Process for denitrification of an aluminum-containing material

Abstract

The present application belongs to the field of chemical metallurgy technology, and particularly relates to a denitrogenation method of aluminum-containing material. The present application provides a denitrogenation method of aluminum-containing material, which comprises the following steps: mixing aluminum-containing material and water to prepare slurry, obtaining slurry; mixing the slurry and a washing aid to perform conditioning, and then filtering to obtain primary denitrogenated aluminum-containing material; and washing the primary denitrogenated aluminum-containing material with water to obtain denitrogenated aluminum-containing material. The present application utilizes the washing aid to perform ion exchange, replacement or desorption on the nitrogen-containing anions in the aluminum-containing material, changes the coating structure of the aluminum-containing material on the nitrogen-containing anions, so that the nitrogen-containing anions are free on the surface of the aluminum-containing material; and the nitrogen-containing anions in the aluminum-containing material are removed through subsequent washing.

Description

Technical Field

[0001] This invention belongs to the field of chemical and metallurgical technology, and specifically relates to a method for denitrification of aluminum-containing materials. Background Technology

[0002] With the rapid development of the aluminum industry, the demand for alumina is constantly increasing. Bauxite is the main raw material for alumina production and the foundation for the rapid development of the aluminum industry. Large-scale bauxite mining inevitably leads to the accumulation of large amounts of tailings. Bauxite tailings have low viscosity and turn into muddy sludge when exposed to rainwater, making them difficult to store, occupying large areas of land, and polluting the environment. To reduce the environmental impact of bauxite tailings and to meet the ever-increasing demand for alumina, researchers have begun to study methods for extracting alumina from bauxite tailings. Currently, aluminum is mainly extracted from bauxite tailings using the nitric acid wet process. Specifically, bauxite tailings are mixed with a nitric acid solution for leaching, and the leachate is mixed with an alkaline substance for precipitation to obtain aluminum-containing material. However, the nitrogen content in the aluminum-containing material obtained by this method is too high. Whether in smelting or leaching, denitrification treatment is necessary to remove nitrogen; otherwise, downstream products may become substandard. Currently, denitrification is mainly achieved by washing aluminum-containing materials with water. Although washing can remove a large amount of nitrogen-containing substances from aluminum-containing materials, the nitrogen content in the aluminum-containing materials after water washing and denitrification will still be greater than 4.0%, which limits the application range of aluminum-containing materials. Summary of the Invention

[0003] In view of this, the present invention provides a method for denitrification of aluminum-containing materials. The method provided by the present invention can effectively remove nitrogen from aluminum-containing materials, so that the mass percentage of nitrogen in the aluminum-containing materials is less than 0.023%.

[0004] To address the aforementioned technical problems, this invention provides a method for denitrifying aluminum-containing materials, comprising the following steps:

[0005] Aluminum-containing materials are mixed with water to form a slurry;

[0006] The slurry and washing aid are mixed, conditioned, and then filtered to obtain aluminum-containing material with primary denitrification.

[0007] The aluminum-containing material undergoing primary denitrification is washed with water to obtain denitrified aluminum-containing material.

[0008] Preferably, the detergent additive includes one or more of neutral salt detergent additives, alkaline detergent additives, and weak acid-strong base salt detergent additives.

[0009] Preferably, the neutral salt detergent additive includes one or more of sodium sulfate, magnesium sulfate, and sodium carbonate;

[0010] The alkaline detergent additives include one or more of sodium hydroxide, potassium hydroxide, urea, and ammonia water;

[0011] The weak acid and strong base salt detergent additives include one or more of sodium bicarbonate, magnesium carbonate, magnesium oxide, and sodium carbonate.

[0012] Preferably, the mass ratio of the aluminum-containing material to the detergent additive is 1:0.15 to 0.35.

[0013] Preferably, the conditioning is carried out under stirring conditions, the stirring temperature is 60-100℃, and the stirring time is 0.2-1.5h.

[0014] Preferably, the washing process includes performing a first rinse and a second rinse in sequence.

[0015] Preferably, the liquid-to-solid mass ratio of the first and second rinsings is independently 3 to 10:1.

[0016] Preferably, the mass ratio of the aluminum-containing material to the pulping water is 1:4 to 10.

