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RUTHENIUM
Natural Abundance, Stable Isobars Ru96, 5.57%, aZr96 Ru98, 1.86%, Mo96 Ru99, 12.7%, Mo98 Ru100, 12.6%, Mo100 Ru101, 17.1%, Pd102 Ru102, 31.6%, Pd104 Ru104, 18.5% Powdered ruthenium metal is the only charge material which has been used for the separation of the isotopes of ruthenium. The metal is used in a special graphite source block which is heated by electron bombardment. Because of the initial cost of Ru, unresolved charge material is recycled and recovered. A preliminary recovery of unused material by mechanical means will reclaim approximately 90% of the ruthenium available from the source. The source, receiver and liner parts are then washed with nitric acid. The washings are filtered and the filtrate is discarded after testing determines that no ruthenium is present. The solids are dried, combined with the carbon salvage, and ignited at 800ºC until only ash remains. It is necessary to use a hydrochloric acid trap to scrub exhaust gases from this ignition in the event that any volatile ruthenium tetroxide forms. The carbon must be burned completely to eliminate reducing conditions in subsequent operations. Ash from the ignition is given an oxidizing fusion using 5:1 potassium hydroxide-potassium nitrate in a silver dish. The molten mass is poured into a stainless steel tray and allowed to cool. The melt is leached with water in a plastic container and filtered. The solids are added to the next batch of salvage to be processed. The filtered leachings, containing Ru as potassium ruthenate, are acidified with hydrochloric acid, and sodium bicarbonate is added until the pH is 7. Boiling at this point precipitates the Ru as the hydrated dioxide which is removed by filtration, washed with water, and dried. The filter paper and contents are ignited at 800ºC in a hydrogen atmosphere reducing ruthenium to metal. The metal product is washed with water until all sodium salts are removed; washed successively with hydrochloric acid, nitric, acid and water; dried; and returned to use. Ruthenium is considered toxic. When heated in air it evolves fumes which are injurious to the eyes and lungs, a characteristic ruthenium has in common with osmium. Gas-tight goggles and a respirator should be worn when handling ruthenium and its compounds. Ruthenium tetroxide is an explosive compound and if it is to be stored, it should not be placed next to organics or other substances which oxidize readily. aZr 96, natural abundance 2.8%, is radioactive with a half-life of 2 × 1014 years. |
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