DE2506717B1 - Separation of rhodium opt. iridium and or ruthenium - from platinum, palladium and or gold involving conversion to halides or perchlorates - Google Patents

Abstract

Rh and opt. Ir and/or Ru are sepd. from Pt, Pd and/or Au from concentrates contg. these metals, obtd. by standard processing of their ores, by converting these metals to salts, i.e. to halides using a hydrogen halide, or to perchlorates using HClO4, then heating the salts to 575-625 degrees C followed by treatment with aqua-regia and sepn. of sol. Pt, Pd and/or Au salts as filtrate and of Rh and opt. Ir and Ru as residue. Pt, Pd and Au are obtd. in sol. form. i.e. in filtrate of aqua-regia following heating. Residue contains pure Rh and opt. Ir and/or Ru.

Description

It has been found that this separation is particularly effective from rhodium as well optionally iridium and / or ruthenium independently of platinum, palladium and / or gold from the previous work-up method, which generally became partially soluble Salts of these metals, which can be further improved,

when these metals are first converted to halides or perchlorates and then heated.

This makes platinum, palladium and gold in a soluble form, i.e. H. obtained in the filtrate of the aqua regia treatment that takes place after heating, while in particular rhodium and any iridium still present and / or Remaining ruthenium in the residue in quite pure form.

The inventive method for separating rhodium and optionally Iridium and / or ruthenium from platinum, palladium and / or gold from concentrates, which contain these metals and which are known from the processing of these metals containing ores can be obtained by converting these metals into salts by heating the salts to a temperature of 575 to 625 "C and subsequent treatment with Aqua regia and separation of soluble salts of platinum, palladium and / or Gold as a filtrate and of rhodium and optionally iridium and ruthenium as The residue is characterized in that these metals are removed by means of hydrohalic acid converted into halides or perchloric acid into perchlorates before the Performs heating.

It may be useful here to transfer z. B. in chlorides by treating with hydrochloric acid and then adding nitric acid. This forms an aqua regia solution which, after evaporation, removes the chlorides who leaves metals behind. If the evaporation is carried out in the presence of perchloric acid, this leaves the perchlorates behind. Preference is therefore given to producing the chlorides or perchlorates this method was chosen.

The temperature range when heating is critical, since below 575 "C the rhodium for the most part remains in soluble form, while above 625 "C C the palladium is made increasingly insoluble.

The metals are processed from the ore or concentrate in a known manner, e.g. B. according to laid-open specification 2340183 in that by reducing melting with a lead compound, a reducing agent and a Flux, the alkaline earth metals as well as silicon and basic metals separated beforehand will.

Melting with the lead compound is preferably carried out at a Temperature between 1100 and 1200 "C carried out. The lead compound is preferably made of lead oxide, but can also be made of lead carbonate, lead sulfide, lead sulfate, for example or lead acetate. A basic flux should serve as the flux, such as sodium carbonate, preferably mixed with a melting point depressant Medium such as borax or fluorspar. The reducing agent that is required in many cases can be, is preferably made of charcoal. Will lead acetate or lead formate used as a lead compound, no reducing agent is required. Also is it is advantageous to carry out the process according to the invention with a metal mixture, in which the metals have been oxidized to the highest stable oxidation state, for example by boiling this solution in aqua regia with sodium bromate.

Pre-separation can also be achieved by melting with sodium hydrogen sulfate and subsequent leaching with hydrochloric acid (1: 1) takes place, whereby the main amount Platinum, palladium, gold, ruthenium and iridium is separated.

In general, concentrates are made of metals the platinum group and Gold extracted in the form of raw stone leach residues or sludge. The metals The platinum group and gold are separated and purified from these concentrates.

The invention is illustrated in more detail by the following examples.

Example 1 2.5 kg of a raw stone leaching sludge were obtained as follows Composition Element Platinum (Pt) 6.92 Palladium (Pd) 3.04 Gold (Au) 0.59 Rhodium (Rh) 0.32 ruthenium (Ru) 0.60 iridium (Ir) 0.08 silver (Ag) 0.03 aluminum oxide (au03) 3.60 antimony (Sb) 0.05 bismuth (Bi) 0.11 calcium oxide (CaO) 0.49 copper (Cu) 6.91 Cobalt (Co) 0.19 Iron (Fe) 4.57 Magnesium Oxide (MgO) 0.35 Nickel (Ni) 3.50 Organic Substances [C (H2O) m] 23.1 Potassium (K) 0.03 Silicon dioxide (SiO2) 12.92 Sodium (Na) 9.25 Sulfur (total) (S) 19.63 Tellurium (Te) 0.29 Zinc (Zn) <0.001 Others Ingredients + O2 + H20 (as difference) 3.43 100.00 in a stream of air for two hours Roasted at 600 "C to remove all sulfides and all free sulfur at this stage 1 to be converted into oxides.

