Method for green recovery of platinum / palladium from platinum / palladium-containing waste catalyst based on ore phase regulation and control

Abstract

The invention relates to the technical field of solid waste recycling, in particular to a method for green recovery of platinum / palladium from a platinum / palladium-containing waste catalyst based on mineral phase regulation and control. The method comprises the following steps: adding PbO, mixing with platinum / palladium-containing waste catalyst powder, carrying out oxidizing roasting, directly leaching the roasted product through a hydrochloric acid solution to obtain a Pt or Pd-containing leachate, and finally carrying out ammonium chloride precipitation and solid-liquid separation to obtain a crude platinum / palladium product ammonium chloroplatinate / ammonium chloropalladate. According to the method, the PbO is used for conducting ore phase regulation and control on the Pt / Pd metal simple substance in the platinum / palladium-containing waste catalyst powder, the Pt or Pd metal simple substance is converted into the composite oxide which is easily dissolved in hydrochloric acid, then the composite oxide is directly leached through the hydrochloric acid, adding of leaching oxidants such as H2O2 and aqua regia is avoided, then generation of toxic gas Cl2 is avoided, and the method has important significance on relieving environmental pollution. According to the method, the recovery rate of Pt or Pd in the platinum / palladium-containing waste catalyst is 96% or above, and the method is simple in process, environmentally friendly and easy to industrially apply.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste resource utilization, and in particular to a method for greenly recovering platinum / palladium from waste catalysts containing platinum / palladium based on mineral phase regulation. Background Art

[0002] Platinum and palladium metals have unique physical and chemical properties, such as thermal stability and catalytic activity, and are widely used as catalysts in the petrochemical, automotive and other industries. However, platinum and palladium resources are mainly concentrated in South Africa, the United States, Canada and other countries, while my country's platinum and palladium reserves are extremely scarce and face severe supply risks. After a certain period of use, platinum / palladium catalysts will undergo some changes in physical and chemical properties, thereby losing their catalytic activity and becoming waste catalysts. In order to make up for the shortage of primary platinum and palladium resources, the recovery of platinum and palladium metals from secondary resources has received increasing attention. This is a necessary way to reduce environmental pollution and develop a "green circular economy."

[0003] At present, the main methods for recovering platinum and palladium from waste catalysts include pyrometallurgy and hydrometallurgy. Pyrometallurgy has problems such as large equipment investment and high energy consumption. Chloride leaching in hydrometallurgy has been the most studied, however, it is often necessary to add strong oxidants such as Cl2, H2O2, HNO3, etc. to promote the dissolution of precious metals such as platinum and palladium in hydrochloric acid solution. The addition of these oxidants will produce toxic and corrosive gases such as Cl2, posing serious risks to production operations and the environment. Therefore, it is particularly important to develop a green recovery process that does not require the addition of oxidants. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a method for green recovery of platinum / palladium from waste catalysts containing platinum / palladium based on mineral phase regulation. The present invention adds PbO and mixes with waste catalyst powder containing platinum / palladium, then oxidizes and roasts it, and then directly leaches the roasted product through a hydrochloric acid solution to obtain a leachate containing Pt or Pd, and finally obtains a crude platinum product ammonium chloroplatinate or a crude palladium product ammonium chloropalladate after precipitation and solid-liquid separation through ammonium chloride. The present invention uses PbO to perform mineral phase regulation on the Pt / Pd metal element in the waste catalyst powder containing platinum / palladium, converts the Pt or Pd metal element into a composite oxide that is easily soluble in hydrochloric acid, and then directly leaches it through hydrochloric acid, avoiding the addition of leaching oxidants such as H2O2 and aqua regia, thereby avoiding the generation of toxic gas Cl2, which is of great significance to alleviating environmental pollution. The recovery rate of Pt or Pd in ​​the waste catalyst containing platinum / palladium of the method of the present invention is above 96%, the process is simple, and it is easy to be industrially applied, which is a green recovery method.

[0005] To achieve the above object, the present invention adopts the following technical scheme: a method for green recovery of platinum / palladium from waste catalyst containing platinum / palladium based on mineral phase regulation, comprising the following steps:

[0006] (1) crushing the waste catalyst containing platinum / palladium to obtain waste catalyst powder containing platinum / palladium;

[0007] (2) mixing the waste catalyst powder containing platinum / palladium with lead oxide and then performing oxidative roasting to obtain a roasted product;

[0008] (3) adding the calcined product into a hydrochloric acid solution for immersion and filtering to obtain a leaching solution containing platinum complex ions / palladium complex ions;

[0009] (4) adding ammonium chloride to the leachate and stirring continuously until no precipitation is generated, and performing solid-liquid separation after standing to obtain a crude platinum / palladium product and a lead-containing leachate, respectively.

