Improvements in the Manufacture of Scoria or Slag Blocks for Paving and other purposes.
Year: 1892

page_text: Date of Application, 5th Mar., 1892
Complete Specification Left, 27th Apr., 1892-Accepted, 28th May, 1892
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Scoria or Slag Blocks for
Paving and other purposes.
I, CHARLES JAMES DOBBS of Post Office Chambers, Middlesborough in the
County of York do hereby declare the nature of this invention to be as
follows:-
It has been found that when manufacturing blocks of scoria or slag for paving
or other purposes by running the liquid slag into moulds, cavities are formed in the
blocks on their solidifying even when such solidifying is carried on in annealing
kilns, and the blocks are thus rendered liable to fracture, or to wear into holes.
The said cavities may be produced either by the existence of gas bubbles in the
liquid mass of slag, or by the fact that the slag shrinks on solidifying, and as the
outer crust solidifies some time before the interior mass, it follows that the block
cannot shrink uniformly throughout the mass, thus necessarily causing the formation
of cavities in the interior.
Such blocks are also subject to the disadvantage that when the slag is run into
open moulds, as at present, these are never filled to exactly the same extent,
so that the resulting blocks vary more or less in depth, causing considerable
difficulty when laying them for paving, to bring their top surfaces all to the
same level.
According to my present invention I obviate both the above named defects by
casting the blocks in moulds so formed that in addition to the capacity that is
required for one or more blocks, there is at top a farther capacity for containing a
certain amount of liquid slag in excess of that required for the block or blocks, so
that when the slag is run in, such excess forms a head on the block or blocks. By
preference I make the moulds of a size to contain two or more blocks, and on the
interior of the mould I form projecting fillets at the points of the junction of the
blocks and of that of the uppermost block with the head, so that when the blocks
are cast and set, corresponding grooves are produced all round the blocks at the
points of juncture, thus enabling them to be readily separated by a sharp blow at
such points.
The said mould having been filled with liquid slag and allowed to stand until the
outer skin of the blocks has sufficiently set to allow of their being removed
from the mould while the interior mass is still liquid, I place the blocks on end
with the head uppermost into an annealing kiln or chamber, whereupon, firstly, any
gas bubbles that may exist in the liquid mass enclosed in the skin, will rise up into
the head, and secondly, as the internal mass shrinks in gradually cooling, the liquid
portion in the head will sink down more or less into the blocks below so as to
inake good such shrinkage, and consequently a condition of perfect solidity will
thus be insured for the blocks. In order to prevent the sets of blocks when packed
in the above described manner from coming into close contact along their entire
surface and thus interfering with the annealing process, I prefer to make the head
of a somewhat larger size transversely than the blocks so that only the heads will
come in contact when they are packed closely side by side. The junction of the
head with the uppermost block being however formed with grooves all round as
above described so that the head can be afterwards readily separated by a
blow, the several blocks being also separated from each other by grooves in a similar
manner.
In this case the fractured surfaces may either form the ends of the blocks,
or the wearing surface thereof according as the blocks are cast end to end or side
by side.

