IMPROVEMENTS IN THE MANUFACTURE OF BLOCKS FOR PAVING AND OTHER LIKE PURPOSES, AND IN APPARATUS EMPLOYED THERE- FOR
Year: 1872

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine,
Lake, & Co., Patent Agents, Southampton Buildings, London,
for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF BLOCKS
FOR PAVING AND OTHER LIKE PURPOSES, AND IN APPARATUS EMPLOYED THERE-
FOR." A communication from abroad by Frederic Augustus
Luckenbach, of the City and State of New York, United States of
America.
Sealed the 15th November 1872, and dated the 23rd May 1872.
PROVISIONAL SPECIFICATION left by the said William Robert Lake
at the Office of the Commissioners of Patents, with his Petition,
on the 23rd May 1872.
I, WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co.,
Patent Agents, Southampton Buildings, London, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN THE Manufacture of
BLOCKS FOR PAVING AND OTHER LIKE PURPOSES, AND IN APPARATUS EMPLOYED
THEREFOR," a communication, to be as follows:-
The purpose of my Invention is chiefly to utilize for pavement blocks
the slag from irọn smelting furnaces, and by a suitable treatment

page_text: substantially as herein-after specified to render the pavement blocks
made therefrom of unsurpassed strength, durability, and in other respects
desirable, especially where subjected to great and heavy traffic. Build-
ing and other blocks or pieces may also be made from this material by
these improvements.
The said slag in its natural state is exceedingly brittle and vitreous
and unfit for the purpose to which I apply it. The first object of my
Invention is to transform the substance into an exceedingly hard, tough,
and compact material, equal or superior in strength, solidity, and
durability to the best natural rock. By my process of treatment it is
moulded into blocks of uniform size, even surface, and of a shape to
bind the courses together when laid so that one cannot settle below the
general surface of all, and spaces are left between the courses to be filled
with gravel, asphaltum, or other material, whereby foothold to prevent
slipping is provided. Thus with a material harder and more durable
than stone all the roughness and uneveness of stone is avoided, and
a pavement as smooth and even as one of wood is produced at a
reasonable cost. It also has the advantage of not becoming too smooth
and slippery like stone.
The transformation of the slag from the vitreous brittle condition in
which it naturally exists into the hard and tough substance required
is effected by adding silica and alumina to it in its melted state; this
addition of these substances making up for the deficiency thereof
naturally existing in the slag, or in other words counteracting the excess
of lime therein derived from the flux used in the smelting.
The process of adding these ingredients, viz., the silica and alumina,
and of moulding and annealing the blocks is as follows:-The slag
is taken in its liquid state as it runs from the furnace so that no
additional expenditure of heat is required for producing the blocks.
As it comes from the furnace it is conveyed through a pipe or con-
ductor made of iron, fire-clay, or other suitable material, and kept
entirely free from moisture, and is conducted therefrom into a suitable
ladle. While the melted slag is flowing from the furnace to the ladle,
the additional silica and alumina are incorporated with it. A close
box, funnel, or hopper is arranged in a suitable position above the.
conductor and ladle so that the materials placed therein will run by.
gravity therefrom through a pipe or conductor which conducts them
into the slag conductor. The flow through this pipe is stopped or

