Method for preparing aluminum hydroxide from aluminum-containing nitric acid solution and denitration

Abstract

The invention provides a method for preparing aluminum hydroxide from an aluminum-containing salpeter solution and denitration, and belongs to the field of metallurgical solid waste treatment.The method comprises the following steps that S1, aluminum-containing tailings are subjected to nitric acid leaching and then subjected to solid-liquid separation, and aluminum-containing leaching liquid and silicon-containing leaching residues are obtained; s2, carrying out homogeneous precipitation on the aluminum-containing immersion liquid and lime milk, and then carrying out solid-liquid separation to obtain basic aluminum nitrate and calcium-containing mother liquor; and S3, carrying out denitration reaction on the basic aluminum nitrate and the aluminum hydroxide hydroxide, carrying out solid-liquid separation to obtain aluminum hydroxide and an aluminum nitrate solution, and freezing and crystallizing the calcium-containing mother solution to obtain a calcium nitrate product. The solid waste aluminum-containing tailings are recycled, the technological process is short, the aluminum recovery rate is high, and the byproduct utilization rate is high.

Description

Technical Field

[0001] The invention belongs to the field of metallurgical solid waste treatment, and particularly relates to a method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution. Background Art

[0002] In the production process of metallurgy, chemical industry and other industries, aluminum tailings are a common solid waste. These tailings contain a large amount of aluminum and have the potential value of recycling. However, due to the complex composition of tailings, aluminum exists in the form of complex compounds, which leads to technical challenges in the recycling of aluminum. If the aluminum tailings are not effectively treated, it will not only cause a waste of resources, but also may cause environmental pollution, such as soil and water pollution.

[0003] At present, the main methods for recovering aluminum resources from aluminum tailings are alkaline dissolution, electrolysis and acid leaching. However, these methods have some shortcomings. For example, alkaline dissolution requires high temperature and high pressure conditions, high energy consumption, and strict requirements on the corrosion resistance of equipment; the electrolysis process is complicated and the cost is high; although the acid leaching method can be carried out under milder conditions, the commonly used hydrochloric acid or sulfuric acid may cause secondary pollution. In addition, these methods still need to be improved in terms of aluminum recovery rate and product purity.

[0004] As an important chemical raw material, aluminum hydroxide is widely used in catalyst carriers, flame retardants, adsorbents and other fields. The traditional method of preparing aluminum hydroxide usually uses aluminum ore as raw material, and undergoes a complex purification and chemical reaction process, resulting in high production costs. The use of aluminum tailings to prepare aluminum hydroxide can not only reduce production costs, but also realize waste resource utilization.

[0005] Therefore, it is of great economic and environmental significance to develop a method for preparing high-purity aluminum hydroxide by using aluminum-containing tailings through effective leaching and precipitation processes. This can not only realize the recycling of aluminum resources and reduce production costs, but also reduce the impact of industrial waste on the environment, which meets the requirements of green chemistry and sustainable development.

[0006] Patent CN115947359B discloses a method for preparing aluminum hydroxide from aluminum-containing waste, which adopts a two-stage alkali leaching + carbon decomposition process to prepare aluminum hydroxide. However, the alkali leaching method has strict requirements on the corrosion resistance of the equipment, and the equipment cost investment is large. At the same time, the alkali consumption is large, and the aluminum recovery rate is about 50%, which is a low aluminum recovery rate. The process flow of the present invention is short, the aluminum recovery rate is above 80%, and the utilization rate of by-products is high. For example, silicon-containing leaching residue can be used as silicon fertilizer or other raw materials for industrial production. The calcium-containing mother liquor is treated by a freezing crystallization process to generate calcium nitrate solid, which can be used as calcium nitrate magnesium fertilizer, and the aluminum nitrate solution can be returned to continue the cycle to prepare aluminum hydroxide. Summary of the invention

[0007] In order to solve the above technical problems, the present invention recycles aluminum tailings or aluminum ore in solid waste, has a short process flow, a high aluminum recovery rate, a high by-product utilization rate, high resource utilization and environmental benefits, and has broad application prospects in industrial production.

[0008] The present invention provides the following technical solutions:

[0009] A method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution, the method comprising the following steps:

[0010] S1, the aluminum-containing tailings are leached with nitric acid and then separated into solid and liquid to obtain aluminum-containing leaching solution and silicon-containing leaching residue;

[0011] S2, the aluminum-containing leaching solution and the lime milk are homogeneously precipitated and then solid-liquid separated to obtain basic aluminum nitrate and a calcium-containing mother liquor, wherein the basic aluminum nitrate is a solid and the calcium-containing mother liquor is a liquid;

[0012] S3. After the denitration reaction of basic aluminum nitrate and aluminum hydroxide, the solid and liquid are separated to obtain aluminum hydroxide and aluminum nitrate solution. The calcium-containing mother liquor is frozen and crystallized to obtain calcium nitrate product.

