RU2104320C1 - Method for processing products contained ruthenium and iridium - Google Patents

Abstract

FIELD: technique of refining metals of platinum group. SUBSTANCE: method includes melting of products contained ruthenium and iridium with addition into charge of collector in the form of alloy of nickel with silicon separation of obtained melt of alloy of metals of platinum group from slag, grinding and leaching of ground alloy of platinum metals groups in hydrochloric acid in the presence of oxidizer. Consumption of collector amounts to 50-100% of initial product weight. The process of top-and-bottom smelting of materials containing metals of platinum group with addition into charge of nickel-silicon collector, results in formation of friable chemically active multicomponent alloy based on solid solution of nickel silicides and platinum metals. After separation from slag and grinding, alloy is chlorinated in solution of hydrochloric acid. All metals of platinum group including ruthenium and iridium contained in alloy pass into formed in process chloride solution in the amount above 90%. EFFECT: high recovery of metals of platinum group into chloride solution from the most rebellious type of raw materials and intermediate products with high content of ruthenium and iridium and reduced total expenditures for their processing. 3 cl

Description

 The invention relates to the metallurgy of noble metals and can be used in the technology of refining metals of the platinum group (PGM).

 Refining platinum metals from various types of raw materials includes operations to transfer PGM to a solution. The dissolution methods used depend on the nature of the feedstock, in particular on the content of the most resistant iridium and ruthenium in it.

 A known method of processing raw PGM with a high content of rhodium, iridium and ruthenium, including sintering with barium peroxide, grinding and processing cake with hydrochloric acid, precipitation of barium in the form of sulfate, filtration, evaporation of the filtrate with nitric acid additives, nitration of the evaporated solution with separation and washing of the precipitate hydroxides of base elements, precipitation from a solution of sparingly soluble salts of rhodium, iridium, and ruthenium [1].

 The disadvantages of this processing method include the high consumption of expensive barium peroxide, the significant costs of obtaining and evaporation of solutions, as well as the loss of PGM due to their coprecipitation with barium sulfate.

 A known method of processing raw materials PGM, in which products containing iridium, are melted in the presence of silicon, which acts as a collector. The alloy of PGM with silicon is separated from the slag, ground and leached with hydrochloric acid in the presence of an oxidizing agent (abstract of application N 93057292, 1996). This method is closest to the proposed and adopted as a prototype.

 The disadvantage of the prototype method is the low extraction of PGM in a solution in cases where the content of iridium and (or) ruthenium in the feedstock is equal to or exceeds the total content of the remaining PGMs. Extraction into chloride solutions from such products is 10–20% for ruthenium and 20–40% for iridium. In this case, platinum, palladium and rhodium pass into the solution by no more than 80%.

 Thus, the main part of ruthenium and iridium from certain types of raw materials does not enter chloride solutions, and hence refining limits, and remains in solid insoluble residues (HO). This leads to the need to repeat the operation of melting BUT with silicon, grinding alloys, their hydrochlorination, filtration, etc. The cost of processing such materials increases many times.

 The objective of the invention is to increase the extraction of chloride PGM from the most resistant types of raw materials and industrial products with a high content of ruthenium and iridium, as well as reducing due to this the total cost of their processing.

 The goal is achieved by the fact that in the known processing method, which includes melting with the addition of a silicon-containing collector, separating the resulting PGM alloy from slag, grinding and leaching the powdered PGM alloy in hydrochloric acid in the presence of an oxidizing agent, separating the chloride solution from the insoluble residue, nitration of the chloride solution and separating a solution of PGM nitro complexes from a precipitate of hydroxides of base elements, a nickel-based alloy is used as a silicon-containing collector la and silicon and collector flow is 50-100% by weight of the starting material.

 The essence of the invention lies in the fact that in the process of separation melting of materials containing PGM, with the addition of a nickel-silicon collector in the charge, a brittle, chemically active multicomponent alloy is formed based on a solid solution of nickel silicides and platinum metals. After separation from the slag and grinding, the alloy is chlorinated in a solution of hydrochloric acid. More than 90% of all PGMs contained in the alloy, including ruthenium and iridium, are transferred to the chloride solutions formed in this process.

 Insoluble during chlorination, the remainder of the material is separated by filtration. It contains mainly silica, silver and a small amount of platinum metals and can be processed using existing technology as an intermediate product without a high content of iridium and (or) ruthenium.

 The solution of nitro complexes after separation of hydroxides of base elements from it is processed, as well as ordinary solutions of this type, not containing nickel.

 The presence of nickel in a nitrite solution (up to 30% of all nickel put into the process passes into it) does not affect the refining indices. Used nickel can be removed from the refining cycle to cakes at the final operation of neutralizing industrial stocks.