[0010] As a further improvement of the method for green recovery of platinum / palladium from spent catalysts containing platinum / palladium based on mineral phase regulation:

[0011] Preferably, the particle size of the platinum / palladium-containing waste catalyst powder in step (1) is 0.074-0.15 mm.

[0012] Preferably, in step (2), the equipment used for oxidative roasting is a tubular furnace, the gas introduced is air, the temperature of oxidative roasting is 500-900° C., and the time is 1-12 h.

[0013] Preferably, in step (2), the temperature of the oxidative roasting is 600-800° C., and the roasting time is 1-8 hours.

[0014] Preferably, in step (2), the mixing mass ratio of the waste catalyst containing platinum / palladium to lead oxide is (2-20):1.

[0015] Preferably, in step (2), the mixing mass ratio of the waste catalyst containing platinum / palladium to lead oxide is (4-10):1.

[0016] Preferably, in step (3), the device used for hydrochloric acid leaching is a stainless steel reactor.

[0017] Preferably, in step (3), the concentration of the hydrochloric acid solution is 1-12 mol / L, the leaching temperature is 50-120° C., the leaching time is 1 h-5 h, and the mass ratio of the volume of the hydrochloric acid solution to the roasting product is 10-50 mL / g.

[0018] Preferably, in step (3), the concentration of the hydrochloric acid solution is 3-12 mol / L, the leaching temperature is 80-120° C., the leaching time is 2h-4h, and the mass ratio of the volume of the hydrochloric acid solution to the roasting product is 20-50 mL / g.

[0019] Preferably, in step (4), the crude platinum / palladium product is ammonium chloroplatinate / ammonium chloropalladate, and metallic platinum / palladium is obtained by further complexation and reduction.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) The present invention provides a method for green recovery of platinum / palladium from waste catalysts containing platinum / palladium based on mineral phase regulation, wherein " / " represents the meaning of "or". The method comprises adding PbO and mixing with waste catalyst powder containing platinum / palladium, and then directly leaching the calcined product through a hydrochloric acid solution to obtain a leachate containing Pt or Pd, and finally obtaining a crude platinum / palladium product ammonium chloroplatinate / ammonium chloropalladate after precipitation and solid-liquid separation through ammonium chloride. The principles of the present invention are as follows: 1) PbO can regulate the mineral phase of Pt or Pd at high temperature, converting Pt element into composite oxides PbPt2O4 and Pb2PtO4 that are easily soluble in hydrochloric acid, and converting Pd element into composite oxides PbPdO2 that are easily soluble in hydrochloric acid, thereby promoting direct leaching of Pt or Pd metal in a hydrochloric acid solution; 2) Oxidative roasting removes organic matter and carbon in waste catalysts containing platinum / palladium, thereby eliminating the agglomeration between platinum / palladium metal particles.

[0022] 2) At present, the dissolution of platinum / palladium metal in hydrochloric acid solution often requires the addition of strong oxidants such as Cl2, H2O2, HNO3, etc. to strengthen. The addition of these oxidants will produce highly toxic and corrosive gases such as Cl2, which poses a serious risk to production operations and the environment. The present invention is based on a method for green recovery of platinum / palladium from waste catalysts containing platinum / palladium by mineral phase regulation. Lead oxide is used to regulate the mineral phase of platinum / palladium metal in waste catalysts containing platinum / palladium, and the platinum / palladium element is converted into a composite oxide that is easily soluble in hydrochloric acid solution, and then directly leached by hydrochloric acid solution, avoiding the addition of oxidants such as H2O2 and aqua regia in the leaching process, thereby avoiding the generation of toxic gas Cl2, which is of great significance to alleviating environmental pollution. The recovery rate of Pt or Pd in ​​waste catalysts containing platinum / palladium in the method of the present invention is above 96%, the process is simple, and it is easy to be industrially applied. It is a green recovery method. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a process flow chart for green recovery of platinum / palladium from waste catalysts containing platinum / palladium based on mineral phase regulation. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] This embodiment provides a method for green recovery of platinum from platinum-containing waste catalyst based on mineral phase regulation, which specifically comprises the following steps:

[0027] (1) crushing the Pt / C waste catalyst to obtain Pt / C waste catalyst powder with a particle size of 0.074 mm;

[0028] (2) Pt / C waste catalyst powder and lead oxide were mixed in a mass ratio of 10:1 and placed in a tube furnace for oxidative calcination in an air atmosphere at a calcination temperature of 700° C. for 6 h to obtain a calcined product;

[0029] (3) adding the calcined product into a 12 mol / L hydrochloric acid solution for immersion, wherein the volume ratio of the hydrochloric acid solution to the calcined product is 20 mL / g, the leaching temperature is 100° C., the leaching time is 2 h, and filtering to obtain a leaching solution containing platinum complex ions;

[0030] (4) adding ammonium chloride to the leachate and stirring continuously until no precipitation is generated, and then standing to separate the solid and liquid to obtain ammonium chloroplatinate precipitate and lead-containing leachate, respectively.

