Improvements in and Apparatus for the Treatment of Waste Rubber Goods to Recover the Rubber therefrom, and the Production of a New Product by such Treatment.
Year: 1889

page_text: Date of Application, 17th Dec., 1889
Complete Specification Left, 17th Mar., 1890-Accepted, 10th May, 1890
PROVISIONAL SIECIFICATION:
Improvements in and Apparatus for the Treatment of Waste Rubber
Goods to Recover the Rubber therefrom, and the Production of
a New Product by such Treatment.
I, JAMES YATE JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, do hereby declare the nature of this Invention (which has been com-
municated to me from abroad by Nathaniel Chapman Mitchell, of Philadelphia, in
the State of Pennsylvania, United States of America, Manufacturer,) to be as
follows:-
This Invention has reference to recovering rubber from waste rubber goods, that
is to say separating the rubber from foreign matters associated with it, and restoring
the rubber itself to such condition that it can be re-used in the manufacture of rubber
goods.
The invention embraces the various steps or operations performed upon the stock
as well as the machinery or apparatus which has been devised for use in carrying
out the process and also a new article of restored rubber produced thereby.
The bulk of the waste stock available for treatment in accordance with this
invention, consists of old boots and shoes, which may be taken as a fair sample of
the articles to be treated. When collected by junk dealers, this stock contains much
dirt and sand, not only on the surface but ground into the fabric. The rubber has a
backing of fibrous material, sometimes cotton, and sometimes wool, upon which it has
been vulcanized, and to which it therefore adheres tenaciously, the fibre being to some
It also contains much
extent impregnated with rubber which is desirable to recover.
All these and other
metal in the shape of buckles, nails, stiffeners and the like.
foreign substances, which are unavoidably mixed with the stock in great quantity,
have to be separated and removed from the rubber, and the latter must be treated in
a special way to bring it again to a condition resembling crude gum, susceptible of
vulcanization.
By long continued effort and experiment my foreign correspondent has succeeded
in developing a process whereby this waste stock can be treated with certainty, and in
an economical manner, removing all foreign matters from the rubber, without
appreciable loss thereof, and resulting in a uniform and satisfactory product.
The mode of procedure is as follows: After the stock is picked over and sorted,
and what is unfit for treatment thrown to one side, the available stock is reduced to
fargments of a size convénient for further treatment. This is the first step of the
process, and it is preferably effected by means of a cracker mill of special construction
and which forms a part of this invention.
The cracker mill consists of several (say three) pairs of rolls, between which the
stock is ground. It is found in using such rolls that it is very desirable to keep
them full to prevent lashing and breaking; but that on the other hand the strain
resulting when the rods are kept full from end to end, produces speedy deterioration.
These difficulties are overcome by the use of a guide block or guide blocks, arranged
to confine the stock to the surface of the rolls on one side of the said block or
blocks, and to cut off the rest of the rolls. By shifting these blocks from time to
time, new acting surfaces are obtained, uniformity of wear is secured and the time
during which the rolls can be used is greatly increased.
A further improvement consists in feeding the rubber to the last pair of cracker
rolls over a screen through which the fragments which are already sufficiently reduced
may pass, while the larger fragments are fed on between the final rolls and further
reduced.
The stock contains much iron and steel in the form of nails, buckles, stiffeners and

