An Improved Process of Separating Metals and other Substances from Molten Slag and the like.
Year: 1888

page_text: [Communicated from abroad by ORRIN BERTON PECK, Room 418, 164, Dearborn
Street, Chicago, Illinois, United States of America.]
An Improved Process of Separating Metals and other Substances
from Molten Slag and the like.
1, HENRY HARRIS LAKE of the firm of Haseltine, Lake & Co. Patent Agents
Southampton Buildings in the County of Middlesex, 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 object of my invention is to separate metal and matte or metallic compounds
from molten slag; and my invention consists in the process hereinafter described
and claimed.
The accompanying sheet of drawings, which forms part of this specification, represents
an apparatus partly in vertical section, which apparatus may be used in carrying out
the process herein described and claimed.
To properly understand the principles upon which the process herein described is
founded, it will be desirable to first consider the materials treated and then the
results attained. By "slag" I mean the product or products of furnaces employed
in smelting ores, and by the term "slag" I intend covering the substance of similar
characteristics produced artificially or found in nature, and by metallic compounds I
mean any compound or salt of metal which may be carried in slag and matte, or like
furnace products which may be separated or treated by my process. The compounds
or salts carried in slags or mattes may be partially fused, or partially-reduced particles
of ores or metals, or both combined; and it is a well-known fact that considerable
quantities of fine particles of molten metal are carried off in slag, causing a material
loss of precious or valuable metals by present smelting operations, which particles,
compounds, and salts can be saved by my process.
As the principle or force employed in my operation is founded upon the law of.
gravitation, it is obvious that it is necessary to have the slag or like materials fluid
while being subjected to the operation herein described.
Metals and matte or metallic compounds are now separated from molten slag simply
by allowing the heavier particles to settle and collect at the bottom of the slag-pot or
like device; but the difficulties experienced by this method are, that much of the
valuable material which should be separated from the lean slag has a specific gravity
very nearly the same as the bulk of the slag in which it is contained, and for this
reason such material is not readily separated from the slag by the ordinary operation

page_text: of settling in slag-pots or like devices. To avoid the loss of these valuable portions it
is necessary to use costly fluxes in the smelter, and to reduce the slag to a very thin
fluid state and retain it in such condition for some length of time while the separation
is taking place, all of which requires the exercise of much care, and, although very
expensive, is quite inefficient.
In the event of difficultly fusible, stiff, or thick slags the losses of the fine particles
of metal above described are very large, because of the resistance to their settling
afforded by the thick or insufficiently-fused or fluid slags, and it is a well-known fact
that by the present methods of separating these metallic products from molten slag by
gravitation there is always a great loss of the particles of valuable metals and matte.
It is evident, therefore, from the above that according to the state of division or the
specific gravity of the particles of metal or other products to be separated the fluidity
of the slag and other conditions that the ordinary gravitation treatment is tedious, at
the same time the results being notably insufficient and unsatisfactory. By the
process herein described the finely-divided and other particles of metal are instantly
and completely separated from the slag or the slag from the metals by centrifugal
force.
In carrying out my process the fluid and mixed products or slag direct from the
smelting-furnace, or remelted slag carrying valuable or precious metals, subjected
to centrifugal action in a suitable machine, which operation I find by actual
demonstration almost instantly separates and retains the metallic or valuable parts to
be saved and throws off the lean slag. This operation is accomplished so rapidly and
effectively that that the lean slag is thrown off in the molten condition and does not
have time to cool perceptibly. In cases wherein molten slag is thick or semi-fluid, so
as not to be capable of treatment by the old method of gravitation, the centrifugal
force is so great as to overcome the resistance it may offer to the separation of particles
of greater specific gravity and to separate them very rapidly.
In making an apparatus for carrying out my process I provide a revoluble tub or
vessel, A, adapted to receive molten slag, preferably mounted upon the upper end of
and carried by a vertical spindle, D, which is provided with a belt-wheel, D',
by which it is revolved, carrying with it the revoluble tub or vessel A. The
spindle D is journaled in and supported by a suitable box, E, which is preferably
secured to a suitable frame-work by the cushions e, so as to be vertically flexible.
The tub or vessel A is made of sufficient strength to withstand the great centrifugal
force while in use, and preferably is arranged to stand vertically with an opening in
its top somewhat smaller than the diameter of the body of the vessel, so as to leave an
annular overhanging ring or portion, as it is shown in the drawing.
I also
prefer to provide this vessel with a suitable lining, D, of cast-iron, and make the
lining and outer shell separable in two or more parts by any well-known means,
which, in the case illustrated, is flanged and provided with cotter-bolts at the point S.
The object of making the vessel separable is to facilitate the removal of the valuable or
hardened material collected within. I further preferably provide a curb, K, to catch
the lean slag as it is discharged from the vessel A, and a revolving table, J, to carry
it away. I also prefer to provide a water or steam pipe G, to keep the exterior
of the vessel A cool, and such other parts as may be necessary to the convenient
operation of the machine, all of which may be varied to suit the operator or conditions
of operating.
In carrying on my process I take molten slag or other products from a smelting-
furnace which contains the parts to be separated, and after first causing the vessel A
to revolve very rapidly by means of a belt from any suitable source or motive power
pour the molten slag C into the vessel through the hole in the top, and as the slag
falls on the bottom of the vessel it will be thrown instantly to the sides of the vessel
by centrifugal force, the heavier particles being carried to the outside. As the slag
continues to flow in, it will be collected on the sides of the vessel and assume a vertical
position, forming a vertical annular wall, H, as shown in the drawing, until the vessel
Das become filled to the inner edge of the annular overhanging ring or portion. Then
as the slag continues to flow into the vessel, striking the bottom and being thrown to

