Method for recovering molybdenum, nickel, bismuth, iron and rare earth from waste catalyst

Abstract

The invention relates to the field of waste catalyst recovery, and discloses a method for recovering molybdenum, nickel, bismuth, iron and rare earth from a waste catalyst. The method comprises the following steps: by taking the waste catalyst as a raw material, adding an inorganic acid solution for leaching to obtain a leaching solution and leaching residues; extracting the leachate and the organic phase 1 to obtain an organic phase containing molybdenum and silicon and raffinate containing nickel, bismuth, iron and rare earth; mixing the organic phase containing molybdenum and silicon with an alkaline solution, and carrying out back extraction to obtain back extraction liquid containing molybdenum and silicon; the raffinate containing nickel, bismuth, iron and rare earth and the saponified organic phase 2 are extracted, and an organic phase containing bismuth, iron and rare earth and the raffinate containing nickel are obtained; the organic phase containing bismuth, iron and rare earth and an inorganic acid solution are subjected to back extraction, and an organic phase containing bismuth and iron and back extraction liquid containing rare earth are obtained; the organic phase containing bismuth and iron and an oxalic acid solution are subjected to back extraction, and a bismuth salt solid and an iron-containing back extraction solution are obtained; the method provided by the invention can realize nearly total recovery of valuable elements in the waste catalyst.

Description

Technical Field

[0001] The present invention relates to the field of waste catalyst recycling, and particularly relates to a method for recycling molybdenum, nickel, bismuth, iron and rare earth from waste catalysts. Background Art

[0002] Molybdenum-containing catalysts often use Al 2 O 3 or SiO 2 as carriers, and elements such as molybdenum, nickel, bismuth, and rare earth are active components. After the catalyst is used for a period of time, it becomes inactivated due to changes in its chemical composition and surface state. Since the content of valuable elements in it is much higher than that in ores, comprehensive recycling of the valuable elements therein has great economic value.

[0003] CN102912132B provides a method for recycling valuable metals from molybdenum-containing waste catalysts, including steps of crushing, alkali roasting, and separately recycling each valuable metal. This method solves the problem of disposal of molybdenum-containing waste catalysts, and not only realizes the recycling of valuable metals with relatively high contents such as molybdenum and bismuth in the waste catalyst, but also realizes the recycling of various low-content metals such as cobalt, nickel, phosphorus, chromium, and palladium, as well as the carrier silica, but the recovery rate and product purity are not reported. Liu Xiuqing et al. developed a new process for comprehensively recycling molybdenum, bismuth, cobalt, and nickel from waste catalysts. This process uses acid leaching first and then alkali leaching to achieve the purpose of inhibiting the dissolution of carriers aluminum oxide and silica and effectively separating each valuable element, and has been applied in production, achieving good economic and social benefits. Zhu Binyao et al. explored the technological conditions for separating and extracting bismuth and nickel from waste catalysts by acid leaching-hydrolysis method, using the method of acid leaching first and then hydrolysis, and realizing the separation of bismuth and nickel in the acid leaching solution by using the hydrolysis characteristics of bismuth nitrate. CN105603195A discloses a method for extracting molybdenum and nickel from waste catalysts, and effective separation and comprehensive recycling of molybdenum and nickel in the waste catalyst can be achieved by oxalic acid oxidative leaching.

[0004] Although the above methods recycle some valuable elements, they do not recycle some key elements, and some elements are only made into enrichments rather than products. For example, the waste catalyst also contains a certain amount of rare earth, and its recycling method has not been reported in the literature. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems in the existing waste catalyst recycling technology that only some elements are recycled and the product purity needs to be further improved, and to provide a method for recycling molybdenum, nickel, bismuth, iron and rare earth from waste catalysts. The method of the present invention can achieve nearly full recovery of valuable elements in the waste catalyst, and can obtain products with relatively high purity.

[0006] To achieve the above object, on the one hand, the present invention provides a method for recovering molybdenum, nickel, bismuth, iron and rare earths from waste catalysts, and the method comprises the following steps:

[0007] (1) Using the waste catalyst as a raw material, adding an inorganic acid solution for leaching to obtain a leaching solution containing molybdenum, silicon, nickel, bismuth, iron and rare earths and a leaching residue;

[0008] (2) Mixing the leaching solution containing molybdenum, silicon, nickel, bismuth, iron and rare earths with organic phase 1 for extraction to obtain an organic phase containing molybdenum and silicon and a raffinate containing nickel, bismuth, iron and rare earths;

[0009] (3) Mixing the organic phase containing molybdenum and silicon with an alkaline solution for back-extraction to obtain a back-extract solution containing molybdenum and silicon and an empty organic phase 1;

[0010] (4) Mixing the raffinate containing nickel, bismuth, iron and rare earths obtained in step (2) with saponified organic phase 2 for extraction to obtain an organic phase containing bismuth, iron and rare earths and a raffinate containing nickel, and the pH of the raffinate containing nickel is 1.5 - 3;

[0011] (5) Mixing the organic phase containing bismuth, iron and rare earths with an inorganic acid solution for back-extraction to obtain an organic phase containing bismuth and iron and a back-extract solution containing rare earths;

[0012] (6) Mixing the organic phase containing bismuth and iron with an oxalic acid solution for back-extraction to obtain bismuth salt solid, an iron-containing back-extract solution and an empty organic phase 2.

[0013] Through the above technical solutions, the beneficial effects of the present invention include:

[0014] The method of the present invention can achieve nearly complete recovery of valuable elements (molybdenum, nickel, bismuth, iron and rare earths) in molybdenum-containing waste catalysts, and high-purity products can be obtained in all cases. Detailed Embodiments

[0015] In the ranges disclosed herein, the endpoints and any value are not limited to the exact range or value, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0016] The "saponification reaction" and "saponification" as used in the present invention refer to the reaction of an organic phase with an alkali.

