The method of extraction of platinum and palladium from materials with a porous base

 

(57) Abstract:

The invention relates to hydrometallurgy of platinum metals. The method of extraction of platinum and palladium from spent catalysts with different types of bases includes translating them into water-soluble oxidation state compounds. Thus forming complex ions of platinum metals in higher oxidation States by the action of reducing agents translate into lower, the resulting solution is separated from the solid residue and extract the metals by known methods. The restoration carried out by a solution of sodium oxalate or sulphate of iron (II). The technical result is an increase in the content of platinum and palladium in the solution and increasing the degree of extraction. 1 C.p. f-crystals.

The invention relates to the metallurgy of platinum metals and can be implemented in specialized enterprises, processing of secondary raw materials, which are deactivated catalysts, as well as refineries, used primary platinum concentrates and intermediates his limit.

The literature describes many ways of processing one of the most intensive on the content of platinum technogenic raw materials, which is Bo the catalysts for petrochemical enterprises, basic organic and inorganic synthesis, synthetic rubber, gas cleaning systems in different industries, including neutralizers automobile emissions, etc.

Great list of developing catalytic processes dictates the expansion of the types of catalysts. This leads not only to changes in the composition of the catalytic metals or their compositions, but also changes in the chemical forms of the basics of the used catalysts, which are constantly expanding. Typical types of media are supported heterogeneous catalysts are the oxides of aluminum and modifications, silicates, various spinels, zeolites, pumice, modified carbon composition, etc., it is Obvious that it is extremely difficult to create a universal method of processing the entire range of existing catalysts. This is due to two main reasons. The first group of methods is based on the principle of the transfer medium in a soluble state by various methods, such as acid or alkaline (patent of Russia 2138568 from 02.09.98, patent of Russia 2124572 from 10.01.99), has the limitation of working only with catalysts on the basis of Al2ABOUT3. However, during operation of the reforming catalyst in it constantly accumulates things"raskoksovyvaniya". This portion of the catalyst having an appreciable amount of aluminum oxide other resistant to opening forms, capsulebuy noble metal and go into a large amount of insoluble residue. The desired high ratio of concentration will not occur. The second group of methods using different oxidizing environment for the purpose of transfer of platinum metals in solution with separation from the basics (patent of Russia 2116362 from 01.04.97 - prototype), also has a significant drawback associated with the difficulty and sometimes impossibility of full recovery of metals. It is connected with the General problem is more complete translation of the metals in solution in the presence of a large number of insoluble substrate with high surface area, reaching values of 120-140 m2/,

The technical result of the invention is the increase in the content of platinum and palladium in the solution and increasing the degree of extraction.

The technical result is achieved in that in the method of extraction of platinum and palladium from spent catalysts with various types of foundations, including their transfer to solution processing oxidizing mixtures and separation of a solution of platinum and palladium, while formed at pervaia reducing agents, the resulting solution is separated from the solid residue and extract platinum and palladium, at the same time as reducing agents use a solution of sodium oxalate or sulphate of iron (II).

Distinctive features of the invention are the translation of complex ions of platinum and palladium from a higher oxidation States in the lower by the action of reducing agents, the use of reducing agents sodium oxalate or sulphate of iron (II).

At the first stage of creation of a unified processing technology catalysts on different bases it is necessary to conduct phase transfer of platinum group metals in water-soluble state. This is achieved in the process of oxidation of a wide range of reagents that are best adapted to the specific production. It is only important to consider the chemical individuality of the noble metal, environmental safety and economic efficiency of the used reagents. In hydrometallurgical variant is concentrated solutions of nitric acid, tsarskovodochnom mixture, chlorinate elemental chlorine, other gloriously compositions, etc.

Another area of application of the proposed method lies in the possibility of the cleaning of the platinum metals, as well as the processing of inorganic sorbents used as fillers locking columns drain solutions refining, where the problem of reducing the content of precious metals held on the surface of hydrated oxides.

The novelty of the proposed method is to conduct further operations that contribute to the shift in the balance of sorption processes complex ions of platinum on well-developed surface of the base and their desorption from going into solution. The shift in the balance of sorption process can be carried out principally by two methods. At first this can be achieved by conducting multiple leaching and subsequent filtering. The volume of new batch of solvent quickly saturated to equilibrium salts of platinum metals and it has to update. However, the introduction of all new portions of the solution leads, ultimately, to get "Razboinik" solutions large volume, which entails the complexity of their further processing. And the main goal is to reduce the residual content of precious metals on the catalyst to the level of their concentration is much less than in natural raw materials, is not solved.

