WO2025003779A1

WO2025003779A1 - Furnace system for precious metal recovery

Info

Publication number: WO2025003779A1
Application number: PCT/IB2024/053688
Authority: WO
Inventors: Norbert Ritschel; Uve KUPKA; Christian Mock
Original assignee: Heraeus Precious Metals GmbH and Co KG
Current assignee: Heraeus Deutschland GmbH and Co KG
Priority date: 2023-06-30
Filing date: 2024-04-16
Publication date: 2025-01-02
Anticipated expiration: 2025-12-30

Abstract

The present invention relates to a method of recovering precious metals from precious metal- containing furnace input materials, the method using a multi-part furnace system which comprises - an upper furnace part UFP which comprises a furnace roof, - at least two lower furnace parts LFP1 and LFP2, wherein each of the lower furnace parts LFP1 and LFP2 - is configured to be releasably attached to the upper furnace part UFP, - comprises an inside which is at least partly covered by a refractory lining, an outside, and an internal volume for receiving a precious metal- containing furnace input material.

Description

FURNACE SYSTEM FOR PRECIOUS METAL RECOVERY

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Patent Application No. 63/511,380 filed June 30, 2023. The aforementioned application is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The present invention relates to a multi-part furnace system and its use for precious metal recovery.

BACKGROUND

[0003] Precious metals, i.e. platinum group metals (PGMs), silver, and gold, are used in numerous industrial processes and commercial applications such as electronic devices, catalysts, automotive parts, jewellery, and dental materials.

[0004] As known to the skilled person, precious metals (PMs) can be recovered from precious metal-containing materials (such as PM-containing ores and PM-containing waste materials) by pyrometallurgical methods such as smelting.

[0005] Smelting is a melting operation carried out at high temperature in a metallurgical furnace wherein the material fed into the furnace is melted and separates into at least two liquid phases, i.e. the so-called slag phase and a phase containing the metal of interest (see e.g. C.K. Gupta, “Chemical Metallurgy: Principles and Practice”, Chapter 4.5 ^Smelting”), pp. 353-354, 2003, Wiley- VCH Verlag).

[0006] Different types of metallurgical furnaces such as blast furnaces and arc furnaces for recovering metals from feed materials by smelting or other pyrometallurgical methods are commonly known. A review of metallurgical furnaces is provided e.g. J. Grzella et al., “Metallurgical Furnaces” , 2005, DOI: 10.1002/14356007.b04_339, Ullmann’s Encyclopedia of Industrial Chemistry. [0007] It is also known that the feed material introduced into the metallurgical furnace for smelting (in the following also referred to as a smelting furnace) may contain additives such as reducing agents, fluxing agents, and collector materials.

[0008] Collector materials might be certain metals (e.g. Fe, Cu, Pb, Ag) or oxides or sulphides (e.g. copper matte or nickel matte) thereof. The collector material acts as a carrier or collector for the metal of interest during the smelting process.

[0009] If the raw material comprises the precious metal to be recovered in oxidized form, said precious metal oxide can be reduced to its metal form by adding a reducing agent such as, for example, carbon (e.g. charcoal), FesC , natural gas, CO, sulfur, wood, and WPCB (waste printed circuit boards). Furthermore, if the collector material initially added to the furnace feed is an oxide (such as an iron oxide), it can be reduced by the reducing agent to a metal (e.g. Fe(0)) in which the metal to be recovered is dissolved.

[0010] Fluxing agents have multiple functions. Together with non-metallic components (such as oxides) of the raw material, they form the slag and ensure appropriate melt viscosity, liquidus temperature and electrical conductivity. Commonly used fluxing agents in smelting processes are e.g. burnt lime CaO, SiCh, magnesium oxide, aluminum oxide, borax, FeO, PbO, CuO, C S/FeS mixtures and soda ash.

[0011] EP 0 173 425 Al describes a process for recovering platinum group metals (PGMs) from feedstock materials including such metals, in a plasma arc furnace which comprises the steps of introducing a charge of flux, a collector material, and a feedstock material to the plasma furnace; forming a melt by heating the charge to at least about 1350°C, the melt comprising a first layer of slag and a second layer of collector material associated with at least some of the platinum group metals from the feedstock material; and impinging a plasma arc flame on a surface of the slag layer so that a superheated puddle is formed on said surface whereby the accumulation of platinum group metals in the second layer is accelerated.

[0012] As precious metals are rare but have high economical value, it is of crucial importance to achieve high recycling rates for these metals. [0013] Precious metal-containing waste materials which might be subjected to recycling processes are numerous and may include waste electric and electronic equipment (WEEE, also referred to as electronic waste or e-waste), spent catalysts (exhausted catalysts), sweeps and mining residues.

[0014] A review on metallurgical recovery of metals from electronic waste is provided by J. Ciu et al., Journal of Hazardous Materials, 158, 2008, pp. 228-256.

[0015] C. Liu et al., “Metals smelting-collection method for recycling of platinum group metals from waste catalysts: A mini review", Waste Management & Research. 2021;39(l):43- 52, provide a review on PGM recovery methods by smelting using a collector material.