page_text: regulated by a stop-cock or valve. The silica and alumina are placed in
a hopper generally in the form of sand and clay mixed; the preparation
of this mixture may be the same as for common sand in making mortar.
The proportions of sand and clay or of silica and alumina may vary
without detriment to the quality of the blocks. I generally use them
in about equal quantities; generally from one-fourth to one-sixth as
much silica and alumina as slag is sufficient. The silica and alumina
should be heated before being incorporated with the slag in order not to
detract from the fluidity thereof. I heat them in the aforesaid hopper
by introducing heat from the furnace through a pipe.
The slag prepared with the addition of the silica and alumina as above
set forth is conveyed in the ladle to a position over the mould or moulds
into which it is to be poured for casting into blocks. For this purpose
a small truck and railway track are most convenient.
The moulds are placed in an annealing oven. The oven is close
except that it has holes at the top through which the moulds are inserted
and withdrawn, and through which the melted slag is poured from the
ladle. The moulds are to be heated to a temperature a few degrees
below the ordinary red heat of cast iron in the oven before the slag, is
poured into them. As soon as the moulds are filled the moveable cover
of each hole in the top of the oven is placed thereon to keep the heat
in the oven, and to prevent the too rapid cooling of the top of the slag
in the moulds. The moulds are kept in the oven till all the redness of
the heat derived from the slag has disappeared. The moulds are then
taken from the oven, the moulded contents removed therefrom, and
separated into single blocks, as several blocks are cast together in each
mould. The blocks are immediately piled in quantities close together
one upon another and allowed there to remain and cool slowly, so that
when cold they are thoroughly annealed and fit for use.
The aforesaid moulds are of peculiar construction. Each mould is
divided into several compartments, and. each compartment moulds
several blocks together.
In order to enable the blocks of each column to be readily and
evenly separated after being taken from the moulds projections are
made on the inner surfaces of the mould at the proper distances apart
to form sharp v shaped notches or grooves around the periphery of the
column. By using a cold chisel or other suitable instrument a few
blows struck in these grooves around the column will readily separate

page_text: the block with a sufficiently even cleavage. This operation must be
performed as soon as the blocks are taken from the moulds.
The compartments of the mould are filled, first, at or near the bottom
and the slag flows in and rises therefrom to the top, whereby but little
air is intermingled with the same, and any air or the gas generated
in the liquid mass escapes readily and completely from it. To effect
this filling of the mould a central compartment is formed between
the moulding compartments, into which central compartment the slag
is first poured from the tapped ladle above, the said compartment
having a flaring top if necessary to prevent any waste of the slag
in filling. From the bottom of this compartment holes open into
the moulding compartments through which the slag flows to fill the
same; thus the slag in the downward flow from the ladle does not
interfere with the filling of the mould, nor mingle air with itself so
much as it would otherwise do. The compartments of the mould
are open at the top for the free escape of the air and gases and to
enable the operator to see when the mould is filled. The central com-
partment is shaped to narrow the upper part of the blocks for forming
the channels in the pavement between the courses. The mould is made
in sections.
The form of the block for locking the courses together in the pave-
ment may vary. In one form adopted one side of each block has a
ledge or shoulder with its face upward, and on the other side is an
overhanging projection or shoulder with its face downward. The
adjacent courses are thereby interlocked. In order to provide for the
taking up of the blocks in street pavements, the end or gutter blocks
of each course have no locking shoulders or projections but have plane
sides so that they can first be lifted directly upward from their bed and
then the other blocks of a course can be drawn out lengthwise. The
gutter blocks may have holes or cavities cast in their upper side faces
to facilitate their withdrawal with a suitable instrument.
In another form of blocks for locking the courses together one side
has a semicircular or other suitably formed projection, and in the other
side is a groove of corresponding size and shape.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Robert Lake in the Great Seal Patent
Office on the 23rd November 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ROBERT LAKE, of the Firm of Haseltine, Lake, and Co., Patent Agents,
Southampton Buildings, London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her.
Letters Patent, bearing date the Twenty-third day of May, in the year
of our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Robert Lake, Her special
licence that I, the said William Robert Lake, my executors, adminis-
trators, and assigns, or such others as I, the said William Robert Lake,
my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for “IMPROVE-
MENTS IN THE MANUFACTURE OF BLOCKS FOR PAVING AND OTHER LIKE PURPOSES,
AND IN APPARATUS EMPLOYED THEREFOR," a communication to me from abroad
by Frederic Augustus Luckenbach, of the City and State of New York,
United States of America, upon the condition (amongst others) that I,
the said William Robert Lake, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and
seals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said William Robert Lake, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and.
by the following statement, reference being had to the accompanying
Drawing forming a part of this Specification.
The purpose of this Invention is to utilize for pavements and other-
wise the slag from iron smelting furnaces which is produced in immense
quantities and is not only a nearly useless material, but also causes a

