The method of obtaining selective concentrates of precious metals

 

(57) Abstract:

The invention relates to the field of non-ferrous metallurgy and can be used to obtain selective concentrates of precious metals from anode slimes of electrorefining of Nickel. In the proposed method, including two-stage sulfatization sulfuric acid, the first stage of which is carried out at temperatures of 150-200°C, followed by water leaching and getting cake, and the second stage cake first stage of the process at temperatures that ensure the concentration of platinum and gold cake and extraction into solution for subsequent water leaching of metals-platinum and palladium, separating from the resulting solution of cake and a selection from the solution of the second stage of sulfatization palladium deposition of the reducing agent, followed by separation of metals-platinum, according to the invention, the second stage of sulfatization carried out at a temperature of 240-300°C for 1.5-3 hours followed by repulpable oxide in sulfuric acid solution with a concentration of 180-250 g/DM3and as a reducing agent in the deposition of palladium using low molecular weight organic compounds or soluble inorganic reducing agents, and gnome electrode. Provides the selective concentrates and reduction of negative effects associated with the evaporation of sulfuric acid. 2 C.p. f-crystals, 3 tables.

The invention relates to the field of non-ferrous metallurgy and can be used to obtain selective concentrates from anode slimes of electrorefining of Nickel containing metals of platinum group.

All known methods for producing selective concentrates focused on joint concentration, along with platinum and gold and also palladium.

A method of obtaining selective concentrates of precious metals from sludge electrolysis of copper and Nickel (I. D. Reznik, Nickel, so 3, M, OOO “Science and technology”, 2003, S. 576 and 577), which includes oxidation-sulfamethizole roasting, leaching the calcine in sulfuric acid at a temperature of 80-90°C for separation of Nickel, copper and iron. Leached calcine sent for recovery smelting and casting of anodes, which are subjected to electrolytic dissolution. The result is a sludge, which is the first platinum concentrate, the second platinum concentrate copper sponge and the electrolyte, which also extract platinum,

The scheme differs if the is a way to obtain selective concentrate from the tailings of the electrorefining of Nickel (A. C. The USSR №389158, MKI 22 In 7/00), which provide, including the selection of palladium in a separate concentrate. In this method, electrolytic slimes sulfatized in two stages with an aqueous leaching and filtering after each stage, the first stage is carried out at a temperature of 150-200°C, providing selective elution in a solution of non-ferrous metals, and the second temperature is maintained in the range of 210-350°C for 4-6 hours when injected into the pulp of sulfatization sulfates of alkali metals is translated into a solution of platinum. At temperatures over 300°C in a solution of 90-98% goes palladium, to highlight which enter the sulphate of oxide of iron when its consumption is about 200% of the stoichiometrically required. The resulting palladium concentrate contains 92-95% palladium.

The most optimal from the point of view of further refining is getting palladium in the form of a separate concentrate, however, selected as a prototype method provides receiving palladium concentrate only at a temperature of sulfatization 300°C and above, and the process time is 4-6 hours. At such high temperatures there is an increase in the vapour pressure of sulphuric acid over her solutions 2"> Object of the invention is the selective allocation of concentrates from sludge Nickel electrolysis. The technical result achieved by the invention is to obtain selective concentrates, including concentrate palladium, while reducing the negative effects associated with the evaporation of sulphuric acid.

The technical result is achieved in that in the method of obtaining selective concentrate from the tailings of the electrorefining of Nickel by the method of two stage sulfatization sulphuric acid leaching of water and separation of the solid phase (cake) after each sulfatization the first stage is carried out at temperatures of 150-200°C, and the second temperatures, providing the concentration of platinum and gold in the cake and transfer to a solution of metals-platinum and palladium recovery of palladium from a solution of the second stage of sulfatization followed by separation of the metals platinum, according to the invention, the second stage of sulfatization carried out at a temperature of 240-300°C for 1.5-3 hours followed by repulpable oxide in sulfuric acid solution with a concentration of 180-250 g/DM3and as a reducing agent in the deposition of palladium using low molecular weight organic spotential in sulfate environment from 0.6 to 0.85, In respect to the hydrogen electrode.

The optimum temperature of the second stage of sulfatization is 250-280°C.

As the organic reducing agent, in particular, can be used such low molecular weight organic compounds as ethyl or propyl alcohol, ethylene glycol, paraldehyde is recommended that you enter in the number of 100-150% of theoretically required for the deposition of palladium.