[0017] Preferably, the pulping is carried out under stirring conditions, the stirring speed is 200-500 rpm, and the stirring time is 0.5-1 h.

[0018] Preferably, the aluminum-containing material includes iron, aluminum, silicon, and nitrogen-containing substances;

[0019] The iron content in the aluminum-containing material is 0.2% to 0.3% by mass;

[0020] The mass percentage of aluminum in the aluminum-containing material is 22-26%;

[0021] The silicon element has a mass percentage content of 0.1% to 0.2% in the aluminum-containing material;

[0022] The nitrogen content of the nitrogen-containing substance in the aluminum-containing material is 2.94% to 3.62% by mass.

[0023] This invention provides a method for denitrifying aluminum-containing materials, comprising the following steps: mixing the aluminum-containing material with water to form a slurry; mixing the slurry with a washing aid, conditioning it, and then filtering it to obtain a primary denitrified aluminum-containing material; washing the primary denitrified aluminum-containing material with water to obtain a denitrified aluminum-containing material. This invention utilizes a washing aid to perform ion exchange, displacement, or desorption of nitrogen-containing anions in the aluminum-containing material, altering the coating structure of the aluminum-containing material on the nitrogen-containing anions, thereby freeing the nitrogen-containing anions on the surface of the aluminum-containing material; subsequently, washing removes the nitrogen-containing anions from the aluminum-containing material. Attached Figure Description

[0024] Figure 1This is a schematic diagram of the process for denitrification treatment of aluminum-containing materials in an example. Detailed Implementation

[0025] This invention provides a method for denitrification of aluminum-containing materials, comprising the following steps:

[0026] Aluminum-containing materials are mixed with water to form a slurry;

[0027] The slurry and washing aid are mixed, conditioned, and then filtered to obtain aluminum-containing material with primary denitrification.

[0028] The aluminum-containing material undergoing primary denitrification is washed with water to obtain denitrified aluminum-containing material.

[0029] This invention mixes aluminum-containing materials with water to form a slurry. In this invention, the aluminum-containing material is preferably a product obtained through hydrometallurgical processing using a nitric acid solution. The method for obtaining the aluminum-containing material preferably includes the following steps: leaching an aluminum-containing mineral with a nitric acid solution, and then precipitating the leachate with an alkaline solution to obtain the aluminum-containing material. In this invention, the aluminum-containing mineral preferably includes bauxite, lithium clay, spodumene, fly ash, or coal gangue, more preferably bauxite or bauxite tailings, and even more preferably bauxite tailings. This invention does not have special requirements regarding the concentration and amount of the nitric acid solution; conventional methods in the art are acceptable. This invention does not have special requirements regarding the leaching process; conventional methods in the art are acceptable. In this invention, the alkaline solution preferably includes sodium hydroxide solution, sodium carbonate solution, potassium hydroxide solution, potassium carbonate solution, magnesium oxide slurry, or magnesium carbonate slurry, more preferably sodium hydroxide solution. This invention does not have special limitations on the concentration and amount of the alkaline solution, as long as it can completely precipitate the aluminum ions in the leachate. In this invention, the precipitation process preferably further includes filtering the precipitated system to obtain an aluminum-containing material. This invention does not impose special requirements on the filtration process; conventional methods in the art can be used.

[0030] In this invention, the aluminum-containing material preferably includes iron, aluminum, silicon, and a nitrogen-containing substance; the mass percentage of iron in the aluminum-containing material is preferably 0.2-0.3%, more preferably 0.25%; the mass percentage of aluminum in the aluminum-containing material is preferably 22-26%, more preferably 23-25%, and even more preferably 24.12%; the mass percentage of silicon in the aluminum-containing material is preferably 0.1-0.2%, more preferably 0.12-0.15%; the mass percentage of nitrogen in the nitrogen-containing substance in the aluminum-containing material is preferably 2.94-3.62%, more preferably 3.5-3.6%, and even more preferably 3.52%. In this invention, the nitrogen-containing substance is preferably a nitrogen-containing anion; the nitrogen-containing anion is preferably nitrate or nitrite, more preferably nitrate. In this invention, the nitrogen-containing anion exists in the aluminum-containing material preferably in one or more of the following forms: free state, adsorbed state, and ion-exchange state.

