A method for processing spent petrochemical catalysts to recover rare metals

Abstract

The application belongs to the technical field of solid waste resource recycling and treatment in petrochemical industry, and particularly discloses a method for treating waste petrochemical catalyst to recycle rare metals. The method directly mixes granular waste petrochemical catalyst with an activating agent, then performs short-time calcination in a microwave environment to obtain calcined slag, and then uses water circulation to rinse the calcined slag to obtain leaching solution containing rare metals and leaching residue. The method can realize rapid recycling of vanadium, molybdenum and other rare metals in waste petrochemical catalyst, has short recycling and treatment time, high recycling rate, and the waste catalyst after recycling and treatment has high alumina content and can be directly used as a catalyst carrier raw material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petrochemical industry solid waste resource recycling and processing, in particular to a method for recycling rare metals from waste petrochemical catalysts. BACKGROUND

[0002] With the rapid development of modern chemical industry at home and abroad, the demand for vanadium, molybdenum and other rare metal raw materials is increasing year by year. It is impossible to meet the demand of production development by extracting vanadium, molybdenum and their compounds from ores alone, so recycling and reusing secondary resources containing vanadium and molybdenum rare metals has important strategic significance.

[0003] Waste petrochemical catalyst is an important secondary resource, which is rich in vanadium, molybdenum and other rare metals, and some even far exceed the content of corresponding components in some poor ores, but it also contains harmful elements such as S and C, and is a dangerous solid secondary resource with important economic value. Because of its complex composition, it is difficult to handle, and if it is randomly piled up without harmless treatment, it not only occupies land resources, but also causes environmental pollution.

[0004] At present, the main methods for recycling and processing waste catalysts are fire method and wet method. The fire method generally involves high-temperature roasting first, followed by leaching. The traditional fire method has problems such as high energy consumption, long time consumption and environmental pollution, and gradually cannot meet the current environmental protection requirements. Wet processing methods include atmospheric acid leaching and atmospheric alkali leaching. The main problems of wet processing methods are poor adaptability of raw materials, metal dispersion and low production efficiency. The existing treatment of waste petrochemical catalysts generally refers to the traditional fire method or wet method, and it is found in the actual treatment process that there are problems such as low recovery rate of rare metals, high energy consumption, and easy leaching of aluminum-based carriers, which increases the difficulty of separation of rare metals and is not conducive to the reuse of catalyst carriers. SUMMARY

[0005] The technical problem solved by the present application is to provide a method for recycling rare metals from waste petrochemical catalysts, which can realize the rapid recovery of vanadium, molybdenum and other rare metals in waste petrochemical catalysts, has short recovery and processing time, high recovery rate, and the recovered waste catalysts can be directly used as catalyst carrier raw materials.

[0006] The technical solution adopted by the present application is: the present application provides a method for recycling rare metals from waste petrochemical catalysts, comprising the following steps:

[0007] Mixing the waste petrochemical catalyst with an activator, then short-time roasting in a microwave environment to obtain roasting slag;

[0008] Circulating washing the roasting slag with water to obtain leaching solution containing rare metals and leaching residue.

[0009] As an embodiment of the present application, the waste petrochemical catalyst is a waste catalyst with alumina as a carrier, preferably mixed with an activating agent after deoiling treatment. The granular waste petrochemical catalyst after deoiling treatment is directly mixed with the activating agent, and subsequent treatment is carried out without the need of grinding the waste petrochemical catalyst and mixing with the activating agent.

[0010] As an embodiment of the present application, the activating agent is sodium carbonate and / or sodium hydroxide. For example, the activating agent can be sodium carbonate, sodium hydroxide or a mixture of sodium carbonate and sodium hydroxide.

[0011] Further preferably, the activating agent is mixed with the waste petrochemical catalyst after being made into a thick slurry by adding water.

[0012] As an embodiment of the present application, the amount of the activating agent is 1.6-2.5 times, preferably 1.8-2.2 times, of the total moles of vanadium and molybdenum in the waste petrochemical catalyst.

[0013] As an embodiment of the present application, the waste petrochemical catalyst mixed with the activating agent is first short-time dried, and then short-time calcined; the short-time drying time is controlled to be 8-12 min, and the drying temperature is controlled to be 80-110℃.

