| 摘要 |
<p>1313959 Phosphoric acid; ammonium phosphate STAMICARBON NV 15 June 1971 [17 June 1970] 28034/71 Heading C1A [Also in Division C2] The decomposition of rock phosphate is carried out using the solution remaining after removal of the lactam from a mixture thereof with sulphuric acid and/or free SO 3 by adding an aqueous solution of ammonium or alkali metal dihydrogen phosphate in a molar ratio of phosphate to sulphuric acid and/or free SO 3 of at least 0À25 : 1 and extracting the lactam by means of an extraction agent. The free phosphoric acid-containing solution remaining after the decomposition of the rock phosphate is treated to remove gypsum therefrom and at least a portion of the solution is neutralized to form ammonium dihydrogen phosphate which may be recycled to the lactam removal zone.</p> |
