Platinum ores oxides

Osmium - the atomic number is 76 and the chemical symbol is Os. The name derives from the Greek osme for smell because of the sharp odor of the volatile oxide. Both osmium and iridium were discovered simultaneously in a crude platinum ore by the English chemist Smithson Tennant in 1803. 

This report, which was entitled "Chemical investigation of the residues of Ural platinum ore and of the metal ruthenium, occupied one hundred and eighty-eight pages in the Scientific Annals of Kazan University for 1844. In the following year it was published in book form. For patriotic reasons and also in recognition of the earlier work of Professor Osann, Klaus retained the name ruthenium, which means Russia. The white substance which Osann had taken for the oxide of this new metal consisted chiefly of silicic and titanic acids, iron peroxide, and zirconia (37). Klaus also found ruthenium in the osmiridium from American ores (36, 128). It constituted only from 1 to l1/o per cent of these residues and did not occur in the portion which is soluble in aqua regia (126). 

Occurrence and History.—The name ruthenium is due to Osann,1 who obtained what he believed to be the oxide of a new metal from the Ural platinum ores. This oxide was subsequently investigated by Claus,8 who found that, although it contained a high proportion of the oxides of silicon, zirconium, titanium, and iron, it nevertheless possessed a small quantity of a new oxide for which he retained the name used by Osann. 

OTHER COMMENTS Platinum metal is used in the manufacture of apparatus used in laboratories and industries, including thermocouples, acid-proof containers, chemical reaction vessels, platinum resistance thermometers, electrodes, etc. has found applications in dentistry, electroplating industry, and in the jewelry industry soluble platinum salts have been used as catalysts in the production of high octane gasoline, vinylesters, petrochemicals, and pharmaceuticals platinum metals, as well as soluble platinum salts, have been employed as oxidation catalysts in the manufacture of sulfuric acid, nitric acid from ammonia, and acetic acid soluble platinum salts have been used and reused in the reclamation of platinum ore. 

As an example of modeling a fluid in redox disequilibrium, we use an analysis, slightly simplified from Nordstrom et al. (1992), of a groundwater sampled near the Morro do Ferro ore district in Brazil (Table 7.2). There are three measures of oxidation state in the analysis the Eh value determined by platinum electrode, the dissolved oxygen content, and the distribution of iron between ferrous and ferric species. 

Deville and Debray A process for extracting the platinum metals from their ores. The ore is heated with galena (lead sulfide ore) and litharge (lead oxide) in a reverberatory furnace. The platinum forms a fusible alloy with the metallic lead, which is also formed. Invented by H. E. St-Claire Deville and H. J. Debray. 

Rhodium compounds, 19 644-648 synthesis of, 19 646 uses for, 19 646-648 Rhodium oxide, 10 42 Rhodium plating, 9 822 19 648 Rhodium-platinum alloys, 19 602 Rhodochrosite, 15 540 Rhodochrosite ore, 15 589 Rhodococcus, as a host system for gene expression, 12 478 Rhodonite, 15 540 color, 7 331 Rhodopsin, 9 512 Rhoeadine, 2 90 Rhoedales... 

In addition to the presence of these elements in ores, they are also available from recycled feeds, such as catalyst wastes, and as an intermediate bulk palladium platinum product from some refineries. The processes that have been devised to separate these elements rely on two general routes selective extraction with different reagents or coextraction of the elements followed by selective stripping. To understand these alternatives, it is necessary to consider the basic solution chemistry of these elements. The two common oxidation states and stereochemistries are square planar palladium(II) and octahedral platinum(IV). Of these, palladium(II) has the faster substitution kinetics, with platinum(IV) virtually inert. However even for palladium, substitution is much slower than for the base metals so long as contact times are required to achieve extraction equilibrium. 

Rhodium is recovered from platinum and other ores by refining and purification processes that start by dissolving the other platinum group metals and related impurities with strong acids that do not affect the rhodium itself Any remaining platinum group elements are removed by oxidation and bathing the mixture in chlorine and ammonia. 

The ore thortveitite is crushed and powdered. It is mixed with a large excess of ammonium hydrogen fluoride and heated at about 400°C for several hours in a platinum container under a stream of dry air. Silica is converted to volatile silicon tetrafluoride and swept out with dry air. Scandium oxide is converted to scandium trifluoride, SCF3 ... 

Only a few metals—gold and platinum are two examples—appear in nature in metallic form. Deposits of these natural metals, also known as native metals, are quite rare. For the most part, metals are found in nature as chemical compounds. Iron, for example, is most frequently found as iron oxide, Fe203, and copper is found as chalcopyrite, CuFeS2. Geologic deposits containing relatively high concentrations of metal-containing compounds are called ores. 

We might also expect to find oxide ores for the s-block metals and sulfide ores for the more electronegative p-block metals. In fact, sulfide ores are common for the p-block metals, except for A1 and Sn, but oxides of the s-block metals are strongly basic and far too reactive to exist in an environment that contains acidic oxides such as CO2 and SiC>2. Consequently, s-block metals are found in nature as carbonates, as silicates, and, in the case of Na and K, as chlorides (Sections 6.7 and 6.8). Only gold and the platinum-group metals (Ru, Os, Rh, Ir, Pd, and Pt) are sufficiently unreactive to occur commonly in uncombined form as the free metals. 

In the 1800s, the most important method for producing H2S04 was by the lead chamber process. Today, sulfuric acid is produced by a method known as the contact process. In the contact process, sulfur is burned to give S02 or the required S02 is recovered from coal burning or ore roasting processes. The S02 is then oxidized in the presence of a catalyst to produce SO3 (see Section 15.7.2). Typical catalysts are spongy platinum or sodium vanadate. Next, the SO3 is dissolved in 98% sulfuric acid ... 

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