page_text: large expenditure to remove it out of the way. By suitable treatment
as herein-after specified I render the pavements and other articles made
from this material of unsurpassed strength and durability, and good in
other respects especially where subjected to heavy traffic. Building
blocks and various other articles may also be made from this material
by this Invention.
The slag as it usually flows from the furnaces is exceedingly brittle
and vitreous and unfit for the purpose to which I apply it. The first
object of my Invention is to transform this substance into an exceedingly
hard, tough, and compact material equal or superior in strength, solidity,
and durability to the best natural rock, and by the treatment herein
described it is moulded into blocks of uniform size, even surface, and of
a shape to bind the courses together when laid, so that one cannot settle
below the general surface of the whole, and spaces are left between the
courses to be filled with gravel, asphaltum, or other material whereby
sure foothold is provided. Thus with a material tougher and more
durable than stone all the roughness and unevenness of hewn stone are
avoided and a pavement produced as smooth and even as it is possible
to obtain, and at a reasonable cost. It also has the advantage of not
wearing too smooth and becoming slippery.
The transformation of the slag from the vitreous brittle condition
which it assumes by rapid cooling while flowing from the furnace into
the hard tough substance is thoroughly effected, first, by adding silica
and alumina to.it (as required) while in a melted state at the time of its
flowing from the furnace; second, by causing an agitation of the liquid
slag for the purpose of removing the confined gasses remaining therein;
third, by having moulds made of iron, fire-brick, slag, or other fire
resisting material placed in an oven and heated to a high temperature
before filling the same, and which after being filled are retained in the
oven for annealing and cooling gradually.
The addition of the silica and alumina is for the purpose of counter-
acting the effect of the excess of lime therein derived from the flux used
in the smelting. The process of adding the silica and alumina and of
moulding and annealing the blocks for use is substantially as follows:-
A, Eigure 1, represents an iron smelting furnace. The slag is taken
in its liquid state as it runs from the furnace so that no additional
expenditure of heat is required to manipulate the material. As it comes
.

page_text: from the furnace it is conveyed by a trough or conductor a made of iron
coated with loam which must be entirely free from moisture before the
slag enters it. Gates or shutters are placed at intervals in the said
conductor to prevent the lighter or coal cinder from passing into the
ladle or receiver B prepared to receive the slag. While the melted slag
is flowing in the conductor just previous to entering the ladle B the
additional silica and alumina are incorporated with it by suitable means.
The device shown in Figure 1 is convenient for the purpose. A close
box funnel or hopper C is arranged in a suitable position above the
conductor a and ladle B, so that the materials placed therein will run
by gravity therefrom through a pipe or conductor b, which conducts
them into the slag conductor a just above where it falls into the ladle as
shown. The flow through this pipe is stopped or regulated by a stop-
cock or valve c. The silica and alumina are placed in the hopper C,
generally in the form of sand and clay or loam sand, the proportions of
which may vary without detriment to the quality of the blocks. When
the furnace is producing the harder grades of iron the slag produced
usually contains sufficient silica and alumina, but when the softer grades
of iron are produced the slag requires an additional proportion of silica
or loam sand, generally to the extent of one-fourth to one-sixth as much
silica as there is slag, and if the proportions are somewhat in excess no
injury will result. The silica and alumina should be made as hot as
possible before being mixed or incorporated with the slag to avoid
detracting from the fluidity thereof, they can be heated most economi-
cally by introducing the hot blast from the furnace A through a pipe d
as the heat can be spared from the furnace without inconvenience.
→
The slag prepared with or without the addition of silica and alumina
as above set forth is then subjected to agitation which can be produced
by various methods, namely, by allowing it to run or flow into the ladle.
over a corrugated or uneven surface thereby widening or spreading the
stream of liquid slag, or by stirring or agitating it with revolving paddles
or any other similar instruments, or by introducing a current of hot air
taken from the hot blast of the furnace and introduced for a few moments
into the body of the liquid slag. The purpose of this agitation is to remove.
the gaseous impurities existing in the slag as they are formed and taken
up by the slag from the iron while in the furnace, and which are retained
in the slag when received in the ladle. The slag thus prepared as abové
set forth is then conveyed in the ladle B to a position over the mould

