Process for preparing aluminum ammonium sulfate from waste catalyst pickle liquor tail water

Abstract

The invention is applicable to the technical field of preparation of aluminum ammonium sulfate, and provides a process for preparing aluminum ammonium sulfate from waste catalyst pickle liquor tail water, which comprises the following steps: step (1), pretreatment and purification; (2) synthesizing aluminum ammonium sulfate; (3) separation and primary crystallization; (4) recrystallization and purification: dissolving aluminum ammonium sulfate crystals obtained by primary crystallization with a proper amount of hot water to prepare a saturated solution; adjusting the pH value to 2-3 by using dilute sulfuric acid, adding powdered activated carbon, carrying out heat preservation and stirring for 20-30 minutes, and then filtering while the solution is hot; re-dissolving the filtered wet solid with a proper amount of hot water to prepare a saturated solution, cooling to 4-10 DEG C at a rate of 0.2-0.5 DEG C / min, and standing overnight; and (5) separating and drying. According to the method, valuable metal aluminum in the waste catalyst is efficiently recycled, the content of heavy metal in the tail water is remarkably reduced, and the discharged wastewater reaches the environmental protection standard.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of aluminum ammonium sulfate preparation, in particular to a process for preparing aluminum ammonium sulfate from waste catalyst acid leaching liquid tail water. BACKGROUND

[0002] Petroleum chemical waste catalysts often contain some toxic ingredients, mainly heavy metals and volatile organic compounds, which have great environmental risks, and it is particularly important to carry out harmless treatment and disposal. In addition, the petroleum chemical waste catalysts contain a high content of noble metals or other valuable metals, some of which are even much higher than the content of the corresponding components in some poor ores, and the metal grade is high, so the waste catalysts can be recycled as secondary resources. Comprehensive utilization of petroleum chemical waste catalysts can not only improve resource utilization, but also avoid environmental problems caused by waste catalysts and realize sustainable development.

[0003] The waste catalyst generated in the petroleum refining process contains about 40-55% of alumina, and part of the aluminum will form aluminum sulfate in the acid leaching process, so the recovery of aluminum is of great significance.

[0004] The application adopts a technology of forming aluminum ammonium sulfate by adding low-ammonium sulfate, which comprehensively utilizes the aluminum in the waste catalyst and stabilizes the leaching of the wet process, reduces the content of heavy metals in the tail water, and makes the discharged wastewater meet the standard.

[0005] At present, there are generally two ways to treat nickel-aluminum slag. One is to form ice nickel alloy through fire reduction smelting, and the other is to extract nickel through acid leaching. Although the fire smelting process is simple, the equipment and production cost are very high, a large amount of auxiliary materials are needed, and a certain amount of waste gas is discharged to the environment. In order to meet the emission requirements, more environmental protection facilities are needed, which affects the overall business pressure.

[0006] And the acid leaching process has the advantages of short process, less investment in environmental protection facilities, and low cost. Therefore, the treatment of the tail water containing aluminum sulfate generated by extracting nickel from the acid leaching of nickel-aluminum slag has become a top priority. SUMMARY

[0007] The application aims to provide a process for preparing aluminum ammonium sulfate from waste catalyst acid leaching liquid tail water to solve the problems in the background art.