[0031] In this invention, the water is preferably pure water. In this invention, the mass ratio of the aluminum-containing material to the pulping water is preferably 1:4 to 10, more preferably 1:4 to 5.

[0032] In this invention, the pulping is preferably carried out under stirring conditions, the stirring speed is preferably 200-500 rpm, more preferably 300-400 rpm, and the stirring time is preferably 0.5-1 h, more preferably 0.6-0.8 h.

[0033] After obtaining the slurry, the present invention mixes the slurry and a washing aid, conditions it, and then filters it to obtain a primary denitrified aluminum-containing material. In the present invention, the washing aid preferably includes one or more of neutral salt washing aids, alkaline washing aids, and weak acid-strong base salt washing aids, more preferably neutral salt washing aids. In the present invention, the neutral salt washing aid preferably includes one or more of sodium sulfate, magnesium sulfate, and sodium carbonate, more preferably sodium sulfate. In the present invention, the alkaline washing aid preferably includes one or more of sodium hydroxide, potassium hydroxide, urea, and ammonia water, more preferably sodium hydroxide or potassium hydroxide. In the present invention, the mass concentration of the ammonia water is preferably 5-20%, more preferably 10-15%. In the present invention, the weak acid-strong base salt washing aid preferably includes one or more of sodium bicarbonate, magnesium carbonate, magnesium oxide, and sodium carbonate, more preferably sodium carbonate. In the present invention, the mass ratio of the aluminum-containing material to the washing aid is preferably 1:0.15-0.35, more preferably 1:0.2.

[0034] In this invention, the conditioning is preferably carried out under stirring conditions, the stirring temperature is preferably 60-100℃, more preferably 80-90℃, and the stirring time is preferably 0.2-1.5h, more preferably 0.5-1h. This invention does not have special requirements for the stirring speed, as long as it ensures that the detergent and slurry are fully mixed.

[0035] In this invention, when the washing aid is a neutral salt washing aid, during the conditioning process, the neutral salt washing aid will replace the adsorbed and ion-exchange nitrogen-containing anions in the aluminum-containing material, making the adsorbed and ion-exchange nitrogen-containing anions free nitrogen-containing anions. When the washing aid is an alkaline washing aid, during the conditioning process, the alkaline washing aid will make the slurry alkaline, and the surface potential of the aluminum slag (aluminum-containing material) will change, causing most of the nitrogen-containing anions to desorb. When the washing aid is a weak acid-strong base salt washing aid, both replacement and desorption will occur simultaneously during the conditioning process. This invention, through conditioning, releases the nitrogen-containing anions coated in the aluminum-containing material to the surface of the material, facilitating the effective separation of the aluminum-containing material and nitrogen-containing substances through subsequent washing.

[0036] The present invention does not have any special requirements for the filtration process; conventional methods in the field can be used.

[0037] To obtain aluminum-containing material after primary denitrification, this invention utilizes water to wash the primary denitrified aluminum-containing material to obtain denitrified aluminum-containing material. In this invention, the water is preferably pure water. In this invention, the washing preferably includes sequentially performing a first rinse and a second rinse. In this invention, the liquid-to-solid mass ratio of the first rinse is preferably 3–10:1, more preferably 3–5:1. In this invention, the temperature of the first rinse is preferably 35–45°C, more preferably 40°C. In this invention, the liquid-to-solid mass ratio of the second rinse is preferably 3–10:1, more preferably 4–5:1. In this invention, the temperature of the second rinse is preferably 35–45°C, more preferably 40°C.

[0038] This invention removes free nitrogen-containing anions formed under the action of washing aids, thereby achieving denitrification of aluminum-containing materials and reducing the mass percentage of nitrogen in nitrogen-containing substances in aluminum-containing materials to below 0.023%.

[0039] This invention employs a two-stage rinsing process to achieve water balance and recycling in industrial production. The washing liquid produced by the first rinsing has a high nitrate (nitrogen) content and can be used to produce nitrogen-containing byproducts. The washing liquid produced by the second rinsing has a low nitrate (nitrogen) content and can be used for pulping to achieve water recycling.

