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INVENTION
Patent of the Russian Federation RU2271399
METHOD OF LEAVING PALLADIUM FROM SLUDGE
The name of the inventor: Tatarinov Aleksey Nikolaevich (RU); Polyakov Leonid Alekseevich (RU); Smirnov Alexey Leonidovich (RU); Rychkov Vladimir Nikolaevich (RU); Monastyrev Yuri Alexandrovich (RU); Konoplina Louisa Yakovlevna
The name of the patent holder: Federal State Unitary Enterprise "Combine" Elektrokhimpribor "
Address for correspondence: 624200, Sverdlovsk Region, Lesnoy city, Federal State Unitary Enterprise "Combine" Elektrokhimpribor ", patent office
Date of commencement of the patent: 2004.08.10
The invention relates to the processing of recycled products containing palladium in the form of metallic, oxide and metal oxide forms and can be used in the production of stable isotopes during processing of the magnetic separation trap collection chambers and in palladium metallurgy in the processing of ores and concentrates containing oxidized and native Palladium, and in the technology of utilization of palladium-containing catalysts, as well as in analytical and preparative chemistry. Leaching of palladium from sludge containing palladium in the form of metallic, oxide and metal oxide forms is carried out by solutions of nitric acid in the presence of ammonium nitrate in the presence of weakly basic anionite of epoxy-polyamine type AN-31 with a concentration of nitric acid in the leaching solution of 120-190 g / l and nitrate Ammonium 160-240 g / l, followed by separation of the resin from the pulp, washing the anionite with water from the mother liquor and desorbing the palladium from the anion exchanger. The technical result is that the degree of leaching of palladium from sludges in a single step is substantially increased; Pure palladium solutions are obtained upon desorption from the anion exchanger; The number of operations of the subsequent solution processing technology is reduced in order to obtain palladium or its compounds, which in turn leads to a reduction in the consumption of reagents, the number of pieces of equipment and a reduction in the working time for servicing the redistribution of palladium.
DESCRIPTION OF THE INVENTION
The method for leaching palladium from slurries relates to the processing of recycled products containing palladium in the form of metallic, oxide and metal oxide forms and can be used in the production of stable isotopes during processing of the units of magnetic separator trapping chambers and in metallurgy of palladium during processing of ores and concentrates, Containing oxidized and native palladium, and in the technology of utilization of palladium-containing catalysts, as well as in analytical and preparative chemistry.
The known method [RU 2211251 C2 (IPC C 22 V 11/00), publ. 27.08.2003] extraction of platinum group metals, including palladium in the form of metallic, oxide and metal oxide forms, from anode slimes formed during the electrorefining of copper. The method includes dissolving the slurry in nitric acid, potentiostatic electrolysis on a porous electrode from the carbon material, and concentrating the remaining metal in the solution on a solid extractant, returning the reextract to the electrolytic metal recovery cycle. This method provides, using nitric acid, a high degree of leaching of palladium from anode copper electrorefining slurries, the completeness of subsequent extraction of metal ions from the obtained leach solutions and a high degree of separation of palladium and impurities.
The disadvantage of the known method - the prototype - is that the acid leaching method does not ensure full palladium opening of a large number of oxidized sludges, which leads to the loss of a valuable product. The completeness of the opening of palladium-containing products is especially important in the production of stable isotopes, since the loss of even a small amount of isotope-enriched material leads to a significant decrease in the economic efficiency of the technology due to the high cost of the isotope separation process. In addition, this method does not ensure selective leaching of platinum group metals. Therefore, in order to extract palladium, it is necessary to carry out additional operations for preparing and processing the resulting solutions, and this leads to an increase in the consumption of reagents and the number of operations, since any leaching process is usually associated with subsequent filtering operations, washing the precipitate from the mother liquor. This leads not only to the hardware complication of the process and the increase in the cycle time, but also to dilution of solutions and losses of the target component.
The technical object of the invention is to eliminate the above drawbacks and to provide a substantial increase in the degree of leaching of palladium from slimes in a single step. The production of pure palladium solutions upon desorption from anion exchanger, the reduction in the number of operations of the subsequent solution processing technology for the production of palladium or its compounds will result in a reduction in the consumption of reagents, the number of units of equipment, and a reduction in the working time for servicing the palladium conversion process.
