RU2490342C1 - Processing method of deactivated catalysts on carriers from aluminium oxide, which contain metals of platinum group and rhenium - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method involves roasting of a catalyst, leaching of a roasted product in acid medium and introduction to the obtained pulp of reagents to improve filtration. Then, non-soluble residue is separated from the solution by filtration and metals of platinum group and rhenium are extracted from the solution. Prior to filtration the pulp is treated with water solution of flocculant of cationic type based on polyacrylamide. The obtained reaction mixture is exposed without mixing till solid and liquid phases are separated. Then, clarified part of the solution is separated by decantation and paper pulp in the form of paper wastes in the quantity of 10-20 kg/m³ of the pulp is added to thickened pulp and mixed, and filtration is performed.

EFFECT: improving efficiency of separation of non-soluble residue from the solution; reducing costs for filtration materials.

1 ex

Description

The invention relates to the field of metallurgy of non-ferrous and noble metals (BM), in particular to methods for the extraction of platinum group metals and rhenium from deactivated (spent) catalysts and can be used in the processing of secondary raw materials.

Catalysts containing platinum metals on alumina supports are widely used in the petrochemical, chemical and several other industries. The platinum (palladium) content in various grades of catalysts varies from 0.05 to 2.0%. Some brands of catalysts contain rhenium along with platinum.

During operation, the catalysts gradually lose their catalytic activity and enter the metallurgical industry for processing in order to extract valuable components.

A known method for the extraction of platinum and rhenium from spent catalysts (Thematic review. Extraction of valuable metals from spent heterogeneous catalysts, TsNIITEneftekhim, M., 1988, p.22). The catalysts are oxidatively fired at 300-500 ° C to burn carbon. Then, the calcined catalyst is leached in hydrochloric acid or “aqua regia” at temperatures of 20-90 ° C. Valuable components are recovered from the resulting solution by ion exchange.

One of the main disadvantages of this method (as well as many other hydrometallurgical methods) is the very low pulp filtration rate.

Closest to the technical nature of the claimed is a method of processing catalysts containing platinum group metals and rhenium on alumina supports, according to which spent catalysts are calcined at a temperature of 600 ° C, the calcined product is leached in sulfuric acid. In the resulting pulp at a temperature of 80-90 ° C, a wet concentrate of dust from refining electrostatic precipitators is added, and then cementation is carried out with aluminum powder and filtered. The solution enters the sorption extraction of rhenium, and the precipitate is dried and subsequently concentrated by separation and smelting (Patent No. 2306347 (Russia). A method for processing catalysts containing platinum metals and rhenium on alumina supports. / Temerov S. A., Efimov V. N.). This method is adopted as a prototype.

The disadvantages of the method of the prototype include the following points. The dust concentrate of electrostatic precipitators is an internal industrial product of refining production. It includes all the metals of the platinum group, silver, as well as a number of base elements in the form of various chemical compounds, including those soluble in acids. When a dust concentrate of electrostatic precipitators is introduced into an acidic solution, part of the noble metals contained in it passes into the solution. In this regard, in the subsequent cementation operation, an additional consumption of aluminum powder is required for the recovery of precious metals electrostatic precipitators that have passed into the solution from dust concentrate. In addition, some of the metals that have passed into the solution are in the form of strong chemical compounds, and during subsequent processing with aluminum powder, they cannot be quantitatively precipitated. Thus, some of the noble metals are irretrievably lost with waste solutions. At the same time, the mass of the insoluble residue increases and its further processing is much more complicated.

The technical result to which the proposed method is directed is to use such reagents that can effectively separate the insoluble residue from the solution, reduce the cost of filter materials, the cost of extracting valuable components from the resulting solutions and at the same time do not have the listed disadvantages inherent prototype method.

