Improvements in and Apparatus for the Treatment of Native Emery.
Year: 1895

page_text: Date of Application, 6th Sept., 1895
Complete Specification Left, 8th June, 1896-Accepted, 25th July, 1896
PROVISIONAL SPECIFICATION.
Improvements in and Apparatus for the Treatment of Native Emery.
I, GEORGE WILLIAM JOHNSON, of 47 Lincoln's Inn Fields, in the County of
London, Patent Agent, do hereby declare the nature of this invention (which has
been communicated to me from abroad by the Firm of Mayer & Schmidt, of Offenbach-
on-the-Main, in the German Empire, Manufacturers of Emery Goods) to be as
follows:-
It is well known that emery as found in its natural condition is not pure corundum,
but a mixture thereof with metallic oxide, more especially with oxide of iron, of which
emery sometimes contains as much as 30 per cent. As the presence of the oxide of
iron is calculated to affect emery, as regards its capability of being ground, it is for
that reason desirable to remove such oxide from the emery. Yet up to the present,
no method or means for effecting a purification of emery in this particular respect,
and in a manner suited to the actual practice of the trade, has been known.
The process forming the subject of this invention enables emery to be freed from
metallic oxide in such a manner as to be serviceable for manufacturing or commercial
purposes, and it consists of the following operations :-
Native emery is mixed with a quantity of carbonaceous matter (powdered coke or
charcoal dust for example) equivalent to the proportion of metallic oxide contained in
the emery, and is placed in an electrical melting furnace wherein it is submitted to
the beating action of a luminous are produced by alternate electrical current. It is
imperative that the current employed should be alternate, as a uniform current, in
addition to the heating action, would exercise a chemical action which must be
avoided.
Under the action of the heat, the whole mass fuses and unites, while at the same
time the metallic oxide, which it contains, is reduced by the carbonaceous matter to
the metallic state, which in its turn, can be melted for use.
Native emery, furthermore, contains moisture, or water chemically fixed or "bound"
the proportion of which may attain say 5 per cent. The presence of this moisture is
apt to prove objectionable especially in cases where the emery is baked into plates or
discs at a high temperature. The present improved process gets rid of the objection-
able moisture, as well as of the metallic oxide, so that pure or practically pure corundum
is obtained. In carrying out this process a furnace is preferably used having its walls
built up of fire or
kiln "
bricks and supported by uprights or pillars, so that an
open space or chamber is formed beneath the furnace, into which space the melted
emery may be discharged through an orifice at the bottom of the furnace. Into the
furnace proper there protrude a pair of carbon electrodes through which the alternate
current is sent.
The operation of the furnace is as follows:
The circular orifice at the bottom thereof is first covered over with a thin fusible
plate, preferably of glass. The electrodes are next inserted and moved close together,
so as only to leave a space of from 3 to 4 centimetres between them, after which the
interior of the furnace is charged with native emery and carbonaceous matter such as
charcoal dust, a few small pieces of charcoal being interposed, as current-transmitters,
between the carbon electrodes.
As soon as the circuit is closed, the intermediate pieces of carbon become heated to
a bright white heat and the emery commences to melt. The several pieces of carbon

