Improvements in the Manufacture of Carbons for Electrical Purposes.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Carbons for Electrical Purposes.
I, CECIL LORD SAUNDERS, of North Tonawanda) State of New York, United
States of America, Engineer and Manufacturer, do hereby declare the nature of
this invention to be as follows:-
My invention consists in a novel and improved process of treating the material
used for manufacturing carbons for arc-light electrodes and for other purposes, and
in an improved method of manufacturing such carbons. My process is inde-
pendent of any special machinery, and may be carried out by any suitable
mechanism adapted to the various operations hereinafter described and in fact
each step of the process is capable of application by means of various different
forms of apparatus.
invention
For a better understanding of the actual improvement effected by my
in the manufacture of carbons for electrical purposes, I will first describe in a general
way the process previously employed in that manufacture, premising that the
various steps of the process are usually conducted in separate departments, and
usually in separate buildings, from one to the other of which the materials in
course of treatment have to be transported between each successive step.
The chief material of electrical carbons is coke, as is well known, the coke from
petroleum stills being very extensively used to which is added as a binder a certain
percentage of pitch, and occasionally in some cases small amounts of other sub-
stances as will be hereinafter described. Starting therefore with the coke, in the
previous process the coko is first crushed, then calcined, then ground, then bolted
or otherwise freed from all coarse particles; the pitch is ground, then sifted, and
the finely ground coke and pitch are intimately mixed, usually by the aid of heat;
the mixed material is then cooled, and finally is is reground, and then constitutes
what is known as 'molder's stuff," and forms the material used in the subse-
quent steps of molding, baking, etc., by which the finished carbons are produced.
In distinction from the foregoing process I proceed in the following manner;
I take the crushed coke resulting from the first step of the previously described
process, which, however, may be much more coarsely crushed than in the previous
process described, or I take any form of carbon, such as lampblack or graphite,
and placing it in a suitable agitator which can be closed vapor tight, I add a
suitable solvent, for which purpose I employ any volatile carbon compound which
is liquid at atmospheric temperature and is a solvent for hydrocarbons, resins and
soluble organic carbon compounds, such liquids as benzole, carbon bisulphide,
eucalyptol, dead oil, etc. being suitable; and I also add the proper proportion of
pitch, tar or oils, and any other desired ingredients such as are frequently added

page_text: in the ordinary manufacture of carbons, such for instance as sulphuric acid, phos-
phates, cyanides, wax, or salts such as those of sodium, calcium, strontium, lithium,
cerium, tungsten, thorium, indium, boron, etc.. etc., for increasing the brilliancy or
luminosity of the arc, or effecting the physical characteristics of the carbon. The
mass is then agitated thoroughly, with the result that by the action of the solvent
the coke becomes friable and soft, the pitch dissolves, and with the waxy hydro-
carbons dissolved from the coke forms a more or less thin solution, whose
consistence depends, of course, upon the amount of solvent used. In practice an
amount about sufficient to cover the solid material is added, and produces a solu-
tion of about the thickness of syrup or molasses.
The effect of such solution and agitation is to secure an absolutely uniform
blending of the ingredients, almost atomic in its nature, whereas the utmost
endeavours to secure a uniform amalgamation and mixture of the ingredients by
the method of dry mixing as before described have proved only approximately
successful.
When the agitation is finished, which ordinarily need not exceed about one
hour's time, the slimy mixture is run out gradually from the agitator (continuing
the agitation meanwhile) into a vapor-tight wet-grinding apparatus, in which it is
reduced to a smooth pulpy condition like that of well ground paint, and from
which grinder it passes to a vapor-tight still, in which the material is heated, either
by steam or fire heat, to a temperature sufficient to evaporate out the solvent and
all volatile extracted hydrocarbons which vaporize at moderate temperatures,
say 250° to 350° F. The vapors so driven off are condensed and removed for
subsequent use. The material left by the removal of the volatile matters is a
dry powder, which is evacuated from the still and cooled, when it constitutes the
"molder's stuff" before referred to, and is molded into the desired form and
baked in the same manner as if it had been prepared by the previous process first
described.
From the condition of "molder's stuff" above described, the common method
of manufacture is to mix the stuff while heated with tar or oil etc and form it into
balls or masses which while still hot are placed in the cylinder of a heavy press
and forced out through a die, thus moulding the carbons into the required form,
after which they are cooled and then baked.
By my improved process I dispense with the remixing and with the forming of
the balls or masses, and by adding the required proportion of oil tar, etc. in the
first place and stopping the distillation at the proper point, when the contents of
the still are at the right consistency. I produce the mixture of a consistency and
temperature adapted to be at once transferred to the cylinder of the forcing press,
and forced into carbons of the required form.
While I have described my improved process as applied to the treatment of coke,
which is the material generally employed in the manufacture of carbons, and
which contains a small proportion of still-wax and undefined heavy hydrocarbons
which, under high temperature, act as binders for the fixed carbon, it is to be.
distinctly understood that I do not limit my invention to the use of such carbon-
aceous compounds as contain hydrocarbons, but include the use of graphite or
other form of carbon not containing hydrocarbons; the essential and primary
feature of my invention being the effecting of the necessary intimate and uniform
mixture of the materials in a wet state by the use of some of the ingredients in
liquid form, instead of by mixing in the dry way. A secondary feature of my
invention is, however, the extraction of the heavy waxy hydrocarbons from coke
by solution instead of by driving off the same by calcining. As a practical matter
the aim and effort of carbon manufacturers is to secure a coke as free as possible
from hydrocarbons, so as to save as much as possible of the expense of calcining;
but by my invention I am enabled to use a coke containing more than the usual
amount of hydrocarbons, since all of it may, if desired, be extracted from the
coke and recovered. To do this I first macerate the crushed coke in the solvent
without the addition of other matters, and with or without agitation, and draw