page_text: It will be seen that by the above described method of casting complete uniformity
in the size of the blocks can be insured, as any inequality in the amounts of liquid
slag run into the different moulds will only occur in the heads, the exact size
of the blocks being determined by the separating grooves formed round them
as described.
Dated this 5th day of March 1802
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Scoria or Slag Blocks for
Paving and other purposes.
I, CHARLES JAMES DOBBS of Post Office Chambers, Middlesborough in the
County of York, 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 :-
It has been found that when manufacturing blocks of scoria or slag for
paving or other purposes by running the liquid slag into moulds, cavities are
formed in the blocks on their solidifying even when such solidifying is carried
on in annealing kilns, and the blocks are thus rendered liable to fracture, or to wear
into holes.
The said cavities may be produced either by the existence of gas bubbles in the
liquid mass of slag, or by the fact that the slag shrinks on solidifying, and as the
outer crust solidifies some time before the interior mass, it follows that the block
cannot shrink uniformly throughout the mass, thus necessarily causing the formation
of cavities in the interior.
Such blocks are also subject to the disadvantage that when the slag is run into
open moulds, as at present, these are never filled to exactly the same extent, so that
the resulting blocks vary more or less in depth, causing considerable difficulty
when laying them for paving, to bring their top surfaces all to the same level.
According to my present invention I obviate both the above named defects
by casting the blocks in moulds so formed that in addition to the capacity that
is required for one or more blocks, there is at top a farther capacity for con-
taining a certain amount of liquid slag in excess of that required for the block
or blocks, so that when the slag is run in, such excess forms a liead on the
block or blocks. By preference I make the moulds of a size to contain two or
more blocks, and on the interior of the mould I form projecting fillets at the
points of the junction of the blocks and of that of the uppermost block with
the head, so that when the blocks are cast and set, corresponding grooves are
produced all round the blocks at the points of juncture, thus enabling them to be
readily separated by a sharp blow at such points.
The said mould having been filled with liquid slag and allowed to stand until the
outer skin of the blocks has sufficiently set to allow of their being removed from
the mould while the interior mass is still liquid, I place the blocks on end with the
head uppermost into an annealing kiln or chamber, whereupon, firstly, any gas
bubbles that may exist in the liquid mass enclosed in the skin, will rise up into the
head, and secondly, as the internal mass shrinks in gradually cooling, the liquid
portion in the head will sink down more or less into the blocks below so as to make
good such shrinkage, and consequently a condition of perfect solidity will thus be
insured for the blocks. In order to prevent the sets of blocks when packed in the
above described manner from coming into close contact along their entire surface,
and thus interfering with the annealing process, prefer to make the head of a
somewhat larger size transversely than the blocks so that only the heads will come
in contact when they are packed closely side by side, the junction of the head with
the upper-most block being however formed with grooves all round as above

page_text: described, so that the head can be afterwards readily separated by a blow,
the several blocks being also separated from each other by grooves in a similar
manner.
In this case the fractured surfaces may either form the ends of the blocks, or
the wearing surface thereof, according as the blocks are cast end to end or side
by side.
It will be seen by the above described method of casting that complete uniformity
in the size of the blocks can be insured, as any inequality in the amounts of liquid
slag run into the different moulds will only occur in the heads, the exact size of
the blocks being determined by the separating grooves formed round them as
described.
The accompanying drawings shew various modes in which the said slag blocks
can be cast according to my invention.
Fig. 1 shews a perspective view of a folding mould (turned down out of its
vertical position) suitable for casting the blocks in the manner which I prefer,
namely two blocks cast end to end, with the head at the end of one of them.
Fig. 2 shews the mould open for the removal of the block.
Fig. 3 shews the combined blocks and head.
Fig. 4 shews the blocks and head separated from each other by a blow.
The mould A, which opens on hinges at B as shown at Fig. 2, is closed at its
lower end and open at the upper end, which is enlarged somewhat at a a while
at a' a are formed internal projecting fillets, so that on running in the molten slag
at the upper end, and allowing the outer crust to solidify a compound block is pro-
duced having V shaped grooves as shewn at Fig. 3 so as to form two blocks C C₂
and an enlarged head C³, partially separated from each other by the V grooves cc;
the compound block thus produced is then placed in an upright position in an
annealing kiln of any suitable construction, by preference closely side by side, so
that while they touch each other at the upper ends by means of the enlargements
of the heads, the lower parts of the blocks stand free of each other. When the
blocks have completely solidified and are sufficiently annealed, they are removed
from the kiln, and they are then subjected to blows so as to fracture them at the
grooves, as shewn at Fig. 4. By this means two perfectly solid blocks C¹ C³ of
uniform dimensions will be obtained as herein before described.
Instead of constructing the mould so as to cast the blocks end to end as described
it may also be constructed so as to cast then side by side either vertically as at
Fig. 5 or horizontally as at Fig. 6, in which case the open head may either
extend along the whole length of the mould or, for reducing the amount of waste,
it may extend only partially across as shewn, a blow hole being provided at D
for the escape of air or gas at that end.
Fig. 7 shews an arrangement for casting four blocks together, with the head C³
extending right across the mould.
The blocks might of course also be cast singly with a head at one end.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
The herein described improved manufacture of scoria or slag blocks whereby
such blocks are cast with a head so that in solidifying during the annealing the
formation of cavities due to shrinkage is prevented by causing a portion of the
liquid material in the head to descend by gravity into the blocks and thereby make
good such shrinkage.
Dated this 27th day of April 1800
ABEL & IMRAY,
Agents for the Applicant.