AN IMPROVED PROCESS OF EXTRACTING GLYCERINE Communicated FROM THE RESIDUARY LIQUORS OF THE SOAP MANUFACTURE
Year: 1882

page_text: LETTERS PATENT to Alexander Melville Clark of the firm of A M and
W Clark of 53, Chancery Lane, in the County of Middlesex, Patent Agents,
for an invention of AN IMPROVED PROCESS OF EXTRACTING GLYCERINE
Communicated
FROM THE RESIDUARY LIQUORS OF THE SOAP MANUFACTURE
to him from abroad by the firm of E Brochon and Company, of Milan,
Italy
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 12th June 1882.
ALEXANDER MELVILLE CLARK of the firm of A, M, and W Clark of 53 Chancery
Lane in the County of Middlesex, Patent Agents, "AN IMPROVED PROCESS OF
EXTRACTING GLYCERINE FROM THE RESIDUARY LIQUORS OF THE SOAP MANU-
FACTURE" [A communication to him from abroad by the firm of E Brochon and
Company, of Milan, Italy.]
This invention relates to an improved process for the extraction of the glycerine
contained in the residuary liquors of the manufacture of soap.
The extraction of this glycerine presents certain difficulties inasmuch as the
liquors resulting from the manufacture of soaps from fatty bodies from which the
glycerine has not previously to their use been extracted, are very impure. Besides
glycerine they contain chlorides, sulphates, carbonates of soda, and caustic soda,
and sometimes salts of potash and soapy matters which have escaped in the
operation of removing the superfluous water from the soap, as well as fatty acids
(oleic and others) gelatinous matters, resins &c. It is therefore necessary to first
purify the liquors but as the purification does not eliminate the salts or even
diminish them in quantity, it is further necessary to effect the separation of the
glycerine from the said salts
I will now describe the method of effecting these operations
Purification. The residuary liquors from the manufacture of soaps are conveyed
to a special manufactory and are stored in tanks or reservoirs where chloride of

page_text: sodium is added (the product of previous operations hereinafter described) in order
to complete the removal of superfluous water. After the lapse of sufficient time to
allow of the separation of all the soapy matters, the clear liquor is removed by
decantation or filtration. This liquor is afterwards acidulated with hydrochloric or
sulphuric acid, in order to separate the fatty acids from the bases with which they
are till then combined, a small excess of acid being therefore necessary. The part
thus rendered insoluble may then be precipitated either by means of albumen,
gelatine, or per-chloride of iron, chloride of aluminum, chloride of zinc, sulphate of
iron, sulphate of alumina and generally by any of the agents capable of producing
this coagulating effect in order to produce the desired result, notably by all the
chlorides and the soluble metallic sulphates The proportions depend on the
degree of impurity of the liquors These re-agents albumen, gelatine, metallic
salts &c effect a real clarification similar to that produced by finings in wines.
All these operations are performed in the cold
The clear liquor removed after deposit or filtration may be immediately
concentrated, but it is better to submit it to a final operation, either by heating it
to ebullition, adding milk of lime or lime wash until the mass is rendered alkaline
and the metallic salts are precipitated, letting settle, and adding to the liquid
which is now exceedingly clear, bi-carbonate of soda or potash, or even carbonate,
but only in the quantity strictly necessary for the precipitation of the lime, and
lastly having freshly taken the clear liquor, now quite free from lime, neutralizing
it with hydrochloric acid
Concentration of the glycerine and separation of the salts. The liquors prepared
as above described now contain only the glycerine and the salts and the separation
of the former from the latter and the concentration of the former are effected at
one time.
This double operation viz the separation of the salts and the simultaneous
concentration of the glycerine can be performed by the process of this invention in
any form of vessels, and with any convenient mode of heating the evaporating
apparatus.
In order that the Invention may be more clearly understood I will describe as
an example the simple case in which the apparatus is heated by an ordinary
furnace to temperature sufficient for effecting the necessary concentrations.
I will take then as an example of an apparatus suitable for carrying out the
process of this Invention, a series of metal boilers, say 12 in number. These boilers,-
which may vary in dimensions (and even in number) according to the quantity of
liquor to be treated and the heating power of the fuel employed,—
―are all cylindrical,
and are by preference heated laterally, as, especially when exposed to the direct
action of the furnace gases, heating them at the end causes rapid scaling, one of
the least inconveniences of which is to compromise the durability of the apparatus.
These boilers have their bottoms and about 15% of their height below the flues
which do not rise to above 70% of their height, there being therefore about 30°
of the boiler above them which with the 15% below leaves only about 55%.
intermediary space exposed in the flues. These boilers are put in operation by
filling them to above the level of the flues, with the purified glycerine liquors above
described, care being taken as the level in the boilers is lowered by evaporation, to
supply more liquor, and this by following the method now to be explained.
of
Suppose the number of boilers to be 12 (a number which may be reduced even
as much as one half, or which on the other hand it may be necessary to increase)
feed boiler No 12 with liquor taken directly from No 11, No 11 with liquor taken
directly from No 10 and so on down to No 1 which is supplied with fresh liquor,
the result of which is that the liquor in No 12 soon becomes more highly
concentrated than that in all the others, and that in No 11 more so than that in
No 10 and so on, that in No 1 being least concentrated of all and in fact hardly
more concentrated than the fresh liquor. The liquor in No 12 quickly reaches the
point of saturation and the salts which it contains begin to deposit at the lower
and non-heated part of the boiler, the same being successively the case in Nos 11, 10