The desired technical result is achieved by the fact that in the known method of processing deactivated catalysts on alumina supports containing platinum group metals and rhenium, which includes calcining the catalysts, leaching the calcined product in an acidic medium, introducing reagents into the resulting pulp to improve filtration, separating the insoluble residue from solution by filtration, extraction of a platinum group and rhenium from a solution of metals by known methods, before filtering, the pulp is treated with an aqueous solution cationic flocculant based on polyacrylamide, the resulting reaction mixture is kept without stirring until the solid and liquid phases are separated, the clarified part of the solution is separated by decantation, and paper pulp is introduced into the thickened pulp (paper waste, waste paper, napkins, toilet paper, filter paper, etc. .) in an amount of 10-20 (kg / m ³ ) pulp, mix and filter.

The essence of the method is as follows. When the calcined catalyst is leached in an acidic medium, in particular hydrochloric acid with the addition of nitric acid as an oxidizing agent, a pulp is formed containing colloidal particles of aluminum oxide. When processing such a pulp with an aqueous solution of a cationic flocculant based on polyacrylamide and keeping the reaction mixture without stirring, the system is divided into a clarified acid solution and a thickened pulp. Most of the clarified solution is then easily separated by simple decantation. Condensed pulp is a gel-like mass containing a solution that is very slowly filtered. Special studies showed that the filtration rate increases sharply if 10-20 (kg / m ³ ) of paper pulp (paper production waste, waste paper, tissue paper, toilet paper, filter paper, etc.) is introduced into the thickened pulp and mixed.

The achievement of the technical result is ensured when the amount of paper pulp additive is from 10 to 20 kg / m ^{3 of} thickened pulp (calculated on the dry pulp).

When adding less than 10 kg of paper pulp per 1 m ^{3 of} thickened pulp, the filtration rate decreases. The addition of more than 20 kg of paper pulp per 1 m ^{3 of} thickened pulp is impractical, since it leads to unproductive consumption of paper pulp, an increase in the mass of insoluble residue and a decrease in the efficiency of filtering equipment.

Process usage example:

100 g of the deactivated catalyst on an alumina carrier containing 0.27% platinum and 0.32% rhenium were taken and calcined in an electric furnace in an atmosphere of air at a temperature of 600 ° C for 1 h. The calcined product was pulp in 200 ml of water, added 3 ml of nitric acid (d = 1.40 g / cm ³ ) and 600 ml of hydrochloric acid (d = 1.18 g / cm ³ ). The pulp was kept for 4 hours with stirring and a temperature of 90 ° C, then it was cooled to a temperature of 30 ° C. Received 780 ml of pulp into which a 0.1% aqueous solution of a cationic flocculant type based on polyacrylamide (trademark "ZETAG") was introduced. The resulting reaction mixture was kept without stirring for 0.5 hours, then 650 ml of the clarified solution were separated by decantation. 1.6 g of filter paper was introduced into the remaining 130 ml of condensed pulp, the pulp was stirred for 0.5 hours, then it was filtered using a Bunsen laboratory flask, a Buchner funnel and a paper filter. The solutions were combined. The specific filtration rate was 188.3 l / (m ² * h). This is 5-7 times higher than in the prototype method (under comparable conditions).

Received 14.4 g of a wet insoluble residue (w = 35%) and 764 ml of a solution containing 349 mg / l of platinum and 410 mg / l of rhenium. Thus, about 99% of platinum and rhenium passed into the solution. The solution was sent to treatment with sodium thiosulfate to obtain a collective sulfide concentrate and the subsequent separation of rhenium and platinum from it by known methods.

The use of the proposed invention in the processing of catalysts containing platinum metals and rhenium allows to simplify and significantly accelerate the separation of the acid solution from the insoluble residue by filtration, to reduce the consumption of filter materials and the cost of processing the resulting industrial products.

Claims (1)

A method of processing deactivated catalysts on alumina supports containing platinum group metals and rhenium, including firing the catalyst, leaching the calcined product in an acidic medium, introducing reagents into the resulting pulp to improve filtration, separating the insoluble residue from the solution by filtration, extracting the platinum group metals from the solution and rhenium, characterized in that before filtering the pulp is treated with an aqueous solution of a cationic flocculant based on polyacrylamide obtained The reaction mixture is kept without stirring until the solid and liquid phases are separated, the clarified part of the solution is separated by decantation, paper pulp is introduced into the thickened pulp in the form of paper waste in an amount of 10-20 kg / m ^{3 of} pulp, mixed and filtered.