DE2340183C3 - Procedure 2 for the separation and purification of the platinum group metals and gold - Google Patents

Description

and a part of the rhodium of ruthenium and or or iridium by leaching with aqua regia, is characterized da-6 ₅ by, treating the solution obtained from the property at the beginning of leaching with aqua regia prior to melting with the lead compound with sodium bromate and sodium carbonate and

The precipitate obtained at this stage is combined with the residue from the initial stage of leaching with aqua regia, melts with the lead inhibitor, leaches out with nitric acid, which gives the cold solution. ^ .. ^ .. w. Residue er-Idtzt again the residue obtained is dissolved at a temperature from 575 to 625 ⁰ C in aqua regia, separating the undissolved rhodium-containing residue and ereut with aqua regia leach, and together with the residue from the leaching with aqua regia, which was made after the Salpeterläurebehandlung , further processed in a manner known per se.

The rhodium dissolved in the aqua regia solution becomes the other platinum metals after alloying with lead and gold made insoluble by heating to about 575 to 625 ° C in aqua regia and dated Platinum, palladium and gold through a further leaching separated 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 digestion stage.

As was found, the melting has to do with the Lead compound means that the silica and the base metals are removed to a far greater extent than is the case with conventional processes, and that too a better separation of the two groups of metals can be achieved. This is partly due to the fact that here the ruthenium and iridium become less soluble than they are otherwise.

The melting connection with the lead is preferably carried out at a temperature of 1100-1200 ⁰ C. The lead compound is preferably made of lead oxide, but can, for example, also consist of lead carbonate, lead sulfide, lead sulfate or lead acetate. A basic flux, such as sodium carbonate, preferably in M ^; -solidification with a melting point depressant such as borax or fluorspar. The reducing agent, which may be required in many cases, preferably consists of charcoal. If acid acetate or lead formate is used as the lead compound, no reducing agent is required.

For a better understanding of the invention, an example will now be given, which includes a separation process Reference to the Fliessscheh. explained in more detail, where the flow sheet serves to illustrate the basic separation operations embodying the invention illustrate.

Generally, concentrates of platinum group metals and gold are in the form of raw stone leach residues or slurries, and the platinum group metals and gold are processed from this stage with the aim of to separate and purify them.

In this example a raw stone leaching sludge, containing the platinum group metals and gold, according to the general procedure below which at the same time embodies the results and processes of a specific example in which the Amounts of the various reagents actually added are in parentheses in the description are specified.

In this embodiment of the invention as the starting material The sludge used had the following composition:

element

Platinum.

r d "ii" j: ..

O * «iiiatiiuiii

Gold Rhodium Ruthenium Iridium ίο Silver

Aluminum oxide antimony bismuth calcium oxide 15 copper cobalt

iron

Magnesia

nickel
Organic substances

potassium

Silicon dioxide

sodium

Sulfur (total)
Tellurium

zinc

Other components

+ O ₂ + H ₂ O

(Pi)

/O YES

(Au)

(RH)

(Ru)

(Ir)

(Ag)

(A1 ₂ O _S )

(Sb)

(Bi)

(CaO)

(Cu)

(Co)

(Fe)

(MgO)

(Ni)

[C _n (H ₂ O) _n ,] (K)
(SiO ₄ )
(N / A)
(S)
(Te)
(Zn)

(as difference)

6.92

3.04

0.59

0.32

0.60

0.08

0.03

3.60

0.05

0.11

0.49

6.91

0.19

4.57

0.35

3.50

23.1

0.03

12.92

9.25

19.63

0.29

<0.001

3.43

100.00

It wvrden first 2.5 kg of the slurry for two hours in an air stream at 600 ⁰ C roasted, in order to convert all of the sulfides and all of the free sulfur in this stage 1 into oxides.

In stage 2, the roasted material was _{heated to refluxing for two hours with 20% H 2} SO ₄ (3 liters) while stirring, then cooled to about 55 ° C. and filtered to remove most of the base metals present.