 Precipitation of hydroxides of base elements contains nickel as the main component. As shown by special laboratory studies, it can be used as a starting product to obtain a nickel-silicon collector.

 It has been experimentally established that the use of a collector containing silicon with any even small nickel additives during melting leads to an increase in the chemical activity of target PGM alloys containing iridium and ruthenium. Thus, it can be argued that the presence of any amount of nickel in the silicide collector increases the chemical activity of PGMs in silicide alloys.

The best conditions for collecting PGMs during melting are provided when using nickel-silicon alloys with a melting point of not higher than 1300-1350 ^o C. as a collector. The indicated temperature range was chosen for reasons of its relative ease and maintenance during melting using widespread simple structures electric and fuel furnaces. As can be seen from the Ni-Si state diagram, in this binary system, alloys containing 5-70% silicon (the ratio of nickel to silicon content 19-0.4) satisfy this low-melting condition (Samsonov G.V., Dvorina L.A. , Rud, B.M., Silicides, Moscow: Metallurgy, 1979, p. 234).

 Example 1. The initial product - insoluble residue (BUT) of a heavy alloy of metal-satellites contained,%: platinum 2.6; palladium 5.3; rhodium 4.5; iridium 5.1; ruthenium 19.1; gold 4.2; silver 7.7.

137.0 g of the starting material was taken, 58.0 g of soda ash, 18.0 g of calcium oxide, 10 g of coke and 99.5 g of crushed nickel-silicon alloy were added. Nickel-silicon alloy contained 67.6% nickel, the rest was silicon. The mixture was mixed, loaded into a crucible and placed in an electric furnace for melting. After 60 minutes at 1350-1400 ^° C, the crucible was removed from the furnace. After cooling, 71.7 g of slag and 200.0 g of an alloy of platinum metals were recovered from the crucible. The alloy contained,%: platinum 1.78; palladium 3.61; rhodium 3.06; iridium 3.45; ruthenium 13.01; gold 2.85; silver 5.21.

After grinding to a particle size of 0.1 mm, the alloy was leached in concentrated hydrochloric acid with a purge of gaseous chlorine. Leaching conditions: T: W = 1: 4, temperature 80 ^o C, duration 5 hours; In the first 3 hours, the oxidation potential with respect to the silver chloride electrode reached 960 mV and did not change further.

 The resulting pulp was filtered, the insoluble residue was washed on the filter with a solution of hydrochloric acid, the products were analyzed for the content of platinum metals.

 Received 800 ml of a solution containing (according to the analysis of ICP), g / l: 4.06 platinum; 8.83 palladium; 7.43 rhodium; 7.96 iridium; 31.27 ruthenium; 7.01 gold; 4.5 copper; 68.2 nickels; 4.6 iron; 5.2 selenium; 21 antimony; 2.3 tin; 1.1 lead; 1.0 bismuth.

 The insoluble residue (84 g by dry weight) according to spectral analysis contained,%: Pt 0.37; Pd 0.2; Rh 0.2; Ir 0.64; Ru 0 1.2; Au 0.1; Ag 10.0.

Thus, the solution was recovered,%: 91.3 platinum; 97.65 palladium; 97.22 rhodium; 92.2 iridium; 96.12 ruthenium; 98.4 gold. The solution was aimed at the deposition of hydroxides of base elements and the selective extraction of gold and platinum metals using known methods. In particular, 120 g of hydroxides of base elements were obtained (by dry weight). The proportion of Ni (OH) ₂ was 71%.

 The resulting hydroxides were used to obtain a nickel-silicon alloy (see example 2).

Example 2. They took 115 g of hydroxides of base elements from the obtained 120 g (see example 1) and added 50 g of silicon. The mixture was loaded into a graphite crucible and melted in an induction furnace at a temperature of 1400-1500 ^o C. The melt was poured from the crucible into a graphite mold. After cooling, the obtained product was weighed, crushed, and analyzed for nickel and silicon contents. It was found that during melting, 115.5 g of brittle, easily grinding multicomponent alloy was obtained, in which the nickel content was 44% and the silicon content was 43.5%. The resulting alloy was used as a nickel-silicon collector during the next heat.

 Example 3. The initial product in this example was a crushed heavy alloy of the following composition,%: platinum 3.2; palladium 3.6; rhodium 4.9; iridium 4.3; ruthenium 14.2; gold 1.9; silver 4.9. This heavy alloy was obtained during the smelting of ruthenium and iridium-rich industrial products with the addition of silicon as a collector, as described in the prototype method.

