TW201617459A - Method for the processing of precious metal-containing materials - Google Patents

Abstract

The present invention relates to a method for the processing of a precious metal-containing composition that contains an inorganic material and one or more precious metals selected from the group consisting of palladium (Pd), platinum (Pt), rhodium (Rh), gold (Au), silver (Ag), ruthenium (Ru), osmium (Os), rhenium (Re), iridium (Ir), and alloys of at least two of these precious metals, whereby the inorganic material of the composition to be processed is a mixture of at least one metal that differs from the precious metals as well as at least one inorganic material selected from the group consisting of oxides, phosphides, carbides, sulfides, nitrides, borides, silicides, and inter-metallic compounds, and whereby (i) the precious metal-containing composition is added into a nitric acid-containing aqueous medium and is subjected to a thermal treatment, and (ii) subsequently hydrochloric acid is added to the aqueous medium and the precious metal-containing composition is subjected to a thermal treatment.

Description

Processing method for materials containing precious metals

This invention relates to a method of processing a material containing precious metals.

The demand for precious metals, in particular as a catalyst component (for example in exhaust gas catalytic converters), has steadily increased in recent years. Therefore, there is an increasing demand for efficient processing methods for materials containing precious metals in the category of precious metal recycling.

It is basically known that materials containing precious metals can be processed by means of wet metallurgy or pyrometallurgy. A combination of these two types of methods is also used.

In pyrometallurgical processes, the separation of precious metals involves melting the starting materials in a melting furnace (for example, in the case of autocatalytic converters, ceramics and so-called "thin coatings"). The collector metal and optionally other additives are added to the mixture in the melting furnace. The ceramic portion is converted to a slag phase and flows out while the precious metal is combined in the scavenger metal (eg, as an alloying element or in the form of finely dispersed precious metal particles). The precious metal concentration in the scavenger metal is significantly higher than that in the starting material (eg, catalytic converter ceramics), which is approximately 50 times higher, and makes it economical to subsequently purify the precious metal by properly processing the precious metal containing scavenger metal.

In the wet metallurgy process, for example, a precious metal-containing material to be processed is treated with a strong acid (acid decomposition) which dissolves a precious metal in the form of a salt. This method step, in which the precious metal is dissolved, is of great importance in any wet metallurgy process. Unless the precious metals are as fully and as quickly as possible soluble in the efficient decomposition step, the economic efficiency of the process is significantly affected damage. Common method steps commonly known to those skilled in the art (eg, precipitation, electrolysis, ion exchange, adsorption, distillation, filtration, and/or extraction) can be used to separate precious metal salts from each other and from other components. Once separated, the precious metal salt can then be transferred to a new use or can be reduced to a substantially precious metal.

The acid decomposition of the starting material containing the precious metal should convert the precious metal into a soluble salt as much as possible in order to minimize the loss of the precious metal. In addition, if the starting material containing the precious metal can be acid-decomposed as much as possible in the shortest possible period of time, that is, if the precious metal is dissolved in the acidic medium as quickly as possible, it will be advantageous for the production, and thus is advantageous for processing. The economic efficiency of the method.

It is known to use HCl/Cl ₂ as an acid decomposition medium in the processing of materials containing precious metals. In this case, hydrogen production can be disadvantageous.

It is also known to contact the precious metal-containing material to be processed with aqua regia. By mixing three parts of 37% HCl and a portion of 65% nitric acid, HNO ₃ to obtain aqua regia. Aqua regia erosion due to acid such as not referred to, but precisely, due to the reaction products formed when the two kinds of mixed acid (nitric nascent acyl chloride with thionyl _{chloride): HNO 3 + 3HCl → NOCl} + 2Cl _newborn +2H ₂ O

As described in more detail below, the Applicant's experiments have shown that the use of aqua regia can result in extremely strong, uncontrollable foaming of the reaction medium. Therefore, only a relatively small number of aliquots of the precious metal-containing material to be processed can be added to the aqua regia, and the yield of the material is low. It has become apparent that the material to be processed is particularly problematic if the material to be processed contains components which are highly reactive with aqua regia in addition to precious metals. Thus, for example, precious metal-containing scavenger metal compositions of the type used in pyrometallurgical processes have proven to be detrimental to processing with aqua regia due to extremely strong foaming. In addition to certain reactive compounds, strong foaming can also result from fine dispersion of precious metal particles, as this is equivalent to very rapid dissolution due to its large surface in the decomposition of aqua regia.

