Improvements in Kilns for Calcining or Fritting Materials used in the Production of Potters' Glazes.
Year: 1897

page_text: Date of Application, 26th Nov.,
1897
Complete Specification Left, 26th Aug., 1898-Accepted, 5th Nov., 1898
PROVISIONAL SPECIFICATION.
Improvements in Kilns for Calcining or Fritting Materials used in
the Production of Potters' Glazes.
I, WILLIAM OWEN, of 48, Moorland Road, Burslem, Staffordshire, Potters'
Agent, do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in kilns for calcining or fritting
materials used in the production of potters' glazes, and is designed to attain the
objects hereinafter referred to.
was
With the view of rendering lead used in the production of glazes used in the
pottery trade less injurious to the workers in the glazing department of that
trade, it has been proposed, in lieu of mixing the lead with the other glaze
the
as
latter being fritted,
materials subsequently to
customary,
to frit the lead together with the other glaze materials. So far as such proposal
has, at present, been carried out, with the ordinary fritting kilns in use in the trade,
the result has been so speedy a destruction of the kiln and so great a waste and
loss of the fritted material that the process has not been practically successful.
The reason of such failure is that such kilns are ordinarily constructed with a
bed or bottom lining of fire-bricks resting upon a foundation of other brickwork,
and that such fire-brick bottom is attacked and destroyed by the frit, when lead
is present in the fused materials, much more quickly than when it is not so
present, and the frit wastes by percolating or eating" through the firebrick
bottom into the brickwork foundation.
This invention is designed, inter alia, to remedy such defects and to enable
lead for potters glazes to be successfully fritted either with the other materials of
a glaze, or with silica to produce a silicate of lead for glaze purposes, which
latter could not be done in such existing kilns sufficiently economically to be a
practical success on account of the excessive destruction of the kiln bottom and
loss of the fritted material there would be in fritting such materials together in
such kilus.
To this end, one of the objects of the invention is to form the kiln bottom in a
stronger and more lasting manner than hitherto and in such a manner as will
prevent the said waste in the fritting of ordinary glaze materials, and will make
practicable the fritting of lead with other glaze materials: while another object
of the invention is to attain a new result, namely, the continuous fritting or pre-
paration of a silicate of lead for potters' glaze purposes, by a process of continuous
fusion, and in the provision of means for enabling such object to be attained
without undue wear of the kiln bottom and without the said waste and loss of the
fritted material.
To attain the firstly stated object, I substitute for the foundation of brickwork
customary in such kilns, a strong bottom supporting plate made of iron or other
suitable metal formed with upwardly turned flanges at the sides and bottom end.
The bottom plate is built into the kiln structure, with a free air space underneath

page_text: it, in a direction declining towards the "running out" hole, which (in a single
kiln, as herein referred to,) would be adjacent to the firebridge. To form the
interior bottom of the kilu upon which the fusing of the glaze materials takes
place, I cover such supporting metal plate preferably by quarries," or, it may
be, by fire-clay bricks, bedding the same in Hint upon the metal plate.
Although the quarries will be attacked in the process of fritting, still, the
solid support of the metal plate will prevent them from sinking and the frit from
running to waste, and the latter object will be further attained by the upwardly
turned Hanges at the sides and bottom end of the supporting plate within which
the inner casing of the kiln or walls of firebrick are built, so that any of the frit
that runs down the sides of the bottom quarries is kept from running away into
the outer brickwork of the kiln. The metal supporting plate is prevented from
being fused by the heat of the kiln interior, by the aforesaid air-space beneath it,
the kiln walls supporting it being formed with arch-ways which permit of a
current of air constantly passing beneath the plate, which current carries off
the heat radiated therefrom, and is then admitted by flues to the glut hole and
ash hole of the furnace, or, it may be, to the combustion chamber above the furnace
bars, whereby such heat is economized and the fire is fed with hot air for the
purpose of combustion and the heat of the kiln is thus intensified.