[0013] Furthermore, in step S1, the main components of the aluminum-containing tailings are SiO2: 40%~50%, Al2O3: 20%~35%, Fe2O3: 5%~10%, CaO: 0.5%~3%, and other oxides and salts: 2%~5%, and the aluminum content in the obtained aluminum-containing leaching solution is 80~100g / L.

[0014] Furthermore, in step S2, the amount of lime milk used is 1.2 to 1.6 times the content of aluminum nitrate in the aluminum-containing leaching solution, and the reaction mechanism of the aluminum-containing leaching solution and lime milk for homogeneous reaction is as follows:

[0015] 4Al(NO3)3+5Ca(OH)2=2Al2(OH)5NO3↓+5Ca(NO3)2

[0016] In this process, the amount of lime milk needs to be controlled. If too much lime milk is added, calcium hydroxide will be entrained in the generated basic aluminum nitrate, resulting in a decrease in the purity of the aluminum hydroxide generated after the denitrification reaction; if a small amount of lime milk is added, aluminum nitrate will exist in the calcium-containing mother liquor, resulting in a decrease in the purity of the calcium nitrate obtained after freeze-drying.

[0017] Furthermore, in step S2, the aluminum content in the basic aluminum nitrate is 24.5% to 26.9%, and the nitrate content is 29.2% to 30.9%.

[0018] Furthermore, in step S3, the denitration reaction conditions are: liquid-solid mass ratio (2-3): 1, denitration temperature is 80-90°C, denitration time is 1-1.5h, and the amount of aluminum hydroxide is 0.8-1 times that of basic aluminum nitrate. In this process, the liquid involved in the reaction is water, and the solids are basic aluminum nitrate and aluminum hydroxide. In actual operation, water is first added to the basic aluminum nitrate, and the liquid-solid mass ratio of water to basic aluminum nitrate is (2-3): 1 for pulping, and then aluminum hydroxide is added to carry out denitration reaction at 80-90°C.

[0019] The reaction mechanism of basic aluminum nitrate and aluminum oxyhydroxide is as follows:

[0020] 3Al2(OH)5NO3+AlO(OH)+H2O=6Al(OH)3↓+Al(NO3)3

[0021] In this process, aluminum hydroxide solid is added for denitration reaction, and the generated aluminum nitrate solution can be reused in S2, that is, lime milk is continuously added to circulate and prepare aluminum hydroxide. If other substances are used for denitration reaction, for example, adding ferric hydroxide will generate aluminum hydroxide solid and ferric nitrate solution. The ferric nitrate solution needs to be further processed, while ferric hydroxide can be used to circulate and prepare strong aluminum oxide. The amount of aluminum hydroxide needs to be controlled in this process. If excessive aluminum hydroxide is added, aluminum hydroxide will be entrained with aluminum hydroxide, and the purity of aluminum hydroxide will be reduced; if a small amount of aluminum hydroxide is added, some basic aluminum nitrate will not participate in the denitration reaction, and the purity of aluminum hydroxide will also be reduced.

[0022] The present invention also provides aluminum hydroxide and calcium nitrate products prepared by the method. The aluminum content in the aluminum hydroxide product is 33.2% to 35.5%.

[0023] Compared with the prior art, the method provided by the present invention has the following advantages:

[0024] 1. The present invention provides an efficient aluminum recovery method. By leaching aluminum-containing tailings with nitric acid, aluminum elements are successfully extracted and aluminum hydroxide is prepared, so that the aluminum resources in the solid waste of aluminum-containing tailings are fully utilized, the discharge of waste materials is reduced, and the comprehensive utilization efficiency of resources is improved.

[0025] 2. The process flow of the present invention is short and efficient separation and recovery of elements such as aluminum, calcium, and silicon are achieved through a series of solid-liquid separations and chemical reactions. The entire process can be achieved using conventional industrial equipment, which reduces production costs and is easy to promote and apply in large-scale industrial production.

[0026] 3. The by-product utilization rate of the present invention is high. While preparing aluminum hydroxide, the calcium nitrate by-product prepared by the freezing crystallization process also has a high industrial application value. The calcium nitrate can be further used in building materials or chemical production, thereby improving the economic benefits of the entire process and conforming to the concept of circular economy.

