A method for separating and recovering metallic platinum, chromium, manganese and aluminum from waste catalysts

Abstract

The present invention discloses a method for separating and recovering metallic platinum, chromium, manganese and aluminum from waste catalysts, belonging to the technical field of metal recycling and utilization. The method comprises: incinerating the waste catalysts to remove carbon and then pulverizing them to obtain a mixed powder; performing an alkali fusion reduction reaction on the mixed powder, caustic alkali and a reducing agent to obtain a mixed solid; adding the mixed solid into water for water leaching, and then performing a first filtration to obtain a first filtrate containing an aluminum compound in solution and a first filter residue; in an alkaline solution, performing an oxidation reaction on the first filter residue and an oxidizing agent, and then performing a second filtration to obtain a second filter residue containing elemental platinum and a second filtrate; adding a water-soluble ferrous salt into the second filtrate for a reduction hydrolysis reaction, and then performing a third filtration to obtain a third filtrate containing a manganese compound in solution and a third filter residue containing a chromium compound. Each step cooperates with each other, jointly realizing the comprehensive utilization of platinum, aluminum, chromium and manganese, and having the characteristics of simple operation and high recovery rate.

Description

Technical Field

[0001] The present invention relates to the technical field of metal recycling, and in particular, to a method for separating and recovering metals platinum, chromium, manganese, and aluminum from waste catalysts. Background Art

[0002] In the process of petroleum refining, the catalysts used mainly contain platinum, and the carriers are mainly alumina, which are used in reforming and isomerization units. At present, about thousands of tons of used catalysts are replaced every year. If they are directly discarded as waste, it will not only cause a large loss of precious metals, but also pollute the environment. Therefore, the comprehensive utilization of such catalysts is particularly important.

[0003] The currently reported recovery methods mainly include pyrometallurgical purification and hydrometallurgical purification. Pyrometallurgical purification not only consumes a large amount of energy, but also produces a large amount of aluminum-containing slag, which is difficult to reprocess. Hydrometallurgical purification mainly uses acids or alkalis to dissolve the alumina carrier, and the precious metals are present in the solid slag. The precious metals are enriched by filtration and then purified. The problem of this method is that the aluminum solution is easy to form a colloid, and the platinum nanoparticles will be wrapped in the colloid, and effective solid-liquid separation cannot be achieved during filtration, which greatly affects the recovery rate of precious metals. There are also some improved methods that use high-temperature calcination of waste catalysts to convert alumina from the γ form to the α form, and then dissolve platinum in aqua regia into the leaching solution, and alumina is insoluble to achieve the enrichment of precious metals. In this method, due to the transformation of the alumina crystal form, platinum microparticles are wrapped, resulting in part of the platinum remaining in the alumina slag when aqua regia leaches platinum, and at the same time, part of the platinum will also become platinum oxide that is insoluble in aqua regia during high-temperature calcination, all of which will reduce the recovery rate of platinum.

[0004] To reduce the use amount of precious metals and improve the catalytic effect at the same time, some newly developed catalysts also contain amphoteric oxides of chromium oxide and manganese oxide similar to alumina. For such new catalysts, the above-reported methods cannot effectively comprehensively utilize such catalysts.

[0005] Therefore, for waste catalysts containing alumina as the carrier and containing platinum, chromium, and manganese, it is very important to develop a new recovery method to achieve the comprehensive utilization of platinum, aluminum, chromium, and manganese. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for separating and recovering metals platinum, chromium, manganese, and aluminum from waste catalysts. For waste catalysts containing alumina as the carrier and containing platinum, chromium, and manganese, this method can achieve the comprehensive utilization of platinum, aluminum, chromium, and manganese, and has the characteristics of simple operation and high recovery rate.

[0007] The embodiments of the present application provide a method for separating and recovering metals platinum, chromium, manganese, and aluminum from waste catalysts. The waste catalysts contain alumina, platinum, chromium, manganese, and aluminum; the method includes:

[0008] The waste catalyst is incinerated to remove carbon and then crushed to obtain a mixed powder;

[0009] The mixed powder, caustic soda and reducing agent are subjected to alkali melting reduction reaction to obtain a mixed solid;

[0010] The mixed solid is added into water for water invasion, and then first filtered to obtain a first filtrate and a first filter residue containing aluminum compounds, so as to separate and recover aluminum from platinum, chromium and manganese;

[0011] In an alkaline solution, the first filter residue is subjected to an oxidation reaction with an oxidant, and then a second filtration is performed to obtain a second filter residue and a second filtrate containing a single substance of platinum, so as to separate and recover the platinum element from the two elements of chromium and manganese;

[0012] Adding a water-soluble ferrous salt to the second filtrate to carry out a reduction hydrolysis reaction, and then performing a third filtration to obtain a third filtrate containing a manganese compound and a third filter residue containing a chromium compound, so as to separate and recover the chromium element and the manganese element;

[0013] Wherein, the weight ratio of the mixed powder, the caustic soda and the reducing agent is 1:1-5:1-3, and the temperature of the alkali fusion reduction reaction is 500-800°C.

