Improvements in the Manufacture of Fatty Matter from Certain Animal Tissues.
Year: 1896

page_text: Date of Application, 12th Nov., 1893-Accepted, 23rd Jan., 1897
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Fatty Matter from Certain
Animal Tissues.
I, JAMES DAVIDSON, of George Street, Sydney, in the Colony of New South
Wales, Grain Merchant, 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 consists of an improved manufacture of fatty matter from suet
and other fatty tissues of sheep, cattle and swine.
In known processes of manufacture of tallow and lard from the substances
named, there is no provision for extracting from the fats the "soup " and other
impurities which are found intermixed with them when they are drawn from the
digester. Separate after-treatment of the product by washing and re-washing it
in water and floating off the fats is sometimes resorted to with the object of effecting
purification. The presence of soup and impurities causes the fats to become rancid,
and they decompose and produce gases which often burst the casks in which the
fats are packed. They make the fats more or less coarse, injure their color, and
depreciate their market value. Some fat is left in the soup, which is usually run
to waste. As the process is deficient in these respects, expert labour must be.
employed to obtain high grade products and to minimise waste.
The object of my invention is to improve the manufacture of these fats in such
a way as to obviate the necessity of employing skilled labour to obtain a maximum
of fat, and to extract the fat readily and economically and free from mechanically
separable impurities.
The fats produced by the operations hereinafter described are homogeneous,
bright in color, and of a high degree of purity.
In the carrying out of my invention, either of two methods, identical in main
principle, is adopted. In one, a digester is used; in the other, the tissues are not
boiled, but rendered in a basket-centrifugal machine.
According to the first method, the modus operandi is as follows:-
Fatty tissues of cattle, sheep or swine, are digested under a steam pressure of
30 to 100 lbs. per square inch for a period of three to six hours (a longer time
being sometimes employed in treating swine) until the cellular tissue has been
broken up and the fat liberated. As the pressure is increased, a shorter time is
required to effect the boiling. Whilst pressure is still on the digester, the soup
and fat in a liquid state are blown out to be separated and treated. The whole of
the soup (which will be blown out first when the digester is discharged through
the bottom) may be sent through a basket-centrifugal and a centrifugal separator
to ensure the abstraction of all the fat; or the bulk of the soup may be run off
into tanks or evaporators and treated for the extraction of the gelatine and other
valuable contents, if that operation should result profitably; if not, it is run to
waste. The last portions of the soup must not be blown out of the digester at
this stage. They must be removed with the fat,, which floats on the surface of the
soup, and sent through the basket-centrifugal and the separator, and the whole
mass washed, steamed, strained and separated..
It is now customary to completely boil out the contents of the digesters used in
rendering operations before blowing them down; but I prefer to blow them
down during the progress of the boiling. To this end, separate steam-supply

page_text: and blow-down services are provided, and both are kept open continuously
during the process of boiling, the valves being adjusted so as to allow some liquid
to remain always in the bottom of the digester to check the outflow of live steam.
The stream of soups and fats discharged through the blow-down service is led
into the basket-centrifugal and its products to a centrifugal separator. Thus the
fats (as well as the soup) are drawn off as quickly as they are formed, and they
are refined and separated whilst the boiling is progressing, whereby time is
economised as well as labour; for immediately one boiling is finished, the digester
inay be recharged and the whole plant again put in action, and one man can
conveniently attend to the digester, the basket-centrifugal, and the separator at
one time. This method of operation also offers the very substantial advantages
of giving a direct indication of the progress of the rendering, of removing the
fats immediately they are rendered, so protecting them from the danger of
scorching and saving them from being unnecessarily re-boiled, and of leaving a
minimum of fat held by or mixed with the digested tissues, which, not being
immersed, as is now the case, readily drain themselves of almost all the fatty
substances which are rendered out by heat and do not act as a bed in which
said fats are caught, and to a great extent held, when the digesters are blown
down as at present. When the separator ceases to discharge fat, the boiling
need not be continued longer. Steam is then cut off fron the digester, which is
immediately discharged and recharged; the basket-centrifugal and the separator
being meantime cleaned if necessary. The solid product of the boiling which is
removed from the digester is dried in another basket-centrifugal, by which
melted fat and liquid matter is extracted from the bones, meat, fibre, etc. The
liquid products are sent to the basket-centrifugal in which the liquid products of
the boiling are treated, and the solid products are manufactured in any known
way, or are sent to waste. The basket-centrifugals are lined with close-grained
fabric, such as moleskin, which will retain any suspended solid matters and pass.
