| 摘要 |
<p>Purification of phosphoric acid soln. contg. as impurities mainly Ca2+ and NO3- ions comprises (a) progressively adding phosphorus (elemental) at 80-130 degrees C and at a pressure =1 at., for 20-80 mins. This ppts the Ca as Ca dihydrogen phosphate; (b) removing dissolved gases by boiling or vacuum desorption; (c) cooling to ambient temps.; (d) adding CaCO3 to ppte. Ca monohydrogen phosphate which is further treated to give the phosphoric acid.</p> |