page_text: and so on in the inverse order of their numbers. As soon as the deposit commences
to form in No 12, it is ladled out or removed by any other convenient means, and
after being lightly drained in such a way that the liquid draining from it falls
back into boiler No 12 it is placed in No 11. Similarly for No 11 and for all the
others, the salts deposited therein and resulting from the concentration in the
preceding apparatus, are ladled into the boiler next lowest in serial number.
When the salts at last begin to be deposited even in No 1 I remove all the salts
from it and after a good draining place them in store. Should the mother liquor
still contain a sufficient proportion of glycerine to make it worth while I submit
it to a final washing in pure water saturated with salt, but this is nearly always
an unnecessary precaution as the liquor in the first boiler will nearly always be
almost fluid, and the little glycerine that remains mixed with the salt is poor
enough to be neglected
When the boiling point in boiler No 12 reaches 120° Centigrade the liquor is
removed and let to settle in order to allow of the thorough deposit of salts and its
concentration is then pushed further until the boiling liquid marks 150° Centigrade,
in special boilers arranged like those previously described as regards the mode of
heating them, the salts being removed from tliese boilers as fast as they are
produced. When this temperature of 150° C. is reached, the concentrated liquid is
left to deposit its salts, and the clear portion removed in order to be sent to the
distillery and the lees composed of salts impregnated with glycerine are returned
to boiler No 12.
The final elimination of the salts must be effected by distillation
The distillation can be performed in the ordinary way except as regards the
precautions necessitated by the presence of a small quantity of salts (lateral
heating &c)
It will be understood that the concentration of the liquids as above described
could be effected equally well in vessels of any other form and heated in any other
way than that described, such as for example by means of steam under pressure or
not, by the passage of heated gases through the mass of the liquid, by the drying
action of the atmosphere, or by the formation of a vacuum &c.
The essential requisite is that the operation for the liquids should be conducted
in the inverse sense to that in which the operation for the salts is conducted, the
former enriching themselves with glycerine and proportionally impoverishing
themselves of salts, whilst the latter correspondingly impoverish themselves of
glycerine

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on
the 12th December 1882.
ALEXANDER MELVILLE CLARK of the firm of A, M, and W, Clark of 53 Chancery
AN IMPROVED PROCESS OF
Lane in the County of Middlesex Patent Agents
EXTRACTING GLYCERINE FROM THE RESIDUARY LIQUORS OF THE SOAP MANU-
FACTURE A communication to me from abroad by the firm of E Brochon and
Company of Milan Italy.
This Invention relates to an improved process for the extraction of the glycerine
contained in the residuary liquors of the manufacture of soap.
The extraction of this glycerine presents certain difficulties inasmuch as the
liquors resulting from the manufacture of soaps from fatty bodies from which the
glycerine has not previously to their use been extracted, are very impure. Besides
glycerine, they contain chlorides, sulphates, carbonates of soda, and caustic soda, and
sometimes salts of potash and soapy matters which have escaped in the operation
of removing the superfluous water from the soap as well as fatty acids (oleic and
others) gelatinous matters, resins, &c. It is therefore necessary to first purify the
liquors, but as the purification does not eliminate the salts or even diminish them
in quantity, it is further necessary to effect the separation of the glycerine from the
said salts. I will now describe the method of effecting these operations.
Purification. The residuary liquors from the manufacture of soaps are conveyed
to a special manufactory and are stored in tanks or reservoirs where chloride of
sodium is added (the product of previous operations hereinafter described) in order
to complete the removal of superfluous water. After the lapse of sufficient time to
allow of the separation of all the soapy matters, the clear liquor is removed by
decantation or filtration. This liquor is afterwards acidulated with bydrochloric
or sulphuric acid in order to separate the fat acids from the bases with which they
The part
are till then combined, a small excess of acid being therefore necessary.
thus rendered insoluble may then be precipitated by means either of albumen or
gelatine, or by perchloride of iron, chloride of aluminum, chloride of zinc, sulphate
of iron, sulphate of alumina, and generally by any of the agents capable of producing
this coagulating effect in order to produce the desired result, notably by all the
chlorides and the soluble metallic sulphates. The proportions depend on the degree
of impurity of the liquors. These reagents albumen, gelatine, metallic salts, &c,
effect a real clarification similar to that produced by finings in wines All these
operations are performed in the cold.
The clear liquor removed after deposit or filtration may be immediately concen-
trated, but it is better to submit it to a final operation by heating it to ebullition,
adding milk of lime until the mass is rendered alkaline and the metallic salts are
precipitated, letting settle, drawing off the clear liquid adding bicarbonate of soda
or potash, or even carbonate, but only in the quantity strictly necessary for the
precipitation of the lime, and lastly, having again drawn off the clear liquor now
quite free from lime, neutralising it with hydrochloric acid.
Concentration of the Glycerine and separation of the Salts. The liquors prepared
as above described now contain only the glycerine and the salts, and the separation
of the former from the latter and the concentration of the former, are effected at
one time. This double operation, viz-the separation of the salts and the simul-
taneous concentration of the glycerine, can be performed by the process of this
Invention in any form of vessels and with any convenient mode of heating the
evaporating apparatus.
In order that the Invention may be more clearly understood, I will describe as