[0017] On the one hand, the present invention provides a method for recovering molybdenum, nickel, bismuth, iron and rare earths from waste catalysts, and the method comprises the following steps:

[0018] (1) Using waste catalyst as raw material, adding inorganic acid solution for leaching to obtain a leaching solution containing molybdenum, silicon, nickel, bismuth, iron and rare earth, and a leaching residue;

[0019] (2) Mixing the leaching solution containing molybdenum, silicon, nickel, bismuth, iron and rare earth with organic phase 1 for extraction to obtain an organic phase containing molybdenum and silicon, and a raffinate containing nickel, bismuth, iron and rare earth;

[0020] (3) Mixing the organic phase containing molybdenum and silicon with an alkaline solution for back-extraction to obtain a back-extract solution containing molybdenum and silicon, and an empty organic phase 1;

[0021] (4) Mixing the raffinate containing nickel, bismuth, iron and rare earth obtained in step (2) with saponified organic phase 2 for extraction to obtain an organic phase containing bismuth, iron and rare earth, and a raffinate containing nickel, with the pH of the raffinate containing nickel being 1.5 - 3;

[0022] (5) Mixing the organic phase containing bismuth, iron and rare earth with an inorganic acid solution for back-extraction to obtain an organic phase containing bismuth and iron, and a back-extract solution containing rare earth;

[0023] (6) Mixing the organic phase containing bismuth and iron with an oxalic acid solution for back-extraction to obtain bismuth salt solid, an iron-containing back-extract solution and an empty organic phase 2.

[0024] The method provided by the present invention has the following inventive ideas:

[0025] (1) First, taking advantage of the characteristics that silicon and molybdenum are easy to form heteropolyacids and are easily extractable species, synchronously and selectively separating molybdenum and silicon to avoid the influence of silicon on the subsequent recovery of nickel, bismuth, iron and rare earth;

[0026] (2) Then, using the saponification process and extraction process to indirectly consume hydrogen ions in the solution, avoiding the hydrolysis of bismuth caused by directly adding an alkaline solution to the raffinate containing nickel, bismuth, iron and rare earth; meanwhile, in this process, taking advantage of the fact that the extraction rate of bismuth ions is greater than the hydrolysis rate, and the extraction rate of rare earth ions is greater than the formation rate of rare earth double salts, avoiding the generation of bismuth basic sulfate and rare earth sulfate double salts. And by controlling the pH of the obtained raffinate containing nickel between 1.5 - 3, it is possible to selectively co-extract bismuth, iron and rare earth from a complex solution containing multiple metal ions, significantly improving the separation efficiency;

[0027] (3) Then, separating bismuth and iron using the different coordination abilities of bismuth and iron with oxalic acid. In an excessive oxalic acid solution, iron can form a complex with oxalic acid and remain in the solution, while bismuth forms bismuth oxalate precipitate and settles. The phase separation is good during the back-extraction process, enabling the efficient separation of bismuth and iron.

[0028] According to the present invention, preferably, in the leaching residue of step (1), the purity of silicon dioxide is not less than 98%. By adopting this preferred embodiment, the silicon dioxide therein can be recovered as an additional product, realizing nearly full recovery and utilization of the catalyst.

[0029] The present invention does not particularly limit the number of times of leaching in step (1), and it can be leached once or multiple times. Similarly, the present invention does not particularly limit the dosage of the inorganic acid solution, as long as the purity of silicon dioxide in the above-mentioned leaching residue is not less than 98%.

[0030] Preferably, the present invention does not particularly limit the type selection of the inorganic acid in the inorganic acid solution, and it can be a conventional selection in the art. The present invention preferably uses sulfuric acid.

[0031] The present invention does not particularly limit the solvent in the inorganic acid solution of step (1), and it can be a conventional selection in the art. The present invention preferably uses water as the solvent.

[0032] Preferably, the concentration of the inorganic acid solution in step (1) is 1 - 2.5 mol / L.

[0033] In the method provided by the present invention, the specific operation processes of extraction and back-extraction mentioned can be carried out with reference to the conventional methods in the art.

[0034] In order to achieve full recovery of molybdenum, preferably, in step (2), the extraction rate of molybdenum is not less than 99%.

[0035] The present invention does not particularly limit the number of times of extraction in step (2), and it can be extracted once or multiple times. Similarly, the present invention does not particularly limit the dosage of organic phase 1, as long as the extraction rate of molybdenum in step (2) is not less than 99%.

[0036] According to the present invention, preferably, the organic phase 1 includes an amine extractant, a modifier, and a diluent.

[0037] The present invention has a relatively wide range of selection for the type of the amine extractant, and it can be a conventional selection in the art. Preferably, the amine extractant is selected from at least one of N235 extractant, Aliquat 336 extractant, and N1923 extractant.

[0038] According to the present invention, preferably, the modifier is selected from at least one of isooctanol, sec-octanol, methyl isobutyl ketone, and tributyl phosphate (TBP).

[0039] The present invention does not particularly limit the type selection of the diluent, and it can be a conventional selection in the art. Preferably, the diluent is selected from at least one of kerosene, n-heptane, and octane.

[0040] According to the present invention, preferably, based on the total volume of the organic phase 1, the volume content of the amine extractant is 10-30%, the volume content of the modifier is 5-25%, and the volume content of the diluent is 45-85%.

[0041] In order to achieve the full recovery of molybdenum, preferably, in step (3), the stripping rate of molybdenum is not less than 99%.

[0042] The present invention does not particularly limit the number of stripping times in step (3), and it can be stripped once or multiple times. Similarly, the present invention does not particularly limit the amount of the alkaline solution in step (3), as long as the stripping rate of molybdenum is not less than 99%.

[0043] Preferably, the empty organic phase 1 obtained in step (3) is returned to step (2) for use as an extractant. Adopting this preferred embodiment is conducive to the reuse of the extractant and cost savings.

[0044] The present invention has a wide selection range for the type of the alkaline solution in step (3), and it can be various alkaline solutions commonly used in the art. Preferably, the alkaline solution in step (3) is selected from at least one of an aqueous sodium hydroxide solution, an aqueous potassium carbonate solution, an aqueous sodium carbonate solution, an aqueous ammonia solution, and a buffer solution of ammonia water and ammonium salt.

[0045] According to the present invention, preferably, the concentration of the alkaline solution in step (3) is 2-7 mol / L.

[0046] In order to achieve the full recovery of valuable metals, preferably, in step (4), the extraction rate of bismuth is not less than 99%.

[0047] Preferably, in step (4), the extraction rate of iron is not less than 99%.

[0048] Preferably, in step (4), the extraction rate of rare earths is not less than 98%.