[0008] To achieve the above-mentioned purpose, the application provides the following technical scheme: a process for preparing aluminum ammonium sulfate from waste catalyst acid leaching liquid tail water, comprising the following steps: Step (1), pretreatment and purification: Collecting acid leaching liquid tail water from spent catalyst recovery process, adding appropriate amount of dilute ammonia water, adjusting pH value, warming, stirring at 100-200 rpm for 0.5-2 h, then standing for 1-2 h, filtering to obtain purified aluminum sulfate solution; Step (2), ammonium aluminum sulfate synthesis: Detecting the molar concentration of aluminum ions in the purified solution, calculating and adding a certain amount of ammonium sulfate; 60-70℃ constant temperature water bath, 150-250 rpm constant temperature stirring for 1-2 h; Step (3), separation and primary crystallization: The mixed solution after step (2) synthesis reaction is centrifuged while hot, 3000-5000 rpm centrifugation for 10-20 min; The wet solid obtained by centrifugation is redissolved with appropriate hot water to prepare a saturated solution, and the temperature is lowered to room temperature and aged for 2-4 h; Step (4), recrystallization purification: The ammonium aluminum sulfate crystals obtained by primary crystallization are dissolved with appropriate hot water to prepare a saturated solution; Adjust the pH to 2-3 with dilute sulfuric acid, add powdered activated carbon, and stir for 20-30 min, then filter while hot; The wet solid obtained by filtration is redissolved with appropriate hot water to prepare a saturated solution, and the temperature is lowered to 4-10℃ at a rate of 0.2-0.5℃ / min, and aged overnight; Step (5), separation and drying: The slurry after recrystallization is separated by centrifugation or suction filtration, and the crystals are washed 1-2 times to quickly remove surface moisture, then the crystals are placed in a vacuum drying oven at 50-60℃ for 4-6 h to obtain high-purity ammonium aluminum sulfate.

[0009] Preferably, the pH value in step (1) is adjusted to 2.5-3.5, and the temperature is raised to 40-50℃.

[0010] Preferably, in step (2), a certain amount of ammonium sulfate is calculated and added, so that the molar ratio of Al 3+ to NH4 + is 1:1~1.05.

[0011] Preferably, the cooling rate in step (3) is 0.5-1℃ / min.

[0012] Preferably, the amount of powdered activated carbon added in step (4) is 0.1%-0.5% of the mass of the solution.

[0013] Preferably, the reagent used to wash the crystals in step (5) is ice ethanol or acetone.

[0014] The present application has at least the following beneficial effects: The process for preparing aluminum ammonium sulfate from waste catalyst acid leaching solution tail water provided by the present application not only realizes efficient recovery of valuable metal aluminum in waste catalyst, but also significantly reduces the content of heavy metals in tail water, so that the discharged wastewater meets environmental protection standards. Compared with the traditional nickel-aluminum slag treatment method, the present process uses acid leaching, which has the significant economic advantages of short process flow, less investment in environmental protection facilities, and low production cost. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. EMBODIMENT

[0016] A process for preparing aluminum ammonium sulfate from waste catalyst acid leaching solution tail water includes the following steps: Step (1), pretreatment and purification: Collect the acid leaching solution tail water from the waste catalyst recovery process, add an appropriate amount of dilute ammonia water, adjust the pH value to 2.5, heat to 40℃, stir at 100 rpm for 0.5h, then stand for aging for 1h, and then filter to obtain a purified aluminum sulfate solution; Step (2), aluminum ammonium sulfate synthesis: Detect the molar concentration of aluminum ions in the purified solution, calculate and add a certain amount of stoichiometric ammonium sulfate, Al 3+ and NH4 + molar ratio 1:1; 60℃ constant temperature water bath, 150 rpm constant temperature stirring for 1h; Step (3), separation and primary crystallization: The mixed solution after step (2) synthesis reaction is centrifuged while hot, 3000 rpm for 10 min; The wet solid obtained by centrifugation is redissolved with an appropriate amount of hot water to prepare a saturated solution, and the temperature is lowered to room temperature at a rate of 0.5℃ / min, and then aged for 2h; Step (4), recrystallization purification: The aluminum ammonium sulfate crystals obtained by primary crystallization are dissolved with an appropriate amount of hot water to prepare a saturated solution; Adjust the pH to 2 with dilute sulfuric acid, add 0.1% of the solution mass of powdered activated carbon, and stir for 20 min, then filter while hot; The filtered wet solids were redissolved with an appropriate amount of hot water to prepare a saturated solution, which was then cooled to 4°C at a rate of 0.2°C / min and allowed to stand overnight. Step (5), separation and drying: The recrystallized slurry was separated by centrifugation or filtration. The crystals were washed once with an appropriate amount of ice-cold ethanol to quickly remove surface moisture. The crystals were then placed in a vacuum drying oven at 50°C and dried for 4 hours to obtain high-purity ammonium aluminum sulfate. Example