Conditions of the second stage of sulfatization shown in the prototype (temperature, time), designed for maximum translation in soluble form metal-platinum. The addition of an alkaline reagent at the second stage of sulfatization facilitates the transition metals of satellites in solution in the form of stable complexes, however, is somewhat lower transition into a solution of palladium. Extraction of palladium in the solution of the prototype occurs only when the temperature of sulfatization 300°C and above, and when the processing time is not less than 4 hours. Studies found that when carrying out the second stage in more mild conditions and without the introduction of an alkaline reagent, namely at a temperature of 240-300°C (mostly 250-280°C) for 1.5-3 hours to translate in soluble form to 90-99% metals-platinum and up to 80-90% of palladium, silver Eddie in a solution of palladium and a metal-satellites displaced if repulpable cake the second stage in sulfuric acid solution with a concentration of 180-250 g/DM3. The claimed concentration range provides an optimum extraction of metals-satellites and palladium in the solution. Obtained in the leaching of sulphate solution is a multi-component system with different redox potentials of the elements. The resulting solution redox potential of the system Ag2SO4/Ag equal to 0.65 V, the system of N2S3/Se - 0,74, which is much below the potential of the system Pd2+/Pd. In these conditions, the palladium can be selectively precipitated soluble inorganic reducing agents having a potential of 0.6-0,85 Century When the use of low molecular weight organic reducing agents may also use reducing agents with a lower redox potential, because even in the presence of excess reductant silver, selenium and metals satellites seacadets with palladium slightly, and the presence of organic matter in solution does not affect the subsequent selection of the metal. Silver can be separated from the leaching solution after the second stage of sulfatization in the form of silver chloride in a known manner. Platinum and gold are concentrated in the insoluble residue. From Ratnikov. Thus, the proposed modes allow you to obtain the necessary range of concentrates, while maintaining all of the recovery indices, thus eliminating the effects associated with the use of sulfuric acid at high temperatures for a long time.

Experiments to obtain selective concentrates in the prototype and the proposed method was carried out in laboratory scale sludge shop electrorefining of Nickel, having the following composition, %: Pt 0,40; Pd 2,21; Au 0,07; Rh 0,063. In the first stage of sulfatization slurries were subjected to treatment with sulfuric acid with a concentration of 700-800 g/DM3at a temperature of 160-180°C for 4 hours at T:W=1:2. Sulfatization mass was diluted with water to the concentration of sulfuric acid 200-250 g/DM3, after which he carried out the separation of the solution and cake first stage. KEK first stage of sulfatization contained, %: Pt 1,74; Pd 9,5; Au 0,31; Rh 0,27; Ag Of 2.26; Se 2,24; Those 1,0, he moved to the second stage of sulfatization. Conditions of the second stage of sulfatization were different in terms of the prototype and the proposed method.

In the comparative experiments in the prototype (table 1) in the pulp of the second stage of sulfatization was administered potassium sulfate in the number who have videlacele in water at a temperature of 80°C for 1 hour, in the pulp leaching was introduced sulfate iron (II) at the rate of 2 mol per 1 mol of palladium. As can be seen from table 1, the experiments in terms of the prototype at temperatures 210-300°C provides at a low content of metals satellites in KEK second stage of sulfatization presence of palladium at temperatures above 300°C is the transition in soluble form and its content in the cake is reduced, but at the same time there is an increase in vapour pressure of sulphuric acid.

In terms of the developed method (tables 2 and 3) second stage of sulfatization conducted at temperatures 250-305°C for 1.5-3 hours, the resulting slurry was diluted to a concentration of sulfuric acid 180-250 g/DM3and were repulation for 1 hour at a temperature of 80°C. Next, the slurry was subjected to leaching with water, the cake was separated from the liquid phase and analyzed for the content of platinum metals. The solution was injected reductant, which were tested: organic ethyl alcohol, inorganic sulfate iron (II) with E°=0,771 Century Precipitate, representing a concentrate of palladium, the content of which was 90-95%, were separated from the solution. The solution contained (g/DM3: Rh 0,2-0,4; EN 0,1-0,2; Ir 0.04 To 0.08. Consumption Vossloh 95-99%, silver - 98-99%. Further processing of the obtained solution can be carried out by known methods.

As can be seen from tables 2 and 3, the second stage of sulfatization at temperatures 240-300°C for 1.5-3 hours without feeding potassium sulfate, but with subsequent repulpable allows you to concentrate in the insoluble residue of a significant number of platinum and gold, separating palladium (examples 1, 3). Adding potassium sulfate at the declared parameters of sulfatization reduces the extraction of palladium in solution (examples 2 and 3), and when the temperature rises above 300°C at a satisfactory parameter extraction is an increase in the evaporation of sulphuric acid.

1. The method of obtaining selective concentrates of precious metals from sludge electrorefining of Nickel, including two-stage sulfatization sulfuric acid, the first stage of which is carried out at temperatures of 150-200°C, followed by water leaching and getting cake, and the second, on which a cake of the first stage is treated at temperatures that ensure the concentration of platinum and gold cake and extraction into solution for subsequent water leaching of metals satellites pupillage deposition of the reducing agent, followed by separation of metals-platinum, characterized in that the second stage of sulfatization carried out at a temperature of 240-300°C for 1.5-3 h, followed by repulpable oxide in sulfuric acid solution with a concentration of 180-250 g/DM3and as a reducing agent in the deposition of palladium using low molecular weight organic compounds or soluble inorganic reducing agents having the normal redox potential in sulfate environment from 0.6 to 0.85, In respect to the hydrogen electrode.

2. The method according to p. 1, characterized in that the temperature of the second stage of sulfatization is 250-280°C.

3. The method according to p. 1 or 2, characterized in that the organic reducing agent is used, for example, ethyl or propyl alcohols, ethylene glycol, paraldehyde is recommended that you enter in the number of 100-150% of theoretically required for the deposition of palladium.



 

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