page_text: become mixed with the emery in process of fusion, are absorbed by the metallic oxide
which is in consequence reduced and there soon forms a luminous arc between the
carbon electrodes.
Within a certain time a mass of molten emery will be seen surrounding the luminous
arc, which mass where it approaches the unmelted material, forms a firm and rigid
crust.
When the reducing action is in operation carbonic oxide escapes through the
interstices in the furnace wall and in the surface of the emery and if kindled the
flames hover around the furnace and indicate that the reduction is going on.
When
the heat has become sufficiently intense to melt the plate over the orifice at the bottom
of the furnace the molten emery will rush in the form of a white incandescent jet
through the said orifice into the space beneath the bottom floor of which should be
preferably strewn with ordinary coarse grained emery powder in order to protect the
brick-work from the effects of the excessively high temperature at which the liquid
emery issues from the furnace.
Care should be taken to enable fresh emery to follow up from the top the material
which is being discharged below and this is best effected by breaking up the hardened
crust by means of an iron bar. The fresh supply of emery will then exercise such a
cooling action upon the molten emery which leaves the furnace last of all-that a
portion of this emery by solidifying will close the discharge orifice or outlet which
outlet will not again reopen until the last mentioned part of the emery is once more
thoroughly melted. In some cases it may be desirable to assist the discharge
somewhat from below by means of an iron hook.
The process may thus be carried on continuously molten emery being discharged at
intervals of from 10 to 15 minutes, while fresh charges of materials are superadded
from time to time to be melted in their turn.
The solidified final product will assume the appearance of a crystalline mass which
will either be colorless, or possess the resinous lustre of quartz; or in some cases it
may be of a hue not unlike that of ruby or a decided blue with small crystalline
protuberances which subsequently form in the recesses and are colored a deep blue,
like sapphires.
As regards the proportion of powdered charcoal or the like to be employed, it would
preferably amount to 5 per cent., added to emery containing, say, 25 per cent. of
metallic oxide. But even an addition of 4 per cent. of charcoal would be sufficient,
seeing that the carbon electrodes projecting inwardly and entering the molten material
to some extent participate in the reducing process.
In
The metal separated naturally contains small quantities of aluminum since, after
the metal has been eliminated in toto, the reducing action of the small surplus
quantities of carbon does not cease abruptly; while, on the other hand such a slight
surplus is necessary,
if a total elimination of the metal is to be ensured.
This aluminium in alloy with the other metal may be partly collected in coarse
lumps whilst the fused mass is being broken up, and partly separated by means of an
electro-magnetic eliminating apparatus (after having been further divided).
carrying out the process an alternate current machine of 300 amperes and of 110 volt
tension is suitable. The strength of current during the operation being say from
250 to 300 amperes, the tension (at the binding posts) being from 40 to 60 volt.
Both the strength and the tension of the current are apt to fluctuate a good deal during
the progress of the operation, more especially while the emery is being discharged
below and followed up by fresh charges from the top.
An essential advantage of this process resides in the fact, that it enables the dust
remaining behind after the grinding of emery which in itself, is of but little marketable
value and scarcely utilisable in the trade, to be employed as initial or raw material:
upon being introduced into the furnace, it fuses into a compact mass free from iron.
Dated this 6th day of September 1895.

page_text: Improvements in and Apparatus for the Treatment of Native Emery.
I, GEORGE WILLIAM JOHNSON, of 47 Lincoln's Inn Fields, in the County of London
Patent Agent, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by the Firm of Mayer & Schmidt of Offenbach-on-the-
Main in the German Empire, Manufacturers of Emery Goods) and in what manner
the same is to be performed to be particularly described and ascertained in and by
the following statement :-
It is well known that emery, as found in its natural condition, is not pure corundum,
but a mixture thereof with metallic oxide, -more especially with oxide of iron, of
which emery sometimes contains as much as 30 per cent. As the presence of the
oxide of iron is calculated to affect emery, as regards its capability of being ground,
it is for that reason desirable to remove such oxide from the emery. Yet, up to the
present, no method or means for effecting a purification of emery in this particular
respect and in a commercially available manner has been known.
The process forming the subject of this invention enables emery to be freed from
metallic oxide in such a manner as to be serviceable for manufacturing or commercial
purposes; and it consists of the following operations :-
Native emery is mixed with a quantity of carbonaceous matter (powdered coke or
charcoal dust for example) equivalent to the proportion of metallic oxide contained in
the emery and is placed in an electrical melting furnace wherein it is submitted to
the heating action of the electric are produced by alternate electrical current. It is
imperative that the electric current employed should be an alternating current, as a
uniform current, in addition to the heating action, would exercise a chemical action
which must be avoided.
Under the action of the heat, the whole mass fuses and unites, while at the same
time the metallic oxide, which it contains, is reduced by the carbonaceous matter to
the metallic state, which can be melted for use.
Native emery, furthermore, contains moisture, or water chemically fixed or "bound"
the proportion of which
say 5
may attain
cent.
per
The presence of this moisture is
apt to prove objectionable especially in cases where the emery is baked into plates or
discs at a high temperature. The present improved process gets rid of the objection-
able moisture, as well as of the metallic oxide, so that pure or practically pure
corundum, is obtained.
In carrying out this process, a furnace such as is illustrated in the accompanying
drawing is preferably used.
The walls A, of this furnace are built up of firebricks or "kiln" bricks, and are
supported by uprights or pillars H, so than an open space or chamber B, is formed
beneath the furnace. Into which space the melted emery may be discharged through
the orifice D, at the bottom of the furnace. Into the furnace proper there protrudes
a pair of carbon electrodes C. C, through which the alternate current is sent.
The operation of the furnace is as follows:
The orifice D, at the bottom of the furnace is first covered over with a thin fusible
plate P, preferably of glass. The electrodes C, are next inserted and moved close
together, so as only to leave a space of from 3 to 4 centimetres between them; after
which the interior of the furnace is charged with native emery and carbonaceous
matter such as charcoal dust, a few small pieces of charcoal being interposed, as
current-transmitters, between the carbon electrodes.
As soon as the circuit is closed, the intermediate pieces of carbon become heated
to a bright white heat and the emery commences to melt. The several pieces of
carbon become mixed with the emery in process of fusion, are absorbed by the metallic
oxide which is. in consequence, reduced, and there soon forms a luminous are between
the carbon electrodes, a humming sound notifying that this stage is reached.