It is an object of the present invention to provide a method by which a composition containing precious metals can be processed as efficiently as possible.

This processing method should minimize the loss of precious metals and achieve the highest possible yield of the material.

The object is achieved by a processing method for a composition comprising a precious metal comprising an inorganic material and one or more precious metals selected from the group consisting of palladium (Pd), platinum (Pt) , rhodium (Rh), gold (Au), silver (Ag), ruthenium (Ru), osmium (Os), ruthenium (Re), iridium (Ir) and at least two alloys of such precious metals, thereby processing combinations The inorganic material is at least one metal different from the precious metals and a mixture of at least one inorganic material selected from the group consisting of oxides, phosphides, carbides, sulfides, nitrides, a boride, a telluride, and an intermetallic compound, and thereby (i) adding the precious metal-containing composition to an aqueous medium containing nitric acid, and performing heat treatment, and (ii) subsequently adding hydrochloric acid to the aqueous medium And the composition containing the precious metal is subjected to heat treatment.

In the context of the present invention, it is apparent that if the precious metal-containing composition does not contact aqua regia and is immediately subjected to a heat treatment, but is contacted with nitric acid and subjected to a heat treatment in the first step, in the composition containing the precious metal Improper strong foaming during processing can be prevented. The nitric acid not only dissolves a portion of the precious metal in the form of a nitrate, but it also oxidizes other reactive components present in the precious metal-containing composition and will result in strong foaming upon exposure to aqua regia. With respect to the reactive components of the composition to be processed, the reactivity of nitric acid is sufficiently high to remove the components, but the reaction does not proceed so rapidly that it will result in strong foaming. When the hydrochloric acid is added to the subsequent step, a very strong oxidized aqua regia can be formed in the reactor at a ratio of 3:1 HCl/HNO ₃ , but annoying foaming no longer occurs because it is responsible for this method. The reactive component has been deactivated by reaction with the nitric acid.

The precious metal is palladium (Pd), platinum (Pt), rhodium (Rh), gold (Au), silver (Ag), ruthenium (Ru), osmium (Os), ruthenium (Re) or iridium (Ir). Palladium, platinum and rhodium are particularly valuable precious metals.

The inorganic material of the composition to be processed comprises at least one metal other than the above specified precious metal and a mixture of at least one inorganic material selected from the group consisting of oxides, phosphides, carbides, sulfides, Nitrides, borides, tellurides and intermetallic compounds.

In order to facilitate the addition to the aqueous medium containing nitric acid, it may be advantageous for the precious metal-containing composition to be in the form of a powder or in the form of particles.

At least one metal other than the precious metal may be, for example, an alkali metal. Those skilled in the art understand that an alkali metal is a metal having a negative standard potential for a standard hydrogen electrode. However, in the context of the present invention, the inorganic material may likewise contain one or more metals (such as copper) having a positive standard potential.

In the context of the present invention, the term "metal" shall also include alloys made of two or more metal elements.

The inorganic material to be processed with the precious metal-containing composition contains at least one metal different from the precious metal. Examples of coherence include iron, copper, nickel, lead, tin, zinc, and antimony.

If the inorganic material of the composition containing the precious metal is to contain an oxide, an oxide of any of the above specified metals (for example, an oxide of an alkali metal such as iron oxide), SiO ₂ , Al ₂ O ₃ or at least two Mixtures of such oxides can be mentioned as examples.

If the inorganic material of the composition containing the precious metal is to contain a phosphide, the phosphide may be, for example, a phosphide of any of the above specified metals (eg, an alkali metal phosphide such as iron phosphide or phosphating) copper).

If the inorganic material of the composition containing the precious metal to be processed contains carbides, the carbide may be, for example, a carbide of any of the above specified metals (for example, an alkali metal carbide such as iron carbide).

If the inorganic material of the composition containing the precious metal contains a nitride, the nitride may be, for example, a nitride of any of the above specified metals (eg, an alkali metal nitride such as iron nitride or copper nitride). ).

