Improvements in the Methods and Apparatus for Drying Cement Slurry and the Subsequent Cooling of the Burnt Cement.
Year: 1887

page_text: Date of Application, 5th Aug., 1887
Complete Left, 7th May, 1888
Complete Accepted, 8th June, 1888
Improvements in the Methods and Apparatus for Drying Cement
Slurry and the Subsequent Cooling of the Burnt Cement.
I, FREDERICK WILFRID SCOTT STOKES of 13 Holland Street Kensington London
Civil Engineer do hereby declare the nature of this invention to be as follows:-
In the Specification of my previous Patent No. 7888 dated June 12th 1886, which
I will call my first Patent" I described certain methods for burning cement in a
powdered state, and also for preparing the cement materials previous to burning.
Also in the Specification of the Patent for which application was made by me on
11th July 1887 and is numbered 9694, which I will call my second invention,"
I described certain methods for burning cement material in a revolving or other
suitable Furnace, and also certain modifications in the preparation of the cement
materials from "my first Patent."
*
The object of my present invention is to dry the plastic slurry by forcing it in thin
sheets or strips, according to my first & second inventions, onto a revolving table,
or annular ring, contained in a circular flue or chamber, so arranged that that the
waste heat from the products of combustion used in the other parts of my process
pass along it and are used to the best advantage in drying the slurry.
The table or annular ring is so contrived that the sheets or strips of slurry fall onto
its surface where they remain exposed to the heated gasses until dry, when they are
removed by a scraper, as the table revolves.
The table is mounted on rollers or on a live ring formed of balls or rollers, and is
driven by a chain drum, rack, or other contrivance.
The rotary motion being in the opposite direction to that of the heated gasses.
The dry material on being removed is ready either for pulverizing and burning as
set forth in my first invention, or for being fed direct into the furnace and treated
as set forth in my second Invention.
The object of my present invention is also to provide means for automatically
removing the cement powder from the regenerative & settling chambers used in my
first invention.

page_text: For this purpose the settling chambers are of circular or annular form, provided
with a revolving table or annular ring and scraper similar to that just described for
drying slurry.
The Cement powder on falling onto the surface is thus continuously removed
by the scraper and fed by a worm or conveyor to a suitable place for handling.
My present invention also relates to a revolving table or annular ring contained in
a circular flue or chamber, contrived similarly to that described for drying slurry, and
arranged so that the burnt cement issuing from the furnace as described in my second
invention falls on its surface, where it is cooled by currents of air passing on their
way to the point of ignition in the furnace by which means the air becomes heated
in order to obtain the requisite high temperature for burning the cement.
The cool cement is removed from the table by a scraper & fed into a suitable
elevator or conveyor to be led away to be ground in the usual manner.
Dated this the 4th day of August 1887.

page_text: Slurry and the Subsequent Cooling of the Burnt Cement.
I, FREDERICK WILFRID SCOTT STOKES, of 13 Holland Street, Kensington, in the
County of Middlesex, Civil Engineer, do hereby declare the nature of the said inven-
tion and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement:-
My invention relates to apparatus for drying cement-slurry, for treating burnt
cement as hereinafter described, and for similar purposes.
An important feature of my said invention is the employment of a revolving or
travelling table or platform arranged within a circular or annular flue or chamber
through which is passed air or products of combustion or other heating, drying or
cooling agent, for the purpose of heating or drying slurry or other substances, or for
abstracting heat from burnt cement, or for similar purposes.
In the Specification of former Letters Patent dated respectively 12th June A.D.
1886 No. 7888, and 11th July A.D. 1887 No. 9694, I have described different
methods or processes of manufacturing cement.
The main object of my present invention is to provide for drying plastic slurry
(produced as described in the said former Specifications or by any other suitable
process) in the form of thin sheets, sticks or strips by means of the products of com-
bustion from other parts or stages of the manufacture of the cement, or by heated
air or other available heating medium.
Another object of my present invention is to provide for automatically removing
the cement-powder from a regenerative or settling chamber, such as is referred to in
the said former Specification No. 7888.
My said invention is further designed to provide for cooling burnt cement, as it
comes from the furnace.
When the said revolving or travelling table is used for drying plastic slurry, the
said slurry is delivered upon the said table in the form of sheets, blocks sticks or
strips, which remain exposed to the heated air or gases until dry, when they are
removed by a scraper, as the said table revolves. The dry slurry on being removed
is ready for pulverizing and burning, or for being fed directly into a furnace. I am
thus enabled to manufacture cement with materials containing
a much smaller per-
centage of water than is usually employed and with much greater speed and economy
than heretofore.
In the accompanying drawings I have shown how my said invention can be
conveniently and advantageously carried into practice.
Figure 1 is a vertical longitudinal central section showing one form of my
apparatus.
Figure 2 is a plan of the same, the pug-mill hereinafter referred to being
removed.