liquids. The machines in which the liquid products of the boiling are treated
are provided with hot water and steam services, by which hot water or steun
under pressure may be blown into the basket and upon its periphery. In
practice, the basket is speeded up and the hot water and steam services put in
action before the liquid to be treated is blown in. Hot water or steam alone
may be used or both alternately. When the other method is adopted, i.e.,
finishing the boiling of the digester before blowing it down, the first product
which will pass into the basket will be soup, next a more or less mixed liquid.
consisting chiefly of soup and fat, and, finally a product consisting almost
entirely of fat. The soup, which contains very little fat, practically all passes
through the outer spout of the separator, to which machine it is sent from the
basket-centrifugal. After the middle product has been disposed of, the separator
receives fats with impurities from the basket-centrifugal wherein the fats are
thoroughly hot washed by hot water or steam or both. The fats pass froin the
separator in a pure, bright and nearly odorless, state into a trough or spout in
which cooling takes place. This trough or spout may be provided with a water
jacket to expedite cooling, and it is provided with gates through which the semi-
cooled fat may be allowed to flow into barrels or other receptacles. The extracted
wash liquor and suspended impurities are run to waste or for further treatment,
as before explained, through the outer spout of the separator. It will usually be
found that fat will not remain sufficiently fluid to flow freely in the separator.
When this is the case, the bowl of the centrifugal should be kept sufficiently warm
by means of steam blown upon it.
According to the alternative method of carrying out my invention, I obtain
fats of similarly high quality from suets or from tissues consisting chiefly of suets,
without a digester. I use this modification also in the re-treatment of rancid,
discolored and low-grade fats-bad tallow for instance-to clarify and sweeten
them, and to effect an improvement in their colour and quality generally.
According to this part of the invention, suet or suety tissue minced, or fats

page_text: more or less foul or impure, are placed in the fabric-lined basket-centrifugal
before mentioned, and the hot water and steam services put in action. The fats
are speedily rendered, and the liquid fats are at the same time washed and
strained, as already described, and are finally extracted in the separator. In
dealing with extracted fats, such as bad tallow, an open basket may be used;
but when substances, such as suet, are required to be actually rendered, the
process will be quickened and rendered more effective by closing the basket in
order to keep the temperature within it as bigh as possible. Speedy loading
and unloading may be facilitated by providing convenient appliances for removing,
replacing and fastening the cover, and also by providing a botton discharge and
hoppers, spouts and shutes where necessary.
Very considerable difficulties present themselves in the attempt to apply the
separator to the extraction of fats from fatty fluids of the kind herein set forth;
and although a certain limited success is obtainable, practical results and economy
are not obtained unless the machines are adapted to the new use by certain
manipulations. Periodically, even when the basket-centrifugal is used, cheesy or
slimy substances of bad color form in the bowl of the separator. In time these
would become so large as to interfere with the action of the machine; but before
this occurs, the bowl must be opened and they must be removed. These matters
sometimes contain some fat, which may be extracted by re-melting them, and
treating the product in the basket-centrifugal and the separator successively, as
already described.
