Improvements in the Treatment or Purification of Fatty Acids and in Apparatus Employed therein.
Year: 1888

page_text: Date of Application, 16th July, 1888
Complete Specification Left, 16th Apr., 1889
Complete Specification Accepted, 1st June. 1889
Improvements in the Treatment or Purification of Fatty Acids and
in Apparatus Employed therein.
I, MARIE VICTOIRE BRISSET, Veuve Charles Petit of Saint Denis, Seine, France,
do hereby declare the nature of this invention to be as follows :-
The fatty acids which result from the saponification of vegetable or animal fats and
oils are formed of mixtures in variable proportions of more or less solid acids such as
margaric, stearic and palmitic and of liquid fatty acids. In order to make these
products suitable for the manufacture of stearic candles it is necessary to effect in as
complete a manner as possible the separation of the solid acids and the liquid acids ;
this result is attained by the employment of presses of different kinds which exert
pressure either cold or hot.
The process which forms the subject of my invention has for object to effect the
purification of the fatty acids under novel conditions which are better than the
methods heretofore followed. It is based on the property possessed by the solid acids
of crystallizing in certain solvents while the liquid acids which have not the same
physical property remain in solution in the solvent.
Any neutral solvent can be employed; I may mention benzine, ligroine, essence of
turpentine, petroleum ether, wood spirit, acetone, ethylic alcohol, propylic, butylic
and amylic alcohols, singly or mixed, sulphide of carbon and ether.
If a solvent be employed which is insoluble or little soluble in water the mixture of
fatty acids is dissolved therein under heat so as to obtain a strongly charged solution ;
it is then left to cool either at the ordinary temperature or at a low temperature
produced artificially, until the solid acid has crystallized. The mother waters are
separated, the crystals are washed with the original liquid saturated cold with stearic
acid so as to remove the last traces of liquid acid; the solvent is then removed by a
jet of steam.
In many cases it is preferable to use solvents which are soluble in water; these
liquids can then be employed either pure or with the addition of water. In the latter
case the quantity of water added should be such that the liquid will dissolve the acids

page_text: to be purified while preserving to them when cold the power of retaining the liquid
acids in solution and that a very small 'addition of fresh water will suffice to
precipitate the liquid acids that remain in the 'mother water after the crystalliza-
tion. The quantity of solvent employed and also the quantity of water to be added
to the solvent will vary according to the nature of the acid to be purified and to
the amount of liquid acid it contains; for alcohol or wood spirit for example it
will be suitable to take from 1 to 10 parts of a solution containing from 65 to
80 per cent. of alcohol and 20 to 30 parts of water, to dissolve therein the raw fatty
acids at a temperature of from 30° to 40° Centigrade and to cool the solution at
about 6° to 10°. The mother waters and added water allow the liquid acid to rise to
the top, and the alcohol after concentration is recovered.
If a better purification be desired the product can be submitted to a fresh crystalliza-
tion; in this case the mother waters, as they contain very little liquid acid, can be
used without any treatment for effecting a first crystallization of the fatty acids.
Such is the principle of my process. To carry it into practice I have tried various
mechanical means in order to find the best for separating in a simple and practical
manner the crystals from. the mother waters.charged with liquid fatty acids.
I
I will describe these means that is to say those that have given the best results.
will first remark that solid fatty acids whatever be their nature and their origin
assume when they crystallize in the midst of the solvent which is employed the form
of very small extremely voluminous crystals which in most cases cause the cooled
solutions to take the form of a semi-solid mass; this great division of the material
which is eminently adapted for a good purification of the product renders the
extraction of the solid acids difficult; this separation is made still more difficult on
account of the volatility of the solvents employed because the operation can only be
economically effected if the loss of the purifying agent is reduced to the minimum..
Therefore the separation should be made in apparatus which are as hermetically closed
as possible.
The apparatus which can be employed are of kinds, viz., presses, apparatus based
on the employment of vacuum, and centrifugal apparatus.