page_text: After a time a mass of molten emery (indicated at F) will surround the luminous
are, which mass, where it approaches the unmelted material S, forms a firm and
rigid crust.
When the reducing action is in progress, carbonic oxide escapes through the inter-
stices in the furnace wall and in the surface of the emery, and if this be kindled the
flames hover around the furnace; and this will indicate that the reduction of the
metallic oxide is in full operation. When the heat has become sufficiently intense to
melt the plate P, the molten emery will rush in the form of a white or incandescent
jet through the said orifice P into the space B beneath, the bottom or floor of which
should be preferably strewn with ordinary coarse-grained emery powder, in order to
protect the brickwork from the effects of the excessively high temperature at which
the liquid emery issues from the furnace.
Care should be taken to enable fresh emery to follow up from the top, the material
which is being discharged below, and this is best effected by breaking up the hardened
crust by means of an iron bar or otherwise. The fresh supply of emery will then
exercise such a cooling action upon the molten emery leaving the furnace that a
portion of this enery, by solidifying will close the discharge-orifice or outlet D which
outlet will not again re-open until the last mentioned part of the emery is once more
thoroughly melted. In some cases, it may be desirable to assist the discharge
somewhat from below which may be done by means of an iron hook.
The process may thus be carried on continuously; molten emery, free from iron,
being discharged at intervals of say from 10 to 15 minutes while fresh charges of
material are superadded from time to time, to be melted in their turn.
The solidified final product will assume the appearance of a crystalline mass which
will either be colourless, or possess the resinous lustre of quartz; or in some cases it
may be of a hue not unlike that of ruby, or it may be a decided blue with small
crystalline protuberances which subsequently form in the recesses and are of a deep
blue or sapphire colour.
As regards the proportion of powdered charcoal or the like to be employed, it
would preferably amount to 5 per cent., added to emery containing say, 25 per cent.
of metallic oxide. But even an addition of 4 per cent. of charcoal or the like would
be sufficient, seeing that the carbon electrodes projecting inwardly and entering the
molten material to some extent participate in the reducing process.
The metal separated naturally contains small quantities of aluminium since, after
all the iron has been eliminated the reducing action of the small surplus quantities of
carbon does not cease abruptly; while on the other hand, such a slight surplus is
necessary, if a total elimination of the iron is to be ensured."
The metallic alloy may be partly collected in coarse lumps, whilst the fused mass
is being broken up, and be partly separated by means of an electro-magnetic elimi-
nating apparatus (after having been further divided). In carrying out the process on
a large scale an alternate current machine of 300 amperes and of 110 volt tension is
suitable. The current during the operation being one say of from 250 to 300 amperes
and the tension (at the binding posts) being from 40 to 60 volts. Both the quantity
and the tension of the current are apt to fluctuate a good deal during the progress
of the operation, more especially while the emery is being discharged below and
followed up by fresh charges from the top.
An important advantage of this process resides in the fact, that it enables the dust
remaining behind after the grinding of emery, which in itself is of but little market-
able value and scarcely utilisable in the trade, to be employed as initial or raw
material as upon being introduced into the furnace, it fuses into a compact mass
free from iron.
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.
1. A process for converting native emery into corundum free from iron and
moisture by mixing the native emery with carbonaceous matter and cubiouting it

page_text: within an electrical melting furnace to be heating action of an electric arc produced
by alternating electrical current, until the mixture is fused and united.
2. An electric furnace for carrying out in a continuous manner the process claimed
by the preceding claiming clause the said furnace being provided at bottom with
a discharge orifice or outlet such as D, temporarily closed by a readily fusible plate
such as P.
Dated this 8th day of June 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.