page_text: an example the simple case in which the apparatus is directly heated in an ordinary
furnace to the temperature necessary for effecting the concentrations.
I will take then as an example of an apparatus suitable for carrying out the
process of this Invention, a series of metal boilers, say 12 in number. These boilers
which may vary in dimensions (and even in number) according to the quantity of
liquor to be treated and the heating power of the fuel employed, are all cylindrical,
and are by preference heated laterally, as, especially when exposed to the direct
action of the furnace gases, heating them at the end causes rapid scaling, and thus
affects the durability of the apparatus. These boilers have their bottoms and about
15% of their height below the flues which do not rise to above 70% of their
height there being therefore about 30% of the boiler above them which with the
15 below, leaves only about 55% of intermediary space exposed in the flues.
These boilers are put in operation by filling them to above the level of the flues
with the purified glyceric liquors above described, care being taken as the level in
the boilers is lowered by evaporation, to supply more liquor and this by following
the method now to be explained.
°
Suppose the number of boilers to be 12 (a number which may be reduced even
as much as one half, or which on the other hand it may be necessary to increase) I
feed boiler No 12 with liquor taken directly from No 11; No 11 with liquor taken
directly from No 10; and so on down to No 1 which is supplied with fresh liquor,
the result of which is that the liquor in No 12 soon becomes more highly concen-
trated than that in all the others, and that in No 11 more so than that in No 10,
and so on, that in No 1 being least concentrated of all, and but little more concen-
trated than the fresh liquor. The liquor in No 12 quickly reaches the point of
saturation and the salts which it contains begin to deposit at the lower and non-
heated part of the boiler, the same being successively the case in Nos 11. 10 and so
on in the inverse order of their numbers. As soon as the deposit commences to
form in No 12 it is ladled out or removed by any other convenient means, and
after being lightly drained (the drainings from it being returned to boiler No 12)
it is placed in No 11. Similarly for No 11 and for all the others, the salts
deposited therein and resulting from the concentration in the apparatus higher in
serial number, are ladled into the boiler next lowest in serial number. When the
salts at last begin to be deposited even in No. 1 I remove all the salts therefrom
and after a good draining place them in store. If however the initial liquor
contained sufficient glycerine to make it worth while, I may submit them to a final
washing in pure water already saturated with salt, but this is nearly always an
unnecessary precaution as the liquor in the first boiler will hardly ever be at all
viscid and will drain off freely and the little that remains mixed with the salt is
poor enough to be neglected. When the boiling point in boiler No 12 reaches
120° Centigrade the liquor is removed and let to settle in order to allow of the
thorough deposit of salts and its concentration is then pushed further until the
boiling point reaches 150° Centigrade in special boilers arranged like those pre-
viously described as regards the mode of heating them, the salts not being removed
from these boilers as they are produced. When this temperature of 150° C. is
reached, the concentrated liquid is left to deposit its salts and the clear portion
removed in order to be sent to the distillery, and the lees composed of salts
impregnated with glycerine are returned to boiler No 12.
The final elimination of the salts must be effected by distillation. The distil-
lation can be performed in the ordinary way except for certain precautions as
regards lateral heating, &c, necessitated by the presence of a small quantity of
salts.
It will be understood that vessels of any other form and heated in any other
way (by steam for instance) may be used, and that the evaporation and concen-
tration of the liquors could be effected by the passage of heated gases through the
mass of the liquid, by the drying action of the atmosphere, or by the formation of
a vacuum, &c.
The essential feature is that the liquids and salts should progress in opposite

page_text: directions the former becoming richer in glycerine and poorer in salts, whilst the
latter become poorer in glycerine.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is.
The herein described process of extracting glycerine from the residuary liquors
of the manufacture of soap, which consists in first purifying these liquors by the
coagulation by acid of a coagulating agent added, such as albumen, blood, gelatine,
or salts of alumina or by the coagulation or precipitation of the organic matters
already contained in the liquors by a metallic salt (chloride or soluble sulphate) on
which the still alkaline liquid reacts; and secondly, concentrating the glycerine and
simultaneously separating the salts therefrom in a series of evaporative apparatus
wherein the liquids are made to progress in one direction towards concentration
whilst the salts progress towards impoverishment in the other (and this whatever
may be the mode of evaporating employed) substantially as herein specified.
In witness whereof I the said Alexander Melville Clark have hereunto set
my hand and seal this twelfth day of December, A.D. 1882.