[0014] Preferably, the short-time drying time is 10 min, and the temperature is 100℃.

[0015] As an embodiment of the present application, the microwave conditions of the short-time calcination are: microwave power 500-1000 W, and the time is controlled to be 5-8 min. The calcination temperature of the short-time calcination is 500-600℃.

[0016] As an embodiment of the present application, the circulating washing of the calcination residue with water includes: loading the calcination residue into a filter screen container, circulating washing with water, and collecting the washing liquid, thereby obtaining a leaching solution containing rare metals.

[0017] Preferably, the circulating washing with water is performed 3-5 times.

[0018] Preferably, normal pressure water is used for the circulating washing.

[0019] Preferably, the temperature of the circulating washing water is 75-90℃.

[0020] As an embodiment of the present application, the leaching residue obtained by the present application has an alumina mass percentage content of ≥98%, high purity, and can be used for preparing petrochemical catalysts, and can be directly used as a carrier raw material for preparing new petrochemical catalysts.

[0021] The raw material waste petrochemical catalyst treated in the application is a waste catalyst with alumina as a carrier after deoiling treatment, which has a unique structure, wherein vanadium and molybdenum mainly exist in the form of oxides and sulfides and are adsorbed on the surface of the alumina carrier. The effective separation of rare metals from the carrier alumina is a common difficult problem, because alumina is amphoteric, and the traditional process generally uses acidic or alkaline medium for recovery of rare metals, so the dissolution of aluminum cannot be avoided, and the treatment causes aluminum to be dispersed in the leaching residue and leaching solution, which is not conducive to subsequent recycling.

[0022] The inventors found that the oxides and sulfides of vanadium and molybdenum in the waste petrochemical catalyst are strong microwave absorbing substances, and the carrier alumina is a weak microwave absorbing substance. Based on the difference in microwave performance and the special structure of the waste catalyst, the recovery treatment scheme of the application is proposed. In the microwave short-time roasting process, the microwave has the characteristic of selective heating of specific substances. The vanadium and molybdenum on the surface of the carrier alumina are rapidly heated to the temperature for reaction with the activator, realizing the soluble conversion of the vanadium and molybdenum phase, while the carrier alumina has poor wave absorption ability and slow heating speed, and basically does not react with the activator, thus realizing the rapid and efficient dissolution of the rare metals vanadium and molybdenum and the effective separation from the carrier metal alumina. The leaching solution obtained by the treatment has high vanadium and molybdenum content and very low aluminum content; the aluminum mainly exists in the leaching residue, and the mass percentage of alumina in the leaching residue is ≥98%, with high purity, which can be directly used as a carrier raw material for preparing new petrochemical catalysts.

[0023] It is also found in the research that if the microwave roasting time is too long, the alumina can also reach the temperature for reaction with the activator due to the effect of heat transfer, so it is very important to control the roasting time. By controlling the microwave roasting time within a suitable range, the effective conversion of vanadium and molybdenum and the inhibition of the reaction of alumina can be realized.

[0024] The application directly roasts the granular waste catalyst by microwave for a short time, which eliminates the grinding process required in the traditional process and significantly reduces the energy consumption of the process. In order to ensure that the activator can uniformly cover the surface of the cylindrical granular waste petrochemical catalyst, the activator is mixed with water to form a viscous state, and then mixed with the cylindrical granular waste catalyst, and then heated and dried for a short time, realizing uniform mixing.

[0025] In order to not destroy the overall particle size and structure of the carrier metal in the roasting residue obtained by microwave roasting, based on the difference in microwave absorption properties between the carrier alumina and the activator, the physical separation of the vanadium and molybdenum roasting products from the carrier metal is promoted, and according to the leaching characteristics of the products, the recycled flushing is directly carried out by using normal pressure water, and the flushing liquid containing rare metals vanadium and molybdenum is obtained, and the high-purity cylindrical carrier can be directly reused.

