IMPROVEMENTS IN THE MANUFACTURE OF BRICKS TO BE USED FOR AND IN FORMING REFRACTORY LININGS FOR FURNACES, CONVERTORS, AND OTHER VESSELS; AND IN THE MANUFacture of CRUCIBLES, TUYERS, AND OTHER ARTICLES WHICH ARE REQUIRED TO WITH- STAND HIGH HEAT
Year: 1879

page_text: LETTERS PATENT to George Edward Dering, of Lockleys, near Welwyn, in the
County of Herts, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF BRICKS TO BE USED FOR AND IN FORMING REFRACTORY LININGS FOR
FURNACES, CONVERTORS, AND OTHER VESSELS; AND IN THE MANUFacture of
CRUCIBLES, TUYERS, AND OTHER ARTICLES WHICH ARE REQUIRED TO WITH-
STAND HIGH HEAT."
Sealed the 30th January 1880, and dated the 29th November 1879.
PROVISIONAL SPECIFICATION left by the said George Edward Dering
at the Office of the Commissioners of Patents on the 29th November 1879.
GEORGE EDWARD DERING, of Lockleys, near Welwyn, in the County of Herts.
"IMPROVEMENTS IN THE MANUFACTURE OF BRICKS TO BE USED FOR AND IN
FORMING REFRACTORY LININGS FOR FURNACES, CONVERTERS, AND OTHER VESSELS;
AND IN THE MANUFACTURE OF CRUCIBLES, TUYERS, AND OTHER ARTICLES WHICH
ARE REQUIRED TO WITHSTAND HIGH HEAT."
In order to realize the advantages which there was reason to believe upon
chemical considerations would attend the use of lime as a basic lining for the furnaces
employed in various metallurgic operations, and notably for Bessemer converters, it
was proposed several years since (Patent No. 908, of the year 1872), to form such a
lining by ramming an-hydrous lime rapidly crushed in a hot state around a core
within the furnace or convertor casing, or to build it up of bricks made (in the
usual ways of brick-making) from ground (lime or) lime-stone, either fired (in the
usual manner of burning bricks) or un-fired. Such linings do not however answer
in practical use, partly because the material formed, as described, rapidly disinte-
grates on exposure to the atmosphere, and partly for want of anything like
sufficient hardness and solidity to withstand mechanically the wear-and-tear to
which the linings are continually exposed; and beyond a few laboratory experi-
ments to this day the Patent has never been worked. It was indeed lately
suggested by the patentee that a measure of success may be attained if his linings
or bricks, instead of being fired at the ordinary heat of brick-burning, be exposed
for a length of time to an exceedingly intense temperature, such as that of the

page_text: Diemens gas-furnace, DUT ԿՈՏ would OL necessity and very greatly to une
expense.
Recently (Patent No. 4780, of the year 1878) a means has been proposed of
overcoming the acknowledged impracticability, according to existing knowledge or
experience, of employing pulverulent quick-lime for the purposes above stated,
without incurring the objection to rendering it plastic by admixture of water that
a chemical hydrate is thereby formed, namely, to make the material into a stiff
paste by the addition of a considerable percentage of petroleum or other liquids
that have no chemical action upon lime, and of this paste to mould the furnace or
convertor linings, or mould, at a pressure of about 1 ton upon the square inch (a
pressure often used in ordinary machine-brick-making), bricks of which to build up
such linings, the same being highly fired before use, and a part of the proposal
being the formation in like manner of crucibles, Bessemer-convertor-tuyeres, and
other articles required to stand an elevated temperature. Obviously, the cost of
the petroleum, stated by the inventor himself to amount to no less a sum than 146/
per thousand bricks, would (if not recovered, which has not been shown to be
practicable) almost prohibit the use of this process upon a manufacturing scale;
and, moreover, bricks 50 made have been found to split up owing to absorption of
moisture when exposed to the air after firing.
