| 摘要 |
<p>An aq. sulphuric acid soln. contg Fe is treated by (a) adjusting the pH pref. to 1-4.5, by adding calcium carbonate to ppte. calcium sulphate which is sepd., (b) adjusting the pH of the mother liquor to >=4.5 at 50 degrees C after which an oxidising gas is bubbled in; (c) adding calcium carbonate to adjust the pH to >5 and sepg. the insoluble solids. Also solids contg. calcium sulphate are recovered by the above process. The process is used to treat e.g. pickle liq from iron processing and esp. liquor from n the sulphate process for TiO2 which may also contain sulphates of Al, Mg, Mn and Cr. The process enables both the release of a satisfactory effluent and the recovery of CaSO4 white enough to be used to make a placoplaster.</p> |
