IMPROVEMENTS IN THE MANUFACTURE OF PORTLAND CEMENT
Year: 1878

page_text: LETTERS PATENT to John Bazley White, junior, and Arthur Glover, both of
Swanscombe, in the County of Kent, for the Invention of "IMPROVEMENTS
IN THE MANUFACTURE OF PORTLAND CEMENT."
Sealed the 13th June 1878, and dated the 4th April 1878.
PROVISIONAL SPECIFICATION left by the said John Bazley White and
Arthur Glover at the Office of the Commissioners of Patents on the 4th
April 1878.
JOHN BAZLEY WHITE, junior, and ARTHUR GLOVER, both of Swanscombe, in the
County of Kent. "IMPROVEMENTS IN THE MANUFACTURE OF PORTLAND CEMENT."
This Invention has for its object improvements in the manufacture of Portland
cement, and relates to the drying and burning of the wet slip or slurry from which
such cement is produced
For this purpose we employ kilns of smaller dimensions than is usual, covered at
the top with an arched dome through which is an opening for charging the materials
into the kiln, and also other openings for allowing the heated gases from the kiln
to pass into a flue or drying chamber on the ground level, and which comes above
and encloses the entire dome.
The flue or chamber may be divided by a horizontal partition of tiles, on to the
top of which slip or slurry containing, say, about 40 per cent. of water, as prepared
by what is known as the Goreham process, can be pumped. A further quantity of
the slip or slurry is also pumped on to the top of the flue or chamber, consisting,
it may be, of iron plates.
The heated gases as they come from the kiln are caused to pass along the
chamber or flue on the under side of the horizontal partition, and at the end
of the chamber to rise up to the top of the chamber and pass back above the
partition, and are afterwards led away by side openings to a flue leading to a
chimney.

page_text: By this construction of kiln and drying flue the heat of the gases evolved in the
burning of a charge in the kiln is utilized, and without using more than the minimum
quantity of fuel necessary for the proper calcination of the Portland cement;
the heat given off is more than sufficient to dry the quantity of slurry required for
the next charge and burning off of the kiln.
The small size of the kiln (about 11 feet deep and 10 feet diameter at top) allows
of its being charged or loaded from the loading eye or opening at the top, as above
stated, instead of, as is usually the case, requiring men to descend into the kiln to
load it.
The advantage of this is absence of delay which enables us to get a much larger
quantity of cement out of this size kiln weekly than is usual. The burning and
cooling of the cement can thus be very quickly effected. The burnt cement is
drawn off from the bottom of the kiln as is usual.
In place of the drying flue being divided by a horizontal partition as above
described, it may be formed without this partition, and slip or slurry be pumped on 1
to the top only of the fluc; in this case, vertical partitions may be used to cause
the gases to travel to the end of the flue, along one of its sides, and then back on
its opposite side, or the gases might simply be passed through the flue direct to a
chimney.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed 2
by the said John Bazley White and Arthur Clover in the Great Seal Patent
Office on the 4th October 1878.
JOHN BAZLEY WHITE, junior, and ARTHUR GLOVER, both of Swanscombe, in the
County of Kent. "IMPROVEMENTS IN THE MANUFACTURE OF PORTLAND CEMENT."
This Invention has for its object improvements in the manufacture of Portland 2
cement, and relates to the drying and burning of the wet slip or slurry from which
such cement is produced.
For this purpose we employ kilns of smaller dimensions than is usual, covered at
the top with an arched dome through which is an opening for charging the materials
into the kiln, and also other openings for allowing the heated gases from the kiln 3
to pass into a flue or drying chamber on the ground level, and which coines above
and encloses the entire dome.
The flue or chamber may be divided by a horizontal partition of tiles, on to the
top of which slip or slurry, containing, say, about 40 per cent. of water, as prepared
by what is known as the Goreham process, can be pumped. A further quantity of 3
the slip or slurry is also pumped on to the top of the flue or chamber, consisting, it
may be, of iron plates.
The heated gases as they come from the kiln are caused to pass along the
chamber or flue on the under side of the horizontal partition, and at the end
of the chamber to rise up to the top of the chamber and pass back above tho 4