If the inorganic material of the composition containing the precious metal is to contain a sulfide, the sulfide may be, for example, a sulfide of any of the above specified metals (e.g., an alkali metal sulfide such as iron sulfide or copper sulfide).

If the inorganic material of the composition containing the precious metal is to contain a boride, the boride may be, for example, a boride of any of the above specified metals (e.g., an alkali metal boride such as iron boride).

If the inorganic material of the composition containing the precious metal to be processed contains a telluride, the telluride may be, for example, a telluride or an alkali metal telluride (for example, iron telluride) of any of the above specified precious metals.

It has proven to be particularly problematic with the decomposition of aqua regia, and compositions containing precious metals which have proven to be particularly advantageous using the process according to the invention are, for example, by pyrometallurgical treatment (starting materials containing precious metals, such as Catalyst system containing precious metals) via the use of a scavenger metal (preferably iron, copper, nickel, lead, tin, zinc, antimony or a combination or alloy of two or more of these metals), and optionally afterwards A composition containing a precious metal obtained by the grinding step.

The production of the composition containing the precious metal to be processed and the processing thereof according to the method of the invention can be carried out in one apparatus. The apparatus can be, for example, a pyrometallurgical processing unit for the production of compositions containing precious metals (e.g., including a suitable melting furnace), and a downstream wet metallurgy processing unit for powder processing of precious metals in accordance with the present invention. Alternatively, in accordance with the present invention, the production of a precious metal-containing composition and the processing of a powder containing a precious metal can be carried out in a separate apparatus.

A composition comprising a precious metal, wherein the advantage of the process according to the invention is particularly pronounced, comprises, for example, from 25 to 90% by mass, preferably from 35 to 80% by mass of metal ("scavenger metal"), preferably an alkali metal Such as Fe, Ni, Pb, Sn, Zn, Bi or a metal (such as Cu) which also has a positive standard potential. The scavenger metal and the precious metal and/or the precious metals are preferably alloyed, that is, the precious metals are at least partially supported by a scavenger metal Bonded by forming an alloy. In addition to or in the formation of alloys, the precious metals may likewise be combined in the form of finely divided particles by the scavenger metal.

The overall precious metal content of this type of composition based on scavenger metal can vary across a wide range. The total content of the precious metals (preferably platinum, palladium and rhodium) may range from 0.1 to 50% by weight, more preferably from 1 to 20% by weight or from 2 to 15% by weight.

The precious metal-containing composition based on the scavenger metal may likewise contain Si, for example, telluride and/or SiO ₂ . The Si content can vary across a wide range depending on the processing parameters of the pyrometallurgical treatment of the composition containing the precious metal. The Si content may, for example, be in the range of 0.05 to 15% by weight or 0.1 to 10% by weight. The method according to the invention allows a precious metal-containing composition having a low Si content, for example, 0.05 to 3% by weight of Si, and a precious metal-containing composition having a relatively high Si content, for example, 4 to 15% by weight, to be processed. No problems.

The precious metal-containing composition containing the scavenger metal may also contain P, for example, in the form of a phosphide of a scavenger metal (e.g., iron phosphide). The P content can vary across a wide range depending on the processing parameters of the pyrometallurgical treatment of the composition containing the precious metal. The P content can be, for example, in the range of 0.1 to 25% by weight or 0.5 to 20% by weight. The process according to the invention allows the composition containing precious metals to be processed without problems, even if its P content (for example in the form of phosphides) is relatively high, for example 5 to 25% by weight or 7 to 20% by weight.

The precious metal-containing composition based on the scavenger metal may likewise contain oxides, nitrides, borides and/or carbides of the scavenger metal. The oxide, nitride, boride or carbide content can vary widely over a wide range depending on the processing parameters of the pyrometallurgical treatment of the composition containing the precious metal. The process according to the invention allows the composition containing precious metals to be processed without problems even if it contains a relatively large amount of oxides, nitrides, borides and/or carbides.

As described above, the composition containing the precious metal is added to an aqueous medium containing nitric acid, and heat treatment is performed.

Heat treatment of a composition containing precious metals in a medium containing nitric acid allows nitric acid and expensive The reactive components in the heavy metal composition are reacted and the reactive components are removed prior to the addition of hydrochloric acid to such an extent that after the addition of HCl, or at least a significant reduction in violent reaction (with strong foaming) is prevented Associated). Preferably, the heat treatment also causes the precious metal to at least partially dissolve in step (i).

