Improvements in the Treatment and Purification of Soap Makers Spent-lye for Extracting Glycerine therefrom.
Year: 1891

page_text: Date of Application, 13th July, 1891.
Complete Specification Left, 11th Apr., 1892-Accepted, 14th May, 1892
PROVISIONAL SPECIFICATION.
Improvements in the Treatment and Purification of Soap Makers
Spent-lye for Extracting Glycerine therefrom.
I, OTTO CHRISTIAN HAGEMANN, of Hillthorpe, Sydenham Hill, in the County
of Surrey, Chemical Engineer, (part of which invention has been communicated' to
me by Ebenezer Kennard. Mitting, of Chicago, Illinois, United States of America,)
do hereby declare the nature of this invention to be as follows::-
In the treatinent and purification of soap makers' spent-lye for, extracting
glycerine therefrom, hydrochloric or sulphuric acid are often added to the lye for
the purpose of neutralizing any free carbonated or caustic alkali contained in the
lye and of acting on soapy and other impurities present.
It is well known that the acids named frequently contain arsenic and that it is
very difficult to procure such acids perfectly free from arsenic, which latter is thus
brought into the glycerine made from the spent Iyes. Moreover the hydrochloric
acid of commerce only contains about 30% of real hydrochloric acid and is difficult
and costly of transport.
Now we have discovered, that in calcium chloride we have a substance which can
be expediently rendered free from arsenic which accomplishes, the purification of
the spent soap lyes and moreover being a solid body it can be easily' transported
and is free from objectionable features in handling the acids.
Tu carrying out our invention we add to the spent soap lye chloride of calcium,
preferably in solution until no further precipitate is produced. We next remove
the clear liquor from the precipitate and may then concentrate the liquor by boiling
in the ordinary manner, or may subject it to further, treatment and purification,
being clearly understood that the treatment of spent lye with calcium chloride is
available as a step in any process or processes in which free alkali is to be removed
from spent soap lye or wherein an action on fatty or organic impurities is
desired.
The action of calcium chloride on the spent lye is as follows-It enters into
combination with the free alkali contained therein, forming by double decomposition
with the carbonate of soda, chloride of sodium and carbonate of lime, and with the
caustic soda, chloride of sodium and hydrate of lime. It renders insoluble the
organic impurities, which being thus turned out of solution in the presence of
the finely divided carbonate of lime combine mechanically therewith forming a
precipitate from which the clear liquor thus purified may be removed by decantation
or filtration and concentrated for the elimination of the water and recovery of the
chloride of sodium and glycerine-the glycerine thus recovered will be free from
arsenic.
Dated this 13th day of July 1891..
COMPLETE SPECIFICATION.
Improvements in the Treatment and Purification of Soap, Makers'
Spent-lye for Extracting Glycerine therefrom.
I, OTTO CHRISTIAN HAGEMANN, of Hillthorpe, Sydenham Hill, in the County
of Surrey, Chemical Engineer, (part of which invention has been communicated to
me by Ebenezer Kennard Mitting, of Chicago, Illinois, United States of America,)
do hereby declare the nature of this invention and in what manner the same is to
D

page_text: .
be performed to be particularly described and ascertained in and by the following
statement:
'
In the treatment and purification of soap makers' spent-lye for extracting
glycerine therefrom, hydrochloric or sulphuric acid are often added to the lye for
the purpose of neutralizing any free carbonated or caustic alkali contained in the
lye and of neting on soapy and other impurities present.
It is well known that the acids named frequently contain arsenic and that it is
very difficult to procure such acids perfectly free from arsenic, which latter is thus
brought into the glycerine made from the spent lyes. Moreover the hydrochloric
acid of commerce only contains about 30% of real hydrochloric acid and is difficult
and costly of transport.
Now we have discovered, that in calcium chloride we have a substance which can
readily be rendered free from arsenic and which accomplishes the purification of
the spent soap lyes and moreover being a solid body it can be easily transported
and is free from objectionable features which arise from the handling of acids.
In carrying out our invention we add to the spent soap lye chloride of calcium,
preferably in solution until no further precipitate is produced. We next remové
the clear liquor from the precipitate and may then concentrate the liquor by
evaporation, thus producing crude glycerine and sodium chloride or may subject
it to further treatment and purification, it being clearly understood that the treat-
ment of spent lye with calcium chloride is available as a step in any process or
processes in which free alkali is to be removed from spent soap lye or wherein
an action on fatty or organic impurities is desired.
The chloride of sodium which as mentioned above crystallizes out during the
concentration we separate from the liquor and it may be used again in the manu-
facture of soap.
L
The action of calcium chloride on the spent lye is as follows:-It enters into
combination with the free alkali contained therein, forming by double decomposition
with the carbonate of soda, chloride of sodium and carbonate of lime, and with the
caustic soda; chloride of sodium. and hydrate of lime. It renders insoluble the
organic impurities, which being thus turned out of solution in the presence of
the finely divided carbonate of lime combine mechanically therewith forming a
precipitate from which the clear liquor thus purified may be removed by decantation
or filtration and concentrated for the elimination of the water and recovery of the
chloride of sodium and glycerine.
The employment of calcium chloride as above described offers an excellent means
for obtaining glycerine free from arsenic.
The hereinbefore described manner of carrying out our invention is the simplest
form in which it can be put into practice but it will be understood that it may be
used as a step or in conjunction, with other steps.in more elaborate treatments.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is
. 1
1. The herein before described improvement in recovering glycerine and salt
from spent soap lye which consists in adding chloride of calcium to the lye to
neutralize the free alkali and render insoluble contained impurities.
•
2. The treatment of spent soap lye with chloride of calcium for the purpose of
recovering useful products.
CARPMAEL & Co., 1
Agents for the Applicant.