[0027] In summary, the present invention provides an economical, environmentally friendly and efficient method with multiple advantages in resource recovery, process simplification and by-product utilization, and has broad application prospects in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 The present invention provides a process flow chart of a method for preparing aluminum hydroxide and denitrification using an aluminum-containing nitric acid solution. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0031] Comparative Example 1

[0032] A method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution, specifically comprising the following steps:

[0033] S1, take 1L aluminum nitric acid solution and 1250g 30% lime milk and mechanically stir and react for 1h at room temperature;

[0034] S2. After the reaction is completed, solid-liquid separation is performed to obtain basic aluminum nitrate and calcium nitrate mother liquor. The calcium nitrate mother liquor is freeze-dried to obtain calcium nitrate solid. The aluminum content in the basic aluminum nitrate is 24.8%, which is relatively low.

[0035] S3, take 500g of basic aluminum nitrate and 170g of aluminum hydroxide, add water, keep warm and stir mechanically, the denitration reaction temperature is 90°C, the denitration reaction time is 1h; the liquid-to-solid ratio is 2:1;

[0036] S4, after the denitration reaction is completed, aluminum hydroxide and aluminum nitrate solution are obtained by solid-liquid separation. The aluminum content in the crude aluminum hydroxide is 33.4%, the purity of aluminum hydroxide is 96.5%, the purity and content of aluminum hydroxide are low, and the recovery rate of aluminum element is 81%. Comparative Example 1: In S1, excessive lime milk is added, and the generated basic aluminum nitrate will carry lime milk, resulting in a low aluminum content in the basic aluminum nitrate.

[0037] Comparative Example 2

[0038] A method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution, specifically comprising the following steps:

[0039] S1, take 1L aluminum nitric acid solution and 1100g 30% lime milk and mechanically stir and react for 1h at room temperature;

[0040] S2. After the reaction is completed, solid-liquid separation is performed to obtain basic aluminum nitrate and calcium nitrate mother liquor. The calcium nitrate mother liquor is freeze-dried to obtain calcium nitrate solid. The aluminum content in the basic aluminum nitrate is 26.8%;

[0041] S3, take 500g of basic aluminum nitrate and 200g of aluminum hydroxide, add water and heat preservation, mechanical stirring, denitration reaction temperature is 90°C, denitration reaction time is 1h; liquid-to-solid ratio is 2:1;

[0042] S4, after the denitration reaction is completed, aluminum hydroxide and aluminum nitrate solution are obtained by solid-liquid separation. The aluminum content in the crude aluminum hydroxide is 35.7%, the purity of aluminum hydroxide is 96.1%, the purity of aluminum hydroxide is low, and the recovery rate of aluminum element is 81.5%. In Comparative Example 2, S3 adds an excess of aluminum hydroxide to carry out denitration reaction. The crude aluminum hydroxide contains aluminum hydroxide, and the aluminum content in aluminum hydroxide is greater than the aluminum content in aluminum hydroxide. Therefore, the aluminum content in the produced aluminum hydroxide is higher than the aluminum content in the theoretical aluminum hydroxide. Since the aluminum hydroxide contains unreacted aluminum hydroxide, the purity is low.

[0043] Example 1

[0044] A method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution, specifically comprising the following steps:

[0045] S1, take 1L aluminum nitric acid solution and 1100g 30% lime milk and mechanically stir and react for 1h at room temperature;

[0046] S2. After the reaction is completed, solid-liquid separation is performed to obtain basic aluminum nitrate and calcium nitrate mother liquor. The calcium nitrate mother liquor is freeze-dried to obtain calcium nitrate solid. The aluminum content in the basic aluminum nitrate is 26.8%;

[0047] S3, take 500g of basic aluminum nitrate and 170g of aluminum hydroxide, add water, keep warm and stir mechanically, the denitration reaction temperature is 80°C, the denitration reaction time is 1h; the liquid-to-solid ratio is 2:1;

[0048] S4. After the denitration reaction is completed, the solid-liquid separation is performed to obtain aluminum hydroxide and aluminum nitrate solution. The aluminum content in the crude aluminum hydroxide is 34.4%, the purity of aluminum hydroxide is 99.4%, and the recovery rate of aluminum element is 83%.

[0049] Example 2

[0050] A method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution, specifically comprising the following steps:

[0051] S1, take 1L aluminum nitric acid solution and 1100g 30% lime milk and mechanically stir and react for 1h at room temperature;

[0052] S2. After the reaction is completed, solid-liquid separation is performed to obtain basic aluminum nitrate and calcium nitrate mother liquor. The calcium nitrate mother liquor is freeze-dried to obtain calcium nitrate solid. The aluminum content in the basic aluminum nitrate is 26.8%;

[0053] S3, take 500g of basic aluminum nitrate and 170g of aluminum hydroxide, add water, keep warm and stir mechanically, the denitration reaction temperature is 90°C, the denitration reaction time is 1h; the liquid-to-solid ratio is 2:1;

[0054] S4. After the denitration reaction is completed, the solid-liquid separation is performed to obtain aluminum hydroxide and aluminum nitrate solution. The aluminum content in the crude aluminum hydroxide is 34.45%, the purity of aluminum hydroxide is 99.56%, and the recovery rate of aluminum element is 83.2%.