page_text: partition, and are afterwards led away by side openings to a flue leading to a
chimney.
By this construction of kiln and drying flue the heat of the gases evolved in the
burning of a charge in the kiln is utilized and without using more than the minimum
quantity of fuel necessary for the proper calcination of the Portland cement; the
heat given off is more than sufficient to dry the quantity of slurry required for the
next charge and burning off of the kiln.
The small size of the kiln (about 11 feet deep and 10 feet diameter at top) allows
of its being charged or loaded from the loading oye or opening at the top, as above
stated, instead of, as is usually the case, requiring men to descend into the kiln to
lond it.
The advantage of this is absence of delay which enables us to get a much larger
quantity of cement out of this size kiln weekly than is usual. The burning and
cooling of the cement can thus be very quickly effected. The burnt cement is
drawn off from the bottom of the kiln as is usual.
In place of the drying flue being divided by a horizontal partition, as above
described, it may be formed without this partition, and slip or slurry be pumped on
to the top only of the flue; in this case, vertical partitions may be used to cause the
gases to travel to the end of the flue, along one of its sides, and then back on the
opposite side, or the gases might simply be passod through the fluo direct to a
chimney.
The Drawing annexed shews an assemblage of kilns and drying flues constructed
in the manner above described.
Figure 1 is a side elevation partly in section; Figure 2, a plan view partly in
section; and Figure 3, a transverse section.
A, A, are the kilns arranged in two parallel rows, with a fluo B between them,
leading to a tall chimney C; one row only of the kilns is shewn, the other row is
ranged just in the same way on the opposite side of the flue; D, D, are the drying
flues, one for each kiln. The flues are similar in their construction to flues which
have now for many years past been used for drying slip. The gases from the kiln
enter the flue through openings E at their top; they pass along under the horizontal
floor F which divides the flue horizontally, and at the end of the flue they riso
up and pass back over the top of the slurry which is on the floor F, and descend
by flues B' to the main flue B, which leads to the chimney, and they enter the
chimney at a temperature of 200 degrees, or thereabouts, carrying with them the
steam evolved in drying the slip. The top of the flues D are covered over by plates
G, upon which slurry can also be pumped. Each kiln is charged through an opening
Hat the top, which is closed whilst the kiln is being fired. Each kiln is circular
in plan, having a chamber of about 10 feet diameter at its upper part, and of a
depth, from furnace bars to the loading eye H, of about 11 feet. The top of the
kiln is covered over by a semicircular dome which is entirely below the closed top
of the drying flue.
When a charge has been burnt in one of the kilns, it is withdrawn from it
at the bottom into a tunnel I, through which it can be conveyed away. Thus
neither for filling or emptying the kiln is it necessary for men to enter it, conse-
quently it is not necessary that the kiln should be allowed to cool down after the
burning of a charge to the same extent as now usual before it can be emptied and
refilled, and a great saving in fuel is thereby effected. K, K, is a roof by which
the whole of the drying floors are covered over.
The advantages derived from the use of kilns and drying flues arranged as herein-
before described, are that the kilns, being of much smaller size than those now
usually employed, renders it possible to throw in the dried stuff that has to be
burnt without injury to the material by breaking, and avoids the necessity of men
entering the kiln and storing it by hand as is now requisite with the larger and
deeper kilns ordinarily employed to avoid breakage, and also allows of their being
rapidly charged and drawn, and by reason of their being built close together in
blocks entirely under the surface with an opening only for charging and one for

page_text: drawing, neither the kiln nor the chamber with which it is connected ever get
really cold. This peculiarity, joined to the underground construction which prevents
all leakage and absorbs the whole of the burnt products, permits the kiln to be
charged and drawn twice in each week, and consequently to yield weekly as large
a quantity of clinker as is usually obtained in that space of time from a kiln of
double the cubic capacity, and also, owing to the absolute freedom from leakage
and the consequent utilization of all the gases, a very large economy is effected
in fuel.
A considerable diminution in wear and tear of the kiln is also obtained consequent
on its not being allowed to cool down, and to undergo the alternate contraction and
expansion which results from such cooling, and an important economy in labour is
effected, owing to the fact of a large producing power in drying and burning being
compressed into a smaller space than has ever yet be realized for a similar yield
of burnt clinker.
It will thus be seen that by the arrangement above described, the primary object
of what is known as the Hoffman kiln, namely, great saving of fuel is effected and
all unpleasant or noxious vapours which may be produced during the drying and
burning operations are discharged with considerable upward velocity from the top
of a tall chimney, as it is necessary that a tall chimney should be used to secure
success with the kilns; as thereby not only is a proper draught secured, which
would not be secured with sufficient certainty or uniformity with a low chimney,
but the higher the chimney the better will the gases passing from it be discharged
in an upward direction.
An important saving in labour is effected owing to a large producing power in
drying and burning being compressed into a smaller space than has ever yet been
employed for a similar yield of burnt clinker.
Having thus described the nature of our Invention and the manner of performing
the same, we would have it understood that we claim as our improvements in the
manufacture of Portland cement,―
First. The combined arrangement of kilns and drying chamber, substantially as
herein-before described, and illustrated in the Drawings annexed, for the manu-
facturo of Portland cement.
Second. The employment in the manufacture of Portland cement of kilns of such
a size that they can be fed and drawn off without the necessity of men entering
them, such kilns being below the ground level, and the gases passing from them
being conducted along drying flues on the ground level or thereabouts, and from
thence to a chimney, substantially as herein described.
In witness whereof, 'I, the said John Bazley White, jr., have hereunto set my
hand and seals, this Second day of October, in the year of our Lord One
thousand eight hundred and seventy-eight.