[0014] Furthermore, the alkali fusion reduction reaction time is 3 to 5 hours.

[0015] Furthermore, the caustic alkali includes at least one of potassium hydroxide and sodium hydroxide, and the reducing agent includes at least one of sodium formate and potassium formate.

[0016] Furthermore, when the mixed solid is added into water for water invasion, the weight ratio of the mixed powder to the water is 1:10-50.

[0017] Furthermore, when the first filter residue is subjected to an oxidation reaction with an oxidant, the mass concentration of the oxidant is 0.1 to 0.5 g / ml.

[0018] Furthermore, the oxidation reaction is carried out at a temperature of 60 to 80° C. and for a time of 3 to 5 hours.

[0019] Furthermore, the oxidant includes at least one of potassium chlorate and sodium chlorate.

[0020] Furthermore, when a water-soluble ferrous salt is added to the second filtrate for reduction and hydrolysis reaction, the weight ratio of the oxidant to the water-soluble ferrous salt is 1:0.3-0.8.

[0021] Furthermore, the water-soluble ferrous salt includes at least one of ferrous sulfate and ferrous chloride.

[0022] Furthermore, the main component of the first filtrate is water-soluble aluminate, the main components of the first filter residue are platinum metal, chromium, manganese, and oxides of other base metals, the main component of the second filtrate is water-soluble permanganate and hexavalent water-soluble chromate, the main component of the second filter residue is platinum metal, the main component of the third filtrate is water-soluble permanganate, and the main component of the third filter residue is trivalent chromium oxide.

[0023] Compared with the prior art, the above solution provided by the embodiments of the present application has at least the following beneficial effects:

[0024] The embodiments of the present application provide a new method for separating and recovering metal platinum, chromium, manganese, and aluminum from waste catalysts. For waste catalysts containing platinum, chromium, and manganese with alumina as the carrier, this method successively undergoes processes such as "alkali fusion reduction reaction + water intrusion", "oxidation reaction in an alkaline solution", and "reductive hydrolysis reaction with water-soluble ferrous salts". Each step cooperates with each other to jointly achieve the comprehensive utilization of platinum, aluminum, chromium, and manganese, and has the characteristics of simple operation and high recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 It is a schematic flow chart of a method for separating and recovering metal platinum, chromium, manganese, and aluminum from waste catalysts provided by the embodiments of the present invention;

[0027] Figure 2 It is a schematic flow chart of a method for separating and recovering metal platinum, chromium, manganese, and aluminum from waste catalysts provided by Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments not specified by the manufacturer can all be obtained as conventional products through commercial purchase.

[0029] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0030] The general idea of the technical solution provided by the embodiments of the present invention is as follows:

[0031] As Figure 1 shown, an embodiment of the present application provides a method for separating and recovering metal platinum, chromium, manganese, and aluminum from waste catalysts. The waste catalysts contain alumina, platinum, chromium, manganese, and aluminum. The method includes:

[0032] Incinerating the waste catalyst to remove carbon and then pulverizing it to obtain a mixed powder;

[0033] Performing an alkali fusion reduction reaction on the mixed powder, caustic alkali, and reducing agent to obtain a mixed solid;

[0034] Adding the mixed solid to water for water invasion, and then performing a first filtration to obtain a first filtrate containing an aluminum compound in solution and a first filter residue, so as to realize the separation and recovery of aluminum element from the three elements of platinum, chromium, and manganese;

[0035] In an alkaline solution, performing an oxidation reaction on the first filter residue and an oxidizing agent, and then performing a second filtration to obtain a second filter residue containing elemental platinum and a second filtrate, so as to realize the separation and recovery of platinum element from the two elements of chromium and manganese;

[0036] Adding a water-soluble ferrous salt to the second filtrate for a reduction hydrolysis reaction, and then performing a third filtration to obtain a third filtrate containing a manganese compound in solution and a third filter residue containing a chromium compound, so as to realize the separation and recovery of chromium element and manganese element;

[0037] Among them, the weight ratio of the mixed powder, the caustic alkali, and the reducing agent is 1:1-5:1-3, and the temperature of the alkali fusion reduction reaction is 500-800°C.