Calcium oxide (CaO) was added to the filtrate in step 3 to remove all nickel and To precipitate cobalt as well as the platinum group metals and gold. This precipitate was collected and contained n mg platinum, 100 mg palladium, 10 mg gold, 50 mg rhodium and 40 mg iridium. In practical In operation, this precipitation would be fed back to the raw stone smelting plant (matte smelter).

The residue from the sulfuric acid treatment was then used in stage 4 for three hours Aqua regia (1.5 liters) leached. This leaching with aqua regia and all the rest that take place later Aqua regia leaching was carried out in the following way:

The material was refluxed with the required amount of hydrochloric acid (HCl) for 30 minutes. The required amount of nitric acid (HNO ₃ ) was then gradually added over a period of 60 minutes. The mixture was then allowed to continue boiling for the remainder of the time (ie ¹ / »hours).

Sodium bromate (NaBrO ₃ ) (30 g) was then added to the solution, which was boiled for an additional 30 minutes after diluting the solution with water (1.5-3 liters) to oxidize the platinum group metals and gold to their highest levels of oxidation that are still stable. The pH was then adjusted to 6.5 (approximately 6O ⁰ C) (1 kg) with sodium carbonate in order to remove all metals.

5 6

took platinum to precipitate as hydrated oxides. The lead regulator was crushed and then poured into The solution was left to stand for 20 minutes and stage 10 with 20% HNO ₃ (5.5 liters) was then filtered under vacuum for 5 hours. In this way it was refluxed to remove the lead. Platinum removed, so as to remove most of the metals. The solution was ^{cooled to 55 °} C. and vacuum filtered under the platinum group and the gold, the lead. The residue had to be subjected to an aqua regia leaching step that had to be reduced by about 50%, which was called step 11. is designated, supplied.

To the filtrate (+ 90% of the platinum [Pt] in the formic acid (0.05 liter) was added to the feed in stage 12) formic acid (0.2 liter) filtrate from the nitric acid leaching of stage 10 was added in stage 5 , and the solution was placed under io for 5 hours and the pH was _{boiled with sodium carbonate Na 2} CO ₃ reflux and stirring. Then sore Na- (0.3 kg) set to 2.0, all metals of the platinum trium carbonate (Na ₂ CO ₃ ) (3 kg) in stage 6 portion group and the gold, which is added by the nitric acid wise within 1 hour to precipitate until a pH has been dissolved. The solution was when it reached -5.0. The solution was then stirred for a further after 5 hours at room temperature and boiled for less than 60 minutes, cooled to 60 ⁰ C and filtered under vacuum 15 and suction filtered.
Vacuum filtered. These steps 5 and 6 were carried out. The obtained precipitate was carried with the residue to precipitate the platinum in the solution. united in the nitric acid leaching stage in

The filtrate was left behind in stage 7 via an anion off stage 10, and this material combination

Exchanger column passed and the drain excreted. nation became the aqua regia leach stage of the

This effluent contained 100 mg Pt, 10 mg Pd, 10 mg ao stage 11 added. The filtrate was in stage 13

Au, 1 mg Rh and 25 mg Ir. NH ₄ OH was added to remove the lead and all

The precipitation was in stage 8 platinum group metals and gold in aqua regia.

(1.0 liter) dissolved, the solution cooled and filtered. fall, and this precipitate was dried and

The remaining residue consisted of chlorine-calcined, and in practical operation it would be put into the

silver (AgCl). »5 lead operation by merging level 9

This aqua regia filtrate contained the main to be recycled.

amount of platinum. This platinum was the main combination of residue and precipitation

amount of palladium and gold, as further un- was in stage 11 with aqua regia (0.75 liters)

th described, combined, and the separation of these 3 hours refluxed. The solution was

Platinum group metals were then cooled to 55 ° C. by means of a separate 30 and filtered under vacuum.

