Improvements in the Treatment of Slag for a Variety of Important Uses, such as Building Blocks, Paving Blocks, and the like.
Year: 1890

page_text: COMPLETE SPECIFICATION.
Improvements in the Treatment of Slag for a Variety of Important
Uses, such as Building Blocks, Paving Blocks, and the like.
I, SAINT GEORGE TUCKER COALTER BRYAN, a citizen of the United States, residing
at Birmingham, in the County of Jefferson, and State of Alabama, United States of
America, Metallurgist, do hereby declare the nature of this invention, and in what
manner the same is to be performed, to he particularly described and ascertained in
and by the following statement:-
The object of my invention is to prepare slag-which is now chiefly a waste product
and troublesome to get rid of-for constructive purposes, such as building blocks,
paving blocks, etc. into which it may be cast or moulded after proper preparation. To
this end I use only such slags as come from smelting furnaces in which the percentage
of metal if present is not great enough to warrant saving.
Accordingly my invention consists in a peculiar treatment of such slags, which is in
part a mechanical process of annealing them, and in part a chemical combination
between them and alumina producing a homogeneous mass and changing its qualities,
This
that is increasing the quantity or per cent. of alumina which is a chemical base.
produces a more basic silicate of alumina. Such slags are never uniform in com-
position and temperature, as they come from different furnaces, and are often admixed
with hurtful gases and fumes, and both solid and liquid foreign matter. The presence
of these foreign substances, and the want of homogeneous composition unfit them for
general use because of the impossibility of satisfactorily annealing these slags and
compositions made from them, which demands a temperature substantially uniform
throughout the mass,
(that can only be maintained in a body which is homogeneous,
during a change from a molten to a solid state), and demands the absence of foreign
mutter during the processes of annealing. I proceed substantially as follows-
To practise one part of my invention-
First. I deliver slag in a molten state as it flows from the furnace into a suitable
receptacle :
Second. I admix with it a small amount of alumina, or other combinations of
aluminium, the amount to be determined by the use to which the material is to be
applied, and the nature of the slag itself. The alumina to be added may be made
anhydrous and be heated and added to the slag while it is flowing from the furnace
into the vessel. From 10 to 25 per cent. of aluminium will generally be found to be
sufficient for all masses of slag in addition to that already contained in them. This
variation of quantity of alumina to be added is necessary on account of the varying
compositions and conditions of slags produced from ordinary smelting furnaces, which
are generally composed of lime, silica and alumina in combination.
Third. I then cause the molten mass to be agitated by stirring it, or by revolving
the vessel containing the molten composition so as to give it a rotary motion. By
this means thoroughly intermingle and fuse the alumina with the slag, and also
The molten and
eliminate gases and fumes, and gas and fume producing matter.
unmolten foreign matter is collected through centrifugal force and gravity and then
removed. Afterwards, by continued stirring and agitation, which is an act of
annealing when done within given limits, a homogeneous molten mass of uniform
temperature is produced. The stirring or agitating may be continued with advantage
-after the satisfactory fusion and combination has taken place during part of the
process of cooling and before or after the composition is discharged into moulds.
Molten and unmolten foreign matter lighter than the slag rises to the top and is
dipped off. Heavy liquid or solid matter sinks to the bottom and is drawn off through
Gaseous
any usual trap hole, or allowed to remain there and is afterwards removed.
foreign matter will rise and pass off in the air.
The composition of slag and alumina that I produce, on account of the admixture

page_text: and uniform combination between the substances constituting the slag and the alumina
added, is a substantially new material from the result of such homogeneous fusion, and
possesses great strength and toughness, and is far less brittle than slag or slag
compositions heretofore made.
Another part of my invention relates to moulding, annealing, and regulating the
cellular structure of cellular slag in various forms, and it consists in delivering molten
slag into suitable moulds and communicating to it rotary motion, such as to develop
the action of centrifugal force in the mass. This may be done either by giving
rotary motion to the mould, or by stirring the mass of molten slag within the mould,
or by both the means mentioned.
It is very useful to employ wood, saturated if desired, paper, or carbon composition,
for lining the interior of moulds, so that the molten slag will be discharged upon such
surfaces rather than upon metal or mineral surfaces. This prevents the contraction of
the slag closing the cells near to and on the surfaces of the moulds, and prevents
brittleness and hardness in the product and increases its toughness.
For
Various useful effects are produced by this method of moulding bodies to be formed
of cellular slag under the action of centrifugal force, aided by stirring with paddles etc.
which controls the number and aids in the perfect distribution of the cells.
example the slag is prevented from chilling at the surface or adhering to the mould.
It is also kept substantially uniform in composition and in temperature and caused to
cool uniformly, by which it is rendered less brittle and tougher. It is also forced
against the sides of the mould so as to form the outline of the mould sharply upon the
object to be cast or moulded.
By regulating the size, number, and distribution of the cells in the slag I greatly
add to its strength and value, as uniform weight and density are secured. I also
make the process of annealing much easier, more uniform, and rapid.
The accompanying drawing is an elevation, partly in section, of a simple mechanism
by which both parts of my method of treating slag can be practised; but this is only
one example of such mechanism. Many varieties of mechanism might serve the
purpose.
Referring to the letters upon the drawing, A designates a suitable base of a frame B,
supporting a vertical shaft C, on the upper end of which is fixed a bevel gear-wheel D,
which is rotated by another bevel gear-wheel E on a shaft F, that may be turned by a
crank G.
H. designates a slag holding vessel, or a mould, of clay, metal, or other substance,
having pins projecting from its bottom into corresponding pin-holes in the upper
part of the wheel D, thus securing the vessel, or mould, in place to be rotated with its
contents.
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 I
claim is
1. The herein described process of treating slag by intimately intermingling and
fusing with it alumina or combinations of aluminium, then rotating it in a suitable
vessel when in a molten state, so as to separate impurities from it through the action
of gravity and centrifugal force, then removing the impurities, and stirring the slag
so as to make the fused inass practically homogeneous and of uniform temperature and
quality, substantially as set forth.
2. The herein described method of moulding, annealing, and regulating the size,
number, and distribution of cells of slag, which consists in delivering the slag in a
molten or plastic state into a suitable mould and there giving it motion to develop the
action of centrifugal force in the mass while being moulded.
3. The improved construction of apparatus substantially as shown and described.
- Dated this 3rd day of I
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.