Improvements in Decolourising Vegetable Oils in the Manufacture of Pale Drying Oils and Varnishes, and Apparatus therefor.
Year: 1890

page_text: Date of Application, 24th July, 1890
Complete Specification Left, 4th Dec., 1890-4ccepted, 24th Jan., 1891
PROVISIONAL SPECIFICATION.
Improvements in Decolourising Vegetable Oils in the Manufacture
of Pale Drying Oils and Varnishes, and Apparatus therefor.
We, WALTER NOEL HARTLEY, of 36, Waterloo Road, Dublin, in the County of
Dublin, Ireland, Fellow of the Royal Society, Professor of Chemistry in the Royal
College of Science, Dublin, and WILLIAM EDMUND BRANDFORD BLENKINSOP, of
15, Earlsfield Road, Wandsworth Common, in the County of Surrey, Manufacturing
Chemist, do hereby declare the nature of this invention to be as follows:-
Our invention relates to improvements in decolourising vegetable oils and in the
manufacture of pale drying oils and varnishes by the removal or destruction from the
vegetable oils of the natural colouring matter which they contain.
In carrying out our invention we add to the oil to be treated a manganese salt of a
suitable fatty acid or a mixture of the manganese salts of more than one fatty acid.
We prefer to use the manganese salt or salts of the acid or acids naturally contained
in the oil to be treated but this is not essential because we have found that we can use
For instance in the treatmen
the manganese salts of the acids contained in other oils.
of cotton seed oil we prepare a soap from the oil by saponifying it with an alkali and
decompose the soap with a pure salt of manganese such as the sulphate. The com-
bination of manganese with the fatty acid or acids of the oil is then added to the oil
in the proportion of about one part of the manganese compound to about 1600 parts
of the oil, the proportions depending on the nature of the oil to be treated.
The mixture of oil and the manganese compound is allowed to stand until the
The clear oil thus
impurities have been separated by subsidence or otherwise.
obtained is then treated in an apparatus which consists of a tank with arrangements
for passing air or oxygen through the oil in the tank. The oil is maintained at a
suitable temperature preferably between 100° and 212° Fahrenheit by suitable means
such or by a steam coil. Should the temperature rise too high the oil is cooled by
passing cold water through the coil. After a considerable volume of air (or suitable
volume of oxygen) has been forced through the oil it becomes darker in colour but
the froth becomes less yellow and subsequently the oil becomes paler, shewing that
the yellow colouring matter which was originally present has been destroyed.
The oil can then be drawn off for storage or otherwise.
It will be obvious that the impurities in the oil instead of being separated therefrom
before treatment in our apparatus may be separated therefrom after treatment.
In manufacturing what is known as pale boiled linseed oil or pale linseed oi
varnish or other pale drying oils or oil varnishes, the fatty acids employed must be
those of drying oils.
In some cases we subject the oil to a preliminary treatment with sulphuric acid of
about 129 specific gravity which clears it from mucous and gummy matters which are
separated by subsidence or otherwise.
1000
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in Decolourising Vegetable Oils in the Manufacture
of Pale Drying Oils and Varnishes, and Apparatus therefor.
We, WALTER NOEL HARTLEY, of 36, Waterloo Road, Dublin, in the County of
Dublin, Ireland, Fellow of the Royal Society, Professor of Chemistry in the Royal
College of Science, Dublin, and WILLIAM EDMUND BRANDFORD BLENKINSOP, of
15, Earlsfield Road, Wandsworth Common, in the County of Surrey, Manufacturing
Chemist, 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 :—
Our invention relates to improvements in decolourising vegetable oils and in
the manufacture of pale drying oils and varnishes by a process of oxidation which
removes or destroys the natural colouring matter which vegetable oils contain.
In carrying out our invention we add to the oil to be treated a manganese salt of
a suitable fatty acid or other organic compound of manganese (such as the oleate of
manganese) easily soluble in oil or we add a mixture of the manganese salts of more
than one fatty acid or other suitable organic compounds of manganese. We prefer
to use the manganese salt or salts of the acid or acids naturally contained in the oil to
be treated but this is not essential because we have found that we can use the
manganese salts of the acids contained in other oils. For instance in decolourising
linseed oil we have prepared a soap from cotton seed oil by saponifying it with an
alkali and decomposing the soap with a pure salt of manganese such as the sulphate.
