Process for the selective deposition of palladium from a palladium - platinum-ammonia solutions
(57) Abstract:The invention relates to ferrous metallurgy, in particular to the separation of platinum group metals, and can be used in refining industries. The method involves the selective deposition of palladium from a palladium-platinum-ammonia solutions of water-soluble xanthates. The deposition of palladium carried out at a pH of 7.75 - 8.5 and pre-processing of the original solutions of hydrogen peroxide with a flow rate of 5.85 - 8,78 g per 1 g of platinum. The method allows for single stage to achieve a high degree of separation of palladium and platinum and simplify instrumentation. table 1. The invention relates to ferrous metallurgy, in particular to the separation of platinum group metals, and can be used in refining industries.Consider known from the prior art solutions selectively precipitate palladium and platinum.The most common method of separation of platinum and palladium deposition from chloride solutions (after tsarskovodochnom dissolution) chloroplatinate ammonium further processing palladium solutions with an excess of ammonia and hydrochloric acid. Get globaladmin perejimaut re-dissolution in ammonia and Osage is SS="ptx2">The disadvantages of the method:
1. Requires prior removal of nitrate ion from chloride solutions;
2. The method involves periodista globaladmin.The closest to the invention to the technical essence is a method of selective deposition of palladium from hydrochloric acid, sulfuric acid, nitric acid and ammonium chloride solutions by xanthates sodium at a flow rate of the precipitator 80-90% of what is needed to complete the deposition of palladium, which is taken as a prototype. [K. A. Karasev, I. A. I. A. Kakovskii. Some of sulfhydryl compounds of palladium. Non-ferrous metals, N 3, 1958. S. 47-54]. Data for hydrochloric acid solutions containing 1% HCl and 0.73 g/DM3platinum, palladium, copper, Nickel, rubidium, iridium and iron.The disadvantage of this method is the coprecipitation of platinum with palladium, which does not ensure receipt of palladium, which meets the requirements of GOST ratio of Pd:Pt over 2000.The analysis described above and analog prototype revealed that none of them achieved the desired result - selectivity of deposition of palladium from ammoniacal solutions containing platinum and palladium.The authors of the invention under the present application is a method of selective deposition PAL who CLASS="ptx2">The method includes the deposition of water-soluble palladium salt from the class of xanthates, such as ethyl or butyl xanthate sodium from ammoniacal solutions containing platinum and palladium.From the prototype of the proposed method differs in that the deposition of palladium soluble xanthate from ammoniacal solutions containing platinum and palladium, is carried out at a pH of 7.7 to 8.5 after pre-processing the original solutions of hydrogen peroxide based 5,85-8,78 g H2O2per gram of platinum.The inventive method for selective deposition of palladium from a palladium-platinum-ammonia solutions meets all the criteria of patentability.It is new, because those known from the prior art solutions do not have the identical set of features, as evidenced by the above analysis of the known technical solutions.Offer for patent protection an invention involves an inventive step, because its essence for professionals engaged in the refining of palladium is not obvious from the prior art, i.e. not identified solutions that have the signs consistent with the distinctive features of the proposed spasovski result.The inventive method for selective deposition of palladium allows to obtain a product with a ratio of Pd:Pt more than 2000, which provides for further processing by known methods, for example by calcining, and palladium production to meet the needs of the brand PDA-2 the content of platinum.The claimed invention is industrially applicable, because it can be used in the production of its purpose, i.e. for the selective deposition of palladium from ammonia solutions. No sign, taken separately, neither the totality of the features of the process does not contradict the possibility of their application in industry and do not hinder the achievement perceived by the applicant of the technical result.The modes of the method chosen experimentally. The deposition of water-soluble palladium xanthates, such as ethyl or butyl xanthate, sodium, lead into the reactor with stirring at a temperature of 15-25oC for 20 minutes. The xanthate was introduced at the rate of deposition of 85-95% palladium. The precipitate xanthate was filtered and washed with water, dried and analyzed for the content of platinum and palladium.Empirically set to pH ISV presented in the table. In the interval pH of the initial solution of 7.75-8.5 and the consumption of hydrogen peroxide 5,85-8,78 g per gram of platinum obtained xanthate precipitation of palladium with a ratio of Pd:Pt from 4942 to 6,138 for more than 2,5 times exceeds the requirements for palladium brand PDA-2.At pH 7.5 ammonia solutions is observed the formation of hydrate precipitation before the introduction of xanthate through joint hydrolysis of platinum and palladium, which eliminates the selectivity of the deposition. The pH of the initial solution of 9.0 dramatically reduces the selectivity of the deposition of palladium; the precipitate with a ratio of Pd:Pt, is equal to 1034.The introduction of hydrogen peroxide prior to deposition of the xanthate palladium increases the selectivity of the process. In the absence of an oxidant and at its expense 4,39 g per gram of platinum obtained indices of selectivity 2286 and 3054, respectively. The consumption of hydrogen peroxide over 8,78 g per gram of platinum reduces the selectivity of the deposition of palladium, which is caused by the occurrence of products of oxidation of xanthate.The method was tested on the industrial ammonium nitrate solutions obtained in the flowsheet silver refining OJSC "Uralelectromed", containing 30,57 g/DM3palladium and 0.44 g/DM3platinum and hadizadeh solution at pH 7.75, and a temperature of 20oC were treated with hydrogen peroxide based 5,854 g per gram of platinum. After this was introduced butyl xanthate sodium based 90% deposition of palladium. Was kept under stirring for 20 minutes. The precipitate was filtered, washed with water. The precipitate contained 24,71% palladium and 0.005% platinum.Other examples were carried out as in example 1. The consumption of the oxidizing agent, the pH of the initial solution, asked reagent precipitator, the composition of the sediment and the rate of selectivity are presented in the table.Positive results on the selective deposition of palladium from ammonium palladium-platinum solutions refining OJSC "Uralelectromed", instrumental and operational adaptability of the method allow us to consider how selective deposition of palladium from a palladium-platinum-ammonia solutions is industrially applicable.The industrial advantages of using the proposed method:
1. a high degree of separation of palladium and platinum, which gives a vintage palladium;
2. the single-stage process method and the simplicity of instrumentation. Process for the selective deposition of palladium from a palladium-platinum-ammonia solutions vadora the development of original solutions of hydrogen peroxide with a flow rate of 5.85 - 8,78 g per 1 g of platinum.
FIELD: noble metal hydrometallurgy.
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.