[0017] A process for preparing ammonium aluminum sulfate from waste catalyst acid leaching tailwater includes the following steps: Step (1), Pretreatment and purification: Collect the acid leaching tailwater from the waste catalyst recovery process, add an appropriate amount of dilute ammonia water, adjust the pH value to 3, heat to 45℃, stir at 150 rpm for 1 hour, then let it stand and age for 1.5 hours, and then filter to obtain a purified aluminum sulfate solution. Step (2), synthesis of ammonium aluminum sulfate: The molar concentration of aluminum ions in the purified solution was detected, and a certain stoichiometric amount of ammonium sulfate was added. 3+ With NH4 + The molar ratio is 1:1.02; Stir at a constant temperature of 65℃ for 1.5 hours using a 200rpm stirring motion. Step (3), separation and primary crystallization: The mixed solution after the synthesis reaction in step (2) was separated by centrifugation while hot, at 4000 rpm for 15 min; The wet solid obtained by centrifugation was redissolved with an appropriate amount of hot water to prepare a saturated solution, which was then cooled to room temperature at a rate of 0.8℃ / min and allowed to stand for 3 hours. Step (4), recrystallization and purification: The aluminum ammonium sulfate crystals obtained from primary crystallization are dissolved in an appropriate amount of hot water to prepare a saturated solution; Adjust the pH to 2.5 with dilute sulfuric acid, add 0.4% powdered activated carbon by mass of the solution, keep warm and stir for 25 minutes, and then filter while hot; The filtered wet solids were redissolved with an appropriate amount of hot water to prepare a saturated solution, which was then cooled to 6°C at a rate of 0.3°C / min and allowed to stand overnight. Step (5), separation and drying: The recrystallized slurry was separated by centrifugation or filtration. The crystals were washed twice with an appropriate amount of acetone to quickly remove surface moisture. The crystals were then dried in a vacuum drying oven at 55°C for 5 hours to obtain high-purity ammonium aluminum sulfate. Example

[0018] A process for preparing ammonium aluminum sulfate from waste catalyst acid leaching tailwater includes the following steps: Step (1), Pretreatment and purification: Collect the acid leaching tailwater from the waste catalyst recovery process, add an appropriate amount of dilute ammonia water, adjust the pH value to 3.5, heat to 50℃, stir at 200 rpm for 2 hours, then let stand and age for 2 hours, and filter to obtain a purified aluminum sulfate solution. Step (2), synthesis of ammonium aluminum sulfate: The molar concentration of aluminum ions in the purified solution was detected, and a certain stoichiometric amount of ammonium sulfate was added. 3+ With NH4 + The molar ratio is 1:1.05; Stir at a constant temperature of 70℃ for 2 hours at 250 rpm in a constant water bath. Step (3), separation and primary crystallization: The mixed solution after the synthesis reaction in step (2) was separated by centrifugation while hot, at 5000 rpm for 20 min; The wet solid obtained by centrifugation was redissolved with an appropriate amount of hot water to prepare a saturated solution. The solution was then cooled to room temperature at a rate of 1℃ / min and allowed to stand for 4 hours. Step (4), recrystallization and purification: The aluminum ammonium sulfate crystals obtained from primary crystallization are dissolved in an appropriate amount of hot water to prepare a saturated solution; Adjust the pH to 3 with dilute sulfuric acid, add 0.5% powdered activated carbon by mass of the solution, keep warm and stir for 30 minutes, and then filter while hot; The filtered wet solid was redissolved with an appropriate amount of hot water to prepare a saturated solution, which was then cooled to 10°C at a rate of 0.5°C / min and allowed to stand overnight. Step (5), separation and drying: The recrystallized slurry was separated by centrifugation or filtration. The crystals were washed twice with an appropriate amount of ice-cold ethanol to quickly remove surface moisture. The crystals were then dried in a vacuum drying oven at 60°C for 6 hours to obtain high-purity ammonium aluminum sulfate.