[0049] The present invention does not particularly limit the number of extractions in step (4), and it can be extracted once or multiple times. Similarly, the present invention does not particularly limit the amount of the organic phase 2 in step (4), as long as the extraction rates of bismuth, iron, and rare earths in step (4) meet the above requirements.

[0050] According to the present invention, preferably, the organic phase 2 includes a phosphoric acid extractant and a diluent.

[0051] The present invention has a wide selection range for the type of the phosphoric acid extractant, and it can be a conventional selection in the art. Preferably, the phosphoric acid extractant is selected from at least one of a P204 extractant, a P507 extractant, and a Cyanex272 extractant.

[0052] The present invention has no particular limitation on the selection of the diluent type, and it can be a conventional selection in the art. Preferably, the diluent is selected from at least one of kerosene, n-heptane, and octane.

[0053] According to the present invention, preferably, based on the total volume of the organic phase 2, the volume content of the phosphoric acid extractant is 20 - 50%.

[0054] In the present invention, the organic phase 2 needs to be saponified before use.

[0055] The present invention has no particular limitation on the type and dosage of the base used in the saponification reaction, and it is based on the pH of the nickel-containing raffinate being 1.5 - 3.

[0056] In order to achieve the full recovery of rare earths, the purity of the rare earth-containing stripping solution obtained in step (5) is not less than 99%.

[0057] The present invention has no particular limitation on the number of stripping times in step (5), and it can be stripped once or multiple times. Similarly, the present invention has no particular limitation on the dosage of the inorganic acid solution in step (5), and it is based on the purity of the rare earth-containing stripping solution being not less than 99%.

[0058] The present invention has no particular limitation on the selection of the type of inorganic acid in the inorganic acid solution, and it can be a conventional selection in the art. Preferably, the inorganic acid in the inorganic acid solution in step (5) is selected from at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0059] The present invention has no particular limitation on the solvent in the inorganic acid solution in step (5), and it can be a conventional selection in the art. The present invention preferably uses water as the solvent.

[0060] According to the present invention, preferably, the concentration of the inorganic acid solution in step (5) is 0.3 - 2 mol / L.

[0061] In order to achieve the nearly full recovery of valuable metals, preferably, the purity of bismuth oxalate obtained in step (6) is not less than 99.5%.

[0062] In order to achieve the nearly full recovery of valuable metals, preferably, in step (6), the stripping rate of iron is not less than 95%.

[0063] The present invention has no particular limitation on the number of stripping times in step (6), and it can be stripped once or multiple times. Similarly, the present invention has no particular limitation on the specific dosage of the oxalic acid solution in step (6), and it is based on the purity of bismuth oxalate and / or the stripping rate of iron meeting the above requirements.

[0064] Preferably, the saponified organic phase 2 obtained in step (6) is returned to step (4) for use as an extractant. Adopting this preferred embodiment is conducive to the reuse of the extractant and cost savings.

[0065] According to the present invention, preferably, the concentration of the oxalic acid solution in step (6) is 0.6 - 1 mol / L.

[0066] The present invention does not particularly limit the solvent in the oxalic acid solution in step (6), and it can be a conventional selection in the art. The present invention preferably uses water as the solvent.

[0067] According to the present invention, preferably, the method further includes: precipitating silicon from the molybdenum- and silicon-containing stripping solution obtained in step (3) at a pH of 7 - 9 to obtain a molybdate solution. Adopting this preferred embodiment is conducive to the separation of silicon and molybdenum.

[0068] The present invention does not particularly limit the method for precipitating silicon from the molybdenum- and silicon-containing stripping solution in step (3), and conventional methods in the art can be used. The present invention preferably uses the method of heating and boiling the molybdenum- and silicon-containing stripping solution to precipitate silicon.

[0069] According to a specific embodiment of the present invention, at a pH of 7 - 9, the molybdenum- and silicon-containing stripping solution obtained in step (3) is heated and boiled to precipitate silicon, and solid-liquid separation is performed to obtain a molybdate solution.

[0070] The present invention does not particularly limit the manner of the solid-liquid separation, and conventional technical means in the art can be used.

[0071] Preferably, the molybdate solution is evaporated and crystallized to obtain a molybdate product.

[0072] Preferably, the purity of the molybdate product is not less than 99.8%.

[0073] According to the present invention, preferably, the method further includes: mixing the nickel-containing raffinate obtained in step (4) with the saponified organic phase 3 for extraction to obtain a nickel-containing organic phase and a raffinate, and the pH of the raffinate is 6.5 - 7.5. Adopting this preferred embodiment is conducive to selectively extracting nickel from the solution and preparing a pure nickel product, and at the same time is conducive to achieving efficient extraction of nickel and efficient separation from impurities.

[0074] In order to achieve nearly complete recovery of nickel, preferably, the extraction rate of nickel is not less than 99%.

[0075] The present invention does not particularly limit the number of extractions above, and it can be extracted once or multiple times. Similarly, the present invention does not particularly limit the amount of the organic phase 3 used, as long as the extraction rate of nickel is not less than 99%.

[0076] In the present invention, the organic phase 3 needs to be saponified before use.

[0077] The present invention has no particular limitation on the type and dosage of the base used in the saponification reaction, and is based on the pH of the raffinate obtained being 6.5 - 7.5.

[0078] Preferably, the organic phase 3 includes a pyridine ester compound, an acidic extractant, and a diluent.

[0079] The present invention has a relatively wide selection range for the type of the pyridine ester compound, which can be a conventional selection in the art. For example, it can be a 4PC extractant. The above substances can all be obtained through commercial purchase.

[0080] The present invention has a relatively wide selection range for the type of the acidic extractant, which can be a conventional selection in the art. Preferably, the acidic extractant is selected from at least one of P204 extractant, Versatic 10 extractant, and dinonylnaphthalenesulfonic acid. The above substances can all be obtained through commercial purchase.

[0081] The present invention can also use an HBL110 extractant and the like which is a compound of two components including a pyridine ester compound and an acidic extractant. The above substances can all be obtained through commercial purchase.

[0082] The present invention has no particular limitation on the type selection of the diluent, which can be a conventional selection in the art. Preferably, the diluent is selected from at least one of kerosene, n - heptane, and octane.

