IMPROVEMENTS IN THE TREATMENT OF BITUMINOUS SHALES AND THE USE OF THE RESULTING PRODUCT IN CERTAIN MANUFACTURES
Year: 1880

page_text: LETTERS PATENT to William Ayrton, of Ormskirk, in the County of Lancaster,
"
Manufacturer, for an Invention of IMPROVEMENTS IN THE TREATMENT OF
BITUMINOUS SHALES AND THE USE OF THE RESULTING PRODUCT IN CERTAIN
MANUFACTURES."
PROVISIONAL SPECIFICATION left by the said William Ayrton at the
Office of the Commissioners of Patents on the 3rd September 1880.
WILLIAM AYRTON, of Ormskirk, in the County of Lancaster, Manufacturer.
IMPROVEMENTS IN THE TREATMENT OF BITUMINOUS SHALES AND THE USE OF
THE RESULTING PRODUCT IN CERTAIN MANUFACTURES."
My Invention consists, first, in separating and removing the oily and colouring
matters from bituminous shales, and thus obtaining a material capable of use for
purposes for which the material known as china clay is used.
According to this part of my Invention I grind the said shales in water by
means of a suitable machine, such as a mortar mill, until the whole is brought to
about the consistency of stiff paste. I then remove the ground shale from the
mortar mill and throw it into a pug mill, into which a stream of water is allowed
to flow. By the action of the pug mill the ground shale is thoroughly mixed with
and diluted with water, and the mixture as it flows from the said mill is directed.
into the first of a series of vats or tanks, and thence into the other vats or tanks of
the series, in which vats or tanks the constituents of the ground shale are deposited
according to their specific gravity, the heavier constituents and coarser particles
being deposited in the first or second of the series of tanks, and the lighter
constituents and finer particles being carried over to the other tanks, the oily
matter passing off with the supernatant water flowing from the last tank or vat.
The precipitate obtained in the second or third and following tanks is silicate of
alumina, sufficiently pure for use in the various manufactures in which china clay
is used. In some cases I add a little alkali to the water in which I grind the
shale.
I do not limit myself to the apparatus hereinbefore described, the essence of this
part of my Invention consisting in separating the oily and colouring matters from
the silicate of alumina contained in bituminous shales by levigating them and
washing the product.
My Invention consists further in the use of the silicate of alumina, obtained as
herein before described, as a substitute for the whiting or china clay ordinarily used
as an ingredient of the composition used in the manufacture of japanned table
baize, American leather cloth, and in analogous manufactures.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Ayrton in the Great Seal Patent Office on the 28th
February 1881.
WILLIAM AYRTON, of Ormskirk, in the County of Lancaster, Manufacturer.
"IMPROVEMENTS IN THE TREATMENT OF BITUMINOUS SHALES AND THE USE OF
THE RESULTING PRODUCT IN CERTAIN MANUFACTURES.'
"
My Invention consists, first, in separating and removing the oily and colouring
matters and free silica from the silicate of alumina contained in bituminous shales,
and thus obtaining a material capable of use for purposes for which the material
known as china clay is used.
The shales which I select for treatment are those which contain not more than .
five or six per cent. of carbonaceous matter, and are of a pale slate colour and free
from iron pyrites.
According to this part of my Invention I grind the said shales in water by means
of a suitable machine, such as a mortar mill, until the whole is brought to about
the consistency of stiff paste. I then remove the ground shale from the mortar
mill and throw it into a pug mill, into which a stream of water is allowed
to flow.
It is important that the shales be thoroughly ground before being put into the
pug mill.
The grinding may be facilitated by sprinkling water over the shales as
they lie in a heap a day or two before putting them into the mill. If the ordinary
mortar mill does not grind them sufficiently fine they must be afterwards passed
through a grinding mill. The ordinary horizontal mill stones of French burr,
such as are used for grinding flour, chocolate, and paint, are the most suitable.
In order to prevent the too rapid precipitation of the constituents of the ground
shales it is necessary that the water flowing into the pug mill be slightly alkaline.
By the action of the pugmill the ground shale is thoroughly mixed with and
diluted with water, and the mixture as it flows from the said mill is directed into
the first of a series of vats or tanks, and thence into the other vats or tanks of the
series, in which vats or tanks the constituents of the ground shale are deposited
according to their specific gravity.
The pug mill should be arranged to run at such a speed, and the stream of water
should be caused to flow through it at such a velocity, that only the properly
ground particles and lighter constituents of the shales will pass from the said mill.
The precipitate required will then be found in the first vat, which precipitate is
nearly pure silicate of alumina. If the pug mill be run at such a speed as to cause
a violent agitation of the water, and the stream of water be allowed to flow too
quickly, the heavier constituents of the shales and the coarser particles will be
carried over to the first vats or tanks, and the silicate of alumina will not be
deposited in a state sufficiently pure for use in the manufacture of the composition
bereinafter referred to. The oily matters pass off with the supernatant water flowing
from the last vat or tank.
In carrying out the manufacture on a large scale one large reservoir may be
constructed in the earth, and the speed of the pug mill and of the stream of water
may be so regulated that all the particles required to be preserved will pass into
and be retained in the said reservoir, the lighter constituents flowing away and the
heavier constituents remaining in the pug mill. By having two or more of these
reservoirs so arranged that they may be worked alternately or in succession, the
processes of grinding and precipitating may be carried on continuously, one of the
said tanks being emptied while the other or others is or are being filled.
The silicate of alumina obtained by the process hereinbefore described is
sufficiently pure for use in many manufactures in which china clay is now used.

page_text: In cases where the small quantities of lime and iron with which the said silicate.
of alumina is contaminated would be objectionable, they may be removed by adding
to it muriatic acid and again washing it.
I do not limit myself to the use of the apparatus hereinbefore described, as any
other apparatus by which the same result will be obtained may be used; but I
claim in respect of this part of my said Invention, the process, hereinbefore
described, for obtaining silicate of alumina from bituminous shales, that is to say,
grinding the said shales and levigating the ground shales, thus obtaining the
silicate of alumina in a state sufficiently pure for use as a substitute for china
clay in many of the manufactures in which china clay is ordinarily used.
My Invention consists further in the use of the silicate of alumina, obtained as
hereinbefore described, as a substitute for the whiting or china clay ordinarily used
as an ingredient of the composition used in the manufacture of japanned table
baize, American leather cloth, and in analogous manufactures.
I claim in respect of this part of my Invention, using silicate of alumina
obtained from bituminous shales as a substitute for whiting or china clay in the
manufacture of japanned table baize and in analogous manufactures.
In witness whereof, I, the said William Ayrton, have hereunto set my hand
and seal, this Twenty-fifth day of February, in the year of our Lord One
thousand eight hundred and eighty one.
W
1773
AYRTON. (L.S.)