The only method then that has hitherto proved in the least degree commercially
available of employing lime for furnace or couvertor linings is the well known
Thomas-Gilchrist system, consisting in forming bricks for the purpose (moulded at
the ordinary pressure of brick-making), from crushed or ground lime-stone worked
up in a pug-inill, for which moulded bricks quarried blocks of lime-stone are some-
times substituted, and firing these moulded bricks or quarried blocks for a
lengthened period, after previous slow drying, at a temperature so excessive that it
is described by the patentee in his Specification, who also states that the heat of
ordinary kilns is quite useless for the purpose, as being "beyond an ordinary white
heat," the temperature of "melting platinum" having even been prescribed as
necessary to a successful result. To maintain such extraordinary temperatures for
many consecutive hours or days, and keep in repair the kilns employed, is of
necessity a very serious element of cost. Besides which, as a matter of fact,
enormous shrinkage of the raw lime-stone bricks or blocks takes place in course of
firing, giving rise to much distortion and mis-shape when finished and many
"wasters." And that, even such as they are, these basic bricks or blocks cannot
be depended upon as a commercial article to last any time in stock in a serviccable
state, may be inferred from the careful precautions enjoined by the patentee in his
Specifications, that they should be kept in a dry place, and used as soon as
possible.
Now, I have made the discovery, after many years of endeavour to arrive at a
satisfactory lime or other basic lining, and several series of costly experiments, that
pulverulent an-hydrous limes, including also highly calcined, or what are termed
"over-burnt" limes (notwithstanding that such a result has been on high authority
pronounced to be impracticable), may by pressure in a mould under certain
circumstances be formed into bricks or other shapes, which after only moderate
(not excessive) firing, the temperature of an ordinary kiln being quite sufficient,
more than fulfil all the requirements in question, being exceedingly hard, even up
to the hardness of stone-ware or porcelain, if desirable, neither shrunk or distorted,
but true to shape, as moulded, and so permanent in character as to stand indefinite
exposure to damp air, and even keeping under water without disintegration, or split-
ting, or deterioration of any sort. The novel condition which I find essential and
effective to bring about this hitherto unknown and unattained result, and necessary
even to make the dry powdery lime practically cohere at all, is to mould the
material under a very high degree of pressure, the pressures ordinarily used in
brick-making, or that have been employed in or described in reference to any
of the different existing or proposed methods of lime-brick manufacture, being
quite inadequate and useless. The pressures which I have employed vary from

page_text: 40 tons down to 7 tons upon the square inch; and, according to my experience, the
greater the pressure the better is the result. Somewhat less than 7 tons to the
superficial inch may perhaps prove partially successful, and what I consider new
and valuable, and in fact to constitute the basis of a new manufacture, is tho
application of a sufficient degree of pressure to afford, after only moderate (not
excessive) firing, bricks sufficiently hard and free from liability to rapid disinte-
gration for practical use for the purposes stated. To ensure a satisfactory result, it
is advisable to charge the lime into the mould red hot or nearly so, and to observe
the precautions not to expose the brick to the air for any appreciable time between
the operations of moulding and firing, and to raise the firing temperature
gradually.
I find likewise that limes moistened by exposure to the vapour of petroleum or
other liquids that have no chemical action upon the material, and also that
partially hydrated, or even slaked limes (put into the mould cold), afford highly
satisfactory results under similar treatment, except only the moulded bricks
requiring to be slowly dried before burning, and that lime-stones and chalks, with
or without slight admixture of water, may be similarly used with success, being,
however, more subject to shrinkage and distortion in the firing.
" over-
I have further discovered that refractory neutral bricks, suitable for furnace, and
possibly also for convertor linings, may be obtained by the use of an-hydrous
burnt gypsum (plaster of Paris), or even highly calcined, or what is termed
burnt plaster of Paris, just in the manner I have described for using dry limes,
but either with or without the final burning part of the process of manufacture;
and I propose to employ plaster of Paris in other ways that may be available as a
material for forming refractory neutral linings or like purposes.
The Invention also consists in manufacturing crucibles, Bessemer-tuyeres, and
other articles to be used for metallurgic operations at high temperatures by the
same methods described for making the refractory bricks from the same several
materials respectively.
Instead of being used alone in the ways stated in the foregoing description, the
several materials may have other refractory substances (for example, ground coke
or plumbago), or binding ingredients (for example, burnt fire clay or oxide of
iron), or both other refractory substances and binding ingredients, mixed with them
in suitable proportions, if found advantageous.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Edward Dering in the Great Seal Patent Office on the
29th May 1880).
"
GEORGE EDWARD DERING, of Lockleys, near Welwyn, in the County of Herts.
'IMPROVEMENTS IN THE MANUFACTURE OF BRICKS TO BE USED FOR AND IN
FORMING REFRACTORY LININGS FOR FURNACES, CONVERTORS, AND OTHER VESSELS ;
AND IN THE MANUFACTURE OF CRUCIBLES, TUYERS, AND OTHER ARTICLES WHICH
ARE REQUIRED TO WITHSTAND HIGH HEAT."
