IMPROVE- MENTS IN THE TREATMENT OF SOAP LYES TO RECOVER GLYCERINE AND OTHER PRODUCTS THEREFROM "
Year: 1882

page_text: LETTERS PATENT to Arthur John Lawson and Henry Livingstone Sulman,
both of Bristol, in the county of Gloucester, for an Invention of "IMPROVE-
MENTS IN THE TREATMENT OF SOAP LYES TO RECOVER GLYCERINE AND OTHER
PRODUCTS THEREFROM
"
PROVISIONAL SPECIFICATION left by the said Arthur John Lawson and
Henry Livingstone Sulman at the Office of the Commissioners of Patents on
the 27th September 1882.
ARTHUR JOHN LAWSON and HENRY LIVINGSTONE SULMAN both of Bristol in
the county of Gloucester "IMPROVEMENTS IN THE TREATMENT OF SOAP LYES TO
RECOVER GLYCERINE AND OTHER PRODUCTS THEREFROM "
This invention has for its objects
-
Firstly. An improved method of recovering glycerine and other useful products
from lyes resulting from soap manufacture
Secondly. To obtain the crude glycerine by such process in a state of greater
purity than usual by the elimination of certain impurities in the said lyes.
The process consists in first evaporating the lyes in suitable vessels to a density
of say 114 to 1-16 and allowing the solution to cool.
The salt liquor being thus concentrated the residual soapy matters remaining in
solution are rendered insoluble and rising to the surface may be readily removed
by skimming or otherwise for further use.
To remove the albuminous matters remaining in the liquor, we heat it and add
a salt of chromium sesquioxide or a persalt of iron or other suitable astringent
metallic salt capable of "tanning" or rendering albumen insoluble.
The albuminous matters thus rendered insoluble by the addition of the salt may
be precipitated and removed.
The removal of these matters at this stage prevents their decomposition by
further evaporation and enables us to secure a purer and more concentrated glycerine
of better color than usual.

page_text: The alkalinity of the liquor is at the same time just neutralized by a suitable
acid,
To obtain these two results ie-the tanning of the albuminous matters and the
neutralization of the alkalinity, we prefer to use the waste liquor resulting from the
bleaching of tallow or other fats or oils.
When treating highly colored lyes we may add a proportion of free chromic acid
to the waste liquor which by the oxidation and destruction of the coloring matters
is reduced to a salt of chromium sesquioxide capable of removing the albuminous
matters as above.
We now treat the liquor with a small excess of calcium carbonate and maintain
at a boiling temperature for a short time
This precipitates the whole of the chromic salts and neutralizes any slight
proportion of acid remaining.
The salts of iron zinc &c or whatever metallic compound be used to precipitate
the albuminous matters, by being contained in the resulting precipitate, can be
recovered for another operation in any suitable and well known manner.
The resultant liquor obtained by removing the precipitate by subsidence or
filtration will be found clear and almost colorless
It is concentrated by further evaporation which causes the gradual separation of
the salt which can be again used to treat fresh lyes.
The crude glycerine finally obtained we find to be of greater purity and better
color than hitherto

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Arthur John Lawson and Henry Livingstone Sulman in the Great
Seal Patent Office on the 27th January 1883.
ARTHUR JOHN LAWSON and HENRY LIVINGSTONE SULMAN both of Bristol in
the County of Gloucester "IMPROVEMENTS IN THE TREATMENT OF SOAP LYES TO
RECOVER GLYCERINE AND OTHER PRODUCTS THEREFROM
This Invention has for its object―
"
Firstly. An improved method of recovering glycerine and other useful products
from lyes resulting from soap manufacture.
Secondly. To obtain the crude glycerine by such process in a state of greater
purity than usual by the elimination of certain impurities in the said lyes.
The process consists in first evaporating the said lyes in suitable vessels to a
density of say 114 to 1·16 and allowing the solution to cool.
The salt liquor being thus concentrated the residual soapy matters remaining in
solution are rendered insoluble and rising to the surface may be readily removed
by skimming or otherwise for further use.
To remove the albuminous matters remaining in the liquor we heat it and add a
salt of chromium sesquioxide which is capable of tanning or rendering albumen
insoluble.
The quantity of the metallic salt added will depend on the percentage of
albumenous matter existing in the lye and must necessarily vary in lyes produced
from different quantities of soap.
The albuminous matters thus rendered insoluble by the addition of the salt are
precipitated and removed.
The removal of these matters at this stage prevents their decomposition by
further evaporation and enables us to secure a purer and more concentrated
glycerine of better color than usual.
The alkalinity of the liquor is at the same time just neutralized by a suitable
acid.
For example taking an ordinary spent lye (after evaporation to the aforesaid
density) we might add half a gallon of strong sulphuric acid, diluted with an equal
bulk of water to every hundred gallons of original lye.
A very convenient method of effecting our Invention so as to obtain these two
results i.e. the tanning of the albuminous matters and the neutralization of the
alkalinity is to use the waste liquor resulting from the bleaching of tallow or other
fats or oils.
For a lye such as the above we may add the bleaching liquor in the proportion
of say one to three gallons for every hundred gallons of original lye, but this must
depend entirely on the strength and color of the lye.
When treating highly colored lyes we add a proportion of free chromic acid to
the waste liquor which by the oxidation and destruction of the coloring matters
is reduced to a salt of chromium sesquioxide capable of removing the albuminous
matters as above.
The quantity of chromic acid will necessarily vary but for the above quantity of
lye we should use say half a pound of bicbromate of potash added to a mixture of
three quarters of a pound of sulphuric acid to two pounds of water and add this
mixture in the proportion of five to twenty pounds to every hundred gallons of
lye according to circumstances.
We now treat the liquor with a small excess of calcium carbonate (say for
example one to two gallons cream of whitening to one hundred of lye) and maintain
at a boiling temperature for a short time.

page_text: This precipitates the whole of the chromic salts and neutralizes any slight
proportion of acid remaining.
The chromic oxide contained in the resulting precipitate can be recovered for
another operation in any suitable and well known manner.
The resultant liquor obtained by removing the precipitate by subsidence or
filtration will be found clear and almost colourless.
It is then concentrated by further evaporation which causes the gradual
separation of the salt which can be again used in the manufacture of soap.
The crude glycerine finally obtained is of greater purity and better color than
usual.
We do not bind ourselves to any exact proportions of materials used in our
process and merely quote the above as an illustrative example..
Having now described our Invention and the manner of performing the same we
would have it understood that we claim as our Invention of improvements in the
treatment of soap lyes to recover glycerine and other products therefrom.
Firstly. The use of salts of chromium as recoverable salts for tanning or
rendering insoluble the albuminous matters contained in soap lyes substantially as
described.
Secondly. The use of waste liquor resulting from the bleaching of fatty or
oleaginous substances for the purpose of rendering insoluble the albuminous matters
contained in the lyes and at the same time neutralizing their alkalinity substantially
as described.
Thirdly. The combined process of treating soap lyes substantially as and for the
purposes described.
In witness whereof we the said Arthur John Lawson and Henry Livingstone
Sulman have hereunto set our hands and seals this twenty second day of
January in the year of our Lord One thousand eight hundred and eighty
three
ARTHUR J LAWSON
(L.S.)
HENRY LIVINGSTONE SULMAN (L.S.)