[0083] According to the present invention, preferably, based on the total volume of the organic phase 3, the volume content of the pyridine ester compound is 5 - 30%, and the volume content of the acidic extractant is 2 - 10%.

[0084] According to the present invention, preferably, the method further includes: mixing the nickel - containing organic phase with an inorganic acid solution for stripping to obtain a nickel - containing stripping solution and a blank organic phase 3.

[0085] In order to achieve the full - amount recovery of nickel, preferably, the purity of the nickel - containing stripping solution is not less than 99%.

[0086] The present invention has no particular limitation on the number of times of the above stripping, and it can be stripped once or multiple times. Similarly, the present invention has no particular limitation on the dosage of the inorganic acid solution, and is based on the purity of the nickel - containing stripping solution being not less than 99%.

[0087] Preferably, the saponified blank organic phase 3 is returned to the nickel extraction process of the nickel - containing raffinate as an extractant for use. Adopting this preferred implementation mode is beneficial to the reuse of the extractant and cost savings.

[0088] For the selection of the type and concentration of the inorganic acid solution in the present invention, reference can be made to the selection of the type and concentration of the inorganic acid solution in step (5).

[0089] According to the present invention, preferably, the iron-containing stripping solution obtained in step (6) is irradiated with light to obtain ferrous oxalate precipitate.

[0090] According to the present invention, preferably, the precipitation rate of the ferrous oxalate is not less than 90%.

[0091] The present invention has no particular limitation on the type of light irradiation and the light irradiation time, as long as the precipitation rate of ferrous oxalate meets the above requirements.

[0092] In the present invention, when the iron-containing stripping solution obtained in step (6) is irradiated with light, there is still oxalic acid solution remaining. The remaining oxalic acid solution is replenished to 0.6 - 1 mol / L and then returned to step (6) for use.

[0093] Preferably, the iron-containing stripping solution obtained in step (6) is irradiated with light, and then solid-liquid separation is carried out to obtain ferrous oxalate precipitate and oxalic acid solution.

[0094] The present invention has no particular limitation on the method of solid-liquid separation, and conventional technical means in the art can be used.

[0095] The method of the present invention is suitable for catalysts containing molybdenum element, nickel element, bismuth element, iron element and rare earth element (RE) with different compositions. According to the present invention, preferably, the waste catalyst includes a carrier and a metal active component, the carrier is silica, and the metal active component includes molybdenum element, nickel element, bismuth element, iron element and rare earth element.

[0096] According to the present invention, preferably, the rare earth element is a lanthanide element, preferably selected from at least one of cerium element, praseodymium element and neodymium element.

[0097] The method of the present invention is suitable for the treatment process of catalysts containing molybdenum element, nickel element, bismuth element, iron element and rare earth element with different concentrations. Preferably, in the waste catalyst, calculated as oxides, the content of molybdenum element is 5 - 25 wt%, the content of nickel element is 1 - 15 wt%, the content of bismuth element is 1 - 8 wt%, the content of iron element is 1 - 8 wt%, and the content of rare earth element is 1 - 8 wt%.

[0098] The present invention will be described in detail below through examples.

[0099] The N235 extractant is a commercially available product from Chongqing Comchem Co., Ltd.;

[0100] The P204 extractant is a commercially available product from Chongqing Comchem Co., Ltd.;

[0101] The 4PC extractant is a commercially available product from Hunan Hongbang Material Technology Co., Ltd.;

[0102] The Aliquat 336 extractant is a commercially available product from Chongqing Comchem Co., Ltd.;

[0103] The P507 extractant is a commercially available product from Chongqing Comchem Co., Ltd.;

[0104] The HBL110 extractant is a commercially available product from Hunan Hongbang Material Technology Co., Ltd.;

[0105] The N1923 extractant is a commercially available product from Jiangxi Jiexin Technology Co., Ltd.;

[0106] The Cyanex 272 extractant is a commercially available product from Chongqing Comchem Co., Ltd.;

[0107] The Versatic 10 extractant is a commercially available product from Chongqing Comchem Co., Ltd.

[0108] Example 1

[0109] Composition of the spent catalyst: MoO 3 21.24 wt%, NiO 4.24 wt%, Bi 2 O 3 3 wt%, RE 2 O 3 4.79 wt%, Fe 2 O 3 4.18 wt%, and the balance is the carrier silica.

[0110] (1) Leaching: Using the spent catalyst as raw material, adding 2.5 mol / L sulfuric acid aqueous solution for leaching to obtain a leaching solution containing molybdenum, nickel, bismuth, rare earth, iron, and silicon and leaching residues. The purity of silica in the obtained leaching residues is 98.5%.

[0111] (2) Extracting molybdenum and silicon: Mixing the leaching solution containing molybdenum, nickel, bismuth, rare earth, iron, and silicon obtained in step (1) with organic phase 1 (20% N235 extractant + 13% isooctanol + 67% kerosene (V / V)), and performing three-stage countercurrent extraction to obtain an organic phase containing molybdenum and silicon and a raffinate containing nickel, bismuth, rare earth, and iron. The extraction rate of molybdenum is 99.6%, and the extraction rate of silicon is 77.1%.

[0112] (3) Stripping molybdenum and silicon: Mixing the organic phase containing molybdenum and silicon obtained in step (2) with a mixed solution of 7 mol / L ammonia water + 1 mol / L ammonium carbonate for stripping to obtain a stripping solution containing molybdenum and silicon and the empty organic phase 1. The empty organic phase 1 returns to step (2) for extraction. The stripping rate of molybdenum is 99.3%.

[0113] (4) Molybdenum-silicon separation: Adjust the pH of the stripping solution containing molybdenum and silicon obtained in step (3) to 7, heat it to boiling, filter to remove silicon, and evaporate and crystallize the obtained liquid to obtain ammonium molybdate product with a purity of 99.97%.

[0114] (5) Extracting bismuth, iron and rare earths: Mix the raffinate containing nickel, bismuth, rare earths and iron obtained in step (2) with saponified organic phase 2 (40% P204 extractant + 60% n-heptane (V / V)), carry out extraction to obtain an organic phase containing bismuth, iron and rare earths and a raffinate containing nickel. The pH of the raffinate containing nickel is 1.5, in which the extraction rate of bismuth is 99.9%, the extraction rate of iron is 100%, and the extraction rate of rare earths is 98.5%.