When the kiln bottom is thus made and supported by quarries or fire-clay bricks
resting on a metal supporting plate, it is easy, when the quarries get worn out, to
renew the working bottom of the kiln by chipping the worn parts from off the
metal plate, and the substitution of fresh quarries or fire-clay bricks (which may
be placed through arched ways made in the kiln side-walls,) is a less troublesome
and expensive process that in ordinary frit kilns, on account of the even and solid
bottom always ready for the operation. It is thus less costly to renew the kiln
bottom, which also lasts longer.
33
The aforesaid improvement is applicable to all frit kilns, whether for fritting
ordinary glaze materials with or without an admixture of lead, worked in the
customary manner, in which the
running out hole is closed until the frit
is fused and has run down the inclined bottom of the kiln and remained a sufficient
time against the fire bridge or at the lowest part of the kiln bottom to be sufficiently
fritted, when the running out hole is opened and the molten frit is allowed to
escape into the receiving water hole or pan, but will be of special utility in
enabling such kilns, if, as I propose, increased in and made of sufficient length,
to be worked in a continuous manner with the "running out" hole always open.
And, to such end, such improvement is especially applicable to the process of
producing silicate of lead for glaze purposes, which, for the reasons above
mentioned, has not been practically possible on the bottom of existing frit kilns,
and allows of such result being practically attained.
I, however, in proceeding to produce a silicate of lead for glaze purposes,
prefer to construct a kiln as follows, as, by such improvements, I am enabled
to effect such production continuously until the kiln, after comparatively long use,
needs repairs to replace the worn out bottom lining, and more economically than
can otherwise be produced.
To this end, I prefer to apply the firebars in a steeply inclined position declining
from the fuel feed hole towards the bridge, and I may admit the current of hot air
from under the said metal plate supporting the kiln bottom, either under the fire
bars so as to pass through the incandescent fuel, or into the furnace chamber
and among the fire gases, as may be most desirable.
The part of the kiln-roof above the fine chamber I make much higher that the
part thereof towards the chimney end of the kiln, so as to provide for a sufficiency
of room for the combustion of the gases generated, before they leave the fire-
chamber. Between the furnace and the fit feed hole, I lower the roof towards the
ascending bed of the kiln, by forming the same of quarries in a step-like manner,
and which quickly become of a white heat and cause any non-combusted furnace
gases to inflame and reverberate onto the quarries forming the kiln bottom at a

page_text: part of the kiln where its interior is much less high than at the furnace end, and
onto the descending frit.
The frit feed opening into the kiln consists of a narrow opening made in the
top of and longitudinally of the kiln and which causes the frit to be deposited
in a long narrow mass along and centrally of the width of the kiln bottom,
leaving channels at each side of the mass for the passage of the furnace gases
to the chimney. The mass of lead and silica from which the silicate is to be pro-
duced is first carefully and completely admixed in correct chemical combining
proportions, and is fed into the kiln in manner aforesaid.
The furnace gases which are brought down by the stepped formation of the
kiln-roof and impinge directly upon the end and along the sides of the mass of
material deposited in the kiln under the feed opening, quickly fuse the said
two components together, as a lead silicate, which runs down over the white hot
bottom quarries, meeting as it runs. the reverberated flame.
The kiln is made of such an increased length (beyond that which is customary
in frit kilns) that, by the time the frit has travelled the length of the kiln and
reaches the running out hole, it escapes thereby from the kiln completely fused
or prepared into the water hole or pan. As the process goes on continuously, the
material being fed into the kiln and running out at the running out hole until
the required amount of silicate has been fitted, or, if desired, until the bottom
quarries of the kiln have been worn out and need renewing. the running out hole
is left open throughout the working of the apparatus, and the process of con-
tinuously producing a silicate of lead for glaze purposes is rendered practicable.
Dated this 94th day of November 1897
DAY, DAVIES & HUNT,
Chartered Patent Agents. 321, High Holborn, London, W.C.,
Agents for the Applicant.
Improvements in Kilns for Calcining or Fritting Materials used in
the Production of Potters' Glazes.
I, WILLIAM OWEN, of 48, Moorland Road, Burslem, Staffordshire, Potters'
Agent, 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 relates to improvements in kilns for calcining or fitting
materials used in the production of potters' glazes, and is designed to attain the
objects hereinafter referred to.