[0016] LIS 4,428,768 describes a process for the recovery of platinum group metals present in a used auto emission control catalyst, said process comprising preparing, in divided form, a charge containing the refractory ceramic substrate bearing the said metals, one or more fluxes, and a collector material or collector material precursor, for the metal or metals to be recovered, feeding said charge into a high intensity plasma arc furnace and heating the charge to a temperature in the range of 1500-1750°C by means of the high intensity plasma arc of said furnace to produce a molten metallic phase containing a substantial proportion of the said metal or metals formerly deposited on or contained in the substrate, and a molten slag phase containing flux, ceramic residues and the remainder of the said metals, separating the two phases, and separating the platinum group metals from the metallic phase.

[0017] WO 2010/058188 Al describes a process for obtaining a precious metal-rich composition from a feedstock material, the process comprising the steps of (i) heating a feedstock material in a plasma furnace to form an upper slag layer and a lower molten metal layer, (ii) removing the slag layer; (iii) removing the molten metal layer; (iv) allowing the removed molten metal layer to solidify; (v) fragmenting the solidified metal layer to form fragments; and (vi) recovering a precious metal-rich composition from the fragments; wherein the feedstock material comprises a precious metal-containing material and a collector metal, said collector metal being a metal or an alloy that is capable of forming a solid solution, an alloy or an intermetallic compound with one or more precious metals. The precious metal-containing material comprises an autocatalyst, a chemical catalyst, a petrochemical catalyst, a pharmaceutical catalyst, electrical and electronic equipment waste, thermal barrier coating waste, foundry sweeps, electroplating and/or metal finishing waste, jewellery and/or jewellery process waste and dental and/or medical waste.

[0018] The melt, in particular the slag, prepared during the smelting process is highly corrosive and may therefore damage the steel parts of the furnace (e.g. roof, side walls, bottom, and tap holes of the furnace). Typically, the inside of a smelting furnace is at least partly covered by a refractory lining (e.g. built by refractory bricks) which provides protection against corrosive damage and acts as a thermal insulator.

[0019] As indicated in ASTM C 71-08, refractories are non-metallic materials having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above 1000°F (538°C). Exemplary refractory materials (e.g. in the form of refractory bricks) mentioned in ASTM C 71-08 and known to the skilled person include magnesia-based refractories (i.e. refractories wherein magnesia is the main component), chromia-based refractories (i.e. refractories wherein chromic oxide is the main component), alumina-based refractories (i.e. refractories wherein alumina is the main component), silica-based refractories (refractories wherein silica is the main component), and silicon carbide-based bricks.

SUMMARY

[0020] Different types of refractories might be needed for different smelting operations. Multiple factors like the type of material processed and the type of smelting operation might affect which type of refractory material is to be selected.

[0021] Just as an example, a refractory material might provide high corrosion protection against a first slag composition, but may provide insufficient protection against another slag composition. So, if a smelting treatment of a first waste material has been completed, it might be necessary to replace the previous refractory lining by a different refractory lining before a second waste material can be subjected to a smelting treatment in the same furnace. Furthermore, as the refractory lining of the melt-receiving lower part of the furnace is exposed to high corrosive stress, it may degrade over time and to be replaced by a new refractory lining. However, replacement of refractory linings is very time-consuming and expensive.

[0022] Alternatively, instead of replacing the refractory lining of the smelting furnace, additional fully equipped complete smelting furnaces (i.e. each of these additional furnaces containing both the melt-receiving bottom part and the roof part) having different refractory linings might stand by at the plant and replace the other furnace, if need be. However, keeping complete furnaces in reserve results in high investment costs.

[0023] If different collector materials are to be used for smelting of a first waste material and a second waste material, it might be necessary to remove residues of the materials used in the previous smelting operation from the refractory lining before subjecting the second waste material to a smelting treatment in the same furnace. This is very time-consuming and significantly impairs process efficiency. Again, instead of operating the plant with a single smelting furnace, complete smelting furnaces (i.e. each of these additional furnaces containing both the melt-receiving bottom part and the roof part) might stand by at the plant and eventually replace the other furnace, which, however, results in high investment costs.

[0024] So, there is a need for tools which can be used for recovering precious metals from waste materials such as spent catalysts and e-scrap and from ores by a flexible and efficient method.

[0025] Typically, a smelting furnace comprises a lower part which receives the melt phase during the smelting treatment and a roof-containing upper part by which the material to be processed is fed into the furnace and off gas is withdrawn from the furnace. So, if a previously used smelting furnace is replaced by a new complete furnace, this means that both a new lower part and a new roof part is provided. However, as realized in the present invention, it is typically the lower furnace part (i.e. the furnace part coming into contact with the molten slag phase and molten precious metal-containing phase) but not the roof part which needs to be replaced.

[0026] The precious metal recovering method of the present invention uses a multi-part furnace system comprising a roof-containing upper part and two or more interchangeable refractory lined lower furnace parts. One and the same furnace roof might be used for a high number of subsequent smelting operations whereas the refractory lined lower furnace parts might be substituted for each other at any time in between different smelting operations, e.g. if a subsequent smelting operation uses a slag phase composition or collector metal which is not consistent with the furnace refractory lining used in the previous smelting operation.