[0038] An embodiment of the present application provides a new method for separating and recovering metal platinum, chromium, manganese, and aluminum from waste catalysts. For waste catalysts with alumina as the carrier and containing platinum, chromium, and manganese, this method successively passes through processes such as "alkali fusion reduction reaction + water invasion", "oxidation reaction in an alkaline solution", and "reduction hydrolysis reaction with a water-soluble ferrous salt". Each step cooperates with each other to jointly realize the comprehensive utilization of platinum, aluminum, chromium, and manganese, and has the characteristics of simple operation and high recovery rate.

[0039] The main principles of the new method for separating and recovering metal platinum, chromium, manganese, and aluminum from waste catalysts provided by the embodiments of the present application include:

[0040] 1) When the mixed powder containing waste catalyst is subjected to a melting reaction with a caustic alkali such as sodium hydroxide, alumina in the mixed powder reacts with the caustic alkali such as sodium hydroxide to form soluble aluminates such as sodium aluminate (the specific type of aluminate is related to the selected caustic alkali). Chromium oxide and manganese oxide are similar in properties to alumina and will also form soluble high-valent alkali metal salts (such as sodium salts), which enter the aluminate solution such as sodium aluminate together, and it is impossible to achieve the rough separation of aluminum, manganese, and chromium. However, in this application, by adding an appropriate amount of reducing agent, the formation of high-valent compounds can be avoided, and they will still precipitate in the form of oxides when dissolved in water. At the same time, the generation of platinum oxide that is difficult to dissolve in aqua regia can also be avoided, realizing the rough separation of platinum, chromium, and manganese from aluminum, obtaining a first filtrate containing aluminum compounds in solution and a first filter residue, so as to separate and recover aluminum element from the three elements of platinum, chromium, and manganese.

[0041] 2) The first filter residue mainly contains platinum metal, chromium, manganese, and oxides of other base metals. When chromium and manganese are in the presence of an oxidizing agent, they will form soluble high-valent chromates such as sodium chromate and permanganates such as potassium permanganate in an alkaline solution. After adding an oxidizing agent such as potassium chlorate to the alkaline solution such as sodium hydroxide in the first filter residue, chromium and manganese are dissolved into the solution as the second filtrate, while platinum and some base metal impurities remain in the solid residue as the second filter residue, realizing the separation and recovery of chromium, manganese, and platinum.

[0042] 3) Potassium permanganate has almost no oxidizing property in an alkaline solution. After adding a water-soluble ferrous salt such as ferrous sulfate to the second filtrate, the high-valent chromates such as sodium chromate are reduced to low-valent (trivalent) chromates such as sodium chromate, and then further hydrolyzed into trivalent chromium oxide and precipitated. The added water-soluble ferrous salt such as ferrous sulfate is oxidized into a trivalent water-soluble iron salt such as ferric sulfate and also hydrolyzed and precipitated, while potassium permanganate does not react and remains in the solution, realizing the separation and recovery of chromium and manganese.

[0043] In the alkali melting reduction reaction, the role of caustic alkalis such as sodium hydroxide is: caustic alkalis such as sodium hydroxide react with amphoteric oxides (mainly aluminum, manganese and chromium) in the mixed powder containing waste catalysts to generate water-soluble sodium salts, etc., so as to separate from the unreactive impurity oxides in a solid-liquid manner, and caustic alkalis such as sodium hydroxide play the role of reaction medium and reactant. The role of reducing agents such as sodium formate is: when manganese and chromium oxides are melted with caustic alkalis such as sodium hydroxide at high temperature, water-soluble sodium manganate and hexavalent sodium chromate will be generated under the oxidation of oxygen, and the product of aluminum oxide and caustic alkali such as sodium hydroxide at high temperature, sodium aluminate, is also soluble in water. Since all three are amphoteric oxides, the difficulty of separation and purification is increased. In addition, platinum oxide is difficult to react with aqua regia. Adding reducing agents such as sodium formate will reduce platinum oxide to elemental platinum that is easily soluble in aqua regia. Based on the above principle, the separation and recovery of aluminum and the three elements of platinum, chromium and manganese are achieved. At the same time, since the platinum element is converted into elemental platinum, it is also beneficial to the subsequent separation and recovery of platinum and the two elements of chromium and manganese.