[0040] Figure 1The following is a schematic diagram of the process for denitrification treatment of aluminum-containing materials in an embodiment. Specifically, the aluminum-containing materials and pure water are stirred and pulped to obtain a slurry; the slurry is mixed with a washing aid and then conditioned and filtered to obtain filtrate and aluminum-containing material 1; the aluminum-containing material 1 is first washed with pure water to obtain filtrate 2 and aluminum-containing material 2; the aluminum-containing material 2 is second washed with pure water to obtain filtrate 3 and aluminum-containing material 3; the filtrate 3 is recycled as a solvent for mixing and pulping.

[0041] The denitrification method provided by this invention uses aluminum-containing materials as raw materials and separates nitrates (nitrogen) through a washing reaction under normal pressure to obtain aluminum-containing materials with a nitrate (nitrogen) content of less than 0.023%. This solves the problems of difficult smelting or leaching treatment and high processing costs caused by high nitrogen content. The denitrified aluminum-containing material obtained can be used as raw material to prepare qualified aluminum hydroxide. This invention uses a washing method to denitrify aluminum-containing materials, using inexpensive auxiliary materials, resulting in low process costs, fast reaction, and high efficiency. The materials used in this invention are all common industrial products, easy to purchase, and inexpensive; the entire process is short, low-cost, has a wide range of raw material sources, is easy to scale up, and is easy to industrialize.

[0042] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0043] Example 1

[0044] The aluminum-containing material with an Al content of 24.12%, Fe content of 0.25%, Si content of 0.12%, and nitrogen content of 3.52% was used as the treatment target; according to Figure 1 The process involves denitrification of aluminum-containing materials; the specific source of the aluminum-containing materials is: leaching bauxite tailings with nitric acid solution, precipitating the leachate with sodium hydroxide solution, and filtering to obtain the aluminum-containing materials;

[0045] S1: Mix aluminum-containing materials with pure water at a liquid-to-solid mass ratio of 4:1 and stir at 400 rpm for 0.8 h to obtain a slurry;

[0046] S2: Add sodium sulfate, a washing aid, to the slurry. The amount of sodium sulfate added is 0.2 times the mass of the aluminum-containing material. After stirring and conditioning at 80°C for 0.5 hours, filter to obtain aluminum-containing material 1 and filtrate 1.

[0047] S3: The aluminum-containing material 1 is first rinsed with pure water at 40℃ (the mass ratio of pure water to aluminum-containing material 1 is 3:1) to obtain filtrate 2 and aluminum-containing material 2.

[0048] S4: Use pure water at 40℃ (the mass ratio of pure water to aluminum-containing material 1 is 4:1) to perform a second rinsing on aluminum-containing material 2, to obtain filtrate 3 and aluminum-containing material 3 (denitrified aluminum-containing material).

[0049] Example 2

[0050] Using the aluminum-containing material from Example 1 as the target material, the specific steps for denitrification treatment of the aluminum-containing material are as follows:

[0051] S1: Mix aluminum-containing slurry with pure water at a liquid-solid mass ratio of 5:1 and stir at 300 rpm for 0.8 h to obtain the slurry;

[0052] S2: Add sodium sulfate, a washing aid, to the slurry. The amount of sodium sulfate added is 0.2 times the mass of the aluminum-containing material. After stirring and conditioning at 80°C for 1 hour, filter to obtain aluminum-containing material 1 and filtrate 1.

[0053] S3: The aluminum-containing material 1 is first rinsed with pure water at 40℃ (the mass ratio of pure water to aluminum-containing material 1 is 3:1) to obtain filtrate 2 and aluminum-containing material 2.

[0054] S4: Use pure water at 40℃ (the mass ratio of pure water to aluminum-containing material 1 is 5:1) to perform a second rinsing on aluminum-containing material 2, to obtain filtrate 3 and aluminum-containing material 3 (denitrified aluminum-containing material).

[0055] Comparative Example 1

[0056] The aluminum-containing material with a mass percentage of Al of 24.12%, Fe of 0.25%, Si of 0.12%, and nitrogen of 3.52% was used as the treatment target.

[0057] S1: Mix aluminum-containing slurry with pure water at a liquid-solid mass ratio of 3:1 and stir at 300 rpm for 0.8 h to obtain the slurry;

[0058] S2: Stir the slurry at 40°C for 1 hour and then filter it to obtain aluminum-containing material 1 and filtrate 1;

[0059] S3: The aluminum-containing material 1 is first rinsed with pure water at 40℃ (the mass ratio of pure water to aluminum-containing material 1 is 3:1) to obtain filtrate 2 and aluminum-containing material 2.