[0115] (6) Stripping rare earths: Mix the organic phase containing bismuth, iron and rare earths obtained in step (5) with 1 mol / L nitric acid aqueous solution, carry out four-stage countercurrent stripping to obtain a stripping solution containing rare earths and an organic phase containing bismuth and iron. The purity of the stripping solution containing rare earths is 99.7%.

[0116] (7) Stripping bismuth and iron: Mix the organic phase containing bismuth and iron obtained in step (6) with 0.8 mol / L oxalic acid aqueous solution (the molar ratio of oxalic acid to iron ions in the organic phase containing bismuth and iron is 20:1), carry out three-stage countercurrent stripping to obtain empty organic phase 2, an iron-containing stripping solution and bismuth oxalate solid phase. The empty organic phase 2 is saponified and then returned to step (5). The purity of bismuth oxalate is 99.7%.

[0117] (8) Preparation of ferrous oxalate: Irradiate the iron-containing stripping solution obtained in step (7) to generate ferrous oxalate precipitate, and obtain ferrous oxalate product and oxalic acid solution by vacuum filtration. The obtained oxalic acid solution is supplemented with oxalic acid to 0.8 mol / L and then returned to step (7) for stripping. The precipitation rate of the ferrous oxalate is 92%, and the purity of the obtained ferrous oxalate product is 99.5%.

[0118] (9) Extracting nickel: Mix the raffinate containing nickel obtained in step (5) with saponified organic phase 3 (25% 4PC extractant + 5% P204 extractant + 70% octane (V / V)), carry out three-stage countercurrent extraction to obtain an organic phase containing nickel and a raffinate. The pH of the raffinate is 6.5, in which the extraction rate of nickel is 99%.

[0119] (10) Stripping nickel: Mix the nickel-containing organic phase obtained in step (9) with 0.5 mol / L nitric acid aqueous solution, carry out stripping to obtain a nickel-containing stripping solution and empty organic phase 3. The empty organic phase 3 is saponified and then returned to step (9) for extraction. The purity of the obtained nickel-containing stripping solution is 99.5%.

[0120] Example 2

[0121] Composition of waste catalyst: MoO 3 5.32 wt%, NiO 10.61 wt%, Bi2 O 3 1.22 wt%, RE 2 O 3 3wt%, Fe 2 O 3 4.18wt%, and the balance is carrier silica.

[0122] (1) Leaching: Using waste catalyst as raw material, adding 1mol / L sulfuric acid solution for two-stage countercurrent leaching to obtain a leaching solution containing molybdenum, nickel, bismuth, rare earth, iron and silicon and leaching residues. The purity of silica in the obtained leaching residues is 98.6%.

[0123] (2) Extracting molybdenum and silicon: Mixing the leaching solution containing molybdenum, nickel, bismuth, rare earth, iron and silicon obtained in step (1) with organic phase 1 (30% Aliquat 336 extractant + 20% sec-octanol + 50% n-heptane (V / V)) for three-stage countercurrent extraction to obtain an organic phase containing molybdenum and silicon and a raffinate containing nickel, bismuth, rare earth and iron. The extraction rate of molybdenum is 99.7%, and the extraction rate of silicon is 80.2%.

[0124] (3) Stripping molybdenum and silicon: Mixing the organic phase containing molybdenum and silicon obtained in step (2) with 7mol / L aqueous NaOH solution for stripping to obtain a stripping solution containing molybdenum and silicon and an empty organic phase. The empty organic phase 1 returns to step (2) for extraction. The stripping rate of molybdenum is 99.5%.

[0125] (4) Separating molybdenum and silicon: Adjusting the pH of the stripping solution containing molybdenum and silicon obtained in step (3) to 8, heating and boiling, filtering to remove silicon, and evaporating and crystallizing the obtained liquid to obtain sodium molybdate product with a purity of 99.8%.

[0126] (5) Extracting bismuth, iron and rare earth: Mixing the raffinate containing nickel, bismuth, rare earth and iron obtained in step (2) with saponified organic phase 2 (45% P507 extractant + 55% kerosene (V / V)) for extraction to obtain an organic phase containing bismuth, iron and rare earth and a raffinate containing nickel. The pH of the raffinate containing nickel is 1.7. The extraction rate of bismuth is 99.9%, the extraction rate of iron is 100%, and the extraction rate of rare earth is 99.5%.

[0127] (6) Stripping rare earth: Mixing the organic phase containing bismuth, iron and rare earth obtained in step (5) with 0.5mol / L sulfuric acid solution for four-stage countercurrent stripping to obtain a stripping solution containing rare earth and an organic phase containing bismuth and iron. The purity of the stripping solution containing rare earth is 99.7%.

[0128] (7) Stripping of bismuth and iron: Mix the organic phase containing bismuth and iron obtained in step (6) with 0.9 mol / L oxalic acid solution (the molar ratio of oxalic acid to iron ions in the organic phase containing bismuth and iron is 18:1), and perform three-stage countercurrent stripping to obtain the empty organic phase 2, the iron-containing stripping solution and bismuth oxalate solid phase. The empty organic phase 2 is saponified and then returned to step (5). The purity of bismuth oxalate is 99.7%.

[0129] (8) Preparation of ferrous oxalate: Irradiate the iron-containing stripping solution obtained in step (7) to generate ferrous oxalate precipitate. After filtration, ferrous oxalate product and oxalic acid solution are obtained. The obtained oxalic acid solution is supplemented with oxalic acid to 0.9 mol / L and then returned to step (7) for stripping. The precipitation rate of the ferrous oxalate is 94%, and the purity of the obtained ferrous oxalate product is 99.8%.

[0130] (9) Extraction of nickel: Mix the nickel-containing aqueous phase obtained in step (5) with the saponified organic phase 3 (20% HBL110 extractant + 80% kerosene (V / V)), and perform three-stage countercurrent extraction to obtain the nickel-containing organic phase and the raffinate. The pH of the raffinate is 6.5, and the extraction rate of nickel is 99.2%.

[0131] (10) Stripping of nickel: Mix the nickel-containing organic phase obtained in step (9) with 0.5 mol / L sulfuric acid solution for stripping to obtain the nickel-containing stripping solution and the empty organic phase 3. The empty organic phase 3 is saponified and then returned to step (9) for extraction. The purity of the obtained nickel-containing stripping solution is 99.5%.

