| 摘要 |
<p>1,131,354. Potassium sulphate; alkali metal chlorides. WOODALL DUCKHAM Ltd. 20 July, 1967 [16 May, 1966], No. 21387/66. Heading C1A. Alkali metal salts are extracted from cement kiln flue dust by (i) digesting with a strong solution of KCl (capable of dissolving alkali metal chlorides but not K 2 SO 4 ), optionally containing NaCl; (ii) separating the solid and extracting alkali metal chlorides from the solution; (iii) digesting the solid with a solvent for K 2 SO 4 ; (iv) separating the solid and extracting K 2 SO 4 from the solution. In continuous operation, the solvent for K 2 SO 4 may be a strong solution of K 2 S0 4 recycled from (iv) after extraction of some K 2 S0 4 and the chloride solution for (i) may be recycled from (ii) after extraction of some salts. Both digestion stages may be carried out at 60‹ to 100‹ C., steam being added to supply heat: carbon dioxide may also be supplied to insolubilize calcium contained in the solids. The treated dust may be pulped or pelletized and recycled to a cement kiln.</p> |