Presses. On account of the extreme division of the crystals and their easy
agglomeration, it is impossible to press them in large masses; it is necessary to employ
presses with large surfaces. Those presses which give the best results are continuous
presses and filter presses. The cloths of the continuous presses should be woven
sufficiently close; the liquid charged with crystals is brought to the press and spread
in a thick layer so that after the pressure the sheet or layer of solid acid shall be only
a few millimetres thick. A mechanical device such as a circular brush or a knife
at the end of the filtering table where the cloth bends round frees this from the
crystals and thoroughly clears it. The filter presses should be of very large surface
and have very narrow chambers or compartments; the washing of the cakes of fatty
acid is effected in the apparatus themselves.
Centrifugal Apparatus. These apparatus can likewise be employed; they effect a
very perfect separation; they are completely closed and receive through special
conduits terminating in, the interior of the apparatus the matter to be filtered and the
liquids for effecting the washing of the crystals. But in practice I believe it is
advantageous to combine these apparatus with those of the kind which I will now
describe.
Apparatus acting by vacuum. These apparatus are of two sorts, intermittent and
continuous. The intermittent apparatus are composed of boxes with filtering surfaces
whose interior is put in communication with an air pump. The thick liquid is
conducted in a thin layer over the filtering surface which is covered with a close
fabric the liquid that passes through this fabric is constantly drawn by the pump
and the solid fatty acids are withdrawn after having been washed with a solvent
previously cooled. The continuous apparatus can be of several types. I will describe
by way of example a novel apparatus which I have designed for the purpose and which
I have found to give good results. It is composed of a cylinder the circumference of
which is a filtering surface and turns in a trough or vessel constantly fed by the

page_text: liquid to be separated. The filtering surface is composed of perforated sheet metal
over which is placed a thick cloth. The interior of the cylinder is in communication
through its hollow trunnions with a pump which rarefies the air beneath the cloth.
A submerged tube removes the liquid that filters through and prevents it accumulating
in the cylinder. When the apparatus is put in work the liquid drawn by the pump
is thrown upon the cloth and covers it with a thin layer of fatty acids which remains
attached thereto and follows the movement of the cylinder; this layer continually
submitted to the action of the vacuum continues to dry up to the instant that the
cloth is about to again enter the trough. At this point it is detached by a revolving
brush or other suitable device and the cloth is at once recharged in its passage
through the liquid in the trough. Instead of the cylinder the apparatus may be
constructed with a table having a filtering surface over which the liquid to be filtered
is conducted in thin layers, the crystallized acid being removed by a scraper or
circular brush. In these apparatus the speed of the tables or cylinders is regulated
according to the composition of the liquid to be filtered so as to allow the layer of
fatty acid time to be deprived as completely as possible of the mother water.
When I use solvents which are soluble in water such as wood spirit, alcohol, and
acetone regenerate the solvent without having recourse to distillation. I effect
this by agitating the liquid (previously deprived of fatty acid by a small addition of
water) with salts or saline solutions which will absorb water, carbonate of potass for
example. A methodic treatment with these salts or saline solutions removes from the
solvent nearly the whole of its water so that it is easy by rapid dosing to bring
it to the desired state. If the alcohol after its concentration holds in solution a small
quantity of absorbent salt it can easily be removed by provoking the insolubility of
this salt by the addition of an appropriate reactive.
By proceeding in this way there is no need to have recourse to distillation except to
revivify the small quantities of liquid too weak to be economically concentrated by
salts, or to purify the solvent when owing to repeated use it becomes too much charged
with impurities.
Dated this 16th day of July 1888.
J. C. MEWBURN,
169, Fleet Street, London;
Agent.

page_text: Improvements in the Treatment or Purification of Fatty Acids and
in Apparatus Employed therein.