[0019] In summary, the present invention utilizes a low-temperature roasting technology to facilitate the leaching of aluminum from the carrier alumina during subsequent high-pressure acid leaching. This technology also significantly enhances the conversion of molybdenum and vanadium elements during sodium roasting and offers a clear advantage for the extraction of molybdenum and vanadium in wet processes. In the acid leaching solution, aluminum sulfate is converted into ammonium aluminum sulfate by adding ammonium sulfate or introducing ammonia.

[0020] This process not only achieves efficient recovery of valuable aluminum from spent catalysts but also significantly reduces the heavy metal content in the effluent, ensuring that the discharged wastewater meets environmental standards. Simultaneously, by optimizing key steps such as pretreatment and purification, ammonium aluminum sulfate synthesis, separation and primary crystallization, recrystallization purification, and separation and drying, the high purity of the final product, ammonium aluminum sulfate, is ensured. Compared to traditional nickel-aluminum slag treatment methods, this process, employing acid leaching, offers significant economic advantages, including a shorter process flow, lower investment in environmental protection facilities, and lower production costs. Furthermore, by precisely controlling the reaction conditions at each step, this process further improves product quality and recovery rate, providing a new and effective approach for the comprehensive utilization of spent catalysts.

[0021] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0022] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for preparing ammonium aluminum sulfate from waste catalyst acid leaching tailwater, characterized in that, Includes the following steps: Step (1), Pretreatment and purification: Collect the acid leaching tailwater from the waste catalyst recovery process, add an appropriate amount of dilute ammonia water, adjust the pH value, raise the temperature, stir at 100-200 rpm for 0.5-2 hours, then let it stand and age for 1-2 hours, and then filter to obtain a purified aluminum sulfate solution. Step (2), synthesis of ammonium aluminum sulfate: The molar concentration of aluminum ions in the purified solution was detected, and a certain stoichiometric amount of ammonium sulfate was calculated and added. Use a constant temperature water bath at 60-70℃ and stir at 150-250 rpm for 1-2 hours. Step (3), separation and primary crystallization: The mixed solution after the synthesis reaction in step (2) was separated by centrifugation while hot, at 3000-5000 rpm for 10-20 min; Dissolve the wet solid obtained by centrifugation in an appropriate amount of hot water to prepare a saturated solution, cool it to room temperature, and let it stand for 2-4 hours. Step (4), recrystallization and purification: The aluminum ammonium sulfate crystals obtained from primary crystallization are dissolved in an appropriate amount of hot water to prepare a saturated solution; Adjust the pH to 2-3 with dilute sulfuric acid, add powdered activated carbon, keep warm and stir for 20-30 minutes, and then filter while hot; The filtered wet solids are redissolved with an appropriate amount of hot water to prepare a saturated solution. The solution is then cooled to 4-10°C at a rate of 0.2-0.5°C / min and allowed to stand overnight. Step (5), separation and drying: The recrystallized slurry is centrifuged or filtered to separate the crystals. The crystals are washed 1-2 times to quickly remove surface moisture. Then, the crystals are dried in a vacuum drying oven at 50-60℃ for 4-6 hours to obtain high-purity ammonium aluminum sulfate.

2. The process for preparing ammonium aluminum sulfate from waste catalyst acid leaching liquid according to claim 1, characterized in that: In step (1), the pH value is adjusted to 2.5-3.5 and the temperature is raised to 40-50℃.

3. The process for preparing ammonium aluminum sulfate from waste catalyst acid leaching liquid tailwater according to claim 1, characterized in that: In step (2), a certain stoichiometric amount of ammonium sulfate is calculated and added so that Al 3+ With NH4 + The molar ratio is 1:1 to 1.

05.

4. The process for preparing ammonium aluminum sulfate from waste catalyst acid leaching liquid according to claim 1, characterized in that: The cooling rate in step (3) is 0.5-1℃ / min.

5. The process for preparing ammonium aluminum sulfate from waste catalyst acid leaching tailwater according to claim 1, characterized in that: In step (4), the amount of powdered activated carbon added is 0.1%-0.5% of the solution mass.

6. The process for preparing ammonium aluminum sulfate from waste catalyst acid leaching tailwater according to claim 1, characterized in that: The reagent used to wash the crystals in step (5) is icy ethanol or acetone.