IMPROVEMENTS IN THE MODE AND MEANS OR APPARATUS FOR TREATING SLURRY OR SLIP IN THE MANUFACTURE OF PORTLAND CEMENT AND BRICKS
Year: 1885

page_text: I, HENRY FAIJA, of 4, Great Queen Street Westminster, in the County of
Middlesex, Civil Engineer, do hereby declare the nature of my invention for
"IMPROVEMENTS IN THE MODE AND MEANS OR APPARATUS FOR TREATING SLURRY
OR SLIP IN THE MANUFACTURE OF PORTLAND CEMENT AND BRICKS," and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:-
As is well known Portland cement is made by three processes which are generally
known as the dry, the wet, and the semi-wet process: the dry is adopted when the
materials have to be ground in order to effect their mechanical admixture; the wet
and semi-wet when the materials are mechanically mixed with water in a machine
known as a wash mill.
C
In the wet process the resulting slurry or slip is run into large reservoirs or backs
where it is allowed, to settle until it has attained a certain consistency whereupon
it is put on the drying floors; in the semi-wet process after leaving the wash mill
the slurry or slip is ground between millstones or their equivalents and then put
on the drying floors.
In the manufacture of bricks in many districts it is the practice to wash the
clay in wash mills, adding thereto such ingredients as may be necessary, such as
chalk et cetera, and taking from it stones and other foreign matter which would
prevent a good brick being produced. The slip as it leaves the wash mill is run
into settling backs or reservoirs and allowed to settle until it has attained sufficient¨
consistency.to be made into bricks.
Now my invention relates to the treatment of the slurry or slip after it has left
the wash mill.
As is well known, a wash mill is provided with gratings having openings of
" or " or it may be larger, through which the slurry or slip passes, and my
invention has for object to deal with the small particles that escape through these
openings.
>
For this purpose the slurry or slip is according to my invention treated in a
centrifugal machine having a sieve that may be of any desired fineness and which
revolves at high speed. The slurry or slip is made to enter the sieve at the top and
the centrifugal force drives the liquid portion through the meshes or holes, coarse
Dmine B1

page_text: particles such as would be detrimental to the cement or bricks being arrested and
removed as hereinafter described. The slurry or slip that has passed through the
Bieve is collected in an outer casing which has a conveniently arranged outlet
whereby the slurry or slip can be conducted away as required.
In the accompanying sheet of drawings Fig 1 is a side elevation, Fig 2 a vertical
section through the centre of the machine, and Fig 3 a plan on the line A B.
Fig 4 is a plan on the line C D. Fig 5 is a central vertical section shewing a
part of the machine in a modified form.
C 19
a is the sieve which is fixed to the spindle by by the collar q on the bottom o of
the sieve, and is made to rotate at the desired speed by means of the driving
pulley, or by other arrangement of gearing, the spindle being carried in the
adjustable toe pot g and the top bearing which are carried respectively by
the cross-trees i. i, which connect the framing j. j as shown in Figs 1 and 2.
the casing around the sieve and e is the outlet from it, d being the spout which
admits the slurry or slip to be treated to the sieve. The casing c may be carried
on the uprights j. j by means of the lugs m. m. As it is necessary that the top
of the sieve should be entirely open, I construct it by connecting the top rim n
to the bottom o by means of diagonal braces p. p and when I use a woven wire
sieve I fix it on the inside of these diagonals so that they support and strengthen
it; I then fix the gauze in position by means of hoops on the inside securely fixed
to the top and bottom rims.
In practice I find that the small particles which do not go through the mesh of
the sieve are kept against it by the action of the centrifugal force and that even the
stopping of the sieve does not always allow them to fall. Therefore I use a brush
to dislodge them. 8. is an inner casing into which the particles adhering to the
sieve are brushed and from which they are delivered by the spout t to be dealt
with as may be desired. The casing 8 has a central hole surrounded by a wall / to
allow of the passage of the sieve spindle. The slurry or slip in the casing c passes
around the outside of the casing s on its passage to the opening or spout e; the
brush for removing the small particles from the inside of the sieve may be of
bristles or similar materials, or it may be a flat scraper of india-rubber or leather,
and it may be arranged to work automatically or to be inserted by hand as
required.
In the arrangement Fig 5 the particles are brushed into the annular groove or
channel where they accumulate and whence they are removed from time to time
as may be found desirable.
By the use of my invention in the manufacture of cement, small particles of
chalk, such as in the wet process of manufacture would evidently be burned into
free lime and thus tend to produce a faulty cement, are effectually removed from
the slurry or slip, and that danger is averted: Furthermore, the centrifugal action
of my machine completes most effectually the mechanical admixture of the raw
materials after they have been treated in the wash mill, while in the semi-wet
process the small particles are arrested before reaching the millstones, thereby
reducing the wear and tear on them and thus effecting considerable economy in
their use.
When dealing with some materials my apparatus as already described
acts as a substitute for millstones and the slurry can be taken direct from it on to
the drying floor, thus effecting a considerable further economy in the manufacture.
In the manufacture of bricks the use of the machine as already described
produces a finer and more dense slurry or slip and consequently a more perfect
manufacture with its attendant advantages.
Where a very great degree of fineness is required I sometimes arrange two
sieves, one inside the other, the inner one being of a coarser mesh than the outer;
or the slurry or slip may be run through two separate machines, the second machine
having the finer mesh.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I desire it to be

page_text: understood that I do not claim broadly the use of centrifugal apparatus for the
extraction of liquids, but what I do claim is
1. In the manufacture of cement and bricks the treatment of the slurry or slip
in a centrifugal machine such as described substantially as and for the purposes
specified.
2. The improved centrifugal machine for treating slurry or slip constructed,
arranged, and operating as shewn in and described with reference to Figs 1 to 4;
or modified as illustrated in Fig 5.
3. In a centrifugal machine for treating slurry or slip the use of a sieve open at
the bottom for escape of particles too coarse to pass through the sieve, substantially
as described.
4. In a centrifugal machine having a sieve such as referred to in claim 3 pro-
viding a bottom or disc such as o of smaller diameter than the interior of the sieve
and so arranged as to throw the material to be sifted against the sieve substantially
as described.