Ruthenium separation from platinum metals

The initial steps are similar to any other mineral extraction process. This involves crushing mineral, froth flotation, gravity concentration and other steps to obtain platinum metal concentrates that may contain about 30 to 40 wt% of platinum group metals. The concentrate is treated with aqua regia to separate soluble metals, gold, platinum, and palladium from other noble metals such as ruthenium, rhodium, iridium, osmium, and silver that remain in... 

The four metals rhodium, palladium, osmium and iridium, share the same centennial and have been dealt with together.147-149 Wollaston separated palladium from platinum ore in 1803 but concealed the identity of the metal until 1804.150 Osmium was isolated from crude platinum by Smithson Tennant in 1804.151 There are accounts of the discoveries of niobium (by Hatchett)152 and ruthenium.153,154... 

Separation of Ruthenium from the Platinum Metals. See Scheme I, p. 344. 

Ruthenium is obtained by separating it from other platinum metals, such as platinum, palladium, and osmium, with which it occurs. These metals are usually obtained as by-products during the refining of nickel metal. They are then separated from each other by a series of chemical reactions. 

In Section II1.2 we discussed ethylene adsorption to a dispersed silver supported on alumina. This section is separated from the earlier discussion for the principal reason that the spectroscopic methods utilized in the silver investigations are generally not applicable to transition metals with partially filled d-orbitals. The most relevant metals (primarily platinum, rhodium, ruthenium, and palladium)... 

Porous anode 1, used in SPE electrolysis (fig.1) consists of mixtxjre of ruthenium dioxide (75%) and iridium oxide bound to the graphite layer. Thickness of such layer depends on the amount of aphitc, covering the anode surface unit. In particular, if this amount is 40 g/m. correspondent thickness reaches 100 0jn [12]. Current feeding to anode is held with the help of point collector 6 (the metal net can sei e as this collector). Anode space is separated from the cathode one with the help of membrane SPE (2). Platinum black, serving as an anode 1, is 100 jim v/ide. Cathode point collector 3 is connected with graphite plate 5, that maintain direct contact with cathode. 

Fire assay describes a group of separation methods in which precious metals (PMs) are separated from other species by dissolution in other molten metals, usually lead, nickel, or tin. Fire assay has been and continues to be fundamental to the determination of PMs. These are defined as gold (Au), silver (Ag), and the platinum group metals (PGMs) platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), and osmium (Os). In the context of fire assaying other elements are referred to as base elements or metals. 

Methods for separating the different platinum metals are comphcated and are partly kept secret. The traditional method with dissolution in aqua regia is still used, in which platinum, palladium and gold are dissolved while the other platinum metals stay undissolved. Gold is obtained from the solution by reduction, platinum is precipitated as ammonium hexachloroplatinate and palladium as a dichlorodiammine compound. The residue after the first aqua regia treatment contains iridium, rhodium, osmium and ruthenium. They are separated in several complicated steps. 

PEM fuel cells operate at relatively low temperatures, around 80°C. Low temperature operation allows them to start quickly (less warm-up time) and results in less wear on system components, resulting in better durability. However, they require that a noble-metal catalyst (typically platinum) be used to separate the hydrogen s electrons and protons, adding to system cost. The platinum catalyst is also extremely sensitive to CO poisoning, making it necessary to employ an additional reactor to reduce CO in the fuel gas if the hydrogen is derived from an alcohol or hydrocarbon fuel. This also adds cost. Developers are currently exploring platinum/ruthenium catalysts that are more resistant to CO. 

The solution from which the ammonium chlor-platinate has been separated still contains a little platinum with practically all the rhodium, ruthenium, and palladium. All are precipitated by metallic iron and dissolved in aqua regia. Addition of more ammonium chloride effects the precipitation of the remaining platinum, and the filtrate may be worked for the other metals (see p. 154). 

Separation of Osmium from ruthenium, rhodium, iridium and platinum may be effected by addition of zinc or magnesium to the solution containing these metals, whereby they are all precipitated as a black deposit.. 

The metals osmium and ruthenium can be selectively oxidized to their tetroxides and separated by extraction with carbon tetrachloride [24]. Reference 24 also deals with enrichment procedures of palladium, rhodium, iridium, and platinum chloro complexes from hydrochloric acid solutions... 

Ruthenium is produced mainly from an anode slime yielded when crude copper or crude nickel, obtained from nickel sulfide ores, is electrolytically refined. The anode slime contains precious metal elements. It is treated with hot aqua regia and platinum, palladium and gold are separated as their chloro complexes. Then, by nitric acid treatment, fusion treatment with NaHS04, and fusion treatment with Na202, silver, rhodium and iridium are separated. The residual ruthenium and osmium salts are dissolved in water, and the osmium is separated by treatment with chlorine, hydrochloric acid and nitric acid. The ruthenium salt is treated with ammonium chloride to afford a ruthenium salt ((NH4)3RuCl6), and the reduction with hydrogen yields ruthenium powder [1,4-6]. 

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