[0026] The method for treating waste petrochemical catalyst to recover rare metals provided by the application directly mixes the granular waste catalyst with an activating agent, then performs short-time calcination in a microwave environment to obtain calcined slag, and then directly performs water circulation washing on the calcined slag to obtain leaching liquor and leaching residue. Experiments show that the method can leach most of vanadium and molybdenum rare metals in the waste petrochemical catalyst, the recovery rate of vanadium and molybdenum is high, the leaching rate of the carrier metal aluminum is less than 0.5%, the purity of the obtained leaching liquor is high, and the subsequent purification process of the rare metals vanadium and molybdenum is greatly simplified. The aluminum oxide content in the leaching residue after leaching is greater than or equal to 98%, the purity is high, and the leaching residue can be directly used as a new petrochemical catalyst carrier raw material.

[0027] The method for treating waste petrochemical catalyst to recover rare metals provided by the application realizes rapid recovery of rare metals vanadium and molybdenum in the waste catalyst and effective separation of the rare metals from the carrier metal, and the recovery treatment method has low production cost, low labor intensity, short treatment time, and high waste catalyst treatment capacity, which is more conducive to promoting the resource treatment of the waste catalyst and realizing energy saving, emission reduction and green production of the vanadium and molybdenum rare metal industry. DETAILED DESCRIPTION

[0028] The technical solutions of the application will be described in detail below through specific examples.

[0029] In the following examples or comparative examples, the reagents used are all commercially available products. The percentages in each example are mass percentages.

[0030] Example 1

[0031] The raw material waste petrochemical catalyst treated in this example is a waste aluminum-based catalyst after deoiling treatment provided by a domestic petrochemical enterprise, which has a cylindrical solid particle shape, and its main valuable metal chemical component analysis is shown in the following table, wherein the content of each element is a mass percentage content.

[0032]

[0033] The method for treating and recovering rare metals in this example specifically includes the following steps:

[0034] S1: Mix the activating agent sodium carbonate (the amount is 2.2 times the total molar number of vanadium and molybdenum in the waste petrochemical catalyst) with water to form a thick slurry, then directly add the granular waste petrochemical catalyst, and stir to mix uniformly;

[0035] Then, place it in an oven for short-time drying, the drying time is 10 min, and the drying temperature is 100℃;

[0036] After drying, the waste petrochemical catalyst is placed in a microwave calcination device for short-time calcination, and the microwave conditions are controlled as follows: microwave power 1000 W, calcination temperature 550 DEG C, and calcination time 8 min, to obtain calcination residue;

[0037] S2: The calcination residue obtained in step S1 is loaded into a filter screen container and is subjected to cyclic washing with water, and the washing liquid is collected to obtain leaching liquid containing rare metals. The leaching liquid is subjected to cyclic washing with normal-pressure water for 5 times, and the temperature of the water used for cyclic washing is 80 DEG C. The solid after washing is leaching residue.

[0038] Analysis shows that vanadium and molybdenum in the waste petrochemical catalyst are mostly in the leaching liquid, the vanadium recovery rate is 99%, the molybdenum recovery rate is 98%, and the aluminum leaching rate is 0.3%. The content of aluminum oxide in the leaching residue is 99%.

[0039] In the leaching liquid, the mass fraction of vanadium is 57.71% and the mass fraction of molybdenum is 41.90% according to the total mass of metals, the leaching liquid mainly contains vanadium and molybdenum, and has high purity.

[0040] Example 2

[0041] The raw material waste petrochemical catalyst treated in this example is the same as that in Example 1.

[0042] The method for treating and recovering rare metals in this example specifically includes the following steps:

[0043] S1: Sodium hydroxide (an activating agent, the amount is 2 times the total molar number of vanadium and molybdenum in the waste petrochemical catalyst) is mixed with water to form a thick slurry, and then the waste petrochemical catalyst in the form of particles is directly added and uniformly stirred and mixed;

[0044] Then, the mixture is placed in an oven for short-time drying, the drying time is 10 min, and the drying temperature is 100 DEG C.

[0045] After drying, the waste petrochemical catalyst is placed in a microwave calcination device for short-time calcination, and the microwave conditions are controlled as follows: microwave power 1000 W, calcination temperature 550 DEG C, and calcination time 8 min, to obtain calcination residue;

[0046] S2: The calcination residue obtained in step S1 is loaded into a filter screen container and is subjected to cyclic washing with water, and the washing liquid is collected to obtain leaching liquid containing rare metals. The leaching liquid is subjected to cyclic washing with normal-pressure water for 5 times, and the temperature of the water used for cyclic washing is 80 DEG C. The solid after washing is leaching residue.