page_text: The
or moulds into which it is to be poured for casting it into blocks of
any desired shape. For this purpose a small truck D and railway
truck E, as shewn in Figures 1 and 2 are most convenient.
moulds G, G, are placed in an annealing oven H of any suitable
construction. That represented has a furnace I below with apertures f
to conduct the products of combustion upward, into, and through the
oven into the chimney g. The oven is close except that it has holes h
at the top through which the moulds are inserted and withdrawn, and
through which the melted slag is poured from the ladle B above, the
railway track lying over the oven so that the ladle on the track can be
brought into exact position over the moulds. The moulds are required
to be heated to a temperature of about 1800 to 2000 degrees or a bright
cherry red before the slag is poured into them. The moulds being all
filled the oven should at once be securely closed to retain all the heat
possible during the first two hours after filling the moulds, and thereby
prevent a too rapid cooling of the slag in the moulds. The oven may be
so arranged that a very gradual cooling process can be effected without
reducing the temperature of the receiving part of the oven or removing
the moulds from the oven until they are sufficiently cooled to be handled
by having the oven made with several compartments divided by movable
partitions, each compartment in succession being cooler in temperature
than the preceeding or receiving oven, and the moulds arranged on
suitable trucks moved on a railway track on the bottom of the oven
extending through the entire length of the oven. By these means a
large number of moulds can be placed in successive stages of filling and
cooling in rotation, the moulds after being filled in the receiving a
hottest part of the oven may be removed into the next or adjoining
compartment within two to three hours time. The receiving oven may
then again be filled with moulds as before. As the moulds are removed
from the colder part or outlet of the oven the blocks are removed from
the moulds and separated into single blocks, as several blocks are cast
together in one mould. The said blocks are immediately piled in
quantities one upon another closely together thus being allowed to cool
very slowly and being thereby thoroughly annealed and made fit for
1280

page_text: same.
and a vertical section of one side of a mould as I usually construct the
Each mould is divided into several compartments 1. Each com-
partment moulds several blocks together as indicated by the divisions
in Figure 3, and at m in Figure 6 which is a vertical section through a
mould, and the moulded blocks cast therein. This moulding of several
blocks together is not merely for the sake of economy and convenience
of .construction of the moulds, nor for the sake of expedition in mould-
ing, although there is an important advantage gained, but the main
object of casting two or more blocks m vertically in each compartment
of the mould and lengthwise of the blocks is that a more thorough
and uniform annealing shall be produced, together with a greater com-
pactness and solidity from the greater weight and pressure of the
column of melted slag flowing into each compartment of the mould.
In order to enable these blocks m of each column to be readily and
easily separated after being taken from the moulds, projections N are
made on the inner surfaces of the mould and at the proper distances apart,
so as to form sharp V-shaped notches or grooves around the periphery
of the column as indicated most clearly in Figure 6. By using a cold
chissel or other suitable instrument a few blows struck in these grooves
around the column will readily separate the blocks with a sufficiently
even clearage. This operation must be performed as soon as the blocks
are taken from the moulds. The compartments of the moulds are filled
by allowing the slag to flow into them at or near the bottom of the
same, the slag rising therefrom to the top whereby less air is inter-
mingled with the same, and any air or the gas generated in the liquid
by the action of the slag on entering the mould is caused to escape more
readily and completely. To effect the filling of the moulds in this
manner a separate or central compartment P, is formed or placed
between the moulding compartments 7, as shewn in Figures 3 and 4,
into which separate or central compartment the slag is first run from
the tapped ladle above. The said compartment has a flaring top P if
necessary to prevent any waste of the slag in filling. From the bottom
of this compartment holes 8, Figure 4, open into the moulding compart-
ment 1, through which the slag flows to fill the same. The compart-
5 ments of the mould are open at the top for the free escape of the air
and gases and to enable the operator to see when the mould is filled
as desired. The mould is made in sections as shewn.
The form of the blocks for locking the courses together in street pave-.
ments may vary. In Figure 7 is shown one form with parts of several.