The manganese soap, that is to say, the combination of manganese with the fatty acid
or acids of the oil is very soluble both in oil and in turpentine. We find that it is
convenient to make a solution of one part by weight of the manganese soap in two
parts by weight of turpentine or thereabouts. We add one measure of this solution
to eight hundred ineasures of oil or one measure to four hundred measures of oil or
such other proportion as may prove more suitable for any particular oil, but these 2
proportions we have found to be very effective.
2
The mixture of oil and manganese soap is allowed to stand until the impurities have
separated and these are removed by subsidence or otherwise. The clear oil thus
obtained is then treated in an apparatus which consists of a tank with arrangements
for purifying and for passing air or oxygen through the oil in the said tank. The oil a
is treated at a suitable temperature which need not exceed 212° F. and we generally
maintain it at or about 190° F. by suitable means such as a steain coil. The change
in the colour will take place at ordinary temperatures and it is not necessary to employ
artificial heat, but it is more convenient.
Should the temperature rise too high which it is liable to do the oil can be cooled
by passing cold water through the coil.
The oil becomes darker in colour after a considerable volume of air or suitable volume
of oxygen has been forced through it, but the froth becomes less yellow and
subsequently the oil becomes paler, showing that the yellow or greenish colouring
matter which was originally present has been removed or destroyed. The oil can then 4
be drawn off for storage or otherwise.
It will be obvious that the impurities in the oil instead of being separated therefrom
before treatment in our apparatus may be separated therefrom after treatment but it
is more satisfactory to treat a clear oil.
In order to enable our invention to be more fully understood reference is had to the 4
accompanying drawings, in which-
Figures 1 and 2 are a sectional elevation and a plan respectively of an arrangement
of apparatus adapted for carrying out our process.
Figures 3 and 4 are a vertical and horizontal section of a portion of one of the
vessels or tanks drawn to a larger scale; and,
Figure 5 is a detail of the same.
5

page_text: Figure 6 is a vertical section of a closed tank which we use when pressure is
employed.
a and b are open vessels or tanks provided with loose covers c, e into either of which
tanks the vegetable oil to be decolourised can be introduced for treatment by the
manganese soap, such introduction being effected through pipes c', c from a tank d
by means of a suitable pump such as driven from a rotating shaft ƒ by an
eccentric g and rod h. The pipes c', c¹ are also connected with another open
vessel or tank i hereinafter described and also provided with a loose cover_c.
², care cocks for governing the admission of the oil to the said tanks a, b and i.
a and 6' are cocks on the tanks a and b respectively for ascertaining when the
impurities have separated from the oil, and a and are cocks for drawing off
such impurities, and after that the clear oil which is then introduced again into
the tank d and pumped into the tank i, which latter tank serves to allow of the
air or oxygen being passed through the oil. This is effected by means of a pipe j,
provided at its lower end, which is located at the bottom of the tank i, with
perforated branches, as shewn clearly in Figures 3 and 4, which represent,
respectively, a vertical section and plan of the lower portion of the said tank and
pipe. Figure 5 is a section through one of the branches of the pipe j showing
that the perforations are inclined so as to distribute the air or oxygen through
the oil. The air or oxygen is forced through the pipe by a suitable blowing
engine to which it is connected by the pipe k¹, air-vessel k and pipe ³. The
pipe is provided with a valve to control the supply of air or oxygen to the
tanki and the air-vessel is provided with a relief valve and pressure gauge m.
n is the air or oxygen purifier, which is connected by a pipe n' to the blowing
engine and consists of a chamber having an opening n at its lower end and
provided with a number of trays n³ carrying caustic soda, over which the air or
oxyger. is drawn by the said blower as indicated by the arrows in Figure 1.
o is the coil in the tank through which steam can be passed from a steamn
supply pipe p in order to heat the oil in the said tank, and through which cold water
can also be passed from a cold water supply pipe if the temperature of the oil
rises too high. and q¹ are cocks for controlling the supply of steam and cold
water respectively to the coil o. r is a cock at the bottom of the tank i for
drawing off the oil when treated.
When separating the impurities from the oil after treatment with the air or oxygen
instead of before we first charge the tank with the oil where it can be treated with
the manganese soap as herein before described and we cause such air or oxygen to
pass through it, after which we cause it to pass into either of the tanks a and b
through a pipes and the impurities are then allowed to settle. s¹, s¹ are cocks for
controlling the supply of oil to the said tanks.