[0132] Example 3

[0133] Composition of waste catalyst: MoO 3 21.68 wt%, NiO 1.39 wt%, Bi 2 O 3 2.34 wt%, RE 2 O 3 5.33 wt%, Fe 2 O 3 1.85 wt%, and the balance is carrier silica.

[0134] (1) Leaching: Using the waste catalyst as raw material, add 1.7 mol / L sulfuric acid solution for leaching to obtain the leaching solution containing molybdenum, nickel, bismuth, rare earth and iron, and the leaching residue. The purity of silica in the obtained leaching residue is 99%.

[0135] (2) Extraction of molybdenum and silicon: Mix the leaching solution containing molybdenum, nickel, bismuth, rare earth and iron obtained in step (1) with the organic phase 1 (25% N1923 extractant + 15% TBP + 60% octane (V / V)), and perform four-stage countercurrent extraction to obtain the organic phase containing molybdenum and silicon and the raffinate containing nickel, bismuth, rare earth and iron. The extraction rate of molybdenum is 99.8%, and the extraction rate of silicon is 80.1%.

[0136] (3) Stripping molybdenum and silicon: Mix the organic phase containing molybdenum and silicon obtained in step (2) with 5 mol / L K 2 CO 3 solution for stripping to obtain a stripping solution containing molybdenum and silicon and an empty organic phase 1. The empty organic phase 1 is returned to step (2) for extraction. The stripping rate of molybdenum is 99.6%.

[0137] (4) Separation of molybdenum and silicon: Adjust the pH of the stripping solution containing molybdenum and silicon obtained in step (3) to 9, heat to boiling, filter to remove silicon, and evaporate and crystallize the obtained liquid to obtain potassium molybdate product with a purity of 99.97%.

[0138] (5) Extracting bismuth, iron and rare earths: Mix the raffinate containing nickel, bismuth, rare earths and iron obtained in step (2) with the saponified organic phase 2 (35% Cyanex 272 extractant + 65% n-heptane (V / V)) for extraction to obtain an organic phase containing bismuth, iron and rare earths and a raffinate containing nickel. The pH of the raffinate containing nickel is 3. The extraction rate of bismuth is 99.8%, the extraction rate of iron is 100%, and the extraction rate of rare earths is 99.2%.

[0139] (6) Stripping rare earths: Mix the organic phase containing bismuth, iron and rare earths obtained in step (5) with 0.8 mol / L hydrochloric acid aqueous solution for four-stage countercurrent stripping to obtain a stripping solution containing rare earths and an organic phase containing bismuth and iron. The purity of the stripping solution containing rare earths is 99.4%.

[0140] (7) Stripping bismuth and iron: Mix the organic phase containing bismuth and iron obtained in step (6) with 1 mol / L oxalic acid aqueous solution (the molar ratio of oxalic acid to iron ions in the organic phase containing bismuth and iron is 25:1) for three-stage countercurrent stripping to obtain an empty organic phase 2, an iron-containing stripping solution and bismuth oxalate solid phase. The empty organic phase 2 is saponified and then returned to step (5). The purity of bismuth oxalate is 99.7%.

[0141] (8) Preparation of ferrous oxalate: Irradiate the iron-containing stripping solution obtained in step (7) to generate ferrous oxalate precipitate. After filtration, ferrous oxalate and oxalic acid solution are obtained. The obtained oxalic acid solution is supplemented with oxalic acid to 1 mol / L and returned to step (7) for stripping. The precipitation rate of the ferrous oxalate is 93%, and the purity of the obtained ferrous oxalate product is 99.7%.

[0142] (9) Extracting nickel: Mix the nickel-containing aqueous phase obtained in step (5) with the saponified organic phase 3 (25% 4PC extractant + 5% Versatic 10 extractant + 70% octane (V / V)) for three-stage countercurrent extraction to obtain a nickel-containing organic phase and a raffinate. The pH of the raffinate is 7. The extraction rate of nickel is 99.7%.

[0143] (10) Stripping nickel: Mix the nickel-containing organic phase obtained in step (9) with 0.7 mol / L hydrochloric acid aqueous solution for stripping to obtain a nickel-containing stripping solution and a stripped organic phase 3. After saponifying the stripped organic phase 3, it is returned to step (9) for extraction. The purity of the obtained nickel-containing stripping solution is 99.3%.

[0144] Example 4

[0145] Composition of waste catalyst: MoO 3 10.34 wt%, NiO 8.98 wt%, Bi 2 O 3 5.61 wt%, RE 2 O 3 1.98 wt%, Fe 2 O 3 4.79 wt%, and the balance is carrier silica.

[0146] (1) Leaching: Using the waste catalyst as raw material, add 1.6 mol / L sulfuric acid solution for three-stage countercurrent leaching to obtain a leaching solution containing molybdenum, nickel, bismuth, rare earth, iron, and silicon and a leaching residue. The purity of silica in the obtained leaching residue is 98.8%.

[0147] (2) Extracting molybdenum and silicon: Mix the leaching solution containing molybdenum, nickel, bismuth, rare earth, iron, and silicon obtained in step (1) with organic phase 1 (25% N235 extractant + 15% isooctanol + 60% kerosene (V / V)) for three-stage countercurrent extraction to obtain an organic phase containing molybdenum and silicon and a raffinate containing nickel, bismuth, rare earth, and iron. The extraction rate of molybdenum is 99.4%, and the extraction rate of silicon is 83.6%.

[0148] (3) Stripping molybdenum and silicon: Mix the organic phase containing molybdenum and silicon obtained in step (2) with 2 mol / L sodium carbonate aqueous solution for stripping to obtain a stripping solution containing molybdenum and silicon and a stripped organic phase 1. The stripped organic phase 1 is returned to step (2) for extraction. The stripping rate of molybdenum is 99.5%.

[0149] (4) Separating molybdenum and silicon: Adjust the pH of the stripping solution containing molybdenum and silicon obtained in step (3) to 7.5, heat to boiling, filter to remove silicon, and the obtained liquid is evaporated and crystallized to obtain sodium molybdate product with a purity of 99.9%.