The roasted material was in level 2 for two hours with 20% H2SO4 (3 liters) heated to reflux with stirring, then cooled to approximately 55 "C and filtered so as to remove most of the base metals present.

Calcium oxide (CaO) was added to the filtrate in step 3 to remove everything nickel and cobalt present in the filtrate, as well as the platinum group metals and to fell the gold. The precipitate contained 30 mg platinum, 100 mg palladium, 10 mg gold, 50 mg rhodium and 40 mg iridium. In practical operation, this would be the case return it to the raw stone melting plant.

The residue from the sulfuric acid treatment was then leached with aqua regia (1.5 liters) for three hours in step 4.

For this purpose, the material was treated with the required amount of hydrochloric acid (HCI) refluxed for 30 minutes. The required amount of nitric acid (HNO3) was then added gradually over 60 minutes. The mixture then became allowed to continue boiling for the remainder of the time (i.e., 11/2 hours). Here were palladium oxides passivated in the presence of the HNO3.

Then 30 g of sodium bromate (NaBrO3) were added to the solution, which boiling for an additional 30 minutes after diluting the solution with water (1.5 to 3 liters) for the purpose of oxidizing platinum group metals and gold to their highest oxidation levels, which are still stable. The pH was then with 1 kg of sodium carbonate at about 60 "C adjusted to 6.5, excluding all metals Platinum to precipitate as hydrated oxides. The solution was left to stand for 20 minutes and then filtered under vacuum. In this way the platinum was removed, so the bulk of the platinum group metals and gold which are subject to lead must be reduced by about 50%.

The filtrate (+ 90% of the platinum in the feed) was added in stage 5 formic acid (0.2 liter) was added and the solution was refluxed for 5 hours and stirring cooked. Then 0.3 kg of sodium carbonate in stage 6 was added in portions added within 1 hour until a pH of 5.0 was reached. The solution was then boiled for a further 60 minutes, cooled to 60 "C and filtered in vacuo. This precipitated the platinum in the solution.

In stage 7, the filtrate was passed through an anion exchange column. The effluent contained 100 mg Pt, 10 mg Pd, 10 mg Au, t mg Rh and 25 mg Ir.

The precipitate was dissolved in aqua regia (1.0 liter) in step 8, the solution cooled and filtered. The remaining residue consisted of silver chloride (AgCl).

This aqua regia filtrate contained most of the platinum. It became associated with the bulk of the palladium and gold, and the separation these platinum group metals were identified by means of a separate, not of interest here Procedure.

The combination of residue and precipitation, their constituents from the initial leaching with aqua regia and sodium carbonate precipitation originate in stage 4 (about 1400 g), was mixed with the fluxes A and B and melted together in stage 9 for 75 minutes at 1140C. There were 2.5 kg of the flux A per kg of residue and 335 g of the flux B per 100 g of the metals to be recovered the platinum group plus gold used. These fluxes had the following compositions on: Flux A (active flux) 0.75 kg Borax Na2B407 (20%) 2.75 kg sodium carbonate Na2CO3 (80%) flux B (collector) 0.5 kg black lead PbO (90%) 0.05 kg charcoal C (10%) The molten material was poured into iron molds and allowed to cool therein calmly. The lead regulus thus obtained was separated from the slag, and the Slag was crushed and collected, but would become that in practical operation Raw stone smelting plant to be returned. The slag contained 520 mg Pt, 230 mg Pd, 45 mg Au, 24 mg Rh, 45 mg Ru and 5 mg Ir.

The lead regulator was crushed and then in stage 10 with 20% strength HNO3 (5.5 liters) refluxed for 5 hours to remove the lead. the Solution was cooled to 55 "C and filtered under vacuum.

The residue was a loading according to the invention act that follows is designated as stage 11, supplied.

Formic acid (0.05 liter) was added to the filtrate from the nitric acid leach in stage 12 added to stage 10 and the pH with sodium carbonate Na2CO3 (0.3 kg) to 2.0 set to all the platinum group metals and the gold by the nitric acid have been resolved to fail. The solution was then 5 hours at room temperature stirred and filtered or suction filtered under vacuum.

The resulting precipitate was combined with the residue, which in the nitric acid leach stage in stage 10 was left behind, and this combination of materials was also fed to the stage 11 treatment according to the invention. The filtrate NH40H was added in stage 13 to remove the lead and all metals still present platinum group and gold, and this precipitate was dried and annealed, and in practical use it would pass through to the leading operation Merge level 9 can be traced back.