The technical result is achieved by leaching of palladium from slurries containing palladium in the form of metallic, oxide and metal oxide forms, solutions of nitric acid, with palladium leaching being carried out by solutions of nitric acid (120-190 g / l) with the addition of ammonium nitrate (160-240 G / l) in the presence of weakly basic epoxy-polyamine type anionite AN-31, followed by separation of anionite from pulp, washing with water and desorption of palladium from anionite with ammonia solution.
The choice of concentrations of reagents in solution and anion exchanger for sorption leaching of palladium is due to the fact that under these conditions not only a high degree of extraction of palladium from slimes (more than 99%) is provided, but also separates it from impurities of iron, copper, zinc, nickel, titanium Chromium, manganese, gold, silver, etc. With the use of sorption leaching of palladium, a series of so-called persistent sludges are opened, of which palladium is not leached by solutions of nitric acid, which are offered by the known method.
A comparison of the effectiveness of the proposed and previously known prototype method is given in the examples.
Example 1 . Leaching of palladium was carried out from a sludge with an average palladium content of 1%. The experiment was carried out under the following conditions. Weighed slurry, crushed to a particle size of less than 0.1 mm, in an amount of 5 g was filled with 100 ml of solution with a certain concentration of reagents. In parallel, a similar experiment was conducted to leach palladium in the presence of anionite AN-31, which was introduced into the prepared solution. A resin fraction with a grain size of more than 0.5 mm was used to carry out the leaching, which subsequently ensured easy separation of the resin from the pulp. The leaching was carried out with constant stirring by air for 24 hours. This method of mixing prevented the mechanical destruction of the anion exchanger. After the end of the leaching, the resin was separated from the pulp on a polypropylene sieve having a mesh size of 0.3 mm. The resin was washed with 100 ml of water. The washings were combined with pulp. The pulp was then filtered. The precipitate was washed with water to a neutral pH of the filtrate. The washings were combined with the mother liquor. The precipitate was dried. The filtrate was evaporated to the original volume of the solution. After that, a resin sample was taken for analysis on palladium. The analysis for the content of palladium was subjected to dried sludge and filtrate. In addition, to check the obtained results, palladium from the anion exchanger was desorbed with a 25% solution of ammonia diluted 2 times with distilled water. The eluates were analyzed for the content of palladium. The results obtained as a result of the experiments are presented in Table 1.
As follows from the data presented in Table 1, the degree of leaching of palladium without anionite is much lower than without its addition to pulps. And palladium poorly leached with concentrated nitric acid and a mixture of hydrochloric and nitric acids ("royal vodka"). However, not in all solutions there is complete sorption leaching. At a nitric acid concentration above 3 M, partial destruction of the anion exchanger is observed, which was observed by the decrease in the mass of the resin. The loss of weight of the anion exchanger after 24 hours of contact with a 4 M HNO 3 + 3 M solution of NH 4 NO 3 was 0.95 g (based on the weight of the dry anion exchanger in the NO 3 form), which amounted to about 10% of the initial sample. In tsarist vodka, the anion exchanger almost completely decomposed.
On the other hand, in the range of reagent concentrations of 2-3 M in HNO 3 and 2-3 M in NH 4 NO 3, when anion exchanger AN-31 is added to the pulp, almost complete leaching of palladium is achieved, whereas, without anionite, the degree of palladium leaching is only 65-70%.
