Recovery and Purification of Osmium

1,152,565. Sodium osmate and perosmate; potassium osmate. INTERNATIONAL NICKEL CO. OF CANADA Ltd. 19 Feb., 1968 [21 Feb., 1967], No. 8023/68. Heading C1A. [Also in Division C7] A slurry of sodium osmate is produced by gradually heating an Os-containing material to 1200-2000‹ F. in an atmosphere containing free oxygen (e.g. air), absorbing the volatilized OsO 4 in an aqueous solution and precipitating an Os-containing solid (e.g. absorbing in NaOH solution and precipitating with SO 2 and/or H 2 S or concurrently absorbing and precipitating with a solution of SeO 2 or SO 2 ), separating the solids and slurrying them, together with any Os-containing dust from the OsO 4 volatilization, in water to which is added H 2 SO 4 . The slurry is then heated, air is bubbled through to remove S as SO 2 , an oxidizing agent (e.g. NaClO 3 , NaBrO 3 or HNO 3 ) is then added with heating to volatilize OsO 4 which is collected in aqueous NaOH to form sodium perosmate which is reduced with a water-soluble organic reducing agent, e.g. methanol or ethanol, to form the osmate and precipitate any Ru present. K 2 OsO 4 .2H 2 O may be precipitated as violet crystals from the solution by addition of an excess of saturated aqueous KOH.