# US 10,308,997 B2 · Method for producing elemental rhodium > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,308,997 B2 - Document ID: US10308997B2 - Status: Granted - Kind: B2 - Application number: 15/555,238 - Filed: 2016-02-01 - Published: 2018-02-22 - Granted: 2019-06-04 - Earliest claimed: 2015-03-05 - Assignees: Heraeus Deutschland GmbH & Co. KG - Applicants: Heraeus Deutschland GmbH & Co. KG - Inventors: Martin Stettner; Vasco Thiel; Stefanie F. Alameda; Steffen Voβ - Web page: https://patentgrep.com/patent/US10308997B2 ## CPC - C22B 11/04: {by wet processes (extraction of metal compounds by leaching in organic solutions C22B3/16; treatment or purification of solutions by liquid-liquid extraction C22B3/26)} - C22B 3/44: by chemical processes (treatment or purification of solutions by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42) - C22B 5/00: General methods of reducing to metals - C22B 7/006: {Wet processes} - C22B 11/00: Obtaining noble metals - Y02P 10/20: Recycling - C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract Method for producing elemental rhodium, comprising the steps of: (1) providing an aqueous suspension of diethylene triammonium hexahalogenorhodate adjusted with hydrohalic acid to a pH value of −1 to +2; (2) adding a sufficient quantity of reducing agent for complete conversion of the diethylene triammonium hexahalogenorhodate to the suspension provided in step (1) and allowing the reaction to proceed until the formation of elemental rhodium is completed; and (3) separating the elemental rhodium formed in step (2) from the hydrohalic aqueous composition formed in step (2); whereby halogen is bromine and/or chlorine. ## Claims ### Claim 1 A method for producing elemental rhodium, comprising the steps of: (1) providing an aqueous suspension of diethylene triammonium hexahalogenorhodate adjusted with a hydrohalic acid to a pH value of −1 to +2; (2) adding a sufficient quantity of at least one reducing agent to the suspension provided in step (1) to form a hydrohalic aqueous composition and elemental rhodium; and (3) separating the elemental rhodium formed in step (2) from the hydrohalic aqueous composition formed in step (2); wherein the halogen of the diethylene triammonium hexahalogenorhodate is bromine and/or chlorine. ### Claim 2 (depends on 1) The method of claim 1, wherein the pH value of the aqueous suspension provided in step (1) is in the range of −0.5 to +0.5. ### Claim 3 (depends on 1) The method of claim 1, wherein the diethylene triammonium hexahalogenorhodate originates from a rhodium separation step of a precious metals refining process. ### Claim 4 (depends on 1) The method of claim 1, wherein the diethylene triammonium hexahalogenorhodate is suspended in water and the hydrohalic acid is added until the pH value of the aqueous suspension is adjusted to within the range of −1 to +2. ### Claim 5 (depends on 1) The method of claim 1, wherein the aqueous suspension has 5 to 40% by weight of diethylene triammonium hexahalogenorhodate. ### Claim 6 (depends on 1) The method of claim 1, wherein the aqueous suspension is agitated during step (2). ### Claim 7 (depends on 1) The method of claim 1, wherein the at least one reducing agent is a combination of reducing agents, and wherein the combination of reducing agents are used one after the other, at the same time or overlapping in time. ### Claim 8 (depends on 1) The method of claim 1, wherein the at least one reducing agent is selected from the group consisting of hydrazine hydrazine hydrate, Sn(II) compounds, zinc, iron, aluminium, and tin. ### Claim 9 (depends on 1) The method of claim 1, wherein iron powder is used as the reducing agent. ### Claim 10 (depends on 1) The method of claim 1, wherein the pH value is maintained in the range of −1 to +2 during step (2). ### Claim 11 (depends on 1) The method of claim 1, wherein the temperature of the reaction material is maintained in the range of 20 to 70° C. during step (2). ### Claim 12 (depends on 1) The method of claim 1, wherein a hydrohalic filtrate is obtained during the separation of the elemental rhodium from the hydrohalic aqueous composition, and wherein the hydrohalic filtrate is used in a step (4) to precipitate Rh3+ as diethylene triammonium hexahalogenorhodate. ### Claim 13 (depends on 12) The method of claim 12, the at least one reducing agent or an oxidation product of the at least one reducing agent is removed from the hydrohalic filtrate before using it in step (4). ### Claim 14 (depends on 1) The method of claim 1, wherein the diethylene triammonium hexahalogenorhodate is diethylene triammonium hexachlororhodate. ### Claim 15 (depends on 1) The method of claim 1, wherein the diethylene triammonium hexahalogenorhodate is added to and suspended in the hydrohalic acid, the hydrohalic acid having a pH in the range of −1 to +2. ### Claim 16 (depends on 1) The method of claim 1, wherein the hydrohalic acid is hydrobromic acid, hydrochloric acid, or a combination thereof. ### Claim 17 (depends on 1) The method of claim 1, wherein the pH value is maintained in the range of −1 to +2 during step (2) by adding a hydrohalic acid. ### Claim 18 (depends on 17) The method of claim 17, wherein the hydrohalic acid is hydrobromic acid, hydrochloric acid, or a combination thereof.