page_text: off the solution, from which by ordinary distillation I recover the solvent and the
heavy hydrocarbon separately. I then add the pitch, oil or other binder and a
fresh quantity of solvent, and proceed in the manner before described for the
application of my process.
In the baking of the carbons a temperature is reached very much higher than is
employed in calcining, and in this baking any traces of hydrocarbon not removed
in the distillation are either driven off or cracked and converted into fixed carbon.
Dated the 8th day of Febru 1898
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.
Improvements in the Manufacture of Carbons for Electrical Purposes.
I, CECIL LORD SAUNDERS, Mechanical and Electrical Engineer, residing at
North Tonawanda, in the County of Niagara and State of New York, United
States of America, 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:-
My invention consists in a novel and improved process of treating the material
used for manufacturing carbons for arc-light electrodes and for other purposes, and
in an improved method of manufacturing such carbons. My process is inde-
pendent of any special machinery, and may be carried out by any suitable
mechanism adapted to the various operations hereinafter described and in fact
each step of the process is capable of application by means of various different
forms of apparatus. In the drawing hereto annexed I have shown one form and
arrangement of apparatus by which my improved process may be applied.
For a better understanding of the actual improvement effected by my invention
in the manufacture of carbons for electrical purposes, I will first describe in a general
way the process previously employed in that manufacture, premising that the
various steps of the process are usually conducted in separate departments, and
usually in separate buildings, from one to the other of which the materials in
course of treatment have to be transported between each successive step.
The chief material of electrical carbons is coke, as is well known, the coke from
petroleum stills being very extensively used to which is added as a binder a certain
percentage of pitch, and occasionally in some cases small amounts of other sub-
stances as will be hereinafter described. Starting therefore with the coke, in the
previous process the coke is first crushed, then calcined, then ground, then bolted
or otherwise freed from all coarse particles; the pitch is ground, then sifted, and
the finely ground coke and pitch are intimately mixed, usually by the aid of heat;
the mixed material is then cooled, and finally is is reground, and then constitutes
what is known as molder's stuff," and forms the material used in the subse-
quent steps of molding, baking, etc., by which the finished carbons are produced.
In distinction from the foregoing process I proceed in the following manner:
I take the crushed coke resulting from the first step of the previously described
process, which, however, may be much more coarsely crushed than in the previous
process described, or I take any form of carbon, such as lampblack or graphite,
and placing it in a suitable agitator which can be closed vapor tight, I add a
suitable solvent, for which purpose I employ any volatile carbon compound which
is liquid at atmospheric temperature and is a solvent for hydrocarbons, resins and
soluble organic carbon compounds, such liquids as benzole, carbon bisulphide,

page_text: eucalyptol, dead oil, etc. being suitable; and I also add the proper proportion of
pitch, tar or oils, and any other desired ingredients such as are frequently added
in the ordinary manufacture of carbons, such for instance as sulphuric acid, phos-
phates, cyanides, wax, or salts such as those of sodium, calcium, strontium, lithium,
cerium, tungsten, thorium, indium, boron, etc., etc., for increasing the brilliancy_or
luminosity of the arc, or effecting the physical characteristics of the carbon. The
mass is then agitated thoroughly, with the result that by the action of the solvent
the coke becomes friable and soft, the pitch dissolves, and with the waxy hydro-
carbons dissolved from the coke forms a more or less thin solution, whose
consistence depends, of course, upon the amount of solvent used. In practice an
amount about sufficient to cover the solid material is added, and produces a solu-
tion of about the thickness of syrup or molasses.
The effect of such solution and agitation is to secure an absolutely uniform
blending of the ingredients, almost atomic in its nature, whereas the utmost
endeavours to secure a uniform amalgamation and mixture of the ingredients by
the method of dry mixing as before described have proved only approximately
successful.
When the agitation is finished, which ordinarily need not exceed about one
hour's time, the slimy mixture is run out gradually from the agitator (continuing
the agitation meanwhile) into a vapor-tight wet-grinding apparatus, in which it is
reduced to a smooth pulpy condition like that of well ground paint, and from
which grinder it passes to a vapor-tight still, in which the material is heated, either
by steam or fire heat, to a temperature sufficient to evaporate out the solvent and
all volatile extracted hydrocarbons which vaporize at moderate temperatures,
say 250° to 350° F. The vapors so driven off are condensed and removed for
subsequent use. The material left by the removal of the volatile.amatters is a
dry powder, which is evacuated from the still and cooled, when it constitutes the
"molder's stuff" before referred to, and is molded into the desired. form and
baked in the same manner as if it had been prepared by the previous process first
described.
The apparatus shown in the drawings, which is suitable fór applying my
improved process, is described as follows:
A represents a macerator provided with an agitator a, this apparatus being in prin-
ciple similar to an ordinary pug-mill; B represents a grinding machine into which the
macerator discharges, and which is substantially like the common paint-mill in
principle and mode of operation; C represents a distilling tank provided also with
an agitator c and heated either by a furnace or by steam which may be blown in
through the agitator arms; D represents a condenser in which the vapors passing
off from the still through the vapor pipe are condensed and from which they are
returned to the storage tank E, whence by gravity or the pump F, the liquid
solvent is returned through pipes f f to the macerator A for a fresh charge.
Preferably a separator G is interposed between the condenser and the storage
tank to separate from the solvent the water condensed from the steam
although, as the solvent is insoluble in water and of a different gravity
they will separate naturally in tank E, and the water can be drawn off therefrom
if it enters the tank. All of the apparatus and connections are vapor-tight so that
the solvent never comes in contact with the air except when charged into the
closed macerator. To expel any vapor of solvent remaining in the macerator
after it is emptied of its charge, a steam pipe a² is connected thereto and steam
is blown in to fill the macerator, thus expelling the vapor of the solvent through
the pipe to the condenser.
From the condition of "molder's stuff" above described, the common method
of manufacture is to mix the stuff while heated with tar or oil etc. and form it into
balls or masses which while still hot are placed in the cylinder of a heavy press
and forced out through a die, thus moulding the carbons into the required form,
after which they are cooled and then baked.
By my improved process I dispense with the remixing and with the forming of