In order to realize the advantages which there was reason to believe upon
chemical considerations would attend the use of lime as a basic lining for the
furnaces employed in various metallurgic operations, and notably for Bessemer
convertors, it was proposed several years since (Patent No. 908, of the year 1872)
to form such a lining by ramming an-hydrous lime rapidly crushed in a hot state
around a core within the furnace or convertor casing; or to build it up of bricks
made (in the usual ways of brick-making) from ground lime-stone, either fired (in
the usual manner of burning bricks) or un-fired. Such linings do not however
answer in practical use, partly because the material formed as described rapidly
disintegrates on exposure to the atmosphere, and partly for want of anything like
sufficient hardness and density to withstand mechanically the wear-and-tear to
which the linings are continually exposed, and beyond a few laboratory experiments
to this day the Patent has never been worked. It was indeed lately suggested by
the patentee that a measure of success may be attained if his linings or bricks
instead of being fired at the ordinary heat of brick-burning be exposed for a length
of time to an exceedingly intense temperature, such as that of the Siemens' gas-
furnace but this would of necessity add very greatly to the expense of
manufacture.
Recently (Patent No. 4780, of the year 1878) a means has been proposed of
overcoming the acknowledged impracticability, according to existing knowledge or
experience, of employing pulverulent quick-lime for the purposes above stated,
without incurring the objection to rendering it plastic by admixture of water that
a chemical hydrate is thereby formed, namely, to make the material into a stiff*
paste by the addition of a considerable percentage of petroleum or other liquids
that have no chemical action upon lime, and of this paste to mould the furnace or
convertor linings, or mould, at a pressure of about 1 ton upon the square inch
(a pressure often used in ordinary machine-brick-making), bricks of which to build
up such linings, the same being highly fired before use, and a part of the proposal
being the formation in like manner of crucibles, Bessemer-convertor-tuyeres, and
other like articles required to stand an elevated temperature. Obviously the cost
of the petroleum, stated by the inventor himself to aimount to no less a sun than
14 per thousand bricks, would (if not recovered, which has not been shown to be
practicable) almost prohibit the use of the process upon a manufacturing scale; and,
moreover, bricks so made have been found to split up owing to absorption of
moisture when exposed to the air after firing.
The only method then that has hitherto proved in the least degree commercially
available of einploying lime for furnace or convertor linings is the well known
Thomas-Gilchrist system, consisting in formning bricks for the purpose (moulded
at the ordinary pressure of brick-making) from crushed or ground lime-stone
worked up in a pug-mill, for which moulded bricks quarried blocks of line-stone
are sometimes substituted, and firing these moulded bricks or quarried blocks for
a lengthened period, after previous slow drying, at a temperature so excessive that
it is described by the patentee in his Specification, who also states that the heat of
ordinary kilns is quite useless for the purpose, as being "beyond an ordinary white
heat," the temperature of "melting platinum" having even been prescribed as

page_text: necessary to a successful result. To maintain such extraordinary temperatures for
many consecutive hours or days, and keep in repair the kilns employed, is of
necessity a very serious element of cost, besides which as a matter of fact enormous
shrinkage of the raw lime-stone bricks or blocks takes place in course of firing,
giving rise to much distortion and mis-shape when finished, and many "wasters."
And that, even such as they are, these basic bricks or blocks cannot be depended
upon as a commercial article to last any time in stock in a serviceable state may
be inferred from the careful precautions enjoined by the patentee in his Specifi-
cations that they should be kept in a dry place and used as soon as possible.