I, MARIE VICTOIRE BRISSET, Veuve Charles Petit of Saint Denis, Seine, France,
do hereby declare the nature of this invention and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement:
-
The fatty acids which result from the saponification of vegetable or animal fats and
oils are formed of mixtures in variable proportions of more or less solid acids such
as margaric, stearic and palmitic and of liquid fatty acids. In order to make these
products suitable for the manufacture of stearic candles it is necessary to effect in
as complete a manner as possible the separation of the solid acids and the liquid
acids; this result is attained by the employment of presses of different kinds which
exert pressure either cold or hot.
The process which forms the subject of my invention has for object to effect the
purification of the fatty acids under novel conditions which are better than the methods
heretofore followed. It is based on the property possessed by the solid acids of
crystallizing in certain solvents while the liquid acids which have not the same physical
property remain in solution in the solvent.
Any neutral solvent can be employed; I may mention benzine, ligroine, essence of
turpentine, petroleum ether, wood spirit, acetone, ethylic alcohol, propylic, butylic and
amylic alcohols, singly or mixed, sulphide of carbon and ether.
If a solvent be employed which is insoluble or little soluble in water the mixture
of fatty acids is dissolved therein under heat so as to obtain a strongly charged
solution; it is then left to cool either at the ordinary temperature or at a low
temperature produced artificially, until the solid acid has crystallized. The mother
waters are separated, the crystals are washed with the original liquid saturated cold
with stearic acid so as to remove the last traces of liquid acid; and the solvent is then
removed by a jet of steam.
In many cases it is preferable to use solvents which are soluble in water; these
liquids can then be employed either pure or with the addition of water. In the
latter case the quantity of water added should be such that the liquid will dissolve
the acids to be purified while preserving to them when cold the power of retaining
the liquid acids in solution and that a very small addition of fresh water will suffice
to precipitate the liquid acids that remain in the mother water after the crystallization.
The quantity of solvent employed and also the quantity of water to be added to the
solvent will vary according to the nature of the acid to be purified and to the amount
of liquid acid it contains; for alcohol or wood spirit for example it will be suitable
to take from 1 to 10 parts of a solution containing from 65 to 80 per cent. of alcohol
and 20 to 35 parts of water, to dissolve therein the raw fatty acids at a temperature of
from 30° to 40° Centigrade and to cool the solution at about 6° to 10°. The mother
waters and added water allow the liquid acid to rise to the top, and the alcohol after
concentration is recovered.

page_text: If a better purification be desired the product can be submitted to a fresh
crystallization in this case the mother waters, as they contain very little liquid
acid, can be used without any treatment for effecting a first crystallization of the
fatty acids.
Such is the principle of my process. To carry it into practice I have tried
various mechanical means in order to find the best for separating in a simple and
practical manner the crystals from the mother waters charged with liquid fatty
acids.
I will describe these means that is to say those that have given the best results.
I will first remark that solid fatty acids whatever be their nature and their origin
assumo when they crystallize in the midst of the solvent which is employed the form
of very small extremely voluminous crystals which in most cases cause the cooled
solutions to take the form of a semi-solid mass; this great division of the material
which is eminently adapted for a good purification of the product renders the
extraction of the solid acids difficult; this separation is made still more difficult on
account of the volatility of the solvents employed because the operation can only be
economically effected if the loss of the purifying agent is reduced to the minimum.
Therefore the separation should be made in apparatus which are as hermetically closed
as possible.
The apparatus which can be employed are of 3 kinds, viz., presses, apparatus based on
the employment of vacuum, and centrifugal apparatus.
Presses. On account of the extreme division of the crystals and their easy
agglomeration, it is impossible to press them in large masses; it is necessary to
employ presses with large surfaces. Those presses which give the best results are
continuous presses and filter presses. The cloths of the continuous presses should be
woven sufficiently close; the liquid charged with crystals is brought to the press and
spread in a thick layer so that after the pressure the sheet or layer of solid acid shall
be only a few millimetres thick. A mechanical device such as a circular brush or a
knife at the end of the filtering table where the cloth bends round frees this from the
crystals and thoroughly clears it. The filter presses should be of very large surface
and have very narrow chambers or compartments; the washing of the cakes of fatty
acid is effected in the apparatus themselves.