[0044] In the alkaline fusion reduction reaction, if the amount of caustic soda is too much, the adverse effect is that it causes waste of raw materials, and at the same time it will cause an increase in water consumption during water immersion, and increase the treatment of wastewater in production; the adverse effect of using too little caustic soda is that the reaction is not thorough, leaving part of the alumina in the filter residue.

[0045] In the alkaline melting reduction reaction, if the amount of reducing agent is too much, the adverse effect is the waste of raw materials; the adverse effect of using too little reducing agent is that part of the chromium or manganese will generate high-valent salts soluble in alkaline solution in the presence of oxygen in the air, and enter the aluminum solution during water immersion. Since chromium or manganese and aluminum are similar in that they are amphoteric oxides, it brings great difficulties to the purification effect of aluminum.

[0046] In the alkali fusion reduction reaction, if the temperature of the alkali fusion reduction reaction is too high, the adverse effect is that it causes a waste of energy; if the temperature of the alkali fusion reduction reaction is too low, the adverse effect is that the reaction between the alkali and the alumina is incomplete.

[0047] As an implementation method of the present application, the alkali fusion reduction reaction time is 3 to 5 hours.

[0048] In some specific embodiments, the alkali fusion reduction reaction time may be 3 hours, 3.5 hours, 4 hours, 4.5 hours, or 5 hours.

[0049] As an implementation method of an embodiment of the present application, the caustic alkali includes at least one of potassium hydroxide and sodium hydroxide, and the reducing agent includes at least one of sodium formate and potassium formate.

[0050] In this application, caustic alkalis can be selected such as potassium hydroxide and sodium hydroxide; reducing agents can be selected such as formates like sodium formate and potassium formate.

[0051] As an implementation manner of an embodiment of this application, when adding the mixed solid into water for water intrusion, the weight ratio of the mixed powder to the water is 1:10 to 50.

[0052] In this application, when adding the mixed solid into water for water intrusion, controlling the weight ratio of the mixed powder to the water to be 1:10 to 50 serves to selectively leach out the water-soluble platinum-containing compounds, chromium-containing compounds, and manganese-containing compounds in the mixed solid after the alkali fusion reduction reaction, so as to achieve the separation and recovery of aluminum from the three elements of platinum, chromium, and manganese. If the amount of water used in this process is small, incomplete leaching of sodium aluminate will occur; if the amount is too large, a large amount of wastewater will be generated during production, increasing the environmental protection cost.

[0053] As an implementation manner of an embodiment of this application, when performing an oxidation reaction on the first filter residue with an oxidizing agent, the mass concentration of the oxidizing agent is 0.1 to 0.5 g / ml.

[0054] In this application, when performing an oxidation reaction on the first filter residue with an oxidizing agent, controlling the mass concentration of the oxidizing agent to be 0.1 to 0.5 g / ml serves to convert the low-valent oxides of manganese and chromium into highly soluble high-valent oxides and then form soluble salts and enter the solution; the adverse effect of too high a mass concentration of the oxidizing agent is that the reaction system concentration is too high and the oxides of chromium or manganese are not completely dissolved; the adverse effect of too low a mass concentration of the oxidizing agent is that more water is used, resulting in an increase in the amount of wastewater treatment in production.

[0055] As an implementation manner of an embodiment of this application, the temperature of the oxidation reaction is 60 to 80 °C, and the time is 3 to 5 hours.

[0056] In this application, controlling the oxidation reaction to the above parameters serves to enable the reaction to proceed smoothly.

[0057] As an implementation manner of an embodiment of this application, the oxidizing agent includes at least one of potassium chlorate and sodium chlorate.

[0058] In this application, the oxidizing agent can be selected such as chlorates like potassium chlorate and sodium chlorate.

[0059] As an implementation manner of an embodiment of this application, when adding a water-soluble ferrous salt to the second filtrate for a reduction hydrolysis reaction, the weight ratio of the oxidizing agent to the water-soluble ferrous salt is 1:0.3 to 0.8.

[0060] In the present application, when a water-soluble ferrous salt is added to the second filtrate for a reduction and hydrolysis reaction, the weight ratio of the oxidant to the water-soluble ferrous salt is controlled to be 1:0.3-0.8, so as to reduce the chromium (IV) ions to chromium (III) ions and hydrolyze them to insoluble trivalent chromium oxides, which are precipitated from the solution, thereby achieving the separation of chromium and manganese; if the weight ratio of the oxidant to the water-soluble ferrous salt is too large, the adverse effect is that there are too many iron ions in the solution, affecting the subsequent purification process; if the weight ratio of the oxidant to the water-soluble ferrous salt is small, the adverse effect is that the reaction is not thorough.