page_text: the like which it is very desirable to remove before acting on the stock with acid to
corrode the fibre.
According to this invention the stock is conveyed by an elevator from the reducing
rolls and fed continuously through a magnetic separating apparatus, consisting of a
series of plates, one beneath the other magnetized by permanent magnets and finally
through the field of electro-magnets, the particles of stock being constantly shifted in
falling from one set of magnets to the next, so to expose all parts of the mass to
the magnetic attraction. The combination of permanent and electro-magnets is found
to act very efficiently for the purpose.
This portion of the operation is preferably conducted in a close chamber at the top
of which is a pipe provided with an exhaust fan, which draws out much of the dust
that is freed from the falling mass of rubber.
The stock, freed from all magnetic substances. falls upon an endless belt or conveyor
which travels above a series of receivers, and preferably terminates immediately
above the last of the receivers so as to discharge into it. The belt is provided with a
series of clearers, or dischargers, one for each receiver except the last, and with means
for operating each clearer or discharger independently of the others, so that, at
the will of the operator the stock carried by the belt may be discharged into any
one of the receivers. These dischargers are preferably air pipes having their orifices
above the belt and combined with a mechanical blower. Another air-pipe directed
against the underside of the belt keeps it clear of dust.
These receivers communicate with the cooking tank or vessel, wherein the stock
is treated with acid and steam or by other suitable agents, to corrode and disintegrate
the fibre. This treatment with acid and steam is not new in itself, and is included
only as a step in the process. The cooking tank is provided with a discharge gate
of peculiar construction having a non-corrodible lining, and held fast by a clamping
har detachably mounted on a removable support. This gate prevents leakage and
waste of acid, and being readily removable it permits the contents of the vessel to be
discharged directly into the washing tub, to assist in which a properly directed.
stream of water is employed. Heretofore the cooking vessel has been commonly
emptied by hand, using copper buckets, which was a very laborious and disagreeable
operation.
The washing tub, which is cylindrical in shape, is provided with a large conical
roller. such as is commonly employed in apparatus for washing rags and other
materials. To the beam which draws this roller around the tub, are attached plows or
stirrers. adjustable both vertically and radially, which stir up the stock from the
bottom of the tub. In this apparatus the stock is washed with repeated waters, until
all soluble matters such as mud, decomposed fibre, and other foreign substances, which
can be carried off in this way, are removed. When this is effected the ploughs are
turned at such an angle as to urge the stock towards the periphery of the tub, the
discharge gate in the side of the latter is opened, and by a few turns of the shaft the
tub is emptied, the stock falling into an elevator boof, whence it is conveyed io a
rotatory washer and sand separator.
This latter apparatus is employed to sift out the sand andgrit and all fine impurities.
It is a foraminous cylinder of large diameter. preferably inclined from its feed and
downward, and arranged over a tank or receptacle. As the cylinder rotates a stream
of water is directed into it obliquely striking against the stock with violence as it is
raised by the longitudinal ribs with which the cylinder is provided. The agitation
which the stock receives in passing through the cylinder shakes off most of the
moisture so that the rubber is discharged in practically a dry state.
A small quantity of the rubber is in particles sufficiently fine to pass through the
perforations of the cylinder with the sand and water, and this rubber is of a very fine
quality. To recover it the refuse collected in the tank under the cylinder is carried
by a connecting pipe to the bottom of an apparatus which may be termed a specific
gravity separator. It has inclined walls and vertical partitions, and an overflow or
discharge spout at one side. The partitions form a stagnant portion in the middle
part of the vessel so that sand and heavier matters settle to the bottom, while the

page_text: lighter particles of rubber are carried by the water over the side of the vessel and are
arrested by a very fine screen.
The main portion of the rubber stock may be treated in a similar way to remove
gravel, brass buckles, rivets, eyes, and many other foreign substances.
The next step is the devulcanization and desulphurization of the rubber. In carrying
out this part of the process, the rubber is exposed to the action of heat, preferably
steam heat, in a devulcanizer of special construction.
The steam acts mainly to soften the rubber. and has but little effect in removing
the sulphur. My foreign correspondent has discovered that desulphurization may be
effected by mixing with the rubber a small quantity of sulphide of calcium previously
to the treatment with steam. When calcium sulphide is used alone it requires a very
high degree of heat to effect desulphurization, which high degree of heat dries the
rubber to an injurious extent. it is therefore desirable to mix with the calcium
sulphide some substance which will keep the rubber in a moist condition. For this
purpose it is preferred to use heavy petroleum. Seven pints of the mixture of
petroleum and sulphide of calcium to two hundred pounds of rubber scrap, will
generally he sufficient and seven pints of the fluid contains one-quarter of a pound of
the sulphide. Heavy netroleum alone has been used prior to this invention, and its
use broadly is not claimed.
The devulcanizer in which the operation is carried on, as well as the method of and
apparatus for charging and discharging the same. constitutes special features of this
invention.
It has heretofore been a very tedious and difficult operation to fill the devulcanizer
with a full charge of rubber, and a still more difficult one to remove the charge after
treatment, inasmuch as the rubber becomes compacted and set by the action of the
sicam: It has been customary to introduce the rubber in pans or vessels, which rest
uhon à wagon or truck rolled into the devulcanizer, but by this means. in addition to
the difficulty of handling it is impossible to utilize anything like the full capacity of
the devulcanizer, or to direct the steam through all parts of the mass.
It is an object of this invention to effect devulcanization in bulk, that is to say, with
the rubber charged directly into the cylinder and resting on the bottom thereof, which
1 believe has never before been accomplished.
By so doing a more thorough and uniform distribution of the steam can be effected.
and when it is desired to draw air through it, as presently described; this can he
accomplished without difficulty. It would be obviously impracticable to maintain
such a circulation through all parts of a mass contained in pans, and the result would
not be uniform.
The devulcanizer employed in the process is a long cylinder disposed horizontally.
and say about five feet in diameter and having a capacity of say from sixteen thousand
to twenty