Centrifugal Apparatus. These apparatus can likewise be employed; they effect a
very perfect separation; they are completely closed and receive through special
conduits terminating in the interior of the apparatus the matter to be filtered and
the liquids for effecting the washing of the crystals. But in practice I believe it is
advantageous to combine these apparatus with those of the kind which I will now
describe.
Apparatus acting by vacuum. These apparatus are of two sorts, intermittent and
continuous. The intermittent apparatus are composed of boxes with filtering surfaces
whose interior is put in communication with an air pump. The thick liquid is
conducted in a thin layer over the filtering surface which is covered with a close
fabric; the liquid that passes through this fabric is constantly drawn by the pump
and the solid fatty acids are withdrawn after having been washed with a solvent
previously cooled. The continuous apparatus can be of several types. I will describe
by way of example a novel apparatus which I have designed for the purpose and
which I have found to give good results. It is shown in the annexed drawing and is
composed of a cylinder A the circumference of which is a filtering surface and
turns in a trough or vessel B constantly fed by the liquid to be separated. The
filtering surface is composed of perforated sheet metal Cover which is placed a thick
cloth D; a portion of the sheet C is shown in Figure 2. The interior of the cylinder
is in communication through its hollow trunnions with a pump which rarefies the air
inside or beneath the cloth. A submerged tube removes the liquid that filters through
and prevents it accumulating in the cylinder. When the apparatus is put in work the
liquid drawn by the pump is thrown upon the cloth and covers it with a thin layer of
fatty acids which remains attached thereto and follows the movement of the cylinder;
this layer continually submitted to the action of the vacuum continues to dry up to the

page_text: instant that the cloth is about to again enter the trough. At this point it is detached
by a revolving brush E or other suitable device and the cloth is at once recharged in
its passage through the liquid in the trough. Instead of the cylinder the apparatus
may be constructed with a table having a filtering surface over which the liquid to
be filtered is conducted in thin layers, the crystallized acid being removed by a scraper
or circular brush. In these apparatus the speed of the tables or cylinders is regulated
according to the composition of the liquid to be filtered so as to allow the layer of
fatty acid time to be deprived as completely as possible of the mother water.
When I use solvents which are soluble in water such as wood spirit, alcohol and
acetone I regenerate the solvent without having recourse to distillation. I effect this
by agitating the liquid (previously deprived of fatty acid by a small addition of water)
with salts or saline solutions which will absorb water, carbonate of potass for example.
A methodic treatment with these salts or saline solutions removes from the solvent
nearly the whole of its water so that it is easy by rapid dosing to bring it to the
desired state. If the alcohol after its concentration holds in solution a small quantity
of absorbent salt it can easily he removed by provoking the insolubility of this salt
by the addition of an appropriate reactive.
By proceeding in this way there is no need to have recourse to distillation except
to revivify the small quantities of liquid too weak to be economically concentrated by
salts, or to purify the solvent when owing to repeated use it becomes too much charged
with impurities.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. The process hereinbefore described of treating or purifying fatty acids.
2. In the treatment or purification of fatty acids, the crystallization of the acids
in solvents such for example as benzine, ligroine and ether, which are insoluble in
water, as set forth.
3. In the treatment or purification of fatty acids, the crystallization of the acids
in solvents such for example as wood spirit, alcohol and acetone which are soluble
in water, or in mixtures of water and solvents which are soluble in water, as set
forth.
4. In the treatment or purification of fatty acids, the crystallization of the acids in
solvents and the subsequent separation of the fatty acid crystals from the mother
waters by mechanical means as herein before described.
5. The special construction of apparatus hereinbefore described and represented in
the annexed drawings for the purpose set forth.
Dated this 10th day
fAmil 1000
J. C. MEWBURN,
55 & 56, Chancery Lane, London,
Patent Agent.