[0027] Accordingly, as a previously used lower furnace part can be detached from the furnace roof and replaced by a new lower furnace part within a relatively short period of time (typically less than 24 hours), the method of the present invention is very flexible and allows time efficient processing of very different types of precious metal-containing furnace input materials. On the other hand, as the furnace system used in the present invention comprises just a single furnace roof and does not require two or more complete furnaces (and corresponding power supplies and exhaust lines therefore), investment costs are significantly reduced (if compared to precious metal recovery plants operating with two or more complete furnaces).

[0028] In particular, according to a first aspect, the present invention provides a multi-part furnace system comprising an upper furnace part UFP which comprises a furnace roof, at least two lower furnace parts LFP1 and LFP2, wherein each of the lower furnace parts LFP1 and LFP2 is configured to be releasably attached to the upper furnace part UFP, comprises an inside which is at least partly covered by a refractory lining, an outside, and an internal volume for receiving a precious metalcontaining furnace input material.

[0029] The present invention also relates to a method of recovering precious metals from furnace input materials, the method using said multi-part furnace system of the present invention and comprising the following steps: subjecting a first furnace input material FIM1 containing one or more precious metals (e.g. in elementary or alloyed form or in the form of oxides, sulfides or halides) to a smelting treatment in a furnace Fl, thereby obtaining a first liquid precious metal-containing furnace output material F0M1 which is withdrawn from the furnace Fl, wherein the furnace Fl comprises the lower furnace part LFP1 and the upper furnace part UFP being releasably attached to each other, terminating the smelting treatment of the first furnace input material FIM1 in the furnace Fl and detaching the lower furnace part LFP1 from the upper furnace part UFP, releasably attaching the lower furnace part LFP2 to the upper furnace part UFP, thereby forming a furnace F2, subjecting a second furnace input material FIM2 containing one or more precious metals (e.g. in elementary or alloyed form or in the form of oxides, sulfides or halides) to a smelting treatment in the furnace F2, thereby obtaining a second liquid precious metal-containing furnace output material F0M2 which is withdrawn from the furnace F2.

[0030] Furthermore, the present invention relates to the use of the multi-part furnace system of the present invention for recovering precious metals from different furnace input materials.

DETAILED DESCRIPTION

[0031] As mentioned above, the multi-part furnace system of the present invention comprises an upper furnace part UFP which comprises a furnace roof, at least two lower furnace parts LFP1 and LFP2, wherein each of the lower furnace parts LFP1 and LFP2 is configured to be releasably attached to the upper furnace part UFP, comprises an inside which is at least partly covered by a refractory lining, an outside, and an internal volume for receiving a precious metal-containing furnace input material. [0032] The lower furnace part LFP1 and the upper furnace part UFP, if releasably attached to each other, form a first furnace Fl; and the lower furnace part LFP2 and the upper furnace part UFP, if releasably attached to each other, form a second furnace F2.

[0033] Each of the furnaces Fl and F2 may have an internal volume (IVFI and IVF2, respectively) of for example 500 liters to 5000 liters.

[0034] Each of the lower furnace parts LFP1 and LFP2 may have an internal volume (IVLFPI and IVLFP2, respectively) of e.g. at least 200 liters, preferably under the provision that IVLFPI < 0,6 x IVFI and IVLFP2 < 0,6 x IVF2.

[0035] Each of the furnaces Fl and F2 may have a maximum load capacity of e.g. up to 5000 kg.

[0036] Each of the lower furnace parts LFP1 and LFP2 is preferably configured to be airtightly attached to the upper furnace part UFP.

[0037] For releasable attaching the lower furnace part LFP1 or LFP2 to the upper furnace part UFP, commonly known fixing means can be used. Exemplary fixing means may include bolts, screws, flanges, clamps, and fittings.

[0038] Preferably, the multi-part furnace system comprises just one upper furnace part UFP.

[0039] Appropriate metallurgical furnaces for recovering precious metals by smelting processes are known to the skilled person.

[0040] The furnaces Fl and F2 might be arc furnaces such as plasma arc furnaces (e.g. DC (direct current) plasma arc furnaces). The upper furnace part UFP (in particular the furnace roof) may comprise at least one opening in which an electrode is positioned. Each of the lower furnace parts LFP1 and LFP2 may comprise an electrode.

[0041] The inside of the lower furnace part LFP1 or LFP2 is at least partly covered by a refractory lining. Appropriate refractory materials (e.g. in the form of bricks) are known to the skilled person. [0042] The refractory lining might be a magnesia-based refractory lining (i.e. a refractory lining (e.g. in the form of refractory bricks) wherein magnesium oxide is the main component), an alumina-based refractory lining (i.e. a refractory lining (e.g. in the form of refractory bricks) wherein aluminum oxide is the main component), or a chromia-based refractory lining (i.e. a refractory lining (e.g. in the form of refractory bricks) wherein chromium oxide is the main component). In a preferred embodiment, the refractory lining is a magnesia-based refractory lining or an alumina-based refractory lining.

[0043] The magnesia-based refractory lining might be a refractory lining having a magnesium oxide content of at least 90 wt% or a refractory lining having a magnesium oxide content of at least 50 wt% and a chromium oxide content of more than 10 wt% (but less than 50 wt%).