[0150] (5) Extracting bismuth, iron, and rare earth: Mix the raffinate containing nickel, bismuth, rare earth, and iron obtained in step (2) with saponified organic phase 2 (45% P204 extractant + 55% kerosene (V / V)) for extraction to obtain an organic phase containing bismuth, iron, and rare earth and a raffinate containing nickel. The pH of the raffinate containing nickel is 2.5. The extraction rate of bismuth is 99.9%, the extraction rate of iron is 100%, and the extraction rate of rare earth is 98.8%.

[0151] (6) Rare earth stripping: Mix the organic phase containing bismuth, iron and rare earth obtained in step (5) with 0.9 mol / L nitric acid solution, and perform four-stage countercurrent stripping to obtain a stripped solution containing rare earth and an organic phase containing bismuth and iron. The purity of the stripped solution containing rare earth is 99.8%.

[0152] (7) Bismuth and iron stripping: Mix the organic phase containing bismuth and iron obtained in step (6) with 0.9 mol / L aqueous oxalic acid solution (the molar ratio of oxalic acid to iron ions in the organic phase containing bismuth and iron is 22:1), and perform four-stage countercurrent stripping to obtain the empty organic phase 2, an iron-containing stripped solution and bismuth oxalate solid phase. The empty organic phase 2 is saponified and then returned to step (5). The purity of bismuth oxalate is 99.8%.

[0153] (8) Preparation of ferrous oxalate: Irradiate the iron-containing stripped solution obtained in step (7) to generate ferrous oxalate precipitate. After filtration, ferrous oxalate and oxalic acid solution are obtained. The obtained oxalic acid solution is supplemented with oxalic acid to 0.9 mol / L and then returned to step (7) for stripping. The precipitation rate of the ferrous oxalate is 93.2%, and the purity of the obtained ferrous oxalate product is 99.8%.

[0154] (9) Nickel extraction: Mix the nickel-containing aqueous phase obtained in step (5) with the saponified organic phase 3 (25% HBL110 extractant + 75% n-heptane (V / V)), and perform three-stage countercurrent extraction to obtain a nickel-containing organic phase and a raffinate. The pH of the raffinate is 7.5, and the extraction rate of nickel is 99.2%.

[0155] (10) Nickel stripping: Mix the nickel-containing organic phase obtained in step (9) with 0.5 mol / L hydrochloric acid solution for stripping to obtain a nickel-containing stripped solution and an empty organic phase 3. The empty organic phase 3 is saponified and then returned to step (9) for extraction. The purity of the obtained nickel-containing stripped solution is 99.5%.

[0156] Example 5

[0157] Composition of waste catalyst: MoO 3 15.84 wt%, NiO 4.24 wt%, Bi 2 O 3 3.84 wt%, RE 2 O 3 2.59 wt%, Fe 2 O 3 2.38 wt%, and the balance is carrier silica.

[0158] (1) Leaching: Using the waste catalyst as raw material, add 1.7 mol / L sulfuric acid aqueous solution for two-stage countercurrent leaching to obtain a leaching solution containing molybdenum, nickel, bismuth, rare earth, iron and silicon and a leaching residue. The purity of silica in the obtained leaching residue is 98.7%.

[0159] (2) Extraction of molybdenum and silicon: Mix the leaching solution containing molybdenum, nickel, bismuth, rare earths, iron, and silicon obtained in step (1) with organic phase 1 (10% N235 extractant + 10% N1923 extractant + 13% isooctanol + 67% kerosene (V / V)), and perform three-stage countercurrent extraction to obtain an organic phase containing molybdenum and silicon and a raffinate containing nickel, bismuth, rare earths, and iron. The extraction rate of molybdenum is 99.6%, and the extraction rate of silicon is 85.36%.

[0160] (3) Stripping of molybdenum and silicon: Mix the organic phase containing molybdenum and silicon obtained in step (2) with a mixed solution of 3.5 mol / L ammonia water + 3.5 mol / L potassium carbonate for stripping to obtain a stripping solution containing molybdenum and silicon and the empty organic phase 1. The empty organic phase 1 is returned to step (2) for extraction. The stripping rate of molybdenum is 99.3%.

[0161] (4) Separation of molybdenum and silicon: Adjust the pH of the stripping solution containing molybdenum and silicon obtained in step (3) to 7.6, heat to boiling, filter to remove silicon, and evaporate and crystallize the obtained liquid to obtain a molybdate product with a purity of 99.9%.

[0162] (5) Extraction of bismuth, iron, and rare earths: Mix the raffinate containing nickel, bismuth, rare earths, and iron obtained in step (2) with the saponified organic phase 2 (15% Cyanex272 extractant + 15% P204 extractant + 70% octane (V / V)) for extraction to obtain an organic phase containing bismuth, iron, and rare earths and a raffinate containing nickel. The pH of the raffinate containing nickel is 2.5. The extraction rate of bismuth is 99.9%, the extraction rate of iron is 99.9%, and the extraction rate of rare earths is 98.9%.

[0163] (6) Stripping of rare earths: Mix the organic phase containing bismuth, iron, and rare earths obtained in step (5) with a mixed solution of 0.4 mol / L nitric acid + 0.3 mol / L hydrochloric acid for four-stage countercurrent stripping to obtain a stripping solution containing rare earths and an organic phase containing bismuth and iron. The purity of the stripping solution containing rare earths is 99.6%.

[0164] (7) Stripping of bismuth and iron: Mix the organic phase containing bismuth and iron obtained in step (6) with a 0.6 mol / L aqueous oxalic acid solution (the molar ratio of oxalic acid to iron ions in the organic phase containing bismuth and iron is 15:1) for five-stage countercurrent stripping to obtain the empty organic phase 2, an iron-containing stripping solution, and a bismuth oxalate solid phase. The empty organic phase 2 is saponified and then returned to step (5). The purity of bismuth oxalate is 99.6%.

[0165] (8) Preparation of ferrous oxalate: Expose the iron-containing stripping solution obtained in step (7) to light to form ferrous oxalate precipitate. After filtration, obtain a ferrous oxalate product and an oxalic acid solution. The obtained oxalic acid solution is supplemented with oxalic acid to 0.6 mol / L and then returned to step (7) for stripping. The precipitation rate of ferrous oxalate is 92.6%, and the purity of the obtained ferrous oxalate product is 99.9%.

