Boric acid obtained by stripping ammonium borate soln

摘要

Boric acid is obtained from aqs. solns. of ammonium borate prepd. by carbammonium treatment of boron minerals by (a) separating ammonia from the soln. in a stripping column whose minimum operating temp., which is not 140 degrees C, is fixed for a given H3BO3 content in the column and (b) crystallising the boric acid from the soln. provided by the stripping column by evaporation and cooling. Economies are obtained in the quantity of steam required for stripping. Crystallisation of ammonium pentaborate in the stripping column is avoided and high yields of pure boric acid are obtained.