[0031] Example 2

[0032] This embodiment provides a method for green recovery of platinum from platinum-containing waste catalysts based on mineral phase regulation. The specific steps are referred to in Example 1, with the only difference being that the leaching temperature in step (3) is changed to 80°C, and the other conditions are exactly the same as in Example 1.

[0033] Example 3

[0034] This embodiment provides a method for green recovery of platinum from platinum-containing waste catalysts based on mineral phase regulation. The specific steps are referred to in Example 1, with the only difference being that the leaching time in step (3) is changed to 3 hours, and the other conditions are exactly the same as in Example 1.

[0035] Example 4

[0036] This embodiment provides a method for green recovery of platinum from platinum-containing waste catalysts based on mineral phase regulation. The specific steps refer to those of Example 1, with the only difference being that the concentration of the hydrochloric acid solution in step (3) is changed to 9 mol / L, and the other conditions are exactly the same as those of Example 1.

[0037] Example 5

[0038] This embodiment provides a method for green recovery of platinum from platinum-containing waste catalysts based on mineral phase regulation. The specific steps are referred to in Example 1, with the only difference being that the mass ratio of Pt / C waste catalyst powder to lead oxide in step (2) is changed to 20:1, and the other conditions are exactly the same as in Example 1.

[0039] Example 6

[0040] This embodiment provides a method for green recovery of platinum from platinum-containing waste catalysts based on mineral phase regulation. The specific steps refer to those of Example 1, with the only difference being that the Pt / C waste catalyst in step (2) is replaced with a Pt / Al2O3 waste catalyst, and the other conditions are exactly the same as those of Example 1.

[0041] Example 7

[0042] This embodiment provides a method for green recovery of palladium from palladium-containing waste catalyst based on mineral phase regulation, and the specific steps are as follows:

[0043] (1) crushing the Pd / C waste catalyst to obtain Pd / C waste catalyst powder with a particle size of 0.15 mm;

[0044] (2) Pd / C waste catalyst powder and lead oxide were mixed in a mass ratio of 10:1 and placed in a tube furnace for oxidative calcination in an air atmosphere at a calcination temperature of 600° C. for 2 h to obtain a calcined product;

[0045] (3) adding the calcined product into a 9 mol / L hydrochloric acid solution for immersion, wherein the volume ratio of the hydrochloric acid solution to the calcined product is 20 mL / g, the leaching temperature is 100° C., the leaching time is 2 h, and filtering to obtain a leachate containing palladium complex ions;

[0046] (4) adding ammonium chloride to the leachate and stirring continuously until no precipitation is generated, and performing solid-liquid separation after standing to obtain ammonium chloropalladate precipitate and lead-containing leachate, respectively.

[0047] Example 8

[0048] This embodiment provides a method for green recovery of palladium from palladium-containing waste catalysts based on mineral phase regulation. The specific steps refer to those of Example 1, with the only difference being that the oxidative roasting temperature in step (1) is changed to 700°C, and the other conditions are exactly the same as those of Example 6.

[0049] Example 9

[0050] This embodiment provides a method for green recovery of palladium from palladium-containing waste catalysts based on mineral phase regulation. The specific steps refer to those of Example 1, with the only difference being that the concentration of the hydrochloric acid solution in step (3) is changed to 3 mol / L, and the other conditions are exactly the same as those of Example 6.

[0051] Example 10

[0052] This embodiment provides a method for green recovery of palladium from palladium-containing waste catalysts based on mineral phase regulation. The specific steps are referred to Example 1, with the only difference being that the leaching temperature of the hydrochloric acid solution in step (3) is changed to 80°C, and the other conditions are exactly the same as those in Example 6.

[0053] Embodiment 11

[0054] This embodiment provides a method for green recovery of palladium from palladium-containing waste catalysts based on mineral phase regulation. The specific steps refer to those of Example 1, with the only difference being that the leaching time of the hydrochloric acid solution in step (3) is changed to 3 hours, and the other conditions are exactly the same as those of Example 6.

[0055] Example 12

[0056] This embodiment provides a method for green recovery of palladium from palladium-containing waste catalysts based on mineral phase regulation. The specific steps refer to those of Example 1, with the only difference being that the Pd / C waste catalyst in step (1) is replaced with a Pd / Al2O3 waste catalyst, and the other conditions are exactly the same as those of Example 6.