The second way, which is akin to the metal in order to shift the equilibrium in favor of the solution. Scientific substantiation of such opportunities are experimentally established facts according to extraparameter in the organic phase of the complex ions of the same Central atom with different ligand environment. For example, the extraction constants for ion pairs of the form [PtCl6]2-and [PtCl4]2-, [PdC16]2-and [PdCl4]2-vary at least a thousand times, having a smaller value for PT(II) and PD(II). This effect is associated with an increase in the hydration energy complex of metal ions in low charge state of the Central atom due to the smaller geometrical size and coordination of water molecules on the third coordinate. Experimental data on the anion-exchange extraction of coordination compounds with different ligands and calculations of the hydration energy indicate a sharp increase in energy of hydration of the ions with the lower oxidation state of the Central atom. In other words, you must change the chemical form of finding platinum metal in the solution so that she had the best possible in the particular circumstances of the enthalpies of hydration, since the main contribution to the energetics of the process makes solvation component.

Based on the above it follows that the essence of the method consists in the quantitative translation of chlorocomplexes, such as Pt and / or Pd of the highest degree of oxidation in the lower, which allows to increase the content of platinum and palladium in the solution and, ultimately, leads to high levels of extraction of metals. Such operations associated with the change in the degree of oxidation complex of platinum metals, are often held at affinage, but only for the purpose of separation, for example, Pt and Ir, and are characterized by a high degree of development.

Example 1. 1000 g of spent catalyst reforming AP-64, containing in wt.%: Pt - 0,62, carbonaceous deposits is 2.8, silicon oxide - 1,6, sulfur - 0,9-based-Al2ABOUT3placed in a titanium Cup and pour a solution of hydrochloric acid (1:5) with a volume of 1000 ml and heated to boiling point. After this solution in portions enter 25 ml conc. nitric acid and heating is continued for 0.5 hour. The cooled solution leaching is drained by decantation. Then add 600 ml and the e distillation of nitrogen oxides in the reaction mixture was added 12 g of sodium oxalate and heating continued for 1 hour. The cooled solution is again decanted, transferred to a filter and washed with 200 ml of a 5% solution of sodium oxalate and 400 ml of water under vacuum. Decanted and wash water are combined and emit platinum deposition mobiles aqueous solution of hydrate of hydrazine. Subsequent cleaning is performed by known methods. The residual content of platinum in the insoluble residue, a certain chemical spectral analysis is of 0.003 wt.%. The degree of extraction of platinum is at the level of 99.6 percent.

Example 2. A portion of the catalyst gas purification from nitrogen oxides brand APK-2 with the original palladium content of 1.98 wt.%, deposited on the granules of alumina-modification in the amount of 1200 g, placed in a titanium Cup and pour 800 ml of 20% sodium hypochlorite solution. The solution is heated and the parts make 250 ml conc. hydrochloric acid, then continue heating for 1 to 2 hours. During this period of recovery hydrolysis (as a reducing agent are water molecules) chlorocomplexes Pd(IV) to PD(II). Subsequent isolation and purification of palladium carried out by known methods. Taking into account the deadweight losses of palladium with leachate concentration <1 μg/ml and the residual content in the catalyst is about 0.001 wt.% when containing a series of 0.4% of platinum, applied to the zinc-aluminum spinel, placed in a Teflon reactor, treated with a mixture of 500 ml of 2 M hydrochloric acid and 50 ml of 40% HF. The slurry is heated to a temperature of 80oAnd 1.5 hours pass chlorine gas with a flow rate of 16 l/h After disabling chlorine spend it degassing, barbotine air when heated for 0.5 hours. To the obtained solution a La carte add 10 ml of a solution of FeSO4with a concentration of 1 M. the Selection of platinum is carried out at the conditions of example 1. The number of extracted platinum is 99,2% of its initial content.

Thus, implementation of the proposed method in technological practice does not require changes to existing equipment, the use of expensive or scarce reagents and can be easily adapted to any existing facilities.

1. The method of extraction of platinum and palladium from spent catalysts with various types of foundations, including their transfer to solution processing oxidizing mixtures and separation of a solution of platinum and palladium, characterized in that formed when the translation in the solution of complex ions of platinum and palladium in higher oxidation States translate into lower by the action of reducing agents, the floor is 1, characterized in that the reducing agent used solution of sodium oxalate or sulphate of iron (II).

 

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SUBSTANCE: invention relates to method for acid leaching of platinum method from secondary raw materials, in particular from ceramic support coated with platinum metal film. Target metals are leached with mixture of hydrochloric acid and alkali hypochlorite at mass ratio of OCl-/HCL = 0.22-0.25 and redox potential of 1350-1420 mV.

EFFECT: decreased leaching temperature, reduced cost, improved platinum metal yield.

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