AN IMPROVED PROCESS OF TREATING THE SPENT LYES OF SOAP-WORKS, CHIEFLY FOR THE RECOVERY OF GLYCERINE THEREFROM."
Year: 1881

page_text: LETTERS PATENT to George Payne, of Millwall, in the County of Middlesex,
Chemical Manufacturer, for an Invention of "AN IMPROVED PROCESS OF
TREATING THE SPENT LYES OF SOAP-WORKS, CHIEFLY FOR THE RECOVERY
OF GLYCERINE THEREFROM."
PROVISIONAL SPECIFICATION left by the said George Payne at the Office
of the Commissioners of Patents on the 27th June 1881.
GEORGE PAYNE, of Millwall, in the County of Middlesex, Chemical Manufacturer.
"AN IMPROVED PROCESS OF TREATING THE SPENT LYES OF SOAP-WORKS, CHIEFLY
FOR THE RECOVERY OF GLYCERINE THEREFROM."
This Invention relates to an improved process of treating the spent lyes of soap
works, chiefly for the extraction or recovery therefrom of glycerine.
According to the said Invention I first saturate the unspent alkali in the lye
with hydrochloric acid; then I separate the gelatinous and albuminous matter from
the spent lye by means of a suitable reagent, preferably a solution of tannic acid.
The resulting liquid consists chiefly of raw and impure glycerine and chloride of
sodium (common salt). I then filter this liquid and concentrate the same by
evaporation, and distil and refine the glycerine in any convenient inanner.
The chloride of sodium remains as a residue in the still, and may be removed
therefrom in any convenient manner.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Payno in the Great Seal Patent Office on the 24th December
1881.
GEORGE PAYNE, of Millwall, in the County of Middlesex, Chemical Manufacturer.
"AN IMPROVED PROCESS OF TREATING THE SPENT LYES OF SOAP-WORKS, CHIEFLY
FOR THE RECOVERY OF GLYCERINE TIEREFROM."
This Invention relates to an improved process for treating the spent lyes of soap
works, and has for its object the recovery or oxtraction therefrom of glycerine.
The said Invention consists in the employment for this purpose of tannic acid or
tannin in the following process, that is to say :-
I take the spent lye produced in the manufacture of soap and saturato the
unspent alkali contained therein with an acid to neutralize the same. I prefer to
use for this purpose sulphuric, hydrochloric, or nitric acid, but other acids may be
used instead of though not so advantageously in point of economy as these.
Any scum or precipitate formed by the action of the acid upon the spent lye
should be removed (although its removal is not strictly necessary) before treating
the lye with the tannin or tannic acid.
I then take a solution of the tannin or tannic acid and add the same to the
spent lye which has been previously treated with the acid, as above described. I
prefer that this solution should contain about one part by weight of tannin or
tannic acid to ten parts by weight of water. The addition of the said solution to
the lye is continued until it ceases to precipitate any albuminous or gelatinous
matter.
The precipitate which has been formed is separated by filtration or is allowed to
settle. The liquid remaining consists chiefly of raw or impure glycerine and
chloride of sodium. I prefer that the solution should be warmed, as experience
has demonstrated that the warming of the same facilitates the formation and
separation of the precipitate. In some instances the aforesaid solution may be
found to be slightly acid, if so I can easily bring it to a neutral condition by the
addition of milk of lime.
I subject the mixture of glycerine and spent lye, prepared as above described, to
heat for the purpose of evaporating the water, thereby concentrating the mixture
and removing from the same a large quantity of the salts, which will crystallize out
in the process of evaporation. I may employ for this purpose currents of heated
air or superheated steam, or I may subject the solution to the direct heat of fire.
By my improved process, as above described, I obtain a concentrated solution of
glycerine containing about ten (10) per cent. of salt, and capable of being distilled
and refined in any convenient manner. Moreover I find that the glycerine obtained
by this process may be more easily refined by distillation than that obtained by
any other known process.
Having thus fully described my said Invention and the manner of performing
the same, I wish it understood that I am aware that other reagents than tannin or
tannic acid may be used for effecting the precipitation of the salts from the
glycerine, I do not however employ any of these other substances in my process,
and I make no claim thereto for the purpose of my said Invention, neither do I
claim broadly or generally the extraction of glycerine from the spent lyes of soap
works, as I am aware that other processes have been proposed for this and similar
purposes, but I claim,-
The above described process wherein tannic acid or tannin is used in the treat-

page_text: ment of the spent lyes resulting from the manufacture of soap, as and for the
purpose above set forth.
In witness whereof, I, the said George Payne, have hereunto set my hand
and seal, this Twenty-third day of December, in the year of our Lord One
thousand eight hundred and eighty one.