Improvements relating to the Bleaching of Fats and Oils.
Year: 1886

page_text: Improvements relating to the Bleaching of Fats and Oils.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, 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 :—
This invention relates to the bleaching of fats and oils and comprises the
improved process hereinafter described.
In practising my invention I take a given quantity of fat or oil, at normal
temperature, or very slightly heated, which is placed in a suitable tank or vessel,
and I add to it from four to six parts, by weight, of fullers' earth, which is first
finely pulverized. This earth is intimately mixed with the fat or oil in the vessel'
or tank by mechanical agitation, the mixing process being continued for a reasonable
time, according to the quantity treated, and the nature of the oil or fat. For
ordinary purposes, I have found that an hour is generally sufficient. The product
is then allowed to stand, and the fullers' earth settles to the bottom. This generally
requires from 2 to 8 hours, but it varies according to the conditions of the mixture,
and a greater or less time may be employed for this purpose. This will leave a
clear or bleached product which is then drawn off from the tank. The residuum is
then pumped into a filter, preferably a Johnson" filter, and is submitted therein
to air pressure, by which a portion of the fat or oil held by the earth is extracted.
After this, the residuum is further treated to live steam under pressure of from
twenty to thirty pounds to the square inch, and the remainder of the oil extracted
from the earth.
"
One of the essential features of the method of bleaching fats and oils is that it
is done without heating the fat or oil to a temperature which shall impart to the
product a rank flavour, or a flavour taken from the bleaching clay or earth.
Heretofore it has been customary in bleaching fats and oils to first heat the fat or
oil to a temperature exceeding two hundred degrees before the bleaching earth is
applied. I have ascertained that the rank or clayey flavour of the bleached oils
or fats is due almost entirely to this fact, and to the treatment of the fat or oil
while thus heated with the bleaching powder or earth. I have further ascertained
[Price 4d1

page_text: that it is possible to bleach the fats or oils without first heating them to this
temperature, and that the product obtained by the treatment at a comparatively
low temperature is much superior to that obtained by the hot treatment, both in
flavour and colour.
It is not necessary in practising the invention that the fat or oil be treated at a
merely normal temperature, that is, the temperature of the room in which the
process is practiced, as it is possible to slightly warm or heat fats or oils and still
obtain the desirable results above referred to. But fats or oils should not be
heated to a temperature sufficient to cause the rank or clayey flavour above
mentioned.
The oil filtered by air pressure is of a quality sufficiently good, as a rule, to be
mixed with the first product, or the clear oil drawn from the tank.
I would state that I may vary the proportion of fullers earth to the oil or fat
with which it is used, using more or less than the proportion above given if desired.
Also that I may use as a substitute any equivalent bleaching earth or material.
I would say further that this process is especially applicable in the bleaching of
cotton-seed oil, and also for the bleaching of petroleum and other mineral oils.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is :-
First. The process of bleaching fats and oils at low temperature, consisting in
treating the fat or oil at ordinary atmospheric temperature, or at a comparatively
low temperature, with pulverized fullers earth or other bleaching composition,
intimately mixing or mingling the same together by mechanical agitation, then
allowing the mixture to stand and the bleaching earth or material to settle, and
then removing the clear product from the settling tank, substantially as set forth.
Second. The process of bleaching fats or oils, consisting in intimately mixing
finely powdered fullers earth or other bleaching material therewith at a com-
paratively low temperature, then allowing the mixture to stand and the bleaching
earth or material to settle, then drawing the fat or oil from the settling vessel or
tank and filtering the residuum by first submitting it, in suitable filters, to air
pressure, and then to the pressure of live steam at boiler pressure, all substantially
as described.
Third. In the process of bleaching fats or oils, the treatment of the fat or oil at
ordinary atmospheric temperature with pulverized fullers earth or other bleaching
agent, substantially as described.
HASELTINE, LAKE & Co.,
Agents for the Applicant.