As stated above, the precious metal-containing composition preferably exhibits a powder or granule for as efficient addition as possible to the nitric acid-containing medium.

The composition containing the precious metal can be added to the medium containing nitric acid by placing nitric acid and water in a reaction vessel and/or a reactor, and adding a composition containing a precious metal. The addition of the precious metal-containing composition can be carried out continuously or discontinuously in multiple aliquots. If necessary, an additional amount of nitric acid and/or water may be added to the reactor after the addition of the composition containing the precious metal.

Alternatively, at least a portion of the composition containing the precious metal is placed in the reactor, and subsequent addition of water is as feasible as nitric acid. It is also feasible to add a composition containing precious metals, water and nitric acid at the same time.

The concentration of nitric acid in the aqueous medium in step (i) can vary over a wide range and is, for example, at least 10% by weight or at least 15% by weight.

Preferably, the concentration of nitric acid in the aqueous medium in step (i) is at least 20% by weight. This concentration is not only sufficient to dissolve the precious metal in the majority of its nitrate form, but also sufficient to react with other reactive components present in the precious metal-containing composition. Preferably, the concentration of nitric acid in step (i) is in the range of 20 to 35% by weight or 20 to 30% by weight.

Preferably, the aqueous medium in step (i) is free of hydrochloric acid or contains hydrochloric acid having an insufficient molar concentration of nitric acid. If hydrochloric acid is present in the aqueous medium of step (i), the molars of HCl and HNO _{3 are} preferably less than 0.5, more preferably less than 0.2 or less than 0.1.

Preferably, the aqueous medium in step (i) contains nitric acid as a separate acid. If other acids are present in the aqueous medium of step (i), the other acids and nitric acid are preferably less than 0.5, more preferably less than 0.2 or less than 0.1.

The heat treatment of the composition containing the precious metal in step (i) may be carried out prior to the addition of the composition or, after the addition of the composition, but in either case correspondingly by means of heating the aqueous medium. Preferably, the precious metal-containing composition is added to the nitric acid-containing medium at a temperature ranging from 60 to 120 ° C, more preferably from 80 to 105 ° C or from 87 to 95 ° C.

The period of time during which all of the material to be processed in step (i) is added to the aqueous medium containing nitric acid may vary widely depending on the type and amount of the composition containing the precious metal. For example, the composition containing the precious metal to be processed may be added to the medium containing nitric acid for a period of from 15 minutes to 10 hours or from 20 minutes to 5 hours.

Since the reaction of the nitric acid with the reactive component of the composition to be processed is much less exothermic than the aqua regia and thus minimizes the foaming of the reaction medium, the composition containing the precious metal may be more pronounced than during the decomposition of the aqua regia. Add to the aqueous medium more quickly.

The composition containing the precious metal to be processed may be added to the medium containing nitric acid, for example, 0.01 to 50 kg / (min × m ³ ) or 0.1 to the volume (in m ³ ) relative to the medium containing nitric acid At a rate of 20 kg / (min × m ³ ).

The heat treatment of the precious metal-containing composition in the nitric acid-containing medium is preferably carried out at a temperature in the range of 60 to 120 ° C, more preferably 80 to 105 ° C or 87 to 95 ° C (for example, by heating the aqueous medium accordingly).

After all the precious metal-containing composition to be processed is added to the nitric acid-containing medium, it is preheated to the heat treatment temperature as the case may be, and the composition is subjected to heat treatment in the medium for a sufficient period of time so that the reactive compound is compared. Preferably, the removal is complete, and preferably the largest possible portion of the precious metal has been dissolved in step (i). The period of heat treatment of the composition may vary widely depending on the type and amount of the precious metal-containing composition after it is added to the aqueous medium containing nitric acid. The heat treatment after addition to the medium containing nitric acid can be carried out, for example, within a period of from 0.5 to 15 hours or from 1 to 10 hours.

Step (ii) involves heat treatment of adding hydrochloric acid to the aqueous medium and the composition containing the precious metal.

Preferably, the hydrochloric acid added in step (ii) is 7 to 12 moles (7 to 12 M) or 8 to 11 moles (8 to 11 M) of hydrochloric acid.