| Table 1 | |||||||
| The results on the leaching of palladium from isotope sludge by various solutions in the presence of AN-31 anion exchanger, in comparison with leaching without anion exchanger | |||||||
| Composition of solution for palladium leaching | Leaching of palladium from the slurry with the addition of 10 g of anionite | Leaching without anion exchanger | |||||
| Pd content in the slurry, mg | Content of Pd in solution, mg | Pd content in ionite, mg | The degree of sorption leaching of Pd,% (% Pd to ion exchange / total leaching) | Pd content in the slurry, mg | Content of Pd in solution, mg | Degree of leaching Pd,% | |
| 0.5 M HNO 3 | 56 | 0.0 & gt; | 44.0 | 44.0 | 87.7 | 22.3 | 22.3 |
| 1 M HNO 3 | 0.0 & gt; | 49.4 | 49.4 | 50.6 | 65.7 | 34.3 | 34.3 |
| 3 M HNO 3 | 42.2 | 0.1 | 57.7 | 57.8 | 53.6 | 47.4 | 47.4 |
| * 4 M HNO 3 | 31.7 | 0.5 | 65.3 | 65.8 | 46.1 | 53.0 | 53.0 |
| 1 M HNO 3 +1 M NH 4 NO 3 | 46.0 | 0.0 & gt; | 53.6 | 53.6 | 69.9 | 30.1 | 30.1 |
| 2 M HNO 3 +1 M NH 4 NO 3 | 16.8 | 0.0 & gt; | 83.9 | 83.9 | 51.7 | 48.6 | 48.6 |
| 1 M HNO 3 + 2M NH 4 NO 3 | 17.1 | 0.0 & gt; | 82.6 | 82.6 | 50.9 | 48.9 | 48.9 |
| 2 M HNO 3 + 2M NH 4 NO 3 | but | 0.2 | 99.7 | 99.9 | 35.2 | 64.7 | 64.7 |
| Composition of solution for palladium leaching | Leaching of palladium from the slurry with the addition of 10 g of anionite | Leaching without anion exchanger | |||||
| Pd content in the slurry, mg | Content of Pd in solution, mg | Pd content in ionite, mg | The degree of sorption leaching of Pd,% (% Pd to ion exchange / total leaching) | Pd content in the slurry, mg | Content of Pd in solution, mg | Degree of leaching Pd,% | |
| 3 M HNO 3 + 2 M NH 4 NO 3 | but | 0.6 | 99.3 | 99.9 | 32.0 | 67.8 | 67.8 |
| 2 M HNO 3 +3 M NH 4 NO 3 | but | 0.7 | 99.3 | 100 | 31.5 | 68.5 | 68.5 |
| 3 M HNO 3 +3 M NH 4 NO 3 | but | 2.3 | 97.6 | 99.9 | 27.0 | 72.5 | 72.5 |
| * 4 M HNO 3 + 3 M NH 4 NO 3 | but | 3.6 | 96.3 | 99.8 | 72.8 | 72.8 | |
| 15.7 M HNO 3 at a temperature of 120 ° C | 36.4 | 63.6 | 63.5 | ||||
| 15.7 M HNO 3 at a temperature of 95 ° C | 28.2 | 72.0 | 72 | ||||
| ** HCl conc + HNO conc. In a ratio of 3: 1 (making vodka) | 24.5 | 75.5 | The resin dissolved | 75.5 | 25.7 | 74.2 | 74.2 |
| * Partial dissolution of anion exchanger; ** complete dissolution of anion exchanger | |||||||
Thus, a decrease in the concentration of nitric acid in leaching solutions below 2 M leads to a decrease in the degree of sorption leaching, and an increase in its content exceeding 3 M contributes to the intensive destruction of the anion exchanger.
Example 2 . 5 grams of ground palladium-containing slurry were poured into 100 ml of a solution containing 130 g / l nitric acid and 150 g / l ammonium nitrate. 15 ml of resin AN-31 was introduced into the pulp. In the sludge, the amount of palladium was 0.168 g. After leaching for 24 hours, the resin was separated from the pulp and washed with water. Further palladium from the resin was desorbed with 12% ammonia solution. The volume of the resulting eluate was 200 ml. The eluate was analyzed for impurity content. The data obtained are presented in Table 2. In parallel, palladium leaching was carried out with a solution of 2 M HNO 3 containing 2 M NH 4 NO 3 . After leaching, the precipitate was separated from the solution by filtration and analyzed for impurity content (Table 2).
Table 2 Content of palladium and impurities in solutions obtained after palladium leaching by the known method and in eluates after sorption slurry leaching
Content of the main components in the initial slurry,%: Pd - 3,36; Cu-34; Fe: 23.1; Cr is 4.9; Ti is 0.1; Zn = 1.9; Cd = 0.1; Al - 8.7
| Solutions | Palladium and impurities content, g / l | |||||||
| Pd | Cu | Fe | Cr | Ti | Zn | Cd | Al | |
| A solution of concentrated nitric acid (according to the prototype) | 0.48 | 22.36 | 1.31 | 1.20 | 0.09 | 2.91 | 0.34 | 0.38 |
| Eluates after desorption of palladium from anionite AN-31 | 0.835 | 0.003 | 0.002 | 0.003 | Not exposed. | Not exposed. | Not exposed. | Not revealed. |
The obtained data showed that at a high degree of leaching of palladium from the slurry 99.4% (according to the prototype 57%) the eluates obtained after the desorption of palladium from the anion exchanger contain a small amount of impurities. The metal, which was obtained from the solutions by reduction with hydrazine, contained impurities less than 0.1%.