Now I have made the discovery, after many years of endeavour to arrive at a
satisfactory lime or other basic lining, and several series of costly experiments,
that pulverulent an-hydrous limes ("an-hydrous," that is, in the sense commonly
understood by way of contra-distinction to hydrated limes), including also highly
calcined, or what are termed "over-burut" limes (notwithstanding that such a
result has been on high authority pronounced to be impracticable), may by pressure
in a mould under certain circumstances be formed into bricks or other shapes which
after only moderate (not excessive) firing, the temperature of an ordinary kiln
being quite sufficient, more than fulfil all the requirements in question, being
exceedingly hard, even up to the hardness of stone-ware or porcelain, if desirable,
neither shrunk nor distorted, but true to shape as moulded, and so permanent in
character as to stand indefinite exposure to damp air without disintegration or
splitting, or deterioration of any sort, and which (when of the highest character
attainable under my process) may even be kept under water without injury, and
are so independent of sudden changes of temperature as to bear plunging red-hot
into cold water without cracking. The novel condition which I find essential and
effective to bring about this hitherto unknown and unattained result, and necessary
even to make the dry powdery lime practically cohere at all, is to mould the
material under a very high degree of pressure; the pressures ordinarily used in
brick-making, or that have been employed in or described in reference to any of the
different existing or proposed methods of lime-brick inanufacture, being quite
inadequate and useless. The pressures which I have employed vary from 40 tons
down to 7 tons upon the square inch. According to my experience the greater the
pressure the better is the result, and the higher the temperature that the bricks or
other moulded shapes are intended to bear in use the higher the pressure under
which they should be moulded. Somewhat less than 7 tons to the inch may
perhaps prove partially successful, but from pressures of less than about 4 tons to
the inch of superficial surface to which the pressure is applied, although my
experiments have been very numerous and repeated under many various conditions,
I have never been able to obtain any satisfactory results. On the other hand, a
specimen moulded under a pressure amounting to 40 tons to the superficial inch
proved not only infusible, but almost entirely free from shrinkage when subjected
to an oxy-hydrogen blow-pipe flame, under which a piece of ordinary" basic-brick
of equal size exposed for the same length of time became as fluid as water. What
I consider new and valuable then, and in fact to constitute the basis of a new
manufacture is, the application of a sufficiently high degree of pressure to afford,
after only moderate (not excessive) firing, bricks sufficiently hard and free from
liability to rapid disintegration by absorption of moisture from the atmosphere
when kept in stock, or to shrink or crack or break up when exposed to a high
temperature for practical use for the purposes stated, or which may even be used
for such purposes without previous firing. It may be useful to mention that the
indications which experience has shown to be reliable as to sufficient pressure
having been employed for the fulfilment of these requirements are that the finished
(tired) article when broken should present a smooth or laminar and not a granular
fracture, that the fractured surface should not be porous enough to absorb moisture
when wetted by the tongue, and that there should be an entire absence of any
odour of raw lime. To ensure a satisfactory result it is advisable to charge the lime
into the mould red hot, or nearly so, and it is well to observe the precautions not
""

page_text: to expose the bricks to the air for any length of time between the operations of
moulding and firing, or before use if firing previously to being subjected to heat
when placed in situ as a furnace or convertor lining, or such like, is dispensed with,
and in either case to raise the temperature gradually.
I find likewise that limes moistened by exposure to the vapour of petroleum or
other liquids that have no chemical action upon the material, which may readily be
effected by vaporizing a small portion of the liquid by heat beneath a sheet of wire
gauze, or a perforated plate having a thin layer of the caustic line spread upon it,
and also that partially hydrated or even slaked limes (put into the mould cold)
afford highly satisfactory results under similar treatment, except only the bricks
or other moulded shapes requiring either to be slowly dried in the air or by artificial
means before burning, or else the temperature for the burning to be raised very
gradually in order to avoid splitting by evaporation of the contained moisture, and
that different varieties of lime-stone and chalk, with or without slight admixture of
water, may be similarly used with success, being however more subject to shrinkage
and distortion in the firing.
I have further discovered that refractory neutral bricks or other moulded shapes
suitable for furnace, and possibly also for convertor linings, may be obtained by the
use of an-hydrous burnt gypsum (plaster of Paris), or even highly calcined, or what
is termed "over-burnt" plaster of Paris, and also from very slightly moistened
plaster of Paris, just in the ways I have described for using dry limes and hydrated
limes respectively, and either with or without the final burning part of the process
of manufacture.
The Invention also consists in manufacturing crucibles, Bessemer-tuyeres, aud
other articles to be used for metallurgic operations at high temperatures, by the
sume methods described for making the refactory bricks, from the same several
materials respectively; the caustic lime being the most suitable and successful, and
giving excellent results.