[0044] The alumina-based refractory lining might be a refractory lining having an aluminum oxide content of at least 60 wt%. In an exemplary embodiment, the alumina-based refractory lining might be a refractory lining having an aluminum oxide content of at least 60 wt% and a chromium oxide content of at least 10 wt% (but less than 40 wt%), or a refractory lining having an aluminum oxide content of at least 50 wt% and a silicon dioxide content of at least 20 wt% (but less than 50 wt%).

[0045] Preferably, the lower furnace parts LFP1 and LFP2 differ from each other by their refractory linings (e.g. refractory linings which differ in chemical composition) and/or their internal volumes.

[0046] Each of the lower furnace parts LFP1 and LFP2 may comprise a furnace vessel (e.g. a cylindrical vessel) which comprises a steel wall. On the furnace inside, the steel wall is at least partly covered by the refractory lining. The steel wall may have a thickness of e.g. 5 mm to 50 mm.

[0047] Each of the lower furnace parts LFP1 and LFP2 may comprise one or more sealable tap holes by which molten materials (such as a liquid containing the precious metal to be recovered and optionally a collector metal, or a molten slag phase) can be withdrawn. [0048] The upper furnace part UFP (in particular the furnace roof) may comprise a sealable opening by which the furnace input material can be introduced.

[0049] The furnace roof may comprise one or more steel panels. The furnace roof may comprise an underside which is at least partly covered by a refractory lining (thereby providing thermal insulation and preventing hot gas and/or melt to damage the furnace roof), and an upper side being cooled by appropriate cooling means. The furnace roof may comprise an outlet by which off gas can be withdrawn.

[0050] Preferably, the multi-part furnace system of the present invention comprises at least two moving devices, each moving device having a platform for mounting the lower furnace part LFPl or LFP2.

[0051] Appropriate moving devices for transportation of heavy weight furnace parts are known to the skilled person. The moving device can be a remotely controlled vehicle. The moving device may comprise pivotable wheels (e.g. four dual wheels being pivotable by 70- 120°). The moving device might be rated for carrying a capacity of at least 50000 kg.

[0052] The multi-part furnace system may comprise at least one additional lower furnace part LFP3 which is configured to be releasably attached to the upper furnace part UFP, comprises an inside which is at least partly covered by a refractory lining, an outside, and an internal volume for receiving a precious metal-containing furnace input material.

[0053] With regard to further properties of the lower furnace part LFP3, reference can be made to the properties of the lower furnace parts LFP1 and LFP2.

[0054] The additional lower furnace part LFP3 and the upper furnace part UFP, if releasably attached to each other, form a furnace F3. With regard to further properties of the additional furnace F3, reference can be made to the properties of furnaces Fl and F2. [0055] The additional lower furnace part LFP3 is preferably configured to be air-tightly attached to the upper furnace part UFP.

[0056] Preferably, the additional lower furnace part LFP3 differs from the lower furnace parts LFP1 and LFP2 by its refractory lining (e.g. refractory linings which differ in chemical composition) and/or internal volume.

[0057] For further improving process flexibility, the multi-part furnace system of the present invention may even comprise four or more lower furnace parts (LFP1, LFP2, LFP3, LFP4, . . .) which preferably differ from each other by their refractory linings (e.g. refractory linings which differ in chemical composition) and/or internal volumes. Just like LFP1 to LFP3, each of the additional lower furnace parts (LFP4, ) is configured to be releasably attached to the upper furnace part UFP and comprises an inside which is at least partly covered by a refractory lining, an outside, and an internal volume for receiving a precious metal-containing furnace input material.

[0058] The multi-part furnace system of the present invention is used in a method of recovering precious metals from furnace input materials.

[0059] The precious metal-recovery method comprises the following steps: subjecting a first furnace input material FIM1 containing one or more precious metals (e.g. in elementary or alloyed form or in the form of oxides, sulfides or halides) to a smelting treatment in a furnace Fl, thereby obtaining a first liquid precious metal-containing furnace output material FOM1 which is withdrawn from the furnace Fl (e.g. via a tap hole of the lower furnace part LFP1), wherein the furnace Fl comprises the lower furnace part LFP1 and the upper furnace part UFP being releasably attached to each other, terminating the smelting treatment of the first furnace input material FIM1 in the furnace Fl and detaching the lower furnace part LFP1 from the upper furnace part UFP, releasably attaching the lower furnace part LFP2 to the upper furnace part UFP, thereby forming a furnace F2, subjecting a second furnace input material FIM2 containing one or more precious metals (e.g. in elementary or alloyed form or in the form of oxides, sulfides or halides) to a smelting treatment in the furnace F2, thereby obtaining a second liquid precious metal-containing furnace output material F0M2 which is withdrawn from the furnace F2 (e.g. via a tap hole of the lower furnace part LFP2).

[0060] The precious metal is a platinum group metal (PGM), gold, and/or silver. The platinum group metal is platinum, palladium, iridium, rhodium, ruthenium, or osmium, or a combination or mixture of two or more of these metals.