[0055] Example 3

[0056] A method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution, specifically comprising the following steps:

[0057] S1, take 1L aluminum nitric acid solution and 1100g 30% lime milk and mechanically stir and react for 1h at room temperature;

[0058] S2. After the reaction is completed, solid-liquid separation is performed to obtain basic aluminum nitrate and calcium nitrate mother liquor. The calcium nitrate mother liquor is freeze-dried to obtain calcium nitrate solid. The aluminum content in the basic aluminum nitrate is 26.8%;

[0059] S3, take 500g of basic aluminum nitrate and 170g of aluminum hydroxide, add water, keep warm and stir mechanically, the denitration reaction temperature is 90°C, the denitration reaction time is 1.5h; the liquid-to-solid ratio is 2:1;

[0060] S4. After the denitration reaction is completed, the solid-liquid separation is performed to obtain aluminum hydroxide and aluminum nitrate solution. The aluminum content in the crude aluminum hydroxide is 34.5%, the purity of aluminum hydroxide is 99.7%, and the recovery rate of aluminum element is 83.5%.

[0061] Example 4

[0062] A method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution, specifically comprising the following steps:

[0063] S1, take 1L aluminum nitric acid solution and 1100g 30% lime milk and mechanically stir and react for 1h at room temperature;

[0064] S2. After the reaction is completed, solid-liquid separation is performed to obtain basic aluminum nitrate and calcium nitrate mother liquor. The calcium nitrate mother liquor is freeze-dried to obtain calcium nitrate solid. The aluminum content in the basic aluminum nitrate is 26.8%;

[0065] S3, take 500g of basic aluminum nitrate and 170g of aluminum hydroxide, add water, keep warm and stir mechanically, the denitration reaction temperature is 90°C, the denitration reaction time is 1.5h; the liquid-to-solid ratio is 3:1;

[0066] S4. After the denitration reaction is completed, the solid-liquid separation is carried out to obtain aluminum hydroxide and aluminum nitrate solution. The aluminum content in the crude aluminum hydroxide is 34.6%, the purity of aluminum hydroxide is 99.8%, and the recovery rate of aluminum element is 84.6%.

[0067] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution, characterized in that: The method comprises the following steps: S1, the aluminum-containing tailings are leached with nitric acid and then separated into solid and liquid to obtain aluminum-containing leaching solution and silicon-containing leaching residue; S2, the aluminum-containing leaching solution and the lime milk are homogeneously precipitated and then the solid-liquid separation is performed to obtain basic aluminum nitrate and a calcium-containing mother liquor; S3. After the denitration reaction of basic aluminum nitrate and aluminum hydroxide, the solid and liquid are separated to obtain aluminum hydroxide and aluminum nitrate solution. The calcium-containing mother liquor is frozen and crystallized to obtain calcium nitrate product.

2. The method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution according to claim 1, characterized in that: In step S1, the main components of the aluminum-containing tailings are SiO2: 40%~50%, Al2O3: 20%~35%, Fe2O3: 5%~10%, CaO: 0.5%~3%, other oxides and salts: 2%~5%, and the aluminum content in the obtained aluminum-containing leaching solution is 80~100g / L.

3. The method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution according to claim 1, characterized in that: In step S2, the amount of lime milk used is 1.2 to 1.6 times the content of aluminum nitrate in the aluminum-containing leaching solution.

4. The method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution according to claim 1, characterized in that: In step S2, the aluminum content in the basic aluminum nitrate is 24.5% to 26.9%, and the nitrate content is 29.2% to 30.9%.

5. The method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution according to claim 1, characterized in that: In step S3, the denitration reaction conditions are: liquid-solid mass ratio (2-3): 1, denitration temperature is 80-90° C., and denitration time is 1-1.5 h.

6. The method for preparing aluminum hydroxide and denitrification from an aluminum-containing nitric acid solution according to claim 1, characterized in that: In step S3, the amount of aluminum oxyhydroxide used is 0.8 to 1 times that of basic aluminum nitrate.

7. Aluminum hydroxide and calcium nitrate prepared by the method according to any one of claims 1 to 6.

8. Aluminum hydroxide according to claim 7, characterized in that The aluminum content is 33.2%~35.5%.

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