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PLATINUM
Natural Abundance, Stable Isobars aPt190, 0.0127%, Os190 Pt192, 0.78%, Os192 Pt194, 32.9%, Hg196 Pt195, 33.8%, Hg198 Pt196, 25.2% Pt198, 7.19% Platinum metal and platinum dicarbonyl dichloride have been used as charge material in the separation of platinum isotopes. It was found that platinum dicarbonyl dichloride decomposes under operating conditions of the calutron making it unsatisfactory for use as a feed material. Platinum metal is used in a special graphite source block which is heated by electron bombardment. Due to the high cost of Pt, the unresolved charge material is recycled and recovered. Approximately 90% of the un-ionized feed can be recovered from the charge container by mechanical means. The remainder is recovered by washing calutron components and by igniting graphite salvage. The source, receiver, and liner are washed with nitric acid. After filtering, the wash solution is evaporated to dryness and analyzed for Pt. Usually no Pt is detected in the filtrate and it is discarded. The solids are dried, ignited at 800° C and combined with the ash remaining after all graphite salvage has been burned. Solids from the ignitions are repeatedly leached with aqua regia until no additional Pt is recovered. The remaining solids are dried, reduced with hydrogen at 600° C, and again leached with aqua regia, which yields some additional Pt. The combined aqua regia leach solutions are repeatedly evaporated with hydrochloric acid to remove nitric acid and finally evaporated to dryness yielding chloroplatinic acid. These crystals are dissolved in 1 N hydrochloric acid, filtered, and treated with an excess of ammonium chloride and an equal volume of ethanol, producing the bright yellow salt ammonium chloroplatinate. The insoluble salt is filtered, washed with 20% ammonium chloride, and reduced to metal with hydrogen at 600° C. Spectrographic analysis of the recovered Pt metal indicates only traces of impurity. Unlike salts of the other platinum metals, platinum salts have been known to cause intoxication, wheezing, coughing, irritation of the nose, tightness in the chest, shortness of breath, and cyanosis. To avoid these symptoms, skin contact with these compounds should be minimized, and a chemical respirator should be employed when dusting may be encountered. aPt190, is radioactive with a half-life of 1012 years. |
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