[0061] The precious metal-containing furnace input materials FIM1 and FIM2 may comprise one or more of the following materials: a raw material RM which is selected from spent catalysts (e.g. heterogeneous catalysts comprising a precious metal, in particular a PGM, on a support material; such as automotive catalysts, Diesel oxidation catalysts, chemical catalysts (i.e. catalysts used for the preparation of intermediates and specialty chemicals), mining materials (e.g. mining concentrates and mining residues), waste electrical and electronic equipment (also known as “WEEE” or “e- waste”), such as sparkplugs and circuit boards (ceramic-based or plastic-based circuit boards), industrial alloys (e.g. specialty alloys, batteries, filter cakes, flue dust), fuel cells or parts thereof (such as membranes containing a precious metal or being coated with a precious metal-containing material), sweeps (multi-metal sweeps), a processed raw material P-RM which is obtained from the above-mentioned raw material RM by appropriate processing treatments such as a thermal treatment (e.g. calcination and/or roasting) and/or a mechanical treatment (e.g. mixing, milling, cutting (decanning)).

[0062] Preferably, the smelting treatment of the furnace input material FIM1 is carried out in the presence of one or more of the following additives: a fluxing agent FA1, a reducing agent RA 1 , a collector material CM1, and the smelting treatment of the furnace input material FIM2 is carried out in the presence of one or more of the following additives: a fluxing agent FA2, a reducing agent RA2, a collector material CM2.

[0063] Appropriate collector materials for recovering precious metals by smelting are known to the skilled person. The collector materials CM1 and CM2 (which might be the same or may differ from each other) may comprise metallic iron or an iron oxide or sulfide, metallic copper or a copper oxide or sulfide (e.g. copper matte), metallic silver or a silver oxide or sulfide, metallic lead or a lead oxide or sulfide, metallic nickel or a nickel oxide or sulfide (e.g. nickel matte).

[0064] The fluxing agents FA1 and FA2 (which might be the same or may differ from each other) might be burnt lime CaO, SiCh, magnesium oxide, aluminum oxide, borax, and/or soda ash.

[0065] The reducing agents RAI and RA2 (which might be the same or may differ from each other) might be carbon (e.g. charcoal), FesC , natural gas, CO, sulfur, wood, and/or WPCB (waste printed circuit boards) [0066] Recovering precious metals from precious metal-containing furnace input materials by smelting is commonly known to the skilled person.

[0067] Typically, the furnace input material FIM1 (or FIM2) and the collector material CM1 (or CM2) and optionally the fluxing agent FA1 (or FA2) and/or reducing agent RAI (or RA2) are melted, and the one or more precious metals accumulate in the collector material CM1 (or CM2), thereby obtaining a liquid precious metal-containing furnace output material FOM1 (or FOM2).

[0068] Smelting treatment of the furnace input material FIM1 or FIM2 might be terminated if the concentration of the precious metals in the furnace output material FOM1 or FOM2 has reached a pre-defined level (e.g. at least 2 wt%, more preferably at least 5 wt%).

[0069] In addition to the liquid precious metal-containing furnace output materials FOM1 or FOM2, a liquid slag phase might be obtained in furnace Fl or F2. As the slag phase and the liquid precious metal-containing output material FOM1 or FOM2 differ in density, they form separate layers (the slag phase typically being on top of FOM1 or FOM2) and can be withdrawn separately from furnace Fl or F2. The slag phase of furnace Fl or F2 may optionally comprise a minor part of the precious metals of the furnace input material FIM1 or FIM2.

[0070] In the method of the present invention, the furnace input materials FIM1 and FIM2 may differ from each other (e.g. FIM1 and FIM2 containing different (processed) raw materials); and/or one or more of the additives used for the smelting treatments of the furnace input materials FIM1 and FIM2 may differ from each other (e.g. different collector materials CM1 and CM2; and/or different fluxing agents FA1 and FA2; and/or different reducing agents RAI and RA2); and/or the lower furnace parts LFP1 and LFP2 may differ from each other by their refractory linings (e.g. refractory linings which differ in chemical composition) and/or their internal volumes.

[0071] Corrosion resistance might be improved if the refractory lining of the lower furnace part LFP1 or LFP2 comprises a magnesia-based refractory lining and the furnace input material FIM1 introduced into LFP1 or the furnace input material FIM2 introduced into LFP2 comprises a raw material RM which is selected from a material comprising one or more precious metals being supported on a carrier (such as oxides, metallic carriers, or carbon) or distributed in a matrix (such as an oxide or sulphide matrix), wherein the material comprises silicon (e.g. in the form of an oxide or carbide or in elementary form) in an amount of less than 5 wt%, more preferably less than 1 wt%, or is silicon-free, and optionally comprises iron oxides and calcium oxide in a total amount of less than 30 wt%, more preferably less than 12 wt%; a material comprising aluminum oxide in an amount of less than 30 wt%, more preferably less than 5 wt%; a processed raw material P-RM which is obtained from the above-mentioned raw material RM by appropriate processing treatments such as a thermal treatment (e.g. calcination and/or roasting) and/or a mechanical treatment (e.g. mixing, milling, cutting (decanning), etc.).

[0072] Preferably, the detached lower furnace part LFP1 is mounted on a moving device and is moved away from the upper furnace part UFP, and the lower furnace part LFP2 is mounted on another moving device and is moved to and releasably attached to the upper furnace part UFP. Exemplary moving devices are those described above. The moving device can be a remotely controlled vehicle. The moving device may comprise pivotable wheels (e.g. four dual wheels being pivotable by 70-120°). The moving device might be rated for carrying a capacity of at least 50000 kg.