With the view of rendering lead used in the production of glazes used in the
pottery trade less injurious to the workers in the glazing department of that
trade, it has been proposed, in lieu of mixing the lead with the other glaze
materials subsequently to the latter being fritted, as was previously customary,
to frit the lead together with the other glaze materials. So far as such proposal
has at present, been carried out, with the ordinary fritting kilns in use in the trade,
the result has been so speedy a destruction of the kiln and so great a waste and
loss of the fritted material that the process has not been practically successful.
The reason of such failure is that such kilns are ordinarily constructed with a
bed or bottom lining of fire-bricks resting upon a foundation of other brickwork,
and that such fire-brick bottom is attacked and destroyed by the frit, when lead

page_text: "
is present in the fused materials, much more quickly than when it is not
present, and the frit wastes by percolating or eating through the firebrick
bottom into the brickwork foundation.
This invention is designed, inter alia, to remedy such defects and to enable
lead for potters' glazes to be successfully fritted either with the other materials of
a glaze, or with silica to produce a silicate of lead for glaze purposes, which
latter cannot be done in such existing kilns sufficiently economically to be a
practical success on account of the excessive destruction of the kiln bottom and
loss of the fitted material there would be in fritting such materials together in
such kilns.
To this end, one of the objects of the invention is to form the kiln bottom in a
stronger and more durable manner than hitherto and in such a manner as will
prevent the said waste in the fritting of ordinary glaze materials, and will make
practicable the fritting of lead with other glaze materials: while another object
of the invention is to attain a new result, namely, the continuous fritting or pre-
paration of a silicate of lead for potters' glaze purposes. by a process of continuous
fusion, and in the provision of means for enabling such object to be attained
without undue wear of the kiln bottom and without the said waste and loss of the
fritted material.
On the accompanying drawings:-Fig. 1, represents a longitudinal section of
the improved kiln Fig. 2, represents a transverse section on A-A. Fig. 1;
Fig. 3. represents a like view on B—B, Fig. 1; Fig. 4, represents a horizontal
section on CC, Fig. 1; Fig. 5, represents an end elevation of Figure 1, from
the fire chamber end: and Fig. 6. represents a plan of Fig. 1.
To attain the firstly stated object, I substitute for the brickwork foundation
customary in such kilns, a strong bottom-supporting plate, 1, made of iron or
other suitable metal and formed with a surrounding upwardly turned flange, 2,
building the plate into the kiln walls, 3, in a direction declining towards
the running out hole, 4. The plate serves to support the kiln-bottom upon which
the fusing of the glaze materials takes place, and which is formed of quarries or
fire-clay bricks, 5, bedded in flint upon the plate. Although the quarries will
be attacked in the process of fritting, still, the solid support of the flanged plate, 1,
will prevent them from sinking and the frit from running to waste. The plate, 1,
is built above an air chamber, 6, which extends from the chimney stack, 7, to
the fire-bridge, 8, and communicates with the atmosphere by openings, 9, made
in the kiln walls, and with the combustion chamber. 10, by openings, 11, made
through the fire-bridge. By such means, a current of air is caused to circulate
through the chamber, ti, and to carry off the heat radiated from the plate, 1, and
to be also highly heated while passing through the channels, 10, of the fire-bridge.
which is heated to a white heat when the kiln is at work, and to enter the combustion
chamber, 11, heated to an intense degree which considerably increases the heat of
the kiln. Or, the current of air, instead of being admitted directly into the
combustion chamber, may be admitted under the fire-bars so as to pass through
the incandescent fuel. When the kiln-bottom, 5, is thus supported, it can be easily
renewed by chipping the worn quarries or fire-clay bricks from off the plate,
and replacing the same by new quarries or fire-clay bricks, thus avoiding the
troublesome and expensive process of renewal necessary in ordinary frit kilns
having porous brick-work foundations, the even metal bottom plate rendering it
much less costly to renew the kiln-bottom, and prolonging its life.
