| 摘要 |
<p>Prepn of K/Mg mixed phosphate hydrate. .M6A. by (a) forming an aqs. soln. of a 3-10C (pref. 3-5), straight or branched aliphatic primary, sec. or tert. amine and phosphoric acid, produced by thermal reaction or wet methods in a quantity such that only about half the amine is used, (b) adding stoichiometric amt. or 5% excess K2SO4 (based on P2O5), (c) cooling the soln. pref. over 2-4 hrs. agitating, adding 2 equivs. MgSO4 per equiv. of P2O5 to effect precipitation at pH 11-14, pref. 12.1 to 11.5, (d) separating and washing the KMgPO4 formed, (e) combining the washings and denuded liquor and treating them with equiv. amount of calcined lime, (or up to 20% excess) (f) separating and washing the CaSO4 precipitated and recycling the amine soln. to stage (a). The process obviates the difficult filtration of viscous precipitates and elimination of CaCl2 associated with prior art methods.</p> |