Hydrochloric acid can be added to the aqueous medium continuously or discontinuously as a separate aliquot. The rate of addition of hydrochloric acid can vary over a wide range and is, for example, from 0.1 to 50 l/min or from 0.5 to 25 l/min.

Preferably, the total amount of hydrochloric acid added in the step (ii) is such that the hydrochloric acid added in the step (ii) and the nitric acid initially present in the aqueous medium in the step (i) are added (including the addition of valuables) The molar ratio of the metal composition is in the range of 1.0 to 15.0, preferably in the range of 1.0 to 8.0, more preferably in the range of 1.0 to 4.0 or 2.0 to 3.5.

The heat treatment of the composition containing the precious metal in the step (ii) is preferably carried out at a temperature in the range of 60 to 100 ° C, more preferably 80 to 100 ° C or 87 to 95 ° C. Preferably, hydrochloric acid has been added when the temperature of the aqueous medium is in the range of 60 to 100 ° C, more preferably 80 to 100 ° C or 87 to 95 ° C.

After the addition of hydrochloric acid, the heat treatment in step (ii) is continued until no other precious metals are dissolved. After the addition of hydrochloric acid, the heat treatment can be carried out, for example, for a period of 0.5 to 15 hours or 1 to 10 hours.

The heat treatment of the addition of hydrochloric acid to the aqueous medium and the precious metal-containing composition of step (ii) results in the obtaining of an aqueous medium containing the precious metal in dissolved form (for example in the form of a salt).

Preferably, no acid addition is added in step (ii) except for hydrochloric acid.

Optionally, additional hydrochloric acid can be used to evaporate after step (ii). Separation by smoking can be accomplished, for example, using 7 to 12 molar concentrations (7 to 12 M) of hydrochloric acid. As is known to those skilled in the art, this involves reducing the volume of the aqueous medium followed by the addition of hydrochloric acid and heating. It is preferred not to always reduce the volume to dryness. If applicable, the process can be repeated multiple times. By allowing separation of the residue fuming Cl ₂ and NO _x removed from the aqueous medium.

If applicable, solids for separation of insoluble residues may be performed after step (ii) Liquid separation (eg filtration). Optionally, separation by fuming using hydrochloric acid can be carried out in this case between step (ii) and solid/liquid separation.

After step (ii) or after optionally the step of separation by smoking, the precious metal is predominantly present in the form of a salt dissolved in an aqueous medium (for example in the form of a chlorine complex).

Preferably, after step (ii), one or more separation steps for isolation of the precious metal are performed. As described above, the separation by the use of hydrochloric acid fuming may be performed additionally and optionally, after step (ii) and before the separation step.

Basically, known methods for separating and isolating precious metals include, for example, precipitation reaction, electrolysis, ion exchange, extraction (for example, solvent extraction), oxidation/reduction, adsorption, filtration, or distillation, or two or more of them. A combination of methods.

The invention will be explained in more detail on the basis of the following examples.

Instance

A composition containing precious metals processed in the examples:

Composition 1 containing PM (ZS1 with PM):

The PM-containing ZS1 is obtained by a pyrometallurgical process using iron as a scavenger metal. Elemental analysis revealed the following components in particular:

Pt: 4.7% by weight

Pd: 6.0% by weight

Rh: 0.9% by weight

Cr: 1.3% by weight

Cu: 0.5% by weight

Fe: 51.7 wt%

Ni: 17.5% by weight

P: 12.8% by weight

Si: 0.6% by weight

PM-containing composition 2 (ZS2 with PM):

The PM-containing ZS2 is obtained by a pyrometallurgical process using iron as a scavenger metal. Elemental analysis revealed the following components in particular:

Pt: 2.8% by weight

Pd: 4.6 wt%

Rh: 0.6% by weight

Cr: 4.0% by weight

Cu: 0.9% by weight

Fe: 50.0% by weight

Ni: 8.0% by weight

Si: 6.0% by weight

Reference example 1

Place 2,000 l of aqueous medium containing aqua regia in a container. 180 kg of the composition containing precious metals 1 was to be added. Add at 90 °C.

Even when a very small amount of PM-containing ZS1 is added to a medium containing aqua regia, extremely strong foaming proceeds. Therefore, it is possible to add only small aliquots. It takes approximately 76 hours to add the entire amount.