The above described improvement is applicable to all frit kilns (whether for
fritting ordinary glaze materials or for fritting such materials with an admixture
of lead.) worked in the customary manner, in which the running out hole is closed
until the frit is fused and has run down the inclined kiln-bottom and has remained
accumulated against the fire-bridge or at the lowest part of the kiln-bottom until
sufficiently fritted, when the running out hole is opened to allow the molten frit
to escape into the receiving water hole or pan but will be of special utility in
enabling such kilns, if, as I propose, increased in and made of sufficient length,

page_text: to be worked in a continuous manner with the running out hole always open, and
in enabling silicate of lead for glaze purposes to be economically produced.
To produce a silicate of lead for glaze purposes, I, however, prefer to adapt the
kiln with the following further improvements which enable such substance to be
produced continuously, (until the kiln, after comparatively long use, needs repair
to replace the bottom lining,) and more economically than it can be otherwise
produced.
The firebars, 12, are applied in a steeply inclined position, declining from the
fuel feed hole, 13, towards the bridge, 8, in order to obtain a thin fire, clear flame
and quick combustion and generation of heat.
The part, 14, of the kiln-roof at the fire chamber end of the kiln is also made
much higher than the part, 15, thereof towards the chimney end of the kiln,
where the kiln-bottom, 5, is highest, in order to provide a sufficiency of room for
the combustion of the furnace gases before they leave the fire chamber and
impinge on the frit. Between the parts, 14, 15, of the kiln-roof and immediately
before the frit feed hole, 16. the roof is gradually lowered, as at 17, towards the
ascending kiln-bottom. 5, by forming such part of the kiln-roof of stepped quarries
which, in the operation of the kiln, quickly reach a white heat and cause any non-
combusted furnace gases to inflame and reverberate onto the kiln-bottom, 5, and
onto the descending frit at a part where the kiln interior is much less high than
at the furnace end.
The frit feed hole, 16, is made as a long narrow opening running longitudinally
in the top of the kiln in order to cause the frit to be deposited in a long narrow
mass along and centrally of the width of the kiln-bottom, leaving channels at
each side of the mass for the passage of the furnace gases or their way to the
chimney. The furnace gases being brought down by the stepped formation of
the kiln-roof at 17, impinge directly upon the end and along the sides of the mass
of mixed lead and silica fed into the kiln through the opening, 16, and quickly
fuse the same together as a lead silicate, which runs down over the white hot
bottom quarries, meeting, on its way, the flame reverberated thereonto.
The kiln is also made of such an increased length (beyond that which is
customary in frit kilns) that, by the time the frit has travelled the length of the
kiln and reaches the running out hole, it will have become sufficiently treated,
and may discharge thence into the water hole or pan. 18.
The process is thus rendered continuous, the material being fed into the kiln
and running out at the running out hole until the required amount of silicate has
been fritted; the running out hole being left open throughout the working of the
apparatus.
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 [
claim is:-
The herein before described improvements in kilns for calcining or fritting
materials used in the production of potters' glazes, the same consisting in:-
1. As means of supporting the interior bottom lining upon which the fusing
of the glaze materials takes place, the application of a flanged plate of iron or
other suitable metal built into the kiln walls above an under air chamber through
which air can freely circulate, substantially as herein before described.
2. The construction of an air chamber through which the air can freely circulate
beneath the kiln-bottom, and the utilization of the heat radiated from the kiln-
bottom in heating the air circulating through the chamber and leading the heated
air to below the fire bars or into the furnace chamber, substantially as herein before
described.
3. The formation of the part of the kiln-roof at the combustion chamber end
much higher than the part thereof at the chimney end and the stepped formation
of the part between such higher and lower ends to inflame any non-combusted

page_text: furnace gases and to reverberate the flame onto the frit and kiln-bottom, as set
forth.
4. The fuzing or production of silicate of lead in a frit kiln by a process of
continuous fuzing and constant discharge, as set forth.
5. The improved construction of kiln herein before described with reference to
the accompanying drawings, which is adapted to operate in continuously pro-
ducing silicate of lead.
11
1
DAY, DAVIES & HUNT,
Chartered Patent Agents, 321, High Holborn, London, W.C.,
Agents for the Applicant.