page_text: courses as laid on the road bed. On one side of the block there is a
ledge or shoulder t face upward, and on the other side is an overhanging
projection u or shoulder face downward.
The Drawing clearly shews how the adjacent courses are thereby
interlocked. Figure 8 shews the blocks as laid in a street pavement.
In order to provide for the taking up of the blocks of such pavement
for any purpose the end or gutter blocks of course have no locking
shoulders or projections but have plain sides as shown in Figure 9, so
that they can first be lifted directly upward from their bed, and then
the other blocks can be drawn out lengthwise. The gutter blocks may
have holes or cavities w cast in their upper side faces, as indicated, to
facilitate their withdrawal with a suitable instrument. As the pave-
ment is liable to be taken up in any part it is convenient to have all
the gutter blocks with plain sides, and no ill effects arise therefrom,
since the gutters are not subject to heavy pressure and wear like the
middle of a street.
Figure 10 shews another form of blocks for locking the courses
together. On one side is a semicircular or other shaped projection t,
and in the other side is a groove u of corresponding size and shape.
This Figure shews how the projections and grooves lock the courses.
together. With the blocks so formed the pavement will always remain
smooth and even.
A pavement made of the material and in the manner and form above
specified, besides being harder, tougher, and more durable than those
made from any kind of natural rock or stone, is smooth, even, and
regular, and its channels afford a good foothold for the horses. More-
over the blocks are thoroughly locked together. It has another advan-
tage especially over the ordinary hewn block stone pavement by being
made of blocks of precisely the same thickness or depth, so that the sheet
bed, or foundation can be thoroughly rammed or compressed and made
perfectly even before laying the uniform moulded blocks, and it will
have no tendency afterward to settle unevenly, whereas rough hewn
stone blocks being of various depths or thicknesses have to be bolstered
up with loose sand to form as even a top surface as the rough nature
of them will permit, and the foundation cannot be well compressed
and uniformly compacted, so that in a short time an uneven surface
is inevitably caused by the smaller sized blocks being forced into the

page_text: loose sand bed under them and from the top surface of the larger and
more solidly laid blocks.
Having thus fully described the said Invention as communicated to
me by my foreign correspondent, and the manner of performing the
same, I wish it understood that I claim,―
First. The composition of iron furnace slag with additional silica,
alumina, or both for pavement and building blocks and other analogous
uses as herein specified.
Second. The method of combining the silica and alumina with the
melted slag as the latter is drawn from the furnace as herein described.
Third. In the process of handling and conveying the slag from the
furnace to the moulds producing an effective agitation of the liquid body
for the removal of the gaseous impurities from the same.
Fourth. In the process of moulding and casting pavement blocks and
other articles from the slag, the employment of an oven H in which the
moulds are placed and heated before filling the same and retained for
gradual cooling after filling.
Fifth. The combination and arrangement of the receiving and dis-
charging ladle B, track E, moulds G, and oven H, substantially as
described.
Sixth. A mould G composed wholly or partially of fire-brick or iron
furnace slag provided with compartments 7 for casting several blocks
at once arranged in vertical or horizontal sections as and for the purpose
set forth.
Seventh. A mould G provided with a filling compartment P com-
municating at the bottom with the moulding compartment 7, whether
attached to or detached from the same, as and for the purpose herein
specified.
Eighth. A mould G provided with projections or separating plates n
on its inner surfaces arranged so that two or more blocks may be cast in
one and afterwards readily separated as herein specified.
Ninth. The process of compounding, moulding, casting, and annealing
iron furnace slag for commercial purposes as herein specified.
Tenth. The improved pavement blocks made in the manner herein
described.

page_text: Eleventh. A pavement constructed of blocks made from the materials
and in the manner herein specified.
In witness whereof, I, the said William Robert Lake, have here-
unto set my hand and seal, this Twenty-second day of November,
in the year of our Lord. One thousand eight hundred. and seventy-
two.
Witness,
W. J. LOWE.
Wч.. ROBT. LAKE. (L.S.)