[0061] As an implementation of an embodiment of the present application, the water-soluble ferrous salt includes at least one of ferrous sulfate and ferrous chloride.

[0062] In the present application, the water-soluble ferrous salt may be selected from ferrous sulfate, ferrous chloride and the like.

[0063] As an implementation method of the present application, the main component of the first filtrate is water-soluble aluminate, the main component of the first filter residue is platinum, chromium, manganese and other base metal oxides, the main component of the second filtrate is water-soluble permanganate and hexavalent water-soluble chromate, the main component of the second filter residue is platinum, the main component of the third filtrate is water-soluble permanganate, and the main component of the third filter residue is trivalent chromium oxide.

[0064] In the present application, in some specific embodiments, the main component of the first filtrate may be water-soluble aluminates such as sodium aluminate, the main component of the first filter residue is platinum, chromium, manganese and other base metal oxides, the main component of the second filtrate is water-soluble permanganates such as potassium permanganate and hexavalent water-soluble chromates (such as hexavalent sodium chromate), the main component of the second filter residue is platinum, the main component of the third filtrate is water-soluble permanganate (such as potassium permanganate), and the main component of the third filter residue is trivalent chromium oxide. At the same time, in order to further improve the purity of platinum, aluminum, chromium and manganese or further convert platinum, aluminum, chromium and manganese, the platinum-containing substances, aluminum-containing substances, chromium-containing substances and manganese-containing substances separated and recovered in the present application can be purified or converted by existing disclosed methods, and this application document will not repeat them.

[0065] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0066] Example 1

[0067] This example provides a method for separating and recovering metallic platinum, chromium, manganese, and aluminum from waste catalysts containing alumina, platinum, chromium, manganese, and aluminum (in terms of weight fraction, the platinum content in the waste catalyst is 0.1 - 0.2%, and the total content of chromium and manganese is 1 - 10%). As Figure 2 shown, the method includes:

[0068] (1) After incinerating the waste catalyst to remove carbon, it is crushed and ground to obtain a mixed powder material (referred to as the material in Figure 2 ). Weigh 1000 grams of the mixed powder containing the waste catalyst, then add 3000 grams of sodium hydroxide and 1000 grams of sodium formate. After stirring evenly, heat it to 600 °C in a muffle furnace. After 4 hours, take it out and cool it, then add 20000 grams of water to leach out the soluble substances. After filtration, filtrate 1 and residue 1 are obtained; then carbon dioxide is introduced into filtrate 1 to obtain boehmite solid.

[0069] (2) The residue 1 in step (1) is slurried with a 10% sodium hydroxide solution to obtain a 1.5 L slurry, then add 300 grams of potassium chlorate, react at 70 °C for 4 hours, and then filter to obtain filtrate 2 and residue 2.

[0070] (3) Dry the residue 2 obtained in step (2) to obtain 4 grams of residue 2. Add 20 grams of aqua regia and boil for about 1 h. After cooling and standing, filter the insoluble substances. Concentrate the filtrate to 1 / 3 volume, then add an equal volume of hydrochloric acid and boil to 1 / 3 volume, repeat 3 times. Then add 4 grams of ammonium chloride, filter the resulting ammonium chloroplatinate, and then dissolve it with 25 grams of aqua regia and repeat the above operation, 3 times in total. Incinerate at about 800 °C to obtain 1.97 grams of elemental platinum (in this example, step (3) purifies the obtained residue 2 containing elemental platinum according to the existing publicly disclosed method).

[0071] (4) Add 90 grams of ferrous sulfate solid to filtrate 2 obtained in step (2), react at room temperature for 1 hour, and then filter to obtain filtrate 3 containing manganese compounds in solution and residue 3 containing chromium compounds. Filtrate 3 is concentrated and recrystallized to obtain potassium permanganate solid. Residue 3 is purified to prepare trivalent chromium nitrate.