[0073] As mentioned above, for improving process flexibility, the multi-part furnace system may comprise additional lower furnace parts (LFP3, LFP4, etc.).

[0074] Accordingly, after withdrawal of the second furnace output material FOM2 from the furnace F2, the method may optionally comprise the following steps: terminating the smelting treatment of the second furnace input material FIM2 in the furnace F2 and detaching the lower furnace part LFP2 from the upper furnace part UFP, releasably attaching the lower furnace part LFP1 or LFP3 to the upper furnace part UFP, thereby forming a furnace Fl or F3, subjecting a third furnace input material FIM3 containing one or more precious metals (in elementary form or alloyed form or in the form of oxides, sulfides or halides) to a smelting treatment in the furnace Fl or F3, thereby obtaining a third liquid precious metal-containing furnace output material F0M3 which is withdrawn from the furnace Fl or F3.

[0075] Again, it is preferred that the detached lower furnace part and the lower furnace part to be releasably attached are mounted on and moved by moving devices. Accordingly, the detached lower furnace part LFP2 is preferably mounted on a moving device and is moved away from the upper furnace part UFP, and the lower furnace part LFP1 or LFP3 is preferably mounted on another moving device and is moved to and releasably attached to the upper furnace part UFP.

[0076] The furnace input material FIM3 may comprise one or more of those raw materials RM or processed raw materials P-RM mentioned above.

[0077] The smelting treatment of the furnace input material FIM3 is preferably carried out in the presence of one or more of the following additives: a fluxing agent FA3, a reducing agent RA3, a collector material CM3.

[0078] Fluxing agent, reducing agent and collector material can be one of those mentioned above.

[0079] With regard to further details of the smelting treatment of furnace input material FIM3, reference can be made to the smelting treatments of the furnace input materials FIM1 and FIM2 described above. [0080] The furnace input materials FIM2 and FIM3 may differ from each other (e.g. FIM2 and FIM3 containing different (processed) raw materials); and/or one or more of the additives used for the smelting treatments of the furnace input materials FIM2 and FIM3 may differ from each other (e.g. different collector materials CM2 and CM3; and/or different fluxing agents FA2 and FA3; and/or different reducing agents RA2 and RA3); and/or the lower furnace parts LFP2 and LFP3 may differ from each other by their refractory linings (e.g. refractory linings which differ in chemical composition) and/or their internal volumes.

[0081] According to a further aspect, the present invention relates to the use of the multi-part furnace system of the present invention for recovering one or more precious metals from precious metal-containing furnace input materials.

[0082] The lower furnace part LFP1 being releasably attached to the upper furnace part UFP is used for a smelting treatment of a first furnace input material FIM1, and the lower furnace part LFP2 being releasably attached to the upper furnace part UFP is used for a smelting treatment of a second furnace input material FIM2, the lower furnace part LFP1 being replaced by the lower furnace part LFP2 in between the smelting treatments.

[0083] The present invention relates to the following exemplary Embodiments {01 } to {20}.

[0084] Embodiment {01 } relates to a multi-part furnace system comprising an upper furnace part UFP which comprises a furnace roof, at least two lower furnace parts LFP1 and LFP2, wherein each of the lower furnace parts LFP1 and LFP2 is configured to be releasably attached to the upper furnace part UFP, comprises an inside which is at least partly covered by a refractory lining, an outside, and an internal volume for receiving a precious metal-containing furnace input material.

[0085] Embodiment {02} relates to the multi-part furnace system according to Embodiment {01 }, wherein the lower furnace part LFP1 and the upper furnace part UFP, if releasably attached to each other, form a first furnace Fl; and the lower furnace part LFP2 and the upper furnace part UFP, if releasably attached to each other, form a second furnace F2.

[0086] Embodiment {03} relates to the multi-part furnace system according to Embodiment {01 } or {02}, wherein each of the lower furnace parts LFP1 and LFP2 is configured to be airtightly attached to the upper furnace part UFP.

[0087] Embodiment {04} relates to the multi-part furnace system according to one of the preceding Embodiments {01} to {03}, wherein each of the lower furnace parts LFP1 and LFP2 is configured to be releasably attached to the upper furnace part UFP by one or more of the following fixing means: bolts, screws, flanges, clamps, and fittings.

[0088] Embodiment {05} relates to the multi-part furnace system according to one of the preceding Embodiments {01} to {04}, wherein the refractory lining is a magnesia-based refractory lining, an alumina-based refractory lining, or a chromia-based refractory lining.

[0089] Embodiment {06} relates to the multi-part furnace system according to one of the preceding Embodiments {01 } to {05}, wherein the lower furnace parts LFP1 and LFP2 differ from each other by their refractory linings and/or their internal volumes.

[0090] Embodiment {07} relates to the multi-part furnace system according to one of the preceding Embodiments {01 } to {06}, comprising at least two moving devices, each moving device having a platform for mounting the lower furnace part LFP1 or LFP2.

[0091] Embodiment {08} relates to the multi-part furnace system according to one of the preceding Embodiments {01 } to {07}, comprising at least one additional lower furnace part LFP3 which is configured to be releasably attached to the upper furnace part UFP, comprises an inside which is at least partly covered by a refractory lining, an outside, and an internal volume for receiving a furnace input material.

