Improvements in the Manufacture or Preparation of Furnace Slag and of Cement Partly Made therefrom.
Year: 1886

page_text: Date of Application, 6th Sept., 1886.
Complete Left, 15th Dec., 1886.
Complete Accepted, 6th Sept., 1887.
Improvements in the Manufacture or Preparation of Furnace Slag
and of Cement Partly Made therefrom.
I EDOUARD LARSEN of 26 Mark Lane in the County of Middlesex Engineer, do
hereby declare the nature of this invention to be as follows:-
The present modes of disposing of furnace slags, as they flow from the Blast furnaces
consist in either collecting them in large iron moulds, or by running them into water,
or together with a current of water to reduce them to the so called slag sand, a
spongy coarse gravel, with pumice stone like consistency, or by means of a jet of
steam under high pressure to reduce them to the so called slag wool.
The object of my invention is to treat the fluid or molten slags as they come from
the furnace in such a manner that I at once get them reduced to a fine powder, or to
a finely divided state, suitable for various purposes.
For this purpose I submit the stream of fluid slags, as hot as possible to the
disintegrating, tearing or pulverising and cooling effect of one or more jets of water,
air, or steam alone, or two or more of these combined, supplied under sufficient
pressure and at such a speed in such quantity or quantities and under such an angle
or angles that the stream of slags gets perfectly disintegrated or transferred into a
fine rain, and under the cooling effect of the jet or jets used, hardens in this finely
divided state.
By varying the speed or force, and the combination of the jet or jets, I can vary
the nature of my produce, according to the purpose it is wanted for, and produce
nearly any shade between slag sand and slag wool, but still of a perfectly different
nature to any of these two articles.
If I want to produce my pulverized slags in a dry state, or as nearly dry as possible,
care must be taken when any water or steam is used, not to use more than necessary
for the perfect cooling and hardening or other transformation of the slags or the
steam and heat produced by the sudden cooling of the slags may be utilized by any
convenient means for finally drying the pulverized or disintegrated slags.

page_text: Another manner of reducing the fluid slags to a fine state is by submitting the
stream of slags as hot as possible to a gentle jet of steam, whereby a fine rain of
small still liquid globes are found, which by falling into a tank of water form a multi-
tude of fine balls, exceedingly friable and vitreous, and easy to reduce or crush.
The material produced in this manner acquires by the sudden cooling and disinteg-
ration such qualities as render it specially well adapted for the manufacture of cement,
and for this purpose it offers material advantages over the slag sand now used, as it
requires little or no further reduction by grinding machinery, and little or no drying,
but simply an intimate mixing and incorporation with dried slaked lime. I accordingly
make my cement by taking this finely comminuted slag, and dried slaked lime in
the proportions requisite for forming cement, and mix them together preferably in a
ball mill, or other mixing machine, having a grinding action to still further comminute
the ingredients, but do not confine myself to further grinding, as simple mixing will
suffice to make a very good cement.
Dated this Fourth day of September 1886.
EDUARD LARSEN.
Wm. P. Thompson & Co.,
Of 6, Lord Street, Liverpool,
Patent Agents for the Applicant.

page_text: and of Cement Partly Made therefrom.
I, EDUARD LARSEN of 26 Mark Lane, in the County of Middlesex, Engineer, 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:-
The present modes of disposing of Furnace Slags as they flow from the Blast Furnaces,
consist in either collecting them in large iron moulds, or by running them into water,
or together with a current of water to reduce them to the so called slag-sand, a spongy,
coarse gravel with pumice stone-like consistency, or by means of a jet of steam under
high pressure to reduce them to the so called slag-wool.
By utilizing Furnace Slags for cement manufacture, these must undergo a sudden
cooling or vitrification, and this has hitherto been done by reducing them to the so
called slag-sand by steeping them in water, or running them into a tank, together
with a large proportion of water. This has afterwards involved the evaporation of the
large quantity of water, which the slag-sand owing to its spongy condition has absorbed,
and a further crushing or grinding of the dried material.
The object of my invention is to arrive at similar results, by treating the slags in
their molten state as they flow from the furnace, in such a manner, that the subsequent
drying and grinding is wholly done away with, or at all events a great saving in
these two manipulations is effected.
For this purpose various means can be utilized, the object being always to take
the fullest advantage of the fluid state of slags for rendering them to a fine powder
or finely subdivided state, without using any grinding machines as stones, pulverizers,
crushers etcetera and at the same time if the produce is wanted dry, for instance for
making cement, to effect the necessary sudden cooling and vitrification, without wetting
the material, or at all events with the smallest quantity of moisture. To arrive at this,
I propose submitting the steam of fluid slag as hot as possible to the disintegrating,
tearing, or pulverizing, and at the same time cooling effect of one or more jets
or strong currents of water, steam, or air, either applied separately, or two
or more of these combined, supplied under sufficient pressure, at such a speed, and at
such quantity or quantities, and under such an angle or angles, that the stream of
slags get perfectly disintegrated or transferred into a fine state, and under the cooling
effect of the jet or jets used, hardens in this finely divided state. These Jets or
currents can be supplied by means of reservoirs placed high up, by air or water pumps
direct from boilers, by injectors, or in any other convenient manner.
By varying the speed or force, the angles and the combination of the jet or jets, I
can vary the nature or consistency of my produce according to the purpose it is
wanted for. Thus by giving much water with little speed or force, I would produce
a consistency of the material very like the ordinary slag-sand, and by using a strong

