Secondary aluminum dross fire method of inorganic salt resource recovery

Abstract

The application discloses a secondary aluminum ash fire resource inorganic salt separation method, and specifically comprises the following steps: S1, the secondary aluminum ash is treated by fire resource, in the process, the inorganic salt in the secondary aluminum ash sublimes at high temperature and is discharged with flue gas, after that, with the temperature of the flue gas decreasing, the inorganic salt undergoes desublimation and is separated from the flue gas, and the inorganic salt primary product is recovered; S2, the inorganic salt primary product obtained in the step S1 is recrystallized and purified: the inorganic salt primary product, water and a flocculating agent are mixed to form a slurry, the obtained slurry is filtered, the filter cake is dried, and the filtrate is evaporated and crystallized to obtain the final inorganic salt product. By using the method, the inorganic salt in the secondary aluminum ash can be extracted and separated, the extraction rate can reach more than 95%, the purity of the obtained inorganic salt product can reach more than 98%, the problem that the inorganic salt in the secondary aluminum ash affects the quality of downstream products is solved, and the recycling of the inorganic salt resource is realized.

Description

Technical Field

[0001] This invention relates to the field of environmentally friendly production technology, specifically to a secondary aluminum ash fire-process method for separating inorganic salts. Background Technology

[0002] In 2022, my country's aluminum industry generated over 3 million tons of secondary aluminum ash, a typical hazardous solid waste from the industry. Currently, my country's aluminum industry faces severe solid waste disposal problems, hindering its sustainable and high-quality development. With increasingly stringent national and aluminum industry environmental policies, the harmless and resource-based application of secondary aluminum ash, a hazardous waste from the aluminum industry, has gradually become a hot topic in the environmental protection industry. In terms of secondary aluminum ash resource utilization, pyrometallurgical resource recovery accounts for over 70% of the market, achieving resource recovery through high-temperature processes. These products are mainly used in industries such as cement, steel, alumina, water purification agents, and refractory materials. However, due to the presence of inorganic salts in secondary aluminum ash (accounting for approximately 8-25% of the ash), most pyrometallurgical resource recovery technologies return these inorganic salts to the product system, significantly impacting downstream applications. This negatively affects factors such as cement setting time, alumina decomposition rate, water purification agent quality, and refractory material refractoriness. Furthermore, the inorganic salts in secondary aluminum ash, as a valuable resource, have not yet been utilized.

[0003] Currently, there is no research, literature, or patent on the extraction of inorganic salts in the secondary aluminum ash pyrometallurgical resource recovery process, either domestically or internationally. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to provide a secondary aluminum ash fire-based method for separating inorganic salts.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for separating inorganic salts in the secondary aluminum ash pyrometallurgical resource recovery process specifically includes the following steps:

[0007] S1. The secondary aluminum ash is subjected to pyrometallurgical resource recovery treatment. During this process, the inorganic salts in the secondary aluminum ash sublimate at high temperature and are discharged with the flue gas. Subsequently, as the flue gas temperature decreases, the inorganic salts condense and separate from the flue gas, and the primary inorganic salt product is recovered.

[0008] S2. Recrystallize and purify the inorganic salt primary product obtained in step S1: Mix the inorganic salt primary product, water and flocculant to form a slurry, filter the resulting slurry, dry the filter cake, and evaporate and crystallize the filtrate to obtain the final inorganic salt product.

[0009] Furthermore, in step S2, the dried filter cake is used as a water purification agent, cement, or building material; the final inorganic salt product obtained by evaporating and crystallizing the filtrate is used as a refining agent for aluminum.

[0010] Furthermore, the pyrometallurgical resource recovery process in step S1 refers to calcining secondary aluminum ash or its semi-finished raw materials at a high temperature of 950-1400℃, and then utilizing the products obtained from the calcination process; the semi-finished raw materials are obtained by mixing secondary aluminum ash with sodium-based or calcium-based materials as required.

[0011] Furthermore, the inorganic salts in the secondary aluminum ash include one or more of sodium chloride, potassium chloride, sodium fluoride, and potassium fluoride.

[0012] Further, in step S1, the sublimated inorganic salt enters the deposition system with the flue gas. As the flue gas temperature decreases, the inorganic salt undergoes deposition and separates from the flue gas. At this point, the primary inorganic salt product can be recovered. The deposition system includes one of the following: gravity settling chamber, cyclone dust collector, tubular settling chamber, and bag filter, or a combination of gravity settling chamber, cyclone dust collector, and bag filter.

[0013] Further, in step S2, the mass ratio of the inorganic salt primary product, water, and flocculant is 1:1-2:0.02-0.05. After mixing the inorganic salt primary product, water, and flocculant, the mixture is stirred at room temperature for more than 30 minutes to obtain a slurry.

[0014] Furthermore, in step S2, one or more of the following are used to filter the slurry: a centrifuge, a filter press, and a vacuum filter.

[0015] Furthermore, in step S2, the filtrate is evaporated and crystallized using an MVR evaporator or a multi-effect evaporator at an evaporation temperature of 90-110℃.

