Nitric acid treatment of crude phosphate with water, neutralising and - nitric acid treatment of crude phosphate with water, neutralising and

摘要

In parent patent strontium nitrate is obtd. from the residue remaining after treating crude phosphate with nitric acid by extracting the residue with a solvent, and isolating the strontium nitrate from the extract. In this addn., strontium nitrate is prepd. by (a) sepg. at 20-90 degrees C the residue from the crude phosphate, (b) extracting the residue with water, (c) neutralising the extract with NH3, (d) filtering the ppte., (e) evaporating the filtrate to slightly above the satn. point of the Ca and ammonium nitrate dissolved in the filtrate, and (f) sepg. the pptd. strontium nitrate. Evaporation of the neutral salt soln. is simpler and cheaper than evaporation of dilute nitric acid, giving technically pure strontium nitrate, together with a mother liquor-contg. ammonium nitrate which can be used in fertilisers.