[0166] (9) Extraction of nickel: The nickel-containing raffinate obtained in step (5) is mixed with the saponified organic phase 3 (25% 4PC extractant + 5% dinonylnaphthalenesulfonic acid + 70% kerosene (V / V)) and subjected to three-stage countercurrent extraction to obtain a nickel-containing organic phase and a raffinate, wherein the pH value of the raffinate is 7.5, and the nickel extraction rate is 99.9%.

[0167] (10) Nickel stripping: The nickel-containing organic phase obtained in step (9) is mixed with a mixed solution of 0.3 mol / L nitric acid and 0.2 mol / L hydrochloric acid for stripping to obtain a nickel-containing stripping solution and an empty organic phase 3. The empty organic phase 3 is saponified and returned to step (9) for extraction. The purity of the obtained nickel-containing stripping solution is 99.7%.

[0168] It can be seen from the results of the above examples that the method of the present invention can achieve nearly full recovery of valuable elements (molybdenum, nickel, bismuth, iron and rare earth) in waste catalysts, and can obtain products of higher purity.

[0169] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for recovering molybdenum, nickel, bismuth, iron and rare earths from waste catalysts, characterized in that, the method comprises the following steps: (1) Using waste catalysts as raw materials, adding an inorganic acid solution for leaching to obtain a leaching solution containing molybdenum, silicon, nickel, bismuth, iron and rare earths and leaching residues; (2) Mixing the leaching solution containing molybdenum, silicon, nickel, bismuth, iron and rare earths with organic phase 1 for extraction to obtain an organic phase containing molybdenum and silicon and a raffinate containing nickel, bismuth, iron and rare earths; (3) Mixing the organic phase containing molybdenum and silicon with an alkaline solution for back-extraction to obtain a back-extract solution containing molybdenum and silicon and a blank organic phase 1; (4) Mixing the raffinate containing nickel, bismuth, iron and rare earths obtained in step (2) with saponified organic phase 2 for extraction to obtain an organic phase containing bismuth, iron and rare earths and a raffinate containing nickel, and the pH of the raffinate containing nickel is 1.5 - 3; (5) Mixing the organic phase containing bismuth, iron and rare earths with an inorganic acid solution for back-extraction to obtain an organic phase containing bismuth and iron and a back-extract solution containing rare earths; (6) Mixing the organic phase containing bismuth and iron with an oxalic acid solution for back-extraction to obtain bismuth salt solids, an iron-containing back-extract solution and a blank organic phase 2.

2. The method according to claim 1, wherein, in the leaching residues in step (1), the purity of silicon dioxide is not less than 98%.

3. The method according to claim 1, wherein, in step (2), the extraction rate of molybdenum is not less than 99%; Preferably, the organic phase 1 comprises an amine extractant, a modifier and a diluent; Preferably, the amine extractant is selected from at least one of N235 extractant, Aliquat 336 extractant and N1923 extractant; Preferably, the modifier is selected from at least one of isooctanol, sec-octanol, methyl isobutyl ketone and tributyl phosphate; Preferably, the diluent is selected from at least one of kerosene, n-heptane and octane; Preferably, based on the total volume of organic phase 1, the volume content of the amine extractant is 10 - 30%, the volume content of the modifier is 5 - 25%, and the volume content of the diluent is 45 - 85%.

4. The method according to any one of claims 1 - 3, wherein, in step (3), the back-extraction rate of molybdenum is not less than 99%; Preferably, in step (4), the extraction rate of bismuth is not less than 99%; and / or, in step (4), the extraction rate of iron is not less than 99%; and / or, in step (4), the extraction rate of rare earths is not less than 98%; Preferably, the purity of the rare earth-containing back-extract solution obtained in step (5) is not less than 99%; Preferably, the purity of bismuth oxalate obtained in step (6) is not less than 99.5%; and / or, in step (6), the back-extraction rate of iron is not less than 95%.

5. The method according to any one of claims 1 - 4, wherein, the organic phase 2 comprises a phosphoric acid extractant and a diluent; Preferably, the phosphoric acid extractant is selected from at least one of P204 extractant, P507 extractant and Cyanex272 extractant; Preferably, the diluent is selected from at least one of kerosene, n-heptane and octane; Preferably, based on the total volume of the organic phase 2, the volume content of the phosphoric acid extractant is 20-50%.

6. The method according to any one of claims 1-5, wherein, the method further includes: precipitating silicon from the molybdenum- and silicon-containing stripping solution obtained in step (3) at a pH of 7-9 to obtain a molybdate solution; Preferably, the molybdate solution is evaporated and crystallized to obtain a molybdate solid; Preferably, the purity of the molybdate solid is not less than 99.8%.

7. The method according to any one of claims 1-6, wherein, the method further includes: mixing the nickel-containing raffinate obtained in step (4) with the saponified organic phase 3 for extraction to obtain a nickel-containing organic phase and a raffinate, and the pH of the raffinate is 6.5-7.5; Preferably, the extraction rate of nickel is not less than 99%; Preferably, the organic phase 3 includes a pyridine ester compound, an acidic extractant, and a diluent; Preferably, based on the total volume of the organic phase 3, the volume content of the pyridine ester compound is 5-30%, and the volume content of the acidic extractant is 2-10%.

8. The method according to claim 7, wherein, the method further includes: mixing the nickel-containing organic phase with an inorganic acid solution for back-extraction to obtain a nickel-containing back-extraction solution and the empty organic phase 3; Preferably, the purity of the nickel-containing back-extraction solution is not less than 99%.

9. The method according to any one of claims 1-8, wherein, the iron-containing back-extraction solution obtained in step (6) is irradiated with light to obtain an iron oxalate precipitate; Preferably, the precipitation rate of the iron oxalate is not less than 90%.

10. The method according to any one of claims 1-9, wherein, the waste catalyst includes a carrier and a metal active component, the carrier is silica, and the metal active component includes molybdenum, nickel, bismuth, iron, and rare earth elements; Preferably, in the waste catalyst, based on oxides, the content of molybdenum element is 5-25 wt%, the content of nickel element is 1-15 wt%, the content of bismuth element is 1-8 wt%, the content of iron element is 1-8 wt%, and the content of rare earth element is 1-8 wt%.