[0016] The beneficial effects of this invention are as follows: the method of this invention can be used to extract and separate inorganic salts from secondary aluminum ash, with an extraction rate of over 95% and a final inorganic salt product purity of over 98%. This solves the problem of inorganic salts in secondary aluminum ash affecting the quality of downstream products, while realizing the recycling of inorganic salt resources. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the method flow of various embodiments of the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0019] Example 1

[0020] This embodiment provides a method for separating inorganic salts in the secondary aluminum ash fire-process resource recovery method, such as... Figure 1 As shown, during the pyrometallurgical resource recovery process of secondary aluminum ash, the inorganic salts in the ash sublimate at a high temperature of 950℃ and are discharged with the flue gas. As the flue gas passes through a gravity settling chamber and a cyclone dust collector, the temperature drops from 550℃ to 200℃, causing the inorganic salts in the flue gas to condense and be recovered in a bag filter, yielding a primary inorganic salt product. The purity of the primary inorganic salt product can reach over 75%. Then, the primary inorganic salt product, water, and flocculant are mixed in a mass ratio of 1:1:0.05 to form a slurry, which is stirred at room temperature for 30 minutes. After centrifugal filtration, the filter cake is dried and used in industries such as water purification agents, cement, and building materials. The filtrate is evaporated and crystallized at 95℃ using an MVR evaporator to obtain an inorganic salt product with a purity of 98%. This inorganic salt product is returned to upstream aluminum processing enterprises for use as a refining agent for aluminum.

[0021] Example 2

[0022] This embodiment provides a method for separating inorganic salts in the secondary aluminum ash fire-process resource recovery method, such as... Figure 1 As shown, during the pyrometallurgical resource recovery process of secondary aluminum ash, the inorganic salts in the secondary aluminum ash sublimate at a high temperature of 1350℃ and are discharged with the flue gas. As the flue gas passes through a gravity settling chamber and a three-stage cyclone dust collector, the temperature drops from 600℃ to 180℃, causing the inorganic salts in the flue gas to condense and be recovered by a bag filter, yielding primary inorganic salt products. The purity of the primary inorganic salt products can reach over 75%. The primary inorganic salt products, water, and flocculant are mixed in a mass ratio of 1:2:0.02 to form a slurry, which is then stirred at room temperature for 30 minutes. The slurry is filtered through a plate and frame filter press, and the filter cake is dried and used in industries such as water purification agents, cement, and building materials. The filtrate is evaporated and crystallized at 110℃ using an MVR evaporator to obtain an inorganic salt product with a purity of 98%. This inorganic salt product is returned to upstream aluminum processing enterprises for use as a refining agent for aluminum.

[0023] For those skilled in the art, various corresponding changes and modifications can be made based on the above technical solutions and concepts, and all such changes and modifications should be included within the protection scope of the claims of this invention.

Claims

1. A method for separating inorganic salts in the secondary aluminum ash fire-process resource recovery process, characterized in that, Specifically, the steps include the following: S1. The secondary aluminum ash is subjected to pyrometallurgical resource recovery treatment. During this process, the inorganic salts in the secondary aluminum ash sublimate at high temperature and are discharged with the flue gas. Subsequently, as the flue gas temperature decreases, the inorganic salts condense and separate from the flue gas, and the primary inorganic salt product is recovered. S2. Recrystallize and purify the inorganic salt primary product obtained in step S1: Mix the inorganic salt primary product, water and flocculant to form a slurry, filter the resulting slurry, dry the filter cake, and evaporate and crystallize the filtrate to obtain the final inorganic salt product.

2. The method according to claim 1, characterized in that, In step S2, the dried filter cake is used as a water purification agent or cement; the final inorganic salt product obtained after the filtrate is evaporated and crystallized is used as a refining agent for aluminum.

3. The method according to claim 1, characterized in that, The pyrometallurgical resource recovery process in step S1 refers to calcining secondary aluminum ash or its semi-finished raw materials at a high temperature of 950-1400℃, and then utilizing the products obtained from the calcination process; the semi-finished raw materials are obtained by mixing secondary aluminum ash with sodium-based or calcium-based materials as required.

4. The method according to claim 1, characterized in that, The inorganic salts in secondary aluminum ash include one or more of sodium chloride, potassium chloride, sodium fluoride, and potassium fluoride.

5. The method according to claim 1, characterized in that, In step S1, the sublimated inorganic salt enters the deposition system with the flue gas. As the flue gas temperature decreases, the inorganic salt undergoes deposition and separates from the flue gas, allowing the primary inorganic salt product to be recovered. The deposition system includes one of the following: a gravity settling chamber, a cyclone dust collector, a tubular settling chamber, or a bag filter, or a combination of a gravity settling chamber, a cyclone dust collector, and a bag filter.

6. The method according to claim 1, characterized in that, In step S2, the mass ratio of inorganic salt primary product, water and flocculant is 1:1-2:0.02-0.

05. After mixing the inorganic salt primary product, water and flocculant, the mixture is stirred at room temperature for more than 30 minutes to obtain a slurry.

7. The method according to claim 1, characterized in that, In step S2, one or more of the following are used to filter the slurry: centrifuge, filter press, and vacuum filter.

8. The method according to claim 1, characterized in that, In step S2, the filtrate is evaporated and crystallized using an MVR evaporator or a multi-effect evaporator at a temperature of 90-110℃.

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