Referring to the annexed explanatory drawings, Fig. 1 represents in elevation
and part section an arrangement of apparatus adapted for carrying out the invention
in its first form; whilst Fig. 2 is a similar view illustrative of the alternative
method. In the foriner, 1 is a digester of the usual form, 2 steam-pipe to digester
from boiler, 3 blow-down pipe leading from digester to basket-centrifugal 4, 5 pipe
from monitor of 4 to separator 6, 7 steam-pipe, 8 cooling trough for finished
fats, 9 gates therein, 10 barrels, 11 "soup spout of centrifugal, 12 perforated
pipes dipping into the basket 13 of the centrifugal 4, 14 main pipe thereto
connected to a source of hot water or steam under pressure, either of which can
be turned on at will, 15 is a fabric lining, it lies against the perforated wall of the
basket. When desired, pipes 12" similar to 12 may be fitted outside the basket 13
and serve to direct jets of hot water or steam against the periphery of the basket.
The area of surface required for effective work in the basket-centrifugal-the
construction of which may be identical with that of the usual types of hydro-
extractors will depend on the nature of the material used for lining it, and upon
the temperature of the substances passing through it. When moleskin is used
and the temperature approximates the boiling point, a basket about 30 inches in
diameter is necessary to pass about 400 gallons of liquids per hour to the best
advantage. If canvas be used in place of moleskin, a greater quantity will be
passed, but the degree of purification will be inferior.
The separator may be of the ordinary creamer type. A machine of large
capacity should be used, as much difficulty is experienced with small machines,
owing to the necessity of cleaning them often and to the difficulty of that operation
due to the clogging of the passages with the cheesy or slimy by-product before
mentioned.
Referring to Fig. 2 of the drawings, 16 is the basket-centrifugal. The basket
is closed, and through a central aperture ou the cover 17 passes a pipe 18,
similar to the pipes 12. Through this pipe 18 steam or hot water at will may be
directed into the rendering mass, which is heaped against the walls of the
basket. Another steam and hot water service 19, for operating on the exterior
of the basket, is connected through an opening in the monitor of the machine.
The liquid product of this treatment, consisting chiefly of fats and soup, passes
into the tank 20, in which there is a steam coil 21 to maintain the temperature.
22 is a steam ejector, by means of which the liquid in the tank 20 is raised to the
funnel 23 of the separator 24. The separator, as in the arrangement previously

page_text: described, extracts the fats from the soup and foreign matters; the former passing
through the trough 25 to the barrels 26, and the latter passing to waste, or for
further treatment through the spout 27.
To expedite the cooling of the fats in the barrels or other receptacles, an air-
pressure service may be provided. This consists of a suitable pump, delivering
air under pressure into a main over the trough 25, and a number of metal pipes
connected to the main by pieces of flexible hose. These pipes are hung so as to
direct blasts of air into the barrels whilst the melted fats are being run into them.
Very soon after the barrels are full, their contents will have become sufficiently
solid to allow of their being moved about.
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. An improved manufacture of fatty matter from fatty tissues of sheep, cattle
or swine, consisting essentially in the hot washing and straining of the liquids
obtained by boiling said tissues, and the treatment of the washed strained product
in a centrifugal separator, substantially as herein described.
2. An improved manufacture of fatty matters from fats of sheep, cattle or
swine, consisting essentially in the centrifugal separation of the fats from the non-
fatty portions of the liquid obtained by hot washing and straining crude rendered
fats, substantially as described.
3. An improved manufacture of fatty matter from fatty tissues of sheep, cattle
or swine, consisting in treating the crude fatty products, which are obtained by
boiling said tissues, with hot water and steam and straining them in a basket-
centrifugal, and treating the fats obtained from the product in a centrifugal
separator, substantially as described.
4. An improved manufacture of fatty matter from suet or impure rendered fats
of sheep, cattle or swine, consisting in the treatment of the same with hot water
and steam in a basket-centrifugal, and the further treatment of the product in a
centrifugal separator, substantially as herein described.
5. An improved manufacture of fatty matter from fatty tissues of sheep, cattle
or swine, consisting in boiling down said tissues, withdrawing from the digester
the liquid products of such boiling continuously as they are formed during the
boiling operation, and treating said liquid products in a centrifugal separator after
hot washing and straining them, substantially as described.
Dated this 12th day of November 1000
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Chartered Patent Agent.