[0047] Analysis shows that vanadium and molybdenum in the waste petrochemical catalyst are mostly in the leaching liquid, the vanadium recovery rate is 99%, the molybdenum recovery rate is 98%, and the aluminum leaching rate is 0.3%. The content of aluminum oxide in the leaching residue is 99%.

[0048] The mass fraction of vanadium in the leaching solution is 57.88% and the mass fraction of molybdenum is 41.60% according to the total mass of metals, and the leaching solution mainly contains vanadium and molybdenum, and has high purity.

[0049] Example 3

[0050] The raw material waste petrochemical catalyst treated in the embodiment is the same as that in Embodiment 1.

[0051] The method for recovering rare metals in the embodiment specifically comprises the following steps:

[0052] S1: The activators sodium hydroxide and sodium carbonate (the amount is 1.8 times of the total moles of vanadium and molybdenum in the waste petrochemical catalyst) are mixed with water to form a thick slurry, and then the granular waste petrochemical catalyst is directly added and uniformly stirred and mixed;

[0053] Then, the mixture is placed in an oven for short-time drying, the drying time is 10 min, and the drying temperature is 100°C.

[0054] After drying, the mixture is placed in a microwave roasting device for short-time roasting, and the microwave conditions are controlled as follows: microwave power 750 W, roasting temperature 500°C, and roasting time 7 min, to obtain roasted slag.

[0055] S2: The roasted slag obtained in step S1 is loaded into a filter screen container and is subjected to cyclic washing with water, and the washing liquid is collected to obtain a leaching solution containing rare metals. The cyclic washing with water is performed 5 times, and the temperature of the water used for cyclic washing is 85°C. The solid after washing is the leaching residue.

[0056] Analysis shows that most of the vanadium and molybdenum in the waste petrochemical catalyst enter the leaching solution, the vanadium recovery rate is 98%, the molybdenum recovery rate is 97%, and the aluminum leaching rate is 0.2%. The content of aluminum oxide in the leaching residue is 98.2%.

[0057] The mass fraction of vanadium in the leaching solution is 57.76% and the mass fraction of molybdenum is 41.98% according to the total mass of metals, and the leaching solution mainly contains vanadium and molybdenum, and has high purity.

[0058] Example 4

[0059] The raw material waste petrochemical catalyst treated in the embodiment is the same as that in Embodiment 1.

[0060] The method for recovering rare metals in the embodiment specifically comprises the following steps:

[0061] S1: The activators sodium hydroxide and sodium carbonate (the amount is 1.8 times of the total moles of vanadium and molybdenum in the waste petrochemical catalyst) are mixed with water to form a thick slurry, and then the granular waste petrochemical catalyst is directly added and uniformly stirred and mixed;

[0062] Afterwards, it is put into an oven for short-time drying, the drying time is 10 min, and the drying temperature is 100℃.

[0063] After drying, it is put into a microwave roasting device for short-time roasting, the microwave conditions are controlled as follows: microwave power is 500W, roasting temperature is 550℃, and roasting time is 8 min, so as to obtain roasting slag.

[0064] S2: The roasting slag obtained in step S1 is loaded into a filter screen container, and is circularly washed with water, so as to collect the washing liquid, thereby obtaining leaching liquid containing rare metals, and the circular washing is performed for 3 times by using normal pressure water, the temperature of the circular washing water is 90℃. The solid after washing is leaching slag.

[0065] Through analysis, vanadium and molybdenum in the waste petrochemical catalyst are mostly in the leaching liquid, the vanadium recovery rate is 98%, the molybdenum recovery rate is 99%, and the aluminum leaching rate is 0.3%. The content of aluminum oxide in the leaching slag is 98.8%.

[0066] In the leaching liquid, the mass fraction of vanadium is 57.22% and the mass fraction of molybdenum is 42.40% according to the total mass of metals, the leaching liquid mainly contains vanadium and molybdenum, and the purity is high.

