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INVENTION
Russian Federation Patent RU2132399
METHOD FOR PROCESSING alloy of platinum group metals
Name of the inventor: Bogdanov VI .; Ermakov AV .; Gorbatova LD .; Grokhovsky SV .; Lavrov AA .; Warriors VN .; Gryaznuhina LM .; Ephraim EH .; Grigoriev AN .; Novikov AE
The name of the patentee: Open Joint Stock Company "Ekaterinburg plant for processing non-ferrous metals"
Address for correspondence: 620014, Ekaterinburg, Lenina, 8 OJSC "Ekaterinburg plant for processing non-ferrous metals"
Starting date of the patent: 1998.04.21
The invention relates to metallurgy noble metals, in particular to electrochemical methods of processing alloys of platinum group metals (PGM), preferably binary, such as platinum-rhodium, platinum-iridium. The invention aims at improving the efficiency of the method, it simplified and improved process ecology. For this purpose, the starting material - PGM alloy is dissolved in an acidic medium with the addition of hydrogen peroxide. The essence of the invention is that the starting material takes the form of a briquetted scrap. As acidic medium using concentrated hydrochloric acid, and further affect alternating current density 3 - 30 A / dm 3, bringing it to the electrodes, which are used as scrap briquettes. Impact shock and hydrogen peroxide is carried out simultaneously throughout the dissolution process. The initial concentration of hydrogen peroxide is 1 - 2 g / l and its flow rate - 0,035 - 0,07 g / (Ah).
DESCRIPTION OF THE INVENTION
The invention relates to metallurgy noble metals, in particular to electrochemical methods of processing alloys of platinum group metals (PGM), preferably binary, such as platinum-rhodium, platinum-iridium.
Known method of electrochemical dissolution of the powdered metals of the platinum group metals (PGM), based on dissolution of PGMs powder in concentrated hydrochloric acid under application of an alternating current power of 2.5 A 2 cm 2 of the apparent surface of the powder (AD Styrkas, OP Efimov. The electrochemical dissolution of the powdered metals of the platinum group. Journal of applied chemistry. T. XLIII, p. 177, 1970 YG). The optimum temperature of the process is 90-100 o C. The yield of products in these conditions for 6 hours to 0.8-1.0 g of RhCl 3 · 3H 2.
The process is exclusively for the dissolution of metals with good surface, in particular in the form of powders, and can not be used for processing PGM alloy due to its low efficiency, due to, inter alia, the absence in the process of the oxidizing agent that promotes acceleration PGM dissolution in hydrochloric acid . Furthermore, the method is implemented at high temperature solution and requires pretreatment of the starting material in powder form.
Common to the known methods and the claimed process is the presence in the operation of dissolution of the starting material in concentrated hydrochloric acid when exposed to an alternating current.
The closest in technical essence to the claimed invention is a method for refining precious metals and their alloys, preferably containing rhodium comprising grinding a starting material and by dispersing the electro its subsequent dissolution in aqua regia. Dissolving the starting material is performed with a solution of aqua regia at 100-105 o C for 1 hour and then aqua regia solution with the addition of 0.2-3.0 wt.% Hydrogen peroxide until the end of discharge of nitrogen oxides (Pat. Russian Federation N 2092598, MPK6, C 22 B 11/00, publ. 10.10.97 city).
The known method requires a preliminary preparation of the starting material to dissolve - time-consuming and energy-intensive operation EDM dispersion and implemented in conditions of high temperatures. Furthermore, in the apparatus of the method the service area is allocated a significant amount of nitrogen oxides, which requires appropriate treatment and the presence of these continuously operating ventilation.
The invention aims at improving the efficiency of the method, its simplification and improvement of the ecology of the dissolution process.
This is achieved in that the starting material - pgm alloy taking a briquetted scrap, dissolving it in concentrated hydrochloric acid, which is added in hydrogen peroxide, and further to affect alloy alternating current density 3-35 A / dm 2, bringing it to the electrodes, which is used as a subject to dissolution of the scrap pellets. Exposure to hydrogen peroxide and an alternating current is performed simultaneously during the dissolution process, wherein the initial concentration of hydrogen peroxide of 1-2 g / l at a total flow rate of 0,035-0,07 g / (A · h).
METHOD implemented as follows
Scrap IPY in two waste briquettes PlRd7 alloy wire having a current-supplying contacts and geometric surface area of 10.8 cm 2 was charged into an electrolytic cell filled with concentrated hydrochloric acid (12 m / l), heated to 50 o C. Then, acid is introduced in the oxidation agent - hydrogen peroxide in an amount of 1-2 g / l, and the current-carrying contacts toward the briquettes fed density of 10-12 a / dm 2 alternating current. The cell voltage is 1,65-1,8 B.
In the process of dissolving under the action of an oxidizing agent - hydrogen peroxide and AC claimed density alloy structure collapses and alloy metals into solution. Hydrogen peroxide decomposing during electrolysis, further periodically introduced into the process at a rate 0,035-0,07 g / (Ah). Under these conditions, the alloy PlRd7 dissolution rate is 56.7 g / (m 2 · hr).
When the concentration of PGMs in solution reaches a value of 100-120 g / l, the solution out of the cell for further processing, for example sequential chemical recovery of each of the components of the alloy from the solution to obtain pure IPY. The electrolyzer with unconverted residues scrap poured concentrated hydrochloric acid (12 m / l), hydrogen peroxide is introduced from the above calculation and fed alternating current. The cycle is repeated.
Due to combination of stated features made possible effectively and without any special pre-treatment to dissolve the PGMs alloys for further isolation of these pure metals.
Implementing the method of the claimed current density range, depending on PGM alloy avoids the formation of chlorine gas in the process of dissolution of the alloy and thus improve the environmental performance of the method. Isolation of gaseous oxygen and hydrogen, concomitant electrochemical process, do not affect the atmosphere in the work area of the cell, as can be easily removed natural air ventilation.
CLAIM
A method of processing an alloy of platinum group metals by dissolution in an acidic medium with the addition of hydrogen peroxide, characterized in that the raw material taken as a briquetted scrap in an acidic medium using concentrated hydrochloric acid, and further affect the variable current density of 3 - 35 A / dm 2, summing it to the electrodes, which is used as a subject to dissolution of the scrap pellets, and impact shock and hydrogen peroxide is performed simultaneously during the dissolution process, wherein the initial concentration of hydrogen peroxide of 1-2 g / l at a total flow rate of 0,035-0,07 g / (Ah).
print version
Publication date 14.03.2007gg
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