Example 3 . To determine the necessary amount of resin for the sorption leaching of palladium, various anionite AN-31 samples were introduced into the pulp. The original pulp was prepared as in the previous example. The sample of the slurry in an amount of 5 g was filled with 100 ml of a solution with a concentration of nitric acid and ammonium nitrate of 2 M of each reagent. Anion exchanger AN-31 was then added to the slurry in the amount of 1, 3, 5, 8, 10 g. After leaching, the resin was separated from the pulp, and the content of palladium was determined therein. As described in Example 1, solutions and slurry were analyzed. Based on the results obtained, the degree of leaching of palladium was determined (Table 3). From the data in Table 3 it follows that when 1 g of anionite is introduced into 30 mg of palladium, the degree of palladium leaching reaches more than 98%.
| Table 3 | |||||
| The degree of leaching of palladium from the sludge, depending on the amount of AN-31 anionite introduced into the pulp | |||||
| The amount of anionite AN-31 in the pulp, g | Pd content in the slurry, mg | Content of Pd in solution, mg | The content of Pd in the anion exchanger, mg | The degree of transition of palladium to anionite,% | Total degree of leaching of palladium,% |
| 1 | 60.2 | 44.1 | 63.3 | 37.7 | 63.9 |
| 3 | 11.2 | 4.9 | 152.0 | 90.5 | 93.4 |
| 5 | 1.5 | 1.1 | 165.5 | 98.5 | 99.2 |
| 8 | 0.8 | Not obn. | 167 | 99.4 | 99.4 |
| 10 | Not obn. | Not obn. | 167 | 99.4 | 99.4 |
Example 4 . To establish the optimum ratio of M: T in pulps, a series of experiments was carried out in which 5 g of sludge and 5 g of ion exchanger were taken in different volumes of the leach solution (25 ml, 50 ml, 75 ml, 100 ml) with the concentration of reagents indicated in the example 3. The results of the experiments are summarized in Table 4.
| Table 4 | |||||
| The degree of leaching of palladium as a function of the ratio M: T | |||||
| Volume of leach solution, ml | Pd content in the slurry, mg | Content of Pd in solution, mg | The content of Pd in the anion exchanger, mg | The degree of transition of palladium to anionite,% | Total degree of leaching of palladium,% |
| 25 | 12.3 | Not obn. | 155.9 | 92.8 | 92.8 |
| 50 | 2.1 | Not obn. | 165.7 | 98.6 | 98.6 |
| 75 | 1.3 | 1.1 | 165.5 | 98.5 | 99.2 |
| 100 | 0.9 | 1.1 | 166.3 | 99 | 99.6 |
| 150 | 0.8 | 1.1 | 166.3 | 99 | 99.7 |
From this example it follows that the minimum ratio of M: T should be 5: 1. A further decrease in the ratio of the liquid and solid phases leads to a decrease in the degree of leaching of palladium. In addition, at low values of the ratio Ж: Т, the process of separating the resin from the pulp is complicated.
An increase in the ratio of M: T over 20 is inadvisable, since it leads to an additional expenditure of reagents. It follows that the optimal ratio of G: T in leaching, which provides a high degree of palladium recovery from slimes and does not lead to excessive consumption of reagents, lies in the range 1: 10 ÷ 1: 20.
Thus, the use of the proposed method allows:
A) significantly increase the degree of leaching of palladium from slimes in a single step;
B) to obtain pure solutions of palladium upon its desorption from the anion exchanger;
C) reduce the number of operations of the subsequent processing technology solutions to obtain palladium or its compounds, which in turn leads to a reduction in the consumption of reagents, the number of pieces of equipment and reducing the working time for servicing the redistribution of palladium.
CLAIM
1. A method for leaching palladium from slimes containing palladium in the form of metallic, oxide and metal oxide forms using a nitric acid solution, characterized in that palladium leaching is carried out by solutions of nitric acid with the addition of ammonium nitrate and weakly basic epoxy-polyamine type anionite AN-31, followed by Separation of anionite from pulp, washing with water and desorption of palladium from the anion exchanger with ammonia solution.
2. A process according to claim 1, characterized in that the concentration of nitric acid in the leach solution is maintained within the range of 120-190 g / l, and the ammonium nitrate is 160-240 g / l.
3. A method according to claim 1, characterized in that the ratio of sludge: the leach solution is maintained in the range of 1: 10-1: 20.
4. The method of claim 1, wherein the anion exchanger is introduced into the palladium leaching slurry in an amount of at least 1 g per 30 mg of palladium contained in the slurry.
print version
Date of publication 14.03.2007gg
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