[0067] As can be seen from the above examples, by using the method of the present application to treat the waste petrochemical catalyst, the recovery rates of vanadium and molybdenum can reach 98-99% and 97-99% respectively, and the leaching rate of metal aluminum in the carrier is less than 0.5%. The content of aluminum oxide in the leaching slag after leaching is greater than or equal to 98%, and the purity is high, so that the leaching slag can be directly used as a raw material for preparing a new petrochemical catalyst carrier. The purity of the obtained leaching liquid is high, and the subsequent purification process of vanadium and molybdenum is greatly simplified.

[0068] Comparative Example 1

[0069] The raw material waste petrochemical catalyst treated in the present comparative example is the same as that in example 1. The method for recovering rare metals in the present comparative example specifically includes the following steps:

[0070] S1: The waste petrochemical catalyst is crushed and finely ground, the grinding fineness is 85% less than 0.074 mm (i.e. the material with a particle size less than 0.074 mm accounts for 85% of the total material mass), so as to obtain finely ground slag;

[0071] The finely ground slag is mixed with an activating agent, the activating agent is a mixture of sodium carbonate and sodium hydroxide (the amount is 2 times the total molar number of vanadium and molybdenum in the waste petrochemical catalyst); after the finely ground slag is uniformly mixed with the activating agent, it is put into a microwave roasting device for short-time roasting, the microwave conditions are as follows: microwave power is 800W, roasting temperature is 550℃, and roasting time is controlled to be 8 min; so as to obtain roasting slag.

[0072] S2: The calcined slag obtained in step S1 is loaded into a filter screen container and is subjected to a circulating rinse with water, and the rinse liquid is collected, thereby obtaining a leaching solution containing rare metals, which is subjected to a circulating rinse with normal pressure water for 5 times, and the temperature of the circulating rinse water is 80°C. The solid after the rinse is the leaching residue.

[0073] Through analysis, the vanadium recovery rate is 43%, the molybdenum recovery rate is 28%, and the aluminum leaching rate is 78% when the waste petrochemical catalyst is ground and then treated. The aluminum oxide content in the leaching residue is 30.7%. In the leaching solution, the mass fraction of vanadium is 18.23%, the mass fraction of molybdenum is 8.71%, and the mass fraction of aluminum is 73.07% according to the total mass of metals. The purity of vanadium and molybdenum is low, the composition of the leaching solution is complex, and the difficulty of subsequent process treatment is increased; the aluminum oxide content in the leaching residue after leaching is low, and further treatment is required before it can be used as a catalyst carrier raw material.

[0074] Through the comparative example, it is shown that the method of grinding the waste petrochemical catalyst and then treating has poor effect. The main reason is that after grinding, the contact reaction area between aluminum oxide and the activator increases significantly, and the strong wave-absorbing phase can be transferred to the aluminum oxide through heat conduction, causing the temperature of the aluminum oxide to rise and react with the activator, resulting in a significant decrease in the recovery rate of vanadium and molybdenum and a significant increase in the leaching rate of aluminum.

[0075] Comparative Example 2

[0076] The raw material waste petrochemical catalyst treated in this comparative example is the same as in Example 1. This comparative example mainly investigates the leaching effect of rare metals in the waste petrochemical catalyst when a muffle furnace is used for calcination. The specific treatment steps are as follows:

[0077] S1: The activator (the activator is sodium carbonate, and the amount is 2.2 times the total molar amount of vanadium and molybdenum in the waste petrochemical catalyst) is mixed with water to form a thick slurry, and then the granular waste petrochemical catalyst is directly added and stirred uniformly;

[0078] Then it is placed in an oven for short-time drying, the drying time is 10 min, and the drying temperature is 100°C;

[0079] After drying, it is placed in a muffle furnace for calcination, and the calcination conditions are as follows: calcination temperature 550°C, and calcination time is set to 10 min, 30 min, 60 min, 90 min, 120 min, and 150 min; the calcined slag is obtained;

[0080] S2: The calcined slag obtained in step S1 is loaded into a filter screen container and is subjected to a circulating rinse with water, and the rinse liquid is collected, thereby obtaining a leaching solution containing rare metals, which is subjected to a circulating rinse with normal pressure water for 5 times, and the temperature of the circulating rinse water is 85°C. The solid after the rinse is the leaching residue.