Instead of being used alone in the ways stated in the foregoing description, the
several materials may have other refactory substances (for example, ground coke or
plumbago) or binding ingredients (for example, burnt fire-clay or oxide of iron),
or both other refractory substances and binding ingredients mixed with them
in suitable proportions, if found advantageous, and colouring matters may be
introduced for the sake of appearance. A face or coating of magnesia or other
costly material possessing valuable basic or refractory qualities may be applied by
placing a stratum of such substance (finely powdered) within the mould in contact
with the lime or other material that is to constitute the main body of the brick or
such-like moulded shape previously to the pressure being brought to bear; a
perfect union of the different substances with each other being the result of the
high manufacturing pressures which 1 employ, as hereinbefore described.
It is unnecessary to enter into any particulars of the moulding operations, as
there is nothing new in them, and such processes are well understood and extensibly
performed in the arts and manufactures; but to ensure others obtaining successful
results the following practical details may be useful:-1st. 1 liave found it best to
construct the moulds of very thick cast iron or of cast steel, as they have to be
enormously strong, and any extension of the mould, even within its limits of
elasticity, is certain to cause the solidified or partially solidified material within
to fracture; and the plungers or pressing surfaces which traverse within the mould
and bear upon the surface of the material undergoing compression stand best when
made of tempered steel. 2nd. It is of great advantage to lubricate the interior
surface of the mould with a mixture of oil and plumbago. 3rd. With reference to
the use of dry line; as the line of cominerce is always more or less hydrated the
lime should either be put into the mould hot from the kiln, or be heated and kept
red hot for some hours, preferably in a cast-iron retort, to expel all the moisture..
For the production of large and coarse things, such as bricks, the line need not
necessarily be powdered, but for finer articles, such as crucibles, it is advisable to
do so; or, what I find far preferable, to slake it to powder with water, and then

page_text: drive off all the water by heat, as just described. 4th. The presence of any acqueous
vapour within the kiln or furnace employed for firing the bricks or other moulded
articles, when an-hydrous lime is used, should be carefully avoided, or they are
likely to split in consequence of the exceeding sensitiveness of the caustic lime to
moisture; and owing to its proneness to form sulphurous compounds, the fuel used
should be as pure as possible when the presence of such combinations in the finished
article would be objectionable.
Having thus described the nature of my Invention, and the best modes I am
acquainted with of putting the same into practice, what I claim is,-
First. The manufacture of bricks, crucibles, tuyeres, and such-like articles by
subinitting dry lime to an extremely high pressure, and subsequently firing the
saine, by which means I am enabled to produce bricks and other moulded articles,
which, without the necessity for excessive or more than ordinary or moderate
firing, may be kept in stock for considerable periods without absorption of
moisture and disintegration, and will withstand high temperatures without
shrinking or crumbling away, and which may even be used without previous
firing, substantially as described.
Second. The manufacture of bricks, crucibles, tuyeres, and such-like articles by
submitting partially hydrated lime or slaked lime to an extremely high pressure,
and subsequently firing the same, by which means I am enabled to produce bricks
and other moulded articles, which, without the necessity for excessive or more than
ordinary or moderate firing, may be kept in stock for considerable periods without
absorption of moisture and disintegration, and will withstand high temperatures
without shrinking or crumbling away, and which may, after being slowly dried,
even be used without previous firing, substantially as described.
Third. The manufacture of bricks, crucibles, tuyeres, and such-like articles by
submitting lime-stone or chalk, with or without slight admixture of water, to an
extremely high pressure, and subsequently firing the same, by which means I am
enabled to produce bricks and other moulded articles, which, without the necessity
for excessive or more than ordinary or moderate firing, may be kept in stock for
considerable periods without absorption of moisture and disintegration, and will
withstand high temperatures without shrinking or crumbling away, substantially as
described.
Fourth. The manufacture of bricks, crucibles, tuyeres, and such-like articles by
submitting lime moistened by exposure to the vapour of petroleum or other liquids
that have no chemical action upon it to pressure, and subsequently firing the same,
substantially as described.
Fifth. The manufacture of bricks, crucibles, tuyeres, and such-like articles by
submitting dry or nearly dry plaster of Paris to an extremely high pressure with
or without firing before use, substantially as described.
Sixth. The manufacture of bricks, crucibles, tuyeres, and such-like articles of
dry lime, or partially hydrated lime or slaked lime, or of lime-stone or chalk, with
or without slight admixture of moisture, having a face or coating of magnesia or
other costly basic or refractory material, substantially in the manner as herein before
described.
In witness whereof, I, the said George Edward Dering, have hereunto set my
hand and cool this Tmenty eighth day of May in the wear of our Lord One