| 摘要 |
<p>PREPARATION OF MONOCALCIUM PHOSPHATE AND PHOSPHORIC ACID Monocalcium phosphate, phosphoric acid and/or potassium phosphate containing fertilizers are produced in a process involving acidulation of phosphate rock with phosphoric acid in the presence of added silicon dioxide and potassium ion whereby fluorides contained in the rock are converted to K2SiF6, wherein monocalcium phosphate dissolved in phosphoric acid is formed during acidulation. In an important feature, the K2SiF6 is separated and hydrolyzed to regenerate the K20 from K2SiF6 as recycled KH2P04/H3P04 solution for further reaction with fluoride from fresh phosphate rock feed. A portion of the MCP/H3P04 solution and/or crystallized monocalcium phosphate can then be reacted with potassium sulfate, potassium bisulfate, or mixtures thereof, to form KH2P04, or KH2P04/H3P04 solutions, and gypsum. In a closely related embodiment, the remaining MCP/H3P04 solution is reacted with sulfuric acid to produce phosphoric acid product and/or the recycle phosphoric acid required in the phosphate rock acidulation step.</p> |