page_text: Figure 3 is a plan, partly in section, and
Figure 4 a transverse section, showing a modification of my said invention.
Figure 5 is a sectional side elevation showing details of construction hereinafter
described.
Like letters indicate corresponding parts throughout the drawings.
The drying of the plastic slurry is preferably effected, according to my present
invention, in the following manner, viz.:-The cement materials are crushed or ground
in any suitable mill or machine and are fed into a pug-mill I, the shaft J of which is
fitted with helical blades K and with a worm L. The bottom I of this pug-mill I is
perforated, so that the slurry will be discharged therefrom in the form of thin sheets,
strips, or sticks.
M is a circular flue or chamber in which is arranged a revolving or travelling
table V supported upon a live ring of balls V₁, or it can be mounted on rollers or
wheels adapted to run upon a suitable track. The said table is driven through the
medium of a chain V* resting upon angle irons V2, by means of suitable gearing at V³.
The top or crown of the flue M is preferably provided with a layer of sand M* which
retains the heat therein and which can be readily removed when necessary. An
elevator W is, moreover, provided for removing the dried slurry. The heated products
of combustion from other parts or stages of the manufacture of the cement or from a
separate furnace are conducted to the circular flue M through a flue or passage M'
and are carried away to the chimney-stack through the flue or passage M². V is a
scraper for removing the dried slurry from the travelling table V and delivering the
same to the elevator W.
The operation of the apparatus is as follows, that is to say, the cement materials
are delivered from the crushing or grinding mill to the pug-mill I, where they are
further worked to form the slurry, which is, by the action of the helical blades and
worm in the said pug-mill, forced, in the form of thin sheets, sticks or strips, through
the holes or apertures in the bottom I'. The said sheets or strips fall upon the
revolving or travelling table V, being preferably cut into lengths by a suitable knife
or cutter provided for the purpose. The sheets, sticks or strips of slurry are dried by
the said heated products of combustion passing through the circular flue M. The
table V is preferably caused to travel in the reverse direction to that in which the
products of combustion pass through the flue, so that the sheets or strips of slurry will
be exposed to a gradually increasing temperature. The dried slurry is removed from
the revolving or travelling table V by the scraper V4, and is taken away by the
elevator W.
Figures 3, 4, and 5 show a modification of my invention wherein the slurry
previously prepared by the ordinary "semi-dry" process, is delivered to the revolving
or travelling table V from a slurry tank, through a pipe X. The lower extremity of
the said pipe X is provided with a nozzle X which is spread out or flattened and
provided with a regulating plate X2 so that it will deliver the slurry evenly over the
revolving or travelling table V. A rake is hinged or pivoted in bearings Y₁
in the circular flue M so that the teeth of the said rake will divide the slurry
upon the said revolving or travelling table V into ridges or strips. The rake Y is
provided with an arm Z and counterweight Z to maintain the requisite pressure of
the said rake upon the slurry and at the same time allow any necessary play. The
slurry is dried by the products of combustion from other parts of the process, or
from other available source, passing through the flue M in the reverse direction to
the travelling table V, as hereinbefore described.
To prevent the formation of a cold current of air immediately above the travelling
or revolving table V by reason of the absorption of the heat froin the products of
combustion in drying the slurry, I provide inclined baffle-plates, or deflector plates M³,
which break up the hot air passing through the flue M or mix it with the cooler air.
A baffle-plate M is, moreover, provided to maintain the draught in the flue.
The dried slurry is removed from the travelling table by a scraper Vand
delivered to an elevator as hereinbefore described.
'
In the said former Specification No. 7888, I have referred to regenerative' and