[0057] The crude metal Pt / Pd obtained in Examples 1-12 was digested and then detected by inductively coupled plasma optical emission spectroscopy (ICP-OES), and the recovery rates of Pt and Pd were calculated.

[0058] The calculation formulas for Pt and Pd recovery are as follows:

[0059]

[0060] The recoveries of Pt and Pd by the methods described in Examples 1-12 are shown in Table 1.

[0061] Table 1 Recovery of Pt and Pd in ​​Examples 1-12

[0062]

[0063]

[0064] According to Examples 1-12, the present invention provides a method for green recovery of platinum / palladium from waste catalysts containing platinum / palladium based on mineral phase regulation, which utilizes PbO to regulate the mineral phase of Pt / Pd metal elements in waste catalyst powder containing platinum / palladium, and then directly leaches them through hydrochloric acid, thereby obtaining a higher recovery rate of Pt or Pd, avoiding the addition of leaching oxidants such as H2O2 and aqua regia, and further avoiding the generation of toxic gas Cl2, which is of great significance for alleviating environmental pollution.

[0065] Those skilled in the art should understand that the above are only some specific embodiments of the present invention, rather than all embodiments. It should be noted that for those of ordinary skill in the art, many modifications and improvements can be made, and all modifications or improvements that do not exceed the scope of protection of the present invention should be regarded as the scope of protection of the present invention.

Claims

1. A method for green recovery of platinum / palladium from waste catalysts containing platinum / palladium based on mineral phase regulation, characterized in that: The following steps are involved: (1) crushing the waste catalyst containing platinum / palladium to obtain waste catalyst powder containing platinum / palladium; (2) mixing the waste catalyst powder containing platinum / palladium with lead oxide and then performing oxidative roasting to obtain a roasted product; (3) adding the calcined product into a hydrochloric acid solution for immersion and filtering to obtain a leaching solution containing platinum complex ions / palladium complex ions; (4) adding ammonium chloride to the leachate and stirring continuously until no precipitation is generated, and performing solid-liquid separation after standing to obtain a crude platinum / palladium product and a lead-containing leachate, respectively.

2. The method for green recovery of platinum / palladium from waste catalyst containing platinum / palladium based on mineral phase regulation according to claim 1, characterized in that: The particle size of the platinum / palladium-containing waste catalyst powder in step (1) is 0.074-0.15 mm.

3. The method for green recovery of platinum / palladium from waste catalyst containing platinum / palladium based on mineral phase regulation according to claim 1, characterized in that: In step (2), the equipment used for oxidation roasting is a tubular furnace, the gas introduced is air, the temperature of oxidation roasting is 500-900° C., and the time is 1-12 hours.

4. The method for green recovery of platinum / palladium from waste catalyst containing platinum / palladium based on mineral phase regulation according to claim 2, characterized in that: In step (2), the temperature of oxidative roasting is 600-800° C., and the roasting time is 1-8 hours.

5. The method for green recovery of platinum / palladium from waste catalyst containing platinum / palladium based on mineral phase regulation according to claim 1, characterized in that: In step (2), the mixing mass ratio of the waste catalyst containing platinum / palladium to lead oxide is (2-20):

1.

6. The method for green recovery of platinum / palladium from waste catalyst containing platinum / palladium based on mineral phase regulation according to claim 1, characterized in that: In step (2), the mixing mass ratio of the waste catalyst containing platinum / palladium to lead oxide is (4-10):

1.

7. The method for green recovery of platinum / palladium from waste catalyst containing platinum / palladium based on mineral phase regulation according to claim 1, characterized in that: In step (3), the device used for hydrochloric acid leaching is a stainless steel reactor.

8. The method for green recovery of platinum / palladium from waste catalyst containing platinum / palladium based on mineral phase regulation according to claim 1, characterized in that: In step (3), the concentration of the hydrochloric acid solution is 1-12 mol / L, the leaching temperature is 50-120° C., the leaching time is 1 h-5 h, and the mass ratio of the volume of the hydrochloric acid solution to the roasting product is 10-50 mL / g.

9. The method for green recovery of platinum / palladium from waste catalyst containing platinum / palladium based on mineral phase regulation according to claim 1, characterized in that: In step (3), the concentration of the hydrochloric acid solution is 3-12 mol / L, the leaching temperature is 80-120° C., the leaching time is 2h-4h, and the mass ratio of the volume of the hydrochloric acid solution to the roasting product is 20-50 mL / g.

10. The method for green recovery of platinum / palladium from waste catalyst containing platinum / palladium based on mineral phase regulation according to claim 1, characterized in that: In step (4), the crude platinum / palladium product is ammonium chloroplatinate / ammonium chloropalladate, which is further complexed and reduced to obtain metallic platinum / palladium.

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