page_text: the balls or masses, and by adding the required proportion of oil, tar, etc. in the
first place and stopping the distillation at the proper point, when the contents of
the still are at the right consistency, I produce the mixture of a consistency and
temperature adapted to be at once transferred to the cylinder of the forcing press H,
and forced into carbons of the required form.
While I have described my improved process as applied to the treatment of coke,
which is the material generally employed in the manufacture of carbons, and
which contains a small proportion of still-wax and undefined heavy hydrocarbons
which, under high temperature, act as binders for the fixed carbon, it is to be
distinctly understood that I do not limit my invention to the use of such carbon-
aceous compounds as contain hydrocarbons, but include the use of graphite or
other form of carbon not containing hydrocarbons; the essential and primary
feature of my invention being the effecting of the necessary intimate and uniform
mixture of the materials in a wet state by the use of some of the ingredients in
liquid form, instead of by mixing in the dry way. A secondary feature of my
invention is, however, the extraction of the heavy waxy hydrocarbons from coke
by solution instead of by driving off the same by calcining. As a practical matter
the aim and effort of carbon manufacturers is to secure a coke as free as possible
from hydrocarbons, so as to save as much as possible of the expense of calcining;
but by my invention I am enabled to use a coke containing more than the usual
amount of hydrocarbons since all of it may, if desired, be extracted from the
coke and recovered. To do this I first macerate the crushed coke in the solvent
without the addition of other matters, and with or without agitation, and draw.
off the solution, from which by ordinary distillation I recover the solvent and the
heavy hydrocarbon separately. I then add the pitch, oil or other binder and a
fresh quantity of solvent, and proceed in the manner before described for the
application of my process.
In the baking of the carbons a temperature is reached very much higher than is
employed in calcining, and in this baking any traces of hydrocarbon not removed
in the distillation are either driven off or cracked and converted into fixed carbon.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1st. The process of treating carbonaceous materials for use in the manufacture
of carbons, which consists in mingling the carbonaceous materials with a solvent
for hydrocarbons, grinding the mixture while wet, and then distilling off the
volatile elements of the mixture.
2nd. The above described process of treating carbonaceous material for use
in the manufacture of carbons, which consists in mingling the carbonaceous
material with a binder in the presence of a solvent for the binder, grinding the
mixture while wet, and distilling off the solvent, substantially as described.
3rd. The above described process of treating carbonaceous material for use in
the manufacture of carbons, which consists in mingling the carbonaceous material
with a binder in presence of a solvent for hydrocarbons, grinding the mixture
while wet, and distilling off the volatile elements of the mixture, substantially
as described.
4th. The hereinabove described process for manufacturing carbons, which con-
sists in mixing the carbonaceous material, binder and other substances with a
solvent for the binder, grinding the mass while wet, then distilling off the volatile
elements, and then forming the carbons, substantially as described.
5th. The hereinabove described process for manufacturing carbons, which con-
sists in mixing the carbonaceous material, binder and other substances by
agitation with a liquid solvent for the binder, grinding the mass while wet, then
distilling off the volatile elements, and then forming the carbons, substantially as
described.

page_text: 6th. The hereinabove described process for manufacturing carbons, which con-.
sists in mixing the carbonaceous material, binder and other substances by
agitation with a liquid solvent for the binder, grinding the mass while wet, then
distilling off the volatile elements, and then forming the carbons without cooling.
the material.
VIEW DOC eptember
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.