[0072] Example 2

[0073] This example provides a method for separating and recovering metallic platinum, chromium, manganese, and aluminum from waste catalysts containing alumina, platinum, chromium, manganese, and aluminum. The method includes:

[0074] The waste catalyst is incinerated to remove carbon, then crushed and ground to obtain a mixed powder. Weigh 2000 grams of the mixed powder containing the waste catalyst, then add 2500 grams of sodium hydroxide and 3000 grams of potassium acetate, mix well, and heat to 700 °C in a muffle furnace. After 3 hours, cool and leach the soluble substances with 30000 grams of water. After filtration, carbon dioxide is introduced into the filtrate 1 to prepare boehmite. The filter residue 1 is slurried with a 10% sodium hydroxide solution to obtain 2 L of slurry, then 500 grams of potassium chlorate is added, and the reaction is carried out at 65 °C for 5 hours and then filtered. After filtration and drying, 9 grams of filter residue 2 is obtained. Add 40 grams of aqua regia and boil for about 1 h, cool and stand, then filter the insoluble substances. After concentrating the filtrate to 1 / 3 of its volume, add an equal volume of hydrochloric acid and boil to 1 / 3 of its volume, repeat 3 times, then add about 10 grams of ammonium chloride, filter the obtained ammonium chloroplatinate, and then dissolve it with 40 grams of aqua regia and repeat the above operation, 3 times in total. High-temperature incineration is carried out at about 800 °C to obtain 3.95 grams of elemental platinum. Add 200 grams of ferrous sulfate solid to the filtrate 2 and react at room temperature for about 1 hour and then filter. The filtrate 3 is concentrated and recrystallized to obtain potassium permanganate compounds. The filter residue 3 is purified to chromium and then trivalent chromium nitrate is prepared.

[0075] Example 3

[0076] This example provides a method for separating and recovering platinum, chromium, manganese, and aluminum metals from waste catalysts containing alumina, platinum, chromium, manganese, and aluminum. The method includes:

[0077] The waste catalyst is incinerated to remove carbon, then crushed and ground to obtain a mixed powder. Weigh 10000 grams of the mixed powder containing the waste catalyst, then add 30000 grams of potassium hydroxide and 30000 grams of potassium formate, stir well, and heat to 700 °C in a muffle furnace. After reacting for 5 hours, cool, add 400000 grams of water to leach the soluble substances, stand and filter, and then introduce carbon dioxide into the filtrate 1 to prepare boehmite. The filter residue 1 is slurried with a 10% potassium hydroxide solution to obtain 10 L of slurry, add 2000 grams of potassium chlorate, and react at 70 °C for 5 hours and then stand and filter. After filtration and drying, 45 grams of filter residue 2 is obtained. Add 200 grams of aqua regia and boil for 1 h, cool and stand, then filter the insoluble substances. After concentrating the filtrate to 1 / 3 of its volume, add an equal volume of hydrochloric acid and boil to 1 / 3 of its volume, repeat 3 times, then add 50 grams of ammonium chloride, filter the obtained ammonium chloroplatinate, and then dissolve it with about 200 grams of aqua regia and repeat the above operation, 3 times in total. High-temperature incineration is carried out at about 800 °C to obtain 19.82 grams of elemental platinum. Add 600 grams of ferrous sulfate solid to the filtrate 2 and react at room temperature for 1.5 hours and then filter. The filtrate 3 is concentrated and recrystallized to obtain potassium permanganate compounds. The filter residue 3 is purified to chromium and then trivalent chromium nitrate is prepared.

[0078] Comparative Example 1

[0079] This example provides a method for separating and recovering metals from waste catalysts. The method includes:

[0080] The waste catalyst is incinerated to remove carbon, then crushed and ground to obtain a mixed powder. Weigh 1000 grams of the mixed powder containing the waste catalyst, then add 3000 grams of sodium hydroxide. After stirring evenly, heat it to 600 °C in a muffle furnace. After 4 hours, take it out and cool it, then add 20000 grams of water to leach out the soluble substances. After filtration, pass carbon dioxide into the filtrate 1 to obtain boehmite solid. The filter residue 1 is slurried with 10% sodium hydroxide solution to obtain a 1.5 L slurry, then add 300 grams of potassium chlorate, react at about 70 °C for about 4 hours and then filter. After filtration and drying, 4.2 grams of filter residue 2 is obtained. Add 18 grams of aqua regia and boil for about 1 h. After cooling and standing, filter the insoluble substances. Concentrate the filtrate to 1 / 3 volume, then add hydrochloric acid of equal volume and boil to 1 / 3 volume, repeat 3 times. Then add 4 grams of ammonium chloride, filter the obtained ammonium chloroplatinate, and then dissolve it with 20 grams of aqua regia and repeat the above operation, a total of 3 times. High-temperature incineration at about 800 °C gives 1.93 grams of elemental platinum. Add 90 grams of ferrous sulfate solid to the filtrate 2, react at room temperature for about 1 hour and then filter. The filtrate 3 is concentrated and recrystallized to obtain potassium permanganate solid. The filter residue 3 is purified and 3-valent chromium nitrate is prepared.