Procedure carried out. This procedure is used in this The residue formed part of the charge for

Description of the invention not explained in more detail because it describes the process of separating rhodium, iridium and

for the fundamental stages of separation, soften the ruthenium from one another. This residue contained

characterize the present invention is irrelevant. 850 mg Pt, 700 mg Pd, 100 mg Au, 5000 mg Rh,

This combination of residue and precipitate, 35 14 720 mg Ru and 1420 mg Ir. The precious metals make up their constituents from the usually approx. 50% of this as metal leaching with aqua regia and the sodium carbonate concentrate, while the remaining 50% come from lead precipitation in stage 4 (approx. 1400 g) chloride (PbCl ₂ ).

a flux A and a flux B, which are further defined below for the filtrate from the aqua regia leaching stage, and in stage 9 40 of stage 11 the stoichiometric amount was melted ^{together at 1140 °} C. for 75 minutes. The H ₁ SO ₄ plus 10% excess (100 ml 50% H ₂ SO ₄ ) result of this operation is that it was added in stage 14 in order to precipitate the predominant part of the lead in this solution before rhodium. The solution was heated to boiling for 30 minutes, insoluble in water, in an aqua regia soluble form, cooled to 55 ° C. and filtered. Shape is transformed. At the same time the solubility is also 45 The precipitated lead sulphate was converted in stage 15 by the iridium and ruthenium in aqua regia annealing to gully (PbO) and was further reduced. There were 2.5 kg of the flux A ready for use for the return to the stage of the per kg of residue and 335 g of the flux B per melt lead.

100 g of the platinum group metals to be recovered. The filtrate from the lead fouling stage was in

plus gold used. This flux had the fol- lowing stage 16 evaporated to dryness, and the thus obtained

constricting compositions: requested salts were annealed for 2 hours at 600 ⁰ C. This

The temperature was found to be technically

Flux A (active flux) (3.5 kg) necessary to remove the rhodium in the residue from aqua regia

(1) Solubilize Borax Na ₄ B ₄ O ₇ 20% (0.75 kg).

(2) Sodium carbonate 55 The glow product was then refluxed with aqua regia (0.75 liters) for _{3 hours in step 17 with Na 2} CO _{3 80% (2.75 kg).}

Flux B (collector) (0.55 kg) The solution was cooled and filtered under vacuum

(1) Black lead PbO 90% (0.5 kg) The residue was mixed with the residue from the

(2) Charcoal C 10% (0.05 kg) level 11 aqua regia leaching stage, which is carried out after the

60 alloying operation was performed

The molten material was placed in iron molds to make a combined feed material poured and allowed to cool in it. The one thus obtained for the separation of the secondary group of the platinum metene Lead regulus was separated from the slag, thaw, namely rhodium, ruthenium and iridium, the and the slag was crushed and collected, a content of platinum metals and gold of 1130 mg but would in practical operation result in the raw stone 65 Pt, 850 mg Pd, 120 mg Au, 7480 mg Rh, 14 920 mg Ru Turn the melting plant back. The slag and had 1720 mg of Ir.

contained 520 mg Pt, 230 mg Pd, 45 mg Au, 24 mg Rh, Das in the last aqua regia leach step

45 mg Ru (ruthenium) and 5 mg Ir. the filtrate obtained in stage 17 was mixed with that

agrees that in the aqua regia leach stage of the Stage 8 was incurred, which had been carried out with the metals that were in the beginning Leach Stage 4 had been dissolved to provide an initial charge for the separation processes of platinum, palladium and gold. This starting charge contained metals of the platinum group and of gold of 171 210 mg Pt,

74,790 mg Pd, 14,560 mg Au, 200 mg Rh, 25 mg Ru and 210 mg Ir.

From the description of the invention it can be seen that it is possible by applying the present invention is, the two groups of metals of the platinum group and gold are effective from each other and from the base metal and gangue contained in the starting material.