page_text: jet of steam alone, I would produce the ordinary slag-wool, but by using the steam or
air alone under a lower pressure or in connection with some water, I would produce
a material different to both slag-sand and slag-wool. If I want to produce my finished
disintegrated slags in a dry state, or as nearly dry as possible in this manner, care
must be taken when any water or steam is used, not to use more than exactly neces-
sary for the perfect cooling and hardening or other transformation of the slags. With
different varieties of slag and different quantities of slag flowing from the furnace,
different relative quantities of water, air, and steam are required, so that it is very
difficult except for each particular case to give definite directions. From a furnace
giving about 1 cwt. of slags per minute a very good disintegration was obtained with
an over pressure of only 4.6 inches quick silver measured close to the mouth of the
combined steam and air injector, but I don't limit myself to this.
I will now describe the best mode known to me for carrying out the invention into
practice.
The well known jet apparatus for making slag-wool is slightly altered in the
following manner, and any workman can after a little practice obtain very good results.
Instead of the simple steam jet, which would only produce a very woolly and in some
cases moist material, an injector is used, whereby a small quantity of steam at high
pressure induces from one to four times its volume of air at a good speed. The injector
being set in motion and the stream of slag being made to pass in front of it, a short
brittle material consisting of very fine needles and threads is formed, and by regu-
lating the speed and force of the jet according to the quantity and nature of the slags,
the operator can make the produce more and less bulky.
and
In some cases for instance, for rendering the produce less buiky forest,
for some qualities of slags, it may be desirable and necessary to add some water to
the disintegrating jet to effect a more sudden cooling, and produce a more compact
material. This can be done by placing at the mouth of the injector pointing nearly
in the same direction, but above it, a tap of water preferably under a good pressure,
or the injector can be a treble one which can induce both steam, air, and water.
The injector being set in motion the water is now gradually turned, and intimately
mixing itself with the injected air and steam, and acting on the slag-stream, will
make it fall into more brittle granulations instead of threads. The quantity of water
is now sufficient and the tap should be turned no further. In this manner it is more
difficult to produce the disintegrated slags absolutely dry, but the quantity of water
being comparatively small, a large quantity of overheated steam will be produced
which by means of a system of tubes can be utilized for finally drying the disinte-
grated slags, if required.
According to the quantity of slags flowing from the furnace, the slag-stream can
either be divided into several streams, each one to be acted upon separately, or the
stream, if too large to be perfectly disintegrated by one jet can be treated by several
jets placed underneath or beside one another, preferably from the side as the stream
of slag is falling through the air, or from above at the point where the stream begins
to fall down.
It will be seen from this that the operator has a perfect control of producing the
disintegrating slags in the state best adapted for the purpose it is wanted for, by
applying strong and heavy jets in proportion to the quantity of slag, the material
becomes light, fluffy and voluminous, but exceedingly easy to reduce to an impalpable
powder, by using less powerful jets especially in conjunction with water the material
becomes less bulky, but somewhat harder to reduce. Another mode, which I do not
recommend however, of arriving at the same object, is dropping the stream of fluid
slags on a disc table, or pan revolving horizontally at great speed, or through the
middle between a pair of discs constructed like an ordinary dismembrator revolving
at great speed vertically or horizontally so that the subdivision of the slags is effected
by centrifugal force, and in this manner a perfectly dry material extremely finely
divided can be produced. The room in which the disc is revolving can be kept cool
by currents of air passing through same, and by water passing along the outsides.
This plan though apparently at first sight so different to that previously described,

page_text: is really the same in actual effect, as in each case the effort is to finely subdivide
and suddenly cool the fluid slag, while bringing it in contact with water or air. In
the one case the force of the jet pressure does this, in the other the centrifugal
force, I prefer at present the jet process as simpler and more easy to work and
regulate, but mention this as a possible but untried process, that occurs to me as
likely to be of value in some cases.
The material produced by these disintegrations offers material advantages over
slag-sand for the manufacture of cement, for which it has acquired the necessary
properties by the sudden hardening, cooling, and disintegration.
The manufacture of cement from the material disintegrated in this manner, the
nature of which varies according to the modus operandi utilized, consists in the evapo-
ration of the moisture, if any, a further reduction of the material to a fine powder,
if not already produced fine enough, but as the material will in any case be
exceedingly easy to reduce no heavy machinery is required for this purpose and rollers
or ball-mills, will be found most economical. The fine powder is eventually sifted and
finally most intimately mixed and incorporated in a dry state with a quantity of burnt
lime, preferably slaked, fallen to a dry powder and well sifted beforehand, which will
vary according to the analysis of the slags used and the purpose the cement is wanted
for, generally between 20 to 50 per cent of the quantity of slag. The cement is
then finished and ready for use. By treating ordinary slag-wool in exactly the same
manner, namely by first drying it if necessary, and grinding it by any ordinary
mechanical means to as fine a powder as possible, and mixing and incorporating it
with the requisite quantity of lime, a first class cement can likewise be produced if
the slag wool has been of a suitable chemical composition, but as slag-wool is some-
what more difficult to handle, and to grind to a fine powder it is preferable by the
disintegration, not to make the produce too woolly, although it is in no way detri-
mental to the quality of the cement.
For the further illustrating of my invention, I have appended drawings of the
best form of apparatus known to me for use in working my invention, by way of
illustration.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed I declare that what I claim is :-
1. The manufacture of finely comminuted slag applicable for the purpose of making
cement or mortar by disintegrating furnace-slags, while still molten, in the manner
described (instead of granulating them to slag-sand in the ordinary manner) and
drying and pulverizing as far as it is necessary, substantially as described.
2. The manufacture of slag-cement by disintegrating molten furnace slags, substan-
tially as herein described (instead of granulating them to form slag-sand) drying if
requisite, and, if in the woolly state, or not fine enough, pulverizing the material
further, then adding the necessary amount of lime and intimately mixing and incor-
porating the two ingredients.
Dated this 14th day of December 1886.