page_text: the sides, it will be arrested by the interior of the annular vertical column or wall of
slag and be driven upward and discharged at the top of the vessel, as shown, all by
centrifugal force.
When the operation commences, as above described, and the molten slag is first
introduced into the revolving vessel, the particles of metal and matte or metallic
compounds having the greatest specific gravity or density will be driven to the
outside of the revolving mass, as shown and indicated by O, leaving the lean slag and
lighter portions C¹ on the inside. When the vessel has become sufficiently filled to
discharge the lean slag, the heavier particles of the newly or continuously introduced
slag will be separated and thrown outward while the slag is passing from the bottom
of the vessel up the vertical wall, (indicated by H). The metal or portions thus
thrown back, being the heavier, pass into and through the wall and slag (indicated
by H and C) and displace an equivalent bulk of the lighter slag, (indicated by (¹)
forcing it upward to be discharged at the top, while the heavier metallic or other parts
displacing it are retained. This operation may continue until the parts to be removed
(indicated by O) have filled the vessel so full that they are liable to be discharged or
until they have approached the line H, when they must be emptied or removed, and
the operation may be repeated, although, if desired, in the employment or operation
of my process the vessel while revolving may only be filled with a sufficient amount
of molten slag to approach the line indicated by H and not discharge any of
its contents, and may be revolved until the molten material within has become
cooled and hardened,. when it may be removed and assorted to suit the operator,
the separation of the particles of metal from slag being as described in the first-named.
operation.
As an example of the great power exerted by centrifugal action as applied to the
separation of metals, matte, or metallic compounds from slag, I find as a rough
estiinate from experiments made by me with a vessel twenty inches in diameter,
containing about five hundred pounds of molten slag and revolving eleven hundred
times per minute, that a centrifugal force of about one hundred tons is exerted
upon the particles of the fluid mass, and as.a well-known, law of mechanics this
force will be increased directly in proportion to the square of the velocity of the
centrifugal machine.
The particular machine or apparatus for putting my process into execution which
I have used is herein described and illustrated, as it appears to be useful for a proper
understanding of the process; but I do not herein make any claim for the same, but it is
obvious that any kind of a centrifugal machine may be employed that is of sufficient
strength to withstand the strain of the rapid rotation and that is adapted to hold the
molten material.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed as communicated to me
by my foreign Correspondent I declare that what 1 claim is :-
--
1. The process of separating metals, matte or metallic compounds from molten slag
or like molten materials, which consists in subjecting the same to centrifugal action,
substantially as described.
2. The process of separating metals, matte, or metallic compounds from molten slag
or like molten materials, which consists in subjecting the same to centrifugal action and
discharging the lean slag, substantially as described.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London,
Agents for the Applicant.