[0081] The leaching experiment results of the present comparative example are shown in the following table:

[0082]

[0083] As can be seen from the above table, when using muffle roasting, the leaching rate of aluminum is high during water leaching, and the composition of the obtained leaching solution is complex, which increases the difficulty of subsequent process treatment; the aluminum oxide content in the leaching residue after leaching is less than 70%, which still needs to be further treated before being used as a catalyst carrier raw material.

[0084] Experimental Example 1

[0085] The raw material waste petrochemical catalyst treated in the present experimental example is the same as that in Example 1. The present experimental example mainly investigates the leaching effect of rare metals in waste petrochemical catalyst when using different roasting times under microwave environment. The specific treatment steps are as follows:

[0086] S1: Mix the activating agent (the activating agent is sodium carbonate, and the amount is 2.2 times the total molar number of vanadium and molybdenum in the waste petrochemical catalyst) with water to form a thick slurry, then directly add the granular waste petrochemical catalyst and stir to mix uniformly;

[0087] Then put it into an oven for short-time drying, the drying time is 10 min, and the drying temperature is 100℃;

[0088] After drying, put it into a microwave roasting device for roasting, the roasting conditions are: microwave power 800W, roasting temperature is set to 500℃ and 600℃ respectively, and roasting time is set to 2 min, 4 min, 5 min, 8 min and 11 min respectively; obtain the roasted residue;

[0089] S2: Put the roasted residue obtained in step S1 into a filter screen container, and wash it with water for several times to collect the washing liquid, i.e. the leaching solution containing rare metals, all of which are washed with atmospheric water for 5 times, and the temperature of the circulating washing water is 85℃. The solid after washing is the leaching residue.

[0090] The leaching experiment results of the present experimental example are shown in the following table:

[0091]

[0092] As can be seen from the above experiment, the roasting time has a significant effect on the leaching of vanadium, molybdenum and aluminum when using microwave roasting, and the optimal roasting time is controlled to be 5-8 min.

[0093] The above examples show that the vanadium and molybdenum in the waste catalytic converter can be quickly recovered and effectively separated from the carrier metal by using the method of the application, the recovery efficiency of vanadium and molybdenum is obviously improved; the leaching residue obtained has high purity and can be directly used as a waste catalyst cylindrical carrier, realizing real recycling and reducing the overall process treatment cost.

Claims

1. A method for recovering rare metals from waste petrochemical catalysts, characterized in that, The rare metals are vanadium and molybdenum. The method directly treats granular waste catalysts using microwave short-time roasting, eliminating the need for grinding the waste catalysts required in traditional processes. The method includes the following steps: Waste petrochemical catalyst is mixed with an activator and then subjected to short-time calcination in a microwave environment to obtain calcined residue. The activator is sodium carbonate and / or sodium hydroxide. The activator is mixed with water to form a viscous slurry and then mixed with the waste petrochemical catalyst. The amount of the activator is 1.6 to 2.5 times the total molar amount of vanadium and molybdenum in the waste petrochemical catalyst. The microwave conditions for the short-time calcination are: microwave power of 500 to 1000 W, time of 5 to 8 min, and calcination temperature of 500 to 600 °C. The waste petrochemical catalyst is a cylindrical granular waste petrochemical catalyst with alumina as a carrier, which is mixed with the activator after deoiling treatment. The roasted residue is rinsed with water to obtain a leachate containing rare metals and a leachate residue. The process of rinsing the roasted slag with water circulation includes: placing the roasted slag into a filter screen container, rinsing it with water circulation, and collecting the rinsing liquid to obtain a leachate containing rare metals.

2. The method according to claim 1, characterized in that, The amount of the activator is 1.8 to 2.2 times the total molar amount of vanadium and molybdenum in the waste petrochemical catalyst.

3. The method according to claim 1, characterized in that, The waste petrochemical catalyst is mixed with the activator and then dried for a short time, followed by a short-time calcination; the short-time drying time is 8 to 12 minutes, and the drying temperature is 80 to 110°C.

4. The method according to claim 1, characterized in that, Rinse with water 3-5 times.

5. The method according to claim 1, characterized in that, The temperature of the circulating flushing water is 75–90°C.

6. The method according to claim 1, characterized in that, The leaching residue contains ≥98% alumina and is used to prepare petrochemical catalysts.

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