They took 15.0 g of the starting product, added 15.0 g of the crushed nickel-silicon alloy obtained in Example 2, added 5.5 g of sodium sulfite and 1.0 g of coke. The mixture was mixed, loaded into an alundum crucible and placed in an electric furnace for melting. After 45 minutes at 1300 ^° C., the crucible was removed from the furnace. After cooling, 12.1 g of slag and 23.3 g of an alloy of platinum metals were recovered from the crucible. The alloy contained,%: platinum 2.08; palladium 2.30; rhodium 3.15; iridium 2.75; ruthenium 9.66; gold 1.23; silver 3.16.

 After grinding to a particle size of 0.1 mm, the alloy was leached in concentrated hydrochloric acid with a purge of gaseous chlorine. Leaching conditions did not differ from those in example 1.

 The resulting pulp was filtered, the insoluble residue was washed on the filter with a solution of hydrochloric acid, the products were analyzed for the content of platinum metals.

 Received 100 ml of a solution containing (according to the analysis of ICP), g / l: 4.60 platinum; 5.23 palladium; 7.10 rhodium; 6.10 iridium; 20.8 ruthenium; 2.82 gold.

 The insoluble residue (13.75 g by dry weight) according to spectral analysis contained,%: Pt 0.17; Pd 0.09; Rh 0.17; Ir 0.25; Ru 1.24; Au 0.03; Ag 5.08.

 Thus, from the crushed alloy in the chloride solution is extracted,%: 95.2 platinum; 97.6 palladium; 96.7 rhodium; 94.5 iridium; 92.4 ruthenium; 98.9 gold. The solution was aimed at precipitating hydroxides of base elements and can be further processed using known methods.

 Example 4. The initial product - insoluble residue (BUT) of a heavy alloy of metal-satellites contained,%: platinum 2.6; palladium 5.3; rhodium 4.5; iridium 5.1; ruthenium 19.1; gold 4.2; silver 7.7.

 They took 200 g of the starting product, added 100 g of crushed nickel-silicon alloy, 85 g of soda ash, 25 g of calcium oxide and 15 g of coke. Nickel-silicon alloy contained 51% nickel, the rest was silicon.

The mixture was mixed, loaded into a crucible and placed in an electric furnace for melting. After 60 minutes at 1350-1400 ^° C, the crucible was removed from the furnace. After cooling, 98.5 g of slag and 212.0 g of an alloy of platinum metals were recovered from the crucible. The alloy contained,%: platinum 2.44; palladium 4.95; rhodium 4.20; iridium 4.76; ruthenium 17.64; gold 3.94; silver 7.16.

 After grinding to a particle size of 0.1 mm, the alloy was leached in concentrated hydrochloric acid with a purge of gaseous chlorine. The leaching and subsequent filtration of the pulp did not differ from those given in examples 1 and 3.

 Received 850 ml of a solution containing (according to the analysis of ICP), g / l: 5.67 platinum; 12.02 palladium; 10.12 rhodium; 10.99 iridium; 42.3 ruthenium; 0.79 gold; 2.32 silver.

 An insoluble residue was obtained (104.5 g by dry weight), which according to spectral analysis had the following noble metal contents,%: Pt 0.33; Pd 0.26; Rh 0.30; Ir 0.73; Ru 1.36; Au 0.04; Ag 12.6.

 Thus, the extraction of PGM into the solution was,%: platinum 93.3; palladium 97.4; rhodium 96.5; iridium 92.5; ruthenium 96.2; gold 99.5.

 The use of the prototype method for processing these intermediate products made it possible in laboratory conditions to extract no more than 16% ruthenium and 26% iridium in chloride solutions. The remaining PGMs were recovered by 50-83%.

Claims (3)

 1. A method of processing products containing iridium and ruthenium, including melting with the addition of a silicon-containing collector, obtaining an alloy of platinum group metals and slag, separating the alloy from slag, grinding and leaching the crushed alloy in hydrochloric acid in the presence of an oxidizing agent, and separating the chloride solution from insoluble residue, nitration of a chloride solution and separation of a solution of PGM nitro complexes from a precipitate of hydroxides of base elements, characterized in that as a silicon-containing col during melting, the lecturers use an alloy based on nickel and silicon, the collector consumption is 50 100% by weight of the initial product.  2. The method according to p. 1, characterized in that the nickel-silicon collector is obtained by reductive melting with silicon of hydroxides formed during the nitration (hydrolytic treatment) of nickel-containing chloride solutions.  3. The method according to p. 1 or 2, characterized in that the nickel-silicon collector contains components in the following ratio, wt. Nickel 40 70
Silicon 30 60i