The tanks a and b are also provided with coils o', o' connected to the pipes p and q
so as to heat and cool the oil contained therein, if required.
We sometimes treat the oil with air or oxygen at a pressure greater than that of
the atmosphere, in which case the oil is placed in a closed vessel which is provided
with a relief valve for the escape of the excess of air or oxygen and vapours. A
pipe for the passage of the air or oxygen and a coil are used as in the open tank i.
This vessel is illustrated in vertical section in Figure 6, j being the air or oxygen
pipe, which is provided with a pressure-gauge m and back pressure valve m³, 1 the
relief valve, o the coil, c¹ the inlet, and r, r' cocks for drawing off and sampling
the oil.
Instead of pumping air through the oil we have sometimes made use of an
exhausting apparatus by which air is drawn through a closed vessel containing the
oil. This may be accomplished with an apparatus similar to that shewn at Figure 6,
if a Korting's steam-jet exhauster be attached at e³ and the air-pipe j be disconnected
from the pumps at the joints near m.
In manufacturing what is known as "boiled oil" "boiled linseed oil" pale linseed
oil varnish or other pale drying oils or varnishes, the manganese salt or salts should

page_text: be prepared from drying oils. We employ by preference manganese linoleate, that is
to say, the manganese soap prepared from the fatty acids in linseed oil. The
manganese linoleate is dissolved in oil or in turpentine or other suitable solvent in
the proportion of one part by weight of manganese linoleate to two parts by weight
of turpentine. We add the solution of manganese linoleate to the oil in the
proportion of one measure to eight hundred measures of the oil, or in such other
proportions as the nature of the oil to be produced may render desirable. A
larger proportion of linoleate solution produces an oil which dries more rapidly but
when the proportion is increased beyond two measures of the solution to one
hundred measures of the oil a very pale colour is more difficult to obtain.
Oil which contains much mucilage and water is advantageously mixed and agitated
with dilute sulphuric acid of about 1-29 specific gravity at 60° F. or acid even more
dilute than this in about the proportion of one measure of the dilute acid to one
hundred measures of oil. The mucilage along with the acid may be separated from
the oil by subsidence or otherwise after which the manganese soap dissolved in
turpentine may be added. We attach considerable importance to the strength of the
acid to be used for the purpose because an acid which is a little too strong for
instance of specific gravity 15 causes the oil to become slightly coloured, the
colour so produced not being so easily removed as the natural colouring matter of
the oil.
Or if it is undesirable that any acid substance be added to the oil, we remove the
mucilage by mixing and agitating the oil with a strong solution of pure manganese
sulphate in the proportion of about one measure to one hundred measures of
the oil.
The solution may be as strong as it is convenient to make it because there is no
risk of the oil being discoloured thereby.
Instead of proceeding in the manner we have described in order to decolourise
vegetable oils or to produce drying oils and "boiled oil" or varnishes it
is obvious that we might add to the bulk of the oil to be treated the requisite
quantity of alkali to saponify the proper proportion of the oil at a com-
paratively low temperature, say at 212° F. and convert the alkaline soap by the
addition of manganese sulphate into a manganese soap which would be capable of
converting the oil into a drying oil when air was blown through it, but we do not
recommend such a proceeding because the oil so produced is not so pale nor
invariably of such good quality.
In treating linseed oil for the preparation of a pale drying oil or oil varnish, we
decolourise the oil and convert it into a drying oil at one operation; but we may
first decolourise it by our process and convert it into a drying oil by adding a siccative
material afterwards.
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. The process for decolourising vegetable oils by the joint action of air or oxygen
and a manganese soap or other organic compound of manganese (such as the oleate
of manganese) easily soluble in oil prepared in or dissolved in the oil to be treated
or dissolved in oil or in turpentine or other suitable solvent and added to the
oil to be treated, substantially as described.
2. The process for producing a superior boiled linseed oil or varnish and other
drying oils or varnishes of a superior quality by the treatment of the oil with an
easily soluble manganese soap prepared from a drying oil and a current of air
or suitable supply of oxygen with or without the action of heat, substantially as
described.
3. The purification of linseed oil and other oils from mucilage by agitation with
dilute sulphuric acid with acidified solutions of manganese sulphate or a pure neutral
solution of manganese sulphate, substantially as described.

page_text: 4. The use in carrying out our invention of the combination of parts forming
the apparatus hereinbefore described and illustrated in the accompanying drawings.
Dated the 4th day of December 1890.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.