[0092] Embodiment {09} relates to the multi-part furnace system according to Embodiment {08}, wherein the additional lower furnace part LFP3 differs from the lower furnace parts LFP1 and LFP2 by its refractory lining (e.g. refractory linings having different chemical compositions) and/or internal volume.

[0093] Embodiment { 10} relates to a method of recovering precious metals from furnace input materials, the method using the multi-part furnace system according to one of the Embodiments {01 } to {09} and comprising the following steps: subjecting a first furnace input material FIM1 containing one or more precious metals to a smelting treatment in a furnace Fl, thereby obtaining a first liquid precious metalcontaining furnace output material FOM1 which is withdrawn from the furnace Fl, wherein the furnace Fl comprises the lower furnace part LFP1 and the upper furnace part UFP being releasably attached to each other, terminating the smelting treatment of the first furnace input material FIM1 in the furnace Fl and detaching the lower furnace part LFP1 from the upper furnace part UFP, releasably attaching the lower furnace part LFP2 to the upper furnace part UFP, thereby forming a furnace F2, subjecting a second furnace input material FIM2 containing one or more precious metals to a smelting treatment in the furnace F2, thereby obtaining a second liquid precious metal-containing furnace output material FOM2 which is withdrawn from the furnace F2.

[0094] Embodiment { 11 } relates to the method according to Embodiment { 10}, wherein the precious metal is a platinum group metal (PGM), gold, and/or silver.

[0095] Embodiment { 12} relates to the method according to Embodiment { 10} or { 11 }, wherein each of the precious metal-containing furnace input materials FIM1 and FIM2 comprise one or more of the following materials: a raw material RM which is selected from spent catalysts, preferably heterogeneous catalysts comprising a precious metal on a support material; mining materials; waste electrical and electronic equipment; industrial alloys, in particular specialty alloys, batteries, filter cakes, or flue dust; fuel cells or parts thereof; sweeps; a processed raw material P-RM which is obtained from the raw material RM by a thermal treatment and/or a mechanical treatment.

[0096] Embodiment { 13} relates to the method according to one of the Embodiments { 10} to { 12}, wherein the smelting treatment of the furnace input material FIM1 is carried out in the presence of one or more of the following additives: a fluxing agent FA1, a reducing agent RA 1 , a collector material CM1, and wherein the smelting treatment of the furnace input material FIM2 is carried out in the presence of one or more of the following additives: a fluxing agent FA2, a reducing agent RA2, a collector material CM2.

[0097] Embodiment { 14} relates to the method according to one of the Embodiments { 10} to { 13}, wherein the furnace input materials FIM1 and FIM2 differ from each other, and/or one or more of the additives used for the smelting treatments of the furnace input materials FIM1 and FIM2 differ from each other, and/or the lower furnace parts LFP1 and LFP2 differ from each other by their refractory linings and/or their internal volumes.

[0098] Embodiment { 15} relates to the method according to one of the Embodiments { 10} to { 14}, wherein the detached lower furnace part LFP1 is mounted on a first moving device and is moved away from the upper furnace part UFP, and for being releasably attached to the upper furnace part UFP, the lower furnace part LFP2 is mounted on a second moving device and is moved to the upper furnace part UFP.

[0099] Embodiment { 16} relates to the method according to one of the Embodiments { 10} to { 15}, further comprising the following steps: terminating the smelting treatment of the second furnace input material FIM2 in the furnace F2 and detaching the lower furnace part LFP2 from the upper furnace part UFP, releasably attaching the lower furnace part LFP1 or a lower furnace part LFP3 to the upper furnace part UFP, thereby forming the furnace Fl or a furnace F3, subjecting a third furnace input material FIM3 containing one or more precious metals to a smelting treatment in the furnace Fl or F3, thereby obtaining a third liquid precious metal-containing furnace output material FOM3 which is withdrawn from the furnace Fl or F3.

[0100] Embodiment { 17} relates to the method according to Embodiment { 16}, wherein the smelting treatment of the furnace input material FIM3 is carried out in the presence of one or more of the following additives: a fluxing agent FA3, a reducing agent RA3, a collector material CM3.

[0101] Embodiment { 18} relates to the method according to Embodiment { 16} or { 17}, wherein the furnace input materials FIM2 and FIM3 differ from each other; and/or one or more of the additives used for the smelting treatments of the furnace input materials FIM2 and FIM3 differ from each other; and/or the lower furnace parts LFP2 and LFP3 differ from each other by their refractory linings and/or their internal volumes.

[0102] Embodiment { 19} relates to the use of the multi -part furnace system according to one of the Embodiments {01 } to {09} for recovering one or more precious metals from precious metal-containing furnace input materials.

[0103] Embodiment {20} relates to the use according to Embodiment { 19}, wherein the lower furnace part LFP1 being releasably attached to the upper furnace part UFP is used for a smelting treatment of a first furnace input material FIM1, and the lower furnace part LFP2 being releasably attached to the upper furnace part UFP is used for a smelting treatment of a second furnace input material FIM2, the lower furnace part LFP1 being replaced by the lower furnace part LFP2 in between the smelting treatments.