[0081] Comparative Example 2

[0082] This example provides a method for separating and recovering metals from waste catalysts. The method includes:

[0083] The waste catalyst is incinerated to remove carbon, then crushed and ground to obtain a mixed powder. Weigh 2000 grams of the mixed powder containing the waste catalyst, then add 2500 grams of sodium hydroxide and 3000 grams of sodium formate, mix evenly and heat to 700 °C in a muffle furnace. After 3 hours, cool it and leach out the soluble substances with 30000 grams of water. After filtration, pass carbon dioxide into the filtrate 1 to prepare boehmite. The filter residue 1 is slurried with 10% sodium hydroxide solution, react at about 65 °C for 5 hours and then filter. After filtration and drying, 450 grams of filter residue 2 is obtained. Add 1800 grams of aqua regia and boil for about 1 h. After cooling and standing, filter the insoluble substances. Concentrate the filtrate to 1 / 3 volume, then add hydrochloric acid of equal volume and boil to 1 / 3 volume, repeat 3 times. Then add about 10 grams of ammonium chloride, filter the obtained ammonium chloroplatinate, and then dissolve it with about 40 grams of aqua regia and repeat the above operation, a total of 3 times. High-temperature incineration at about 800 °C gives 3.95 grams of elemental platinum. Add 200 grams of ferrous sulfate solid to the filtrate 2, react at room temperature for about 1 hour and then filter. The filtrate 3 is concentrated and recrystallized to obtain potassium permanganate compound. The filter residue 3 is purified to chromium and 3-valent chromium nitrate is prepared.

[0084] Comparative Example 3

[0085] This example provides a method for separating and recovering metals from waste catalysts. The method includes:

[0086] The waste catalyst is incinerated to remove carbon, then crushed and ground to obtain a mixed powder. Weigh 10,000 grams of the mixed powder containing the waste catalyst. After grinding, add 30,000 grams of potassium hydroxide and 30,000 grams of potassium formate, stir well, heat in a muffle furnace at 700 °C, react for 5 hours, then cool. Add 400,000 grams of water to leach out the soluble substances. After standing and filtering, the filtrate 1 is introduced with carbon dioxide to prepare boehmite. The filter residue 1 is slurried with 10% potassium hydroxide solution to obtain 10 L of slurry. Add 2,000 grams of potassium chlorate and react at 70 °C for 5 hours, then stand and filter. After filtering and drying, 46 grams of filter residue 2 is obtained. Add about 200 grams of aqua regia and boil for about 1 h. After cooling and standing, filter the insoluble substances. Concentrate the filtrate to 1 / 3 volume, then add hydrochloric acid of equal volume and boil to 1 / 3 volume, repeat 3 times. Then add 50 grams of ammonium chloride, filter the obtained ammonium chloroplatinate, and dissolve it with about 200 grams of aqua regia and repeat the above operation, a total of 3 times. High-temperature incineration at about 800 °C gives 19.78 grams of elemental platinum. Concentrate the filtrate, filter the filter residue and then concentrate it to prepare potassium permanganate.

[0087] The specific separation and recovery of platinum, aluminum, chromium, and manganese in the waste catalyst in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1 as follows.

[0088] Table 1

[0089]

