum ash obtained by extracting metallic aluminum from primary aluminum ash and then washing it with water. The aluminum nitride content is 12.29% by mass. The treatment method includes the following steps:
[0050] (1) Put 40g of secondary aluminum ash, 8g of catalytic aid calcium oxide (CaO) and 2g of retarder sucrose into the reaction tank, add water to the reaction tank until the liquid-solid ratio of the reaction slurry is 20mL / g, stir continuously to carry out the hydrolysis reaction of aluminum nitride, the reaction temperature is 30℃ and the reaction time is 10h.
[0051] (2) After the reaction is completed, the denitrified aluminum ash and wastewater are obtained by filtration and separation.
[0052] The dried aluminum ash weighed 54.34 g. A sample was taken and the aluminum nitride content was determined by the Kjeldahl method to be 0.83%. The denitrification rate of the hydrolysis process was calculated to be 90.8%.
[0053] In this embodiment, the hydrolysis temperature was lowered to 30°C, essentially allowing the reaction to proceed at room temperature. The denitrification rate reached 90.8% after 10 hours of reaction. This demonstrates that while the reaction time is longer due to the lower hydrolysis temperature, the overall energy consumption is also lower.
[0054] Example 6
[0055] This embodiment provides a method for removing aluminum nitride from secondary aluminum ash. The secondary aluminum ash being treated is desalinated aluminum ash obtained by extracting metallic aluminum from primary aluminum ash and then washing it with water. The aluminum nitride content is 12.29% by mass. The treatment method includes the following steps:
[0056] (1) Put 40g of secondary aluminum ash, 0.8g of catalytic aid calcium oxide (CaO) and 1g of retarder sucrose into the reaction tank, add water to the reaction tank until the liquid-solid ratio of the reaction slurry is 5mL / g, and stir continuously to carry out the hydrolysis reaction of aluminum nitride. The reaction temperature is 40℃ and the reaction time is 4h.
[0057] (2) After the reaction is completed, the denitrified aluminum ash and wastewater are obtained by filtration and separation.
[0058] The dried aluminum ash weighed 44.63g. A sample was taken and the aluminum nitride content was determined by the Kjeldahl method to be 1.60%. The denitrification rate of the hydrolysis process was calculated to be 85.5%.
[0059] Comparative Example 1
[0060] This comparative example provides a method for removing aluminum nitride from secondary aluminum ash. The secondary aluminum ash being treated is the aluminum ash obtained after extracting metallic aluminum from primary aluminum ash, wherein the mass percentage content of aluminum nitride is 10.63%. The treatment method includes the following steps:
[0061] (1) Put 40g of secondary aluminum ash into the reaction tank, add water to the reaction tank until the liquid-solid ratio of the reaction slurry is 20mL / g, stir continuously to carry out the hydrolysis reaction of aluminum nitride, the reaction temperature is 40℃, and the reaction time is 2h.
[0062] (2) After the reaction is completed, the denitrified aluminum ash and wastewater are obtained by filtration and separation.
[0063] The dried aluminum ash weighed 32.97g. A sample was taken and the aluminum nitride content was determined to be 8.56% by the Kjeldahl method. The denitrification rate of the hydrolysis process was calculated to be 33.6%.
[0064] Compared with Example 1, this comparative example does not include any catalyst or retarder in the hydrolysis system, resulting in a significantly lower denitrification rate.
[0065] Comparative Example 2
[0066] This comparative example provides a method for removing aluminum nitride from secondary aluminum ash. The secondary aluminum ash being treated is the aluminum ash obtained after extracting metallic aluminum from primary aluminum ash, wherein the mass percentage content of aluminum nitride is 10.63%. The treatment method includes the following steps:
[0067] (1) Put 40g of secondary aluminum ash and 4g of catalytic aid calcium oxide (CaO) into the reaction tank, add water to the reaction tank until the liquid-solid ratio of the reaction slurry is 20mL / g, and stir continuously to carry out the hydrolysis reaction of aluminum nitride. The reaction temperature is 40℃ and the reaction time is 2h.
[0068] (2) After the reaction is completed, the denitrified aluminum ash and wastewater are obtained by filtration and separation.
[0069] The dried aluminum ash weighed 38.48 g. A sample was taken and the aluminum nitride content was determined to be 6.59% by the Kjeldahl method. The denitrification rate of the hydrolysis process was calculated to be 40.4%.
[0070] Compared with Example 1, this comparative example only added a catalytic aid to the hydrolysis system, and the denitrification rate was also lower.
[0071] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are included within the patent protection scope of the present invention.
Claims
1. A method for removing aluminum nitride from secondary aluminum ash, characterized in that, Including the following steps: S1: Mix secondary aluminum ash, catalyst aid, and retarder, and add water to form a reaction slurry; the catalyst aid contains calcium oxide and / or calcium hydroxide; the retarder contains sucrose and / or glucose, and the amount of the retarder is 0.2-5% of the mass of the secondary aluminum ash; S2: Stir the reaction slurry to carry out the aluminum nitride hydrolysis reaction to obtain denitrified aluminum ash.
2. The method according to claim 1, characterized in that, The catalyst is calcium oxide; and / or the retarder is sucrose or glucose.
3. The method according to claim 1, characterized in that, The amount of the catalyst is 2-20% of the mass of the secondary aluminum ash.
4. The method according to claim 1, characterized in that, The liquid-to-solid ratio of the reaction slurry is 5~35 ml / g.
5. The method according to claim 4, characterized in that, The hydrolysis reaction is carried out at a temperature of 20-99℃ for a time of 0.5-10 hours.
6. The method according to claim 5, characterized in that, The hydrolysis reaction is carried out at a temperature of 20-40°C for 0.5-6 hours.
7. The method according to claim 1, characterized in that, In step S2, after the aluminum nitride hydrolysis reaction is completed, solid-liquid separation is performed, and the solid obtained by separation is denitrified aluminum ash.