Claims

1. A multi-part furnace system comprising an upper furnace part UFP which comprises a furnace roof, at least two lower furnace parts LFP1 and LFP2, wherein each of the lower furnace parts LFP1 and LFP2 is configured to be releasably attached to the upper furnace part UFP, comprises an inside which is at least partly covered by a refractory lining, an outside, and an internal volume for receiving a precious metalcontaining furnace input material.

2. The multi-part furnace system according to claim 1, wherein the lower furnace part LFP1 and the upper furnace part UFP, if releasably attached to each other, form a first furnace Fl; and the lower furnace part LFP2 and the upper furnace part UFP, if releasably attached to each other, form a second furnace F2.

3. The multi-part furnace system according to claim 1, wherein each of the lower furnace parts LFP1 and LFP2 is configured to be air-tightly attached to the upper furnace part UFP.

4. The multi -part furnace system according to claim 1, wherein each of the lower furnace parts LFP1 and LFP2 is configured to be releasably attached to the upper furnace part UFP by one or more of the following fixing means: bolts, screws, flanges, clamps, and fittings.

5. The multi -part furnace system according to claim 1, wherein the refractory lining is a magnesia-based refractory lining, an alumina-based refractory lining, or a chromia-based refractory lining.

6. The multi -part furnace system according to claim 1, wherein the lower furnace parts LFP1 and LFP2 differ from each other by their refractory linings and/or their internal volumes.

7. The multi -part furnace system according to claim 1, comprising at least two moving devices, each moving device having a platform for mounting the lower furnace part LFP1 or LFP2.

8. The multi-part furnace system according to claim 1, comprising at least one additional lower furnace part LFP3 which is configured to be releasably attached to the upper furnace part UFP, comprises an inside which is at least partly covered by a refractory lining, an outside, and an internal volume for receiving a furnace input material.

9. The multi-part furnace system according to claim 8, wherein the additional lower furnace part LFP3 differs from the lower furnace parts LFP1 and LFP2 by its refractory lining and/or internal volume.

10. A method of recovering precious metals from furnace input materials, the method using the multi-part furnace system according to one of the claims 1 to 9 and comprising the following steps: subjecting a first furnace input material FIM1 containing one or more precious metals to a smelting treatment in a furnace Fl, thereby obtaining a first liquid precious metalcontaining furnace output material FOM1 which is withdrawn from the furnace Fl, wherein the furnace Fl comprises the lower furnace part LFP1 and the upper furnace part UFP being releasably attached to each other, terminating the smelting treatment of the first furnace input material FIM1 in the furnace Fl and detaching the lower furnace part LFP1 from the upper furnace part UFP, releasably attaching the lower furnace part LFP2 to the upper furnace part UFP, thereby forming a furnace F2, subjecting a second furnace input material FIM2 containing one or more precious metals to a smelting treatment in the furnace F2, thereby obtaining a second liquid precious metal-containing furnace output material F0M2 which is withdrawn from the furnace F2.

11. The method of claim 10, wherein the precious metal is a platinum group metal (PGM), gold, and/or silver.

12. The method of claim 10, wherein each of the precious metal-containing furnace input materials FIM1 and FIM2 comprise one or more of the following materials: a raw material RM which is selected from spent catalysts, preferably heterogeneous catalysts comprising a precious metal on a support material; mining materials; waste electrical and electronic equipment; industrial alloys, in particular speciality alloys, batteries, filter cakes, or flue dust; fuel cells or parts thereof; sweeps; a processed raw material P-RM which is obtained from the raw material RM by a thermal treatment and/or a mechanical treatment.

13. The method according to claim 10, wherein the smelting treatment of the furnace input material FIM1 is carried out in the presence of one or more of the following additives: a fluxing agent FA1, a reducing agent RA 1 , a collector material CM1, and wherein the smelting treatment of the furnace input material FIM2 is carried out in the presence of one or more of the following additives: a fluxing agent FA2, a reducing agent RA2, a collector material CM2.

14. The method according to one of the claims 10 to 13, wherein the furnace input materials FIM1 and FIM2 differ from each other, and/or one or more of the additives used for the smelting treatments of the furnace input materials FIM1 and FIM2 differ from each other, and/or the lower furnace parts LFP1 and LFP2 differ from each other by their refractory linings and/or their internal volumes.

15. The method according to claim 10, wherein the detached lower furnace part LFP1 is mounted on a first moving device and is moved away from the upper furnace part UFP, and for being releasably attached to the upper furnace part UFP, the lower furnace part LFP2 is mounted on a second moving device and is moved to the upper furnace part UFP.

16. The method according to claim 10, further comprising the following steps: terminating the smelting treatment of the second furnace input material FIM2 in the furnace F2 and detaching the lower furnace part LFP2 from the upper furnace part UFP, releasably attaching the lower furnace part LFP1 or a lower furnace part LFP3 to the upper furnace part UFP, thereby forming the furnace Fl or a furnace F3, subjecting a third furnace input material FIM3 containing one or more precious metals to a smelting treatment in the furnace Fl or F3, thereby obtaining a third liquid precious metal-containing furnace output material F0M3 which is withdrawn from the furnace Fl or F3.