[0090] As can be seen from Table 1, according to the method of the embodiments of the present application, platinum, manganese, chromium, and aluminum can be effectively roughly separated, and qualified products can be obtained after purification. The recovery rate of platinum is greater than 98.7%. In Comparative Example 1, no formate / acetate reducing agent was added during alkali fusion. Considering the analysis of filter residue 1 and filter residue 2, chromium and manganese form high-valent oxides in the presence of oxygen in the air during alkali fusion, and then further react with alkali to form soluble sodium salts, which enter filtrate 1 together with sodium metaaluminate. Since the properties of the three are similar, qualified alumina cannot be obtained by the conventional method of purifying aluminum. At the same time, the yield of platinum also decreases because some platinum exists in the form of oxides without the participation of a reducing agent, making it difficult to dissolve in aqua regia and unable to enter the aqua regia solution for purification. In Comparative Example 2, no oxidant potassium chlorate was used when leaching filter residue 1. Considering the situation of filter residue 2, most of the manganese and chromium were not leached into filtrate 2. When leaching platinum in filter residue 2 with aqua regia, they also entered the aqua regia solution with platinum. After platinum purification, it was discharged with the wastewater, and potassium permanganate and chromium nitrate products were not obtained; when filter residue 2 was dissolved with sodium hydroxide solution without adding an oxidant, manganese and chromium remained in filter residue 2 and entered the platinum-containing solution after being dissolved with aqua regia. After platinum purification, it was discharged in the form of wastewater. Therefore, there is no manganese and chromium in filtrate 2, and no chromium is reduced when ferrous sulfate is added. Filter residue 3 is mainly some other insoluble substances. In Comparative Example 3, no ferrous salt was used, and the results showed that manganese and chromium could not be separated and purified.

[0091] In summary, the embodiments of the present application provide a new method for separating and recovering metallic platinum, chromium, manganese, and aluminum from waste catalysts. For waste catalysts with alumina as the carrier and containing platinum, chromium, and manganese, this method successively goes through processes such as "alkali fusion reduction reaction + water intrusion", "oxidation reaction in an alkaline solution", and "reductive hydrolysis reaction with water-soluble ferrous salts". Each step cooperates with each other synergistically, jointly realizing the comprehensive utilization of platinum, aluminum, chromium, and manganese, and having the characteristics of simple operation and high recovery rate.

[0092] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the description of the said range has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0093] Furthermore, in the description of the specification of the present application, terms such as "including" and "comprising" mean "including but not limited to". In this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0094] The above-described embodiments are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

Claims

1. A method for separating and recovering metallic platinum, chromium, manganese and aluminum from waste catalysts, characterized in that, The waste catalyst contains alumina, platinum, chromium, manganese and aluminum; the method includes: Incinerating and decarbonizing the waste catalyst and then pulverizing it to obtain a mixed powder; Carrying out an alkali fusion reduction reaction on the mixed powder, caustic alkali and reducing agent to obtain a mixed solid; Adding the mixed solid into water for water leaching, and then carrying out a first filtration to obtain a first filtrate dissolving aluminum compounds and a first filter residue, so as to separate and recover aluminum element from the three elements of platinum, chromium and manganese; In an alkaline solution, carrying out an oxidation reaction on the first filter residue and an oxidant, and then carrying out a second filtration to obtain a second filter residue containing platinum metal and a second filtrate, so as to separate and recover platinum element from the two elements of chromium and manganese; Adding a water-soluble ferrous salt into the second filtrate for a reduction hydrolysis reaction, and then carrying out a third filtration to obtain a third filtrate dissolving manganese compounds and a third filter residue containing chromium compounds, so as to separate and recover chromium element and manganese element; Wherein, the weight ratio of the mixed powder, the caustic alkali and the reducing agent is 1:1-5:1-3, and the temperature of the alkali fusion reduction reaction is 500-800 °C; The time of the alkali fusion reduction reaction is 3-5 hours; When adding the mixed solid into water for water leaching, the weight ratio of the mixed powder and the water is 1:10-50; When carrying out the oxidation reaction on the first filter residue and the oxidant, the mass concentration of the oxidant is 0.1-0.5 g / ml; The main component of the first filtrate is water-soluble aluminate, the main components of the first filter residue are platinum metal, chromium, manganese and oxides of other base metals, the main components of the second filtrate are water-soluble manganate and hexavalent water-soluble chromate, the main component of the second filter residue is platinum metal, the main component of the third filtrate is water-soluble manganate, and the main component of the third filter residue is trivalent chromium oxide.

2. The method according to claim 1, characterized in that, The caustic alkali includes at least one of potassium hydroxide and sodium hydroxide, and the reducing agent includes at least one of sodium formate and potassium formate.

3. The method according to claim 1, wherein The temperature of the oxidation reaction is 60-80 °C, and the time is 3-5 hours.

4. The method according to claim 1, wherein The oxidant includes at least one of potassium chlorate and sodium chlorate.

5. The method according to claim 1, wherein When adding the water-soluble ferrous salt into the second filtrate for the reduction hydrolysis reaction, the weight ratio of the oxidant and the water-soluble ferrous salt is 1:0.3-0.

8.

6. The method according to claim 5, wherein The water-soluble ferrous salt includes at least one of ferrous sulfate and ferrous chloride.

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