The combination of residue and precipitate was made according to the invention by boiling with hydrochloric acid, adding nitric acid and further boiling (corresponding to 0.75 liters of aqua regia) refluxed in step 11 for 3 hours. The solution was then cooled to 55 "C and filtered under vacuum.

The residue formed part of the feed to the process Separation of rhodium, iridium and ruthenium from each other and contained 850 mg Pt, 700 mg Pd, 100 mg Au, 5000 mg Rh, 14720 mg Ru and 1420 mg Ir. Make the precious metals usually approximately 50% of this, while the remaining 50% is lead chloride (PbC12) exist.

The filtrate from the aqua regia leach stage of stage 11 was the stoichiometric amount of H2SO4 plus 10% excess (100 ml of 50% H2SO4) in step 14 was added to precipitate the lead present in this solution. The solution was Heated to the boil for 30 minutes, cooled to 55 "C and filtered.

The precipitated lead sulfate was in stage 15 by annealing in black lead (PbO) and was ready for use again for the return to the stage of Enamel bleaching.

The filtrate from the lead precipitation stage was dried to dryness in stage 16 evaporated, and the salts thus obtained were calcined for 2 hours at 600 "C. These Temperature was found to be technically important to the rhodium in the residue To make aqua regia insoluble and still get a good separation.

The glow product was then refluxed in step 17 for three hours Boiled with aqua regia (0.75 liters). The solution was cooled and under vacuum filtered. The residue was mixed with the residue from the aqua regia leach stage of step 11 performed after the alloying operation are combined and thus resulted in a combined feed for the separation of the secondary group of the platinum metals, namely rhodium, ruthenium and iridium, which have a content of 1130 mg Pt, 850 mg Pd, 120 mg Au, 7480 mg Rh, 14920 mg Ru and 1720 mg Ir.

That obtained from the final stage 17 aqua regia leach Filtrate was combined with that obtained in the aqua regia leach stage of the stage 8 that had been carried out with the metals that were used in the beginning standing leach stage 4 had been solved to such a Outbound loading for the process of separating platinum, palladium and gold. These The initial charge had a content of 171 210 mg Pt, 74790 mg Pd, 14560 mg Au, 200 mg Rh, 25 mg Ru and 210 mg Ir.

Example 2 An aqua regia solution of a prepurified Concentrate with 17 150 mg Pt, 74940 mg Pd, 14580 mg Au, 2680 mg Rh, 225 mg Ru and 321 mg Ir heated to dryness in a quartz crucible. The obtained chloride salts were heated to 600 ° C. for 2 hours. The residue was concentrated with 600 ml Hydrochloric acid heated under reflux for 30 minutes. Thereafter, 200 ml of concentrated nitric acid were added was added and the solution was boiled for an additional 120 minutes.

After cooling, the solution was filtered under vacuum. The residue, containing 280 mg Pt, 150 mg Pd, 20 mg Au, 2600 mg Rh, 200 mg Ru and 300 mg Ir, was fed to the further isolation of Rh, Ru and Ir, while from the filtrate, which contained 16,870 mg Pt, 74,790 mg Pd, 14560 mg Au, 80 mg Rh, 25 mg Ru and 21 mg Ir, was worked up on Pt, Pd and Au in a known manner.

Example 3 A prepurified concentrate with 3390 mg Pt, 2550 mg Pd, 360 mg Au, 22,440 mg Rh, 44,760 mg Ru and 5160 mg of Ir was ten fold Amount by weight of NaHSO4 H2O melted in a quartz crucible at 600 "C for 1 hour. The melt was dissolved in 4 liters of dilute (1: 1) hydrochloric acid. The solution was filtered.

The filtrate contained 300 mg Pt, 200 mg Pd, 20 mg Au, 19,500 mg Rh, 60 mg Ru and 40 mg Ir. It was allowed to boil and 15 g of NaBrO3 were added. The pH of the solution was adjusted to 8.5 with Na2CO3 and the solution became filtered.

The residue contained 100 mg Pt, 1980 mg Pd, no gold. 19,400 mg Rh, 60 mg Ru and 40 mg Ir. It was dissolved in 100ml concentrated hydrochloric acid, for Evaporated to dryness and heated to 600 "C for 2 hours. The residue was 100 ml aqua regia leached as in Example 2 to dissolve Pt and Pd. The filtrate contained 100 mg Pt, 1900 mg Pd and 400 mg Rh, while the residue 80 mg Pd, 19 Contained 000 mg Rh, 60 mg Ru and 40 mg Ir.

