| 摘要 |
<p>1,269,461. Chromium recovery. M & T CHEMICALS Inc. 23 Feb., 1970 [28 March, 1969], No. 8590/70. Heading C1A. The chromium content of BaCrO 4 sludge is recovered by forming an aq. slurry of the sludge, adding H 2 SO 4 to precipitate BaSO 4 which is removed, adding sufficient CaCO 3 , SrCO 3 , BaCO 3 , PbCO 3 or a mixture of these to remove the major portion of the H 2 SO 4 , and removing the resultant precipitated sulphate, and removing the remaining H 2 SO 4 by treatment with SrCO 3 . Preferably stoichiometric quantities of additive are used at all stages except the last, when SrCO 3 is added in excess.</p> |