page_text: settling chambers wherein the cement dust is allowed to deposit upon the floor and is.
removed by hand through openings in the side walls. I now provide for removing
the cement-powder from a settling chamber by mechanical devices. For this purpose
I make the said chamber of circular or annular form and provide it with a revolving
or travelling table and a stationary scraper substantially as bereinbefore described.
The cement powder falling on the surface of the said table is carried around thereby
and is continuously removed therefrom by the scraper, and is fed by a worm or
conveyor to a suitable place for handling.
I also adapt my present invention to the cooling of burnt cement as it comes from
the furnace. For this purpose, I arrange a revolving or travelling table in a circular
flue or chamber substantially as hereinbefore described with reference to Figures 3, 4,
and 5, and I provide means whereby the burnt cement issuing from the furnace will
be delivered upon the surface of the said table, where it is cooled by currents of air
passing through the said circular flue or chamber. The air thus heated is preferably
conducted into the furnace to promote the combustion therein. By this means the air
may be sufficiently heated to ensure the requisite high temperature in the furnace for
burning the cement.
The cooled cement is removed from the table by a scraper such as is hereinbefore
described, and is fed into a suitable elevator or conveyor to be conducted away for
grinding in the usual manner.
It is obvious that I can somewhat further modify my apparatus without departing
from the nature of my said invention. For instance the pug-mill may be horizontal,
terminating in a chamber having holes of suitable size arranged so as to deposit the
strips onto the table in proper layers. Moreover I can construct the travelling or
revolving table V with several trays or shelves placed one above another. In this
case I prefer to place the pug-mill in a horizontal position. The scraper for removing
the slurry or cement may be caused to revolve or otherwise move to effect the removal
of the slurry. The table may be made to revolve in the same direction as the products
of combustion. The slurry may be dried in lumps or bricks suitable for burning in an
ordinary kiln. A combined table comprising two or more trays or shelves one above
the other may be used for cooling the hot cement or clinker and simultaneously drying
the slurry.
I can, if desired, substitute for the annular table shown in the drawings a series of
trucks which may enter and leave the flue or chamber through apertures in the side
thereof.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I wish it understood that
I claim :-
First. An apparatus comprising a table or platform arranged to revolve or travel in
a circular or annular flue or chamber provided with inlet and outlet apertures for air
or products of combustion or other heating, drying or cooling medium, for the
purposes above specified.
Second. An apparatus for drying slurry, wherein provision is made for delivering
the plastic slurry in the form of thin sheets, sticks, strips or blocks upon a table or
platform arranged to revolve or travel in one direction in a circular or annular flue or
chamber through which heated air or products of combustion are caused to pass in the
reverse direction, and for removing the dried slurry from the said table during the
movement of the same, substantially as described.
Third. The combination, with the circular or annular flue or chamber and the
revolving or travelling table or platform, of means for delivering liquid or semi-liquid
slurry upon the said table and for dividing the said slurry into ridges or strips, and
means for removing the dried slurry from the said table, substantially as, and for the
purpose, set forth.
Fourth. The combination, with a furnace for burning cement in the form of powder,
of a circular or annular settling chamber having arranged therein a revolving or

page_text: travelling table or platform and a scraper, substantially as, and for the purpose, set
forth:
Fifth. The combination, with a-furnace for burning cement, of a circular or annular
flue or chamber, a revolving or travelling table or platform therein upon which the
burnt cement from the furnace will be delivered, and means for removing the cement
from the said table or platform, substantially as, and for the purpose, set forth.
Sixth. The modification of my invention wherein 1 provide for simultaneously
cooling burnt cement and drying slurry, substantially as described.
Seventh. The improved apparatus comprising the annular flue or chamber, the
revolving annular table or platform mounted on rollers, balls or wheels, and the.
scraper, all constructed and combined substantially as described with reference to
either of the forms or modifications shown in the accompanying drawings, and
operating as, and for the purposes, above specified.
Dated this 5th day of May, 1888.
F. W. S. STOKES.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C.,.
Agents for the Applicant..