Example 4 The procedure was as in Example 2, but it was carried out evaporation of the aqua regia solution of the noble metals in the presence of 200 ml of 70% strength Perchloric acid.

More than 96% of the Rh present was separated from Pt, Pd and Au.

Claims (4)

Claims: 1. Process for separating rhodium and, if necessary Iridium and / or ruthenium from platinum, palladium and / or gold from concentrates, which contain these metals and which are known from the processing of these metals containing ores were obtained by converting these metals into salts by heating the salts to a temperature of 575 to 625 "C and subsequent treatment with Aqua regia and separation of soluble salts of platinum, palladium and / or Gold as a filtrate and of rhodium, and optionally iridium and ruthenium as Residue, d a u r c h e k e n n -z e i c h n e t that these metals by means of Hydrogen halide into halides or perchloric acid into perchlorates transferred before performing the heating. 2. The method according to claim 1, characterized in that this Metals first by treatment with hydrochloric acid and subsequent addition of nitric acid converted into the chlorides and, if appropriate, the mixture by evaporation in the presence by perchloric acid continues to be converted into perchlorates. 3. The method according to claim 1 or 2, characterized in that converting the metals into halides or perchlorates on a metal mixture performs, from which alkaline earth metals as well as silicon and basic metals through reducing melting with a lead compound have been previously separated. 4. The method according to claims 1 to 3, characterized in that that one converts the metals into halides or perchlorates with a mixture of metals carries out, in which the metals are oxidized to the highest stable oxidation level have been. The present invention relates to the separation and purification of Rhodium and optionally iridium and / or ruthenium from platinum, palladium and / or Gold from concentrates. The five metals of the platinum group, namely platinum, palladium, iridium, Ruthenium and rhodium, which are usually found in nature together with gold and in various ways, e.g. B. by smelting ore with black lead with addition Soda and coal from the ore of base metals must be separated from each other and separated from the gold and purified to make it useful in trade and industry. As a rule, there is a separation first of these elements carried out in two groups. By treating the basic mixture, which is often a raw stone leach residue or sludge, go with aqua regia Platinum, palladium and gold in solution, while iridium, ruthenium and rhodium im remain essentially in the residue. The obtained two groups of metals are then usually subjected to a lengthy and complicated separation process, to separate and clean the individual metals. According to a known method First, a leaching with aqua regia takes place, producing gold, platinum and palladium solved and iridium, rhodium and ruthenium remain. The residue is with Black lead, soda and coal melted and the lead from the resulting alloy e.g. by stripping and dissolving with nitric acid and precipitating the lead with sulfuric acid removed. The dissolved metals are obtained through various precipitation and melting processes separately (see U 11 m a n n, Encyclopedia of Technical Chemistry, 3rd Edition, Vol. 14, p. 23). The two previously separated groups often do not have the desired one Degree of separation. In particular, considerable amounts of platinum are often found, Palladium and gold along with the rhodium, iridium and ruthenium. Usually are at the same time undesirably large amounts of silica and base metals in the group consisting of rhodium, iridium and ruthenium. According to German Offenlegungsschrift 23 40 183, it has already been proposed that a concentrate to separate and purify platinum group metals and gold, which was obtained from raw stone leach residues or sludges that were used for Mainly contain platinum, palladium, iridium, ruthenium, rhodium and gold, together with a lead compound, if necessary a reducing agent and a flux After initially leaching the concentrate with aqua regia, to melt the lead separated from the resulting alloy and then platinum, palladium, gold and part of the rhodium from ruthenium and / or iridium by leaching with Separate aqua regia, with the aqua regia leaching from the beginning obtained solution before melting with the lead compound with sodium bromate and Sodium carbonate is treated and the precipitate obtained at this stage with the residue from the initial stage of aqua regia leaching united, melted with the lead compound, leached with nitric acid, the solution obtained evaporated to dryness, the residue obtained at one temperature Heated from 575 to 625 "C, dissolved again in aqua regia, the undissolved rhodium containing residue separated and leached again with aqua regia and the residue obtained together with the residue from the aqua regia leaching process, which was carried out after the nitric acid treatment, in a manner known per se is further processed. The rhodium dissolved in the aqua regia solution is after alloying with lead, the other platinum metals and gold by heating to about 575 to 625 "C insoluble in aqua regia and from platinum, palladium and gold separated by a further leaching with aqua regia. The basic material for the Separation of rhodium, ruthenium and iridium forms the residue obtained together with the residue from the first aqua regia leaching stage. Melting with the lead compound improves the removal of Silica and base metal and there will also be better separation of the two Groups of metals achieved, since here the ruthenium and the iridium are less soluble than they usually are.