Method for separating enriched palladium from waste Pd/Al2O3 catalyst chloride leaching solution

Abstract

The invention provides a method for separating enriched palladium from a waste Pd/Al2O3 catalyst chloride leaching solution. The method mainly comprises the steps of adjusting pH in advance, performing sulfide precipitation, and acidizing to remove impurities. A waste Pd/Al2O3 catalyst is chloridized and dissolved so as to obtain a leaching solution, firstly, a NaOH solution is added, so that Al<3+> in the leaching solution exists in forms of meta-aluminic acid radical ions, other alkali metal ions are precipitated in the form of hydroxide, then a Na2S solution is added, so that [PdCl4]<2> in the leaching solution is converted into PdS, and finally, hydrochloric acid is added, so that the hydroxide is dissolved, and palladium sulfide is effectively separated from alkali metal impurities. The palladium recovery rate reaches 100%, and the purity is more than 95%. The method has the advantages of good selectivity, simplicity in operation, high enrichment efficiency, economy and environmental friendliness, toxic gas H2S cannot be generated, additionally, aluminum and palladium can be recycled, and the method is suitable for mass production.

Description

technical field [0001] The invention belongs to the field of secondary resource recovery and utilization, and relates to a waste Pd / Al 2 o 3 The method for separating and enriching palladium from the leaching solution by oxidizing and dissolving the catalyst solves the current problems such as the low recovery rate of palladium enriched from the leaching solution by oxidizing and dissolving, causing environmental pollution and the like. Create favorable conditions for realizing the comprehensive recycling of palladium. Background technique [0002] Palladium is the most active metal among platinum group metals. Palladium has many unique chemical and physical properties, which make it have unique catalytic activity and biological activity, stable service life and long-term storage value. Alternative specialty metals. Palladium is an efficient catalyst in chemical reactions. The precious metal palladium is widely used in hydrogenation, dehydrogenation, oxidation, reduction,...

AI Technical Summary

Problems solved by technology

So he stopped adding Na when the precipitation was nearly 100% 2 S, then add excess Na 2 S has no "necessary" means to control Na 2 The amount of S, it can be seen that the end point is difficult to control in the practical application of his method, in order to make the palladium precipitation completely will produce toxic gas H 2 S

[0005] Chen Jing thought in "Reaction Mechanism and Application of Sodium Sulfide and Chloropladium Acid" that Pd can be quantitatively precipitated directly with sodium sulfide, the reaction is rapid and the precipitation rate is high, but because it uses a solution prepared from pure minerals, the interference of impurity ions is small, Especially in the process of leaching palladium with aluminum-based catalysts, a large amount of aluminum will be leached, and aluminum will form aluminum hydroxide precipitation under low pH conditions (4-5), while the pH of the palladium precipitation end point controlled by him is about 7-8, and the hydroxide Aluminum cannot be dissolved, so filtration is difficult, palladium loss is serious, and the green environmental protection requirements of comprehensive utilization of palladium and aluminum cannot be met