[0060] S4: Use pure water at 40℃ (the mass ratio of pure water to aluminum-containing material 1 is 3:1) to perform a second rinsing on aluminum-containing material 2 to obtain filtrate 3 and aluminum-containing material 3.

[0061] The mass percentages of Al, Fe, Si, and nitrogen in the aluminum-containing materials 3 obtained from Examples 1-2 and Comparative Example 1 were determined using colorimetry and ICP detection methods, and the results are listed in Table 1. The nitrogen removal rate in the aluminum-containing materials was calculated according to Formula 1, and the results are also listed in Table 1.

[0062]

[0063] Where m is the nitrogen removal rate, S0 is the mass percentage of nitrogen in the aluminum-containing material, and S1 is the mass percentage of nitrogen in aluminum-containing material 3.

[0064] Table 1. Component content of aluminum-containing material 3 in Examples 1-2 and Comparative Example 1

[0065]

[0066] As can be seen from the test results of Examples 1 and 2 in Table 1, denitrification is more thorough with the increase of the washing liquid-to-solid ratio and the extension of the conditioning time. As can be seen from the test results of Examples 1, 2 and Comparative Example 1 in Table 1, the denitrification method provided by this invention can effectively remove nitrogen-containing substances from aluminum-containing materials.

[0067] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for denitrification of an aluminum-containing material, comprising the following steps: mixing the aluminum-containing material and water to prepare a slurry, thereby obtaining a slurry solution; the method for obtaining the aluminum-containing material comprises the following steps: mixing an aluminum-containing mineral and a nitric acid solution to perform leaching, mixing the leaching solution and an alkaline solution to perform precipitation, thereby obtaining the aluminum-containing material; the aluminum-containing material comprises iron elements, aluminum elements, silicon elements and nitrogen-containing substances, and the nitrogen-containing substances are nitrogen-containing anions; mixing the slurry solution and a washing aid to perform conditioning, and then filtering, thereby obtaining a primary denitrified aluminum-containing material; the washing aid is sodium sulfate; washing the primary denitrified aluminum-containing material with water, thereby obtaining a denitrified aluminum-containing material.

2. The process for the removal of nitrogen from aluminum-containing materials according to claim 1, characterized in that, The mass ratio of the aluminum-containing material to the washing aid is 1:0.15-0.

35.

3. The process of claim 1, wherein the aluminum-containing material is selected from the group consisting of aluminum metal, aluminum alloys, aluminum-containing scrap, aluminum-containing waste, and combinations thereof. The conditioning is performed under stirring, the stirring temperature is 60-100℃, and the stirring time is 0.2-1.5h.

4. The process of claim 1, wherein the aluminum-containing material is selected from the group consisting of aluminum metal, aluminum alloys, aluminum-containing scrap, aluminum-containing waste, and combinations thereof. The washing comprises sequentially performing first leaching and second leaching.

5. The process for the removal of nitrogen from aluminum-containing materials according to claim 4, characterized in that, The liquid-solid mass ratio of the first leaching and the second leaching is independently 3-10:

1.

6. The process of claim 1 wherein the aluminum-containing material is selected from the group consisting of aluminum metal, aluminum alloys, aluminum-containing scrap, and combinations thereof. The mass ratio of the aluminum-containing material to the water for preparing the slurry is 1:4-10.

7. The process according to claim 1 or 6, characterized in that, The slurry preparation is performed under stirring, the stirring speed is 200-500rpm, and the stirring time is 0.5-1h.

8. The process of claim 1 wherein the aluminum-containing material is selected from the group consisting of aluminum metal, aluminum alloys, aluminum-containing scrap, and combinations thereof. The mass percentage of the iron elements in the aluminum-containing material is 0.2-0.3%; The mass percentage of the aluminum elements in the aluminum-containing material is 22-26%; The mass percentage of the silicon elements in the aluminum-containing material is 0.1-0.2%; The mass percentage of the nitrogen elements in the nitrogen-containing substances in the aluminum-containing material is 2.94-3.62%.

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