Subsequently, filtration is performed to remove insoluble residues. It takes approximately 72 hours for all of the aqueous medium to pass through the filter.

Reference example 2

The properties of Composition 2 containing precious metals were tested on a laboratory scale after exposure to aqua regia.

A very drastic and uncontrollable response was observed.

Example 1

program:

• Heat the mixture of water/HNO ₃ supplied as it is to 90 °C.

- A composition containing a precious metal was added over a period of 40 minutes at 90 ° C (no exothermic reaction was observed, no excessive foaming was observed). After the composition was added to the medium containing nitric acid, heat treatment was performed at a temperature of 90 ° C for 5 hours. After the addition, samples were taken every hour for a period of 5 hours and the amount of precious metal dissolved was determined. The results are shown in Figure 1.

• After 5 hours of heat treatment of the composition, the hydrochloric acid was fed into an aqueous medium containing nitric acid (first 3 liter feed rate: 2.5 l/min). This was associated with mild foaming during the first 3 liters of HCl, followed by an increase in flow rate to 8.5 l/min.

• Add 160 l of total HCl over 90 minutes. After the addition of hydrochloric acid, the composition containing the precious metal was heat-treated at 90 ° C for a period of 4 hours.

• Subsequently, filtration is performed to remove insoluble residues. Filtration takes only 4 hours.

With regard to step (i), that is, heat treatment of a composition containing a precious metal in a medium containing nitric acid, the following conclusions are drawn:

●The addition of a composition containing precious metals is not associated with any problems

• Pd and Rh have been almost completely dissolved in step (i).

● 46% Pt dissolved.

● More than 90% of Cr, Cu, Fe Ni and P are dissolved.

With regard to step (ii), that is, the addition of HCl and other heat treatments of the composition containing precious metals, the following conclusions are drawn:

●All Pt dissolved after 1h

● Dissolve the residue and moisten 337g

• Dry in the laboratory, 124 g dry, corresponding to a starting weight of 1.3%.

Example 2

program:

• Heat the mixture of water/HNO ₃ (25%) supplied as it is to 90 °C.

- A composition containing a precious metal was added over a period of 2.5 hours at 90 ° C (no exothermic reaction was observed, no excessive foaming was observed). After the composition was added to the medium containing nitric acid, heat treatment was performed at a temperature of 90 ° C for 3 hours. After the addition, samples were taken every hour for a period of 3 hours and the amount of dissolved palladium was determined.

The results are shown in Figure 2.

• After 3 hours of heat treatment of the composition, the hydrochloric acid was fed into an aqueous medium containing nitric acid (first 25 liter feed rate: 2.5 l/min). This was associated with mild foaming during the first 3 liters of HCl, followed by an increase in flow rate to 10 l/min.

• Add 1,100 l of total HCl within 4 hours. After the addition of hydrochloric acid, the composition containing the precious metal was subjected to heat treatment at a temperature of 95 ° C for 2 hours.

• Subsequently, filtration is performed to remove insoluble residues. Filtration takes only 5 hours.

With regard to step (i), that is, heat treatment of a composition containing a precious metal in a medium containing nitric acid, the following conclusions are drawn:

●The addition of a composition containing precious metals is not associated with any problems

• Pd and Rh were completely dissolved after 3 hours.

● 47% Pt dissolved.

● More than 90% of Cr, Cu, Fe, Ni, and P are dissolved.

With regard to step (ii), that is, the addition of HCl and other heat treatments of the composition containing precious metals, the following conclusions are drawn:

●All Pt dissolved after adding HCl

● Dissolve the residue, wetting 4.327kg

• Dry in the laboratory, 2.53 kg, corresponding to a starting weight of 2%.

Example 3

program:

• Heat a mixture of water/HNO ₃ (25%) supplied as is to 92 °C.

• After each addition of an aliquot of approximately 1 kg, the composition containing the precious metal was added over a period of 30 minutes at 92 ° C with a certain degree of light foaming. After the addition, the temperature was measured to rise to 94.5 °C. After the composition is added to the medium containing nitric acid, heat treatment is performed for a period of 4 hours at about 92 to 95 °C. After the addition, samples were taken every hour for a period of 4 hours and the amount of precious metals dissolved was determined.

The results are shown in Figure 3.