1 sheet of drawings

509 687/319

Claims (5)

ι 2 The present invention betnSt the separation and purification of mixtures of metals of the claims: ^ ΑΤμ ^ Ϊ platinum group, namely platinum, 5 palladium, iridium, ruthenium and rhodium, which in 1. Process for the separation and purification of the normally S ^ " ⁸ ?"""" ¹ " metals of the platinum group and gold by smelting and in ^versct ™ f! zen of a concentrate, which was obtained from raw stone smelting of ore with Ν «β» * " ^β leach residues or sludge soda and coal ^^^ 5 ^ ™? ^^, which must be separated mainly Plaün, palladium, io .! ^ ™ ¹ ™™ "" ™™™ ^ * iridium ruthenium rhodium, and gold containing getrenn..und _f n ^ - ^ n £ ™ Possible along with a Bleiverbmdung, erforderlichen- use in rianuei u _Tr. - _nniin "j: -.- ,. _F ," If a reducing agent and a flux are used, these elements are usually first separated after the initial leaching of the concentrate with two dolls by treating aqua regia, removing the lead from the base mixture, often a raw alloy and then separating Leach residue or sludge with comgs of platinum, palladium, gold and part of the water go ^Platin Pall adl " ^m " ° ^d ° ^ - " ¹ ^ ¹ " * 'Rhodium from ruthenium and / or rridium while Ind.um, Rut ^heni "£ ^Rh ° ^to J 'J ^{m e"} by leaching with aqua regia, e dadurchg sentlichen in R ^"1 ^^ * ^ d _ann in avenue kennzeichnet.daß one selected from the day of arrival * o two groups of Metalllen If standing leaching with aqua regia is successful, the solution is then subjected to a lengthy and complicated separation process before melting with the lead compound in order to ^purify the Ει ™ ** ^ £ ™ * ™ bond with sodium bromate and sodium carbonate. After «" em b This is followed by a leaching with aqua regia, which results in a leaching with the residue from the beginning, gold, latin and palladium and indium, the standing stage of leaching with aqua regia, rhodium and ruthenium. melts with the lead compound, with SaI stand, soda and coal melted pitric acid is leached out with smooth lead, the solution obtained and the lead from the obtained alloy ζ B_ evaporate by drying, the obtained. Residue on stripping and loosing with> t_Salpetersaure as well as precipitation heated to a temperature of 575 to 625 ° C, again 30 of the lead removed with sulfuric acid and separated again with a melting process (cf. U Il m an n, Enzyko-Königswasser leaches, and the received Rückpädie der technischen Chemie, 3rd edition, Vol. 14, was together with the residue from the Lau- p. 23) . treatment with aqua regia, which after the nitric acid 35 The two previously separated groups often point treatment was carried out Way further processed. of which one finds considerable amounts of Plat, n, PaI- 2. The method according to claim 1, characterized by chargeium and gold often together with the rhodium indicates thatmandieMetal of the platinum group, iridium and ruthenium. Usually are at the same time those at the stage of nitric acid leaching in 40 also undesirably large amounts of silica Solution have gone, precipitates, and the residue and base metals in the group fall out consists of the mentioned nitric acid leaching stage to rhodium, iridium and ruthenium, pretends, before the treatment of it with royal hands. water is the subject of the present invention is now 3. The method according to claim 2, characterized in 45 development of a method for cleaning the label, that the metals of the platinum ropes of the platinum group and of gold, which e.ne group using formic acid for improved separation of the two aforementioned groups, whereby one ensures the pH value of the nitric acid pen and that at the same time the removal of the solution adjusts to about 2.0. Silica and base metals from the group 4. The method according to claims 1 to 3, da- 50 pe rhodium, ruthenium and indium begundurch characterized in that the treatments are stigt. Carries out with aqua regia in such a way that one to- The inventive method for separation and first boils with hydrochloric acid and then gradually purifies the metals of the platinum group and gold the required amount of nitric acid is added and the melting of a concentrate made from Ronstein Let the mixture continue to boil. 55 leach residues or sludge recovered 5. The method according to claims 1 to 4, the main platinum, palladium, indium, characterized in that one contains the king ruthenium, rhodium and gold, together water-leaching solution, which in connection with the with a lead compound, if necessary, a leach was obtained with nitric acid, a reducing agent and a flux to first treatment, preferably by means of sulfuric acid, 60 Licher leaching the concentrate with aqua regia, is subjected to the contained lead auszufäl- removing the lead from the resultant alloy and j _en subsequently separating of platinum, palladium, gold