Glycerol and spent lye clarification - Illinois Institute of Technology

sepaj?ated soap has been sTcimmed off it is
removed to the glycerine plant where it is to
be treated before going to the evaporators.
The alkali in the lye must be neutralized and
the organic impurities removed.
The neutralization of the alkali is
affected by the addition of hydrochloric or
sulphuric acids. The use of the former is
open to objection due to high cost. It has
the advantage, however, of producing as a
result of the chemical action, sodium chloride
which after recovery can be used again in the
soap kettle.
Sulphuric acid is most generally used.
Its use introduces sulphate into the lye which
salt is recovered with the common salt from
the evaporator. Sodium sulphate however is
practically useless for graining soap, its
graining qualities being but three fifths that
of sodium chloride and the grain produced is
soft and often hard to separate from the lye.
To remove the organic impurities some
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