• After 4 hours of heat treatment of the composition, the hydrochloric acid was fed into an aqueous medium containing nitric acid (for the first 25 liter feed rate: 2.5 l/min). At a flow rate of from 1.3 l/min to 20 l/min in a 10 l aliquot, there is a certain slight foaming that is always rapidly decomposed.

• Add an overall 120 l of HCl within 5 hours. After the addition of hydrochloric acid, the composition containing the precious metal was subjected to heat treatment for a period of 5 hours at 92 to 95 °C.

• Subsequently, filtration is performed to remove insoluble residues. Filtration takes only 5 hours.

With regard to step (i), that is, the heat treatment of a composition containing a precious metal in a medium containing nitric acid, the following conclusions are drawn:

• The addition of a composition containing precious metals is not associated with any problems.

● After 4 hours, the dissolution rate is as follows: 22% Pd, 12% Pt, 21% Rh, 44% Cr, 35% Cu, 52% Fe, and 51% Ni.

With regard to step (ii), that is, the addition of HCl and other heat treatments of the composition containing precious metals, the following conclusions are drawn:

• Pt, Pd and Rh are almost completely dissolved.

●Soluble residue, wetting 9.527kg

• 3.061 kg dry, corresponding to a starting weight of 30%.

• The dissolved residue contained a total of 2.72% PM of the starting material.

As is apparent from Examples 1 to 3 and Reference Example 1, the processing method according to the present invention promotes a more rapid dissolution of the composition containing precious metals, and thus promotes a much higher yield of the material.

As is apparent from Example 3 and Reference Example 2, the method according to the invention also makes it possible to process the extremely problematic starting material which, if not otherwise, does not undergo processing by decomposition of aqua regia, or it may only be possible Add material very slowly.

As is apparent from Examples 1 to 3 and Reference Example 1, the aqueous medium obtained after the step (ii) of the method according to the present invention can be extremely easily filtered, whereas the decomposition of aqua regia causes the aqueous medium to have poor filtration properties.

Figure 1 shows the results of an internal experiment with a precious metal (PM) dissolution rate at 25% HNO ₃ at 90 ° C, 9.544 kg MM.

2 shows an internal experiment was 25% HNO _3, at 95 ℃, 123.78kg MM results of the dissolution rate of the Pd.

FIG 3 shows the internal Experiment 3 25% HNO _3, at 90 ℃, the results of the dissolution rate of 10kg MM precious metal (PM).

Claims (9)

A method of processing a composition comprising a precious metal comprising an inorganic material and one or more precious metals, the or the precious metals being selected from the group consisting of palladium (Pd), platinum ( Pt), rhodium (Rh), gold (Au), silver (Ag), ruthenium (Ru), osmium (Os), ruthenium (Re), iridium (Ir), and at least two alloys of such precious metals, The inorganic material of the processing composition is at least one metal different from the precious metals and a mixture of at least one inorganic material selected from the group consisting of oxides, phosphides, carbides, sulfides, nitrogen. a compound, a boride, a telluride, and an intermetallic compound, and thereby (i) adding the precious metal-containing composition to an aqueous medium containing nitric acid, and performing heat treatment, and (ii) subsequently adding hydrochloric acid to the An aqueous medium is used, and the composition containing the precious metal is subjected to heat treatment. The method of claim 1, wherein the precious metal-containing composition is in the form of a powder or in the form of particles. The method of claim 1 is such that the precious metal-containing composition is obtained by a pyrometallurgical process using a scavenger metal. The method of claim 1 wherein the concentration of nitric acid in the aqueous medium in step (i) is at least 10% by weight. The method of claim 1, wherein the heat treatment of the precious metal-containing composition in the nitric acid-containing medium in the step (i) is carried out at a temperature in the range of 60 to 120 °C. As in the method of claim 1, The hydrochloric acid added in the step (ii) is 7 to 12 M hydrochloric acid. The method of claim 1, wherein the hydrochloric acid added in the step (ii) and the molar ratio of the nitric acid present in the medium in the step (i) are in the range of 1.0 to 10.0. The method of claim 1, wherein the heat treatment of the precious metal-containing composition in the step (ii) is carried out at a temperature in the range of 60 to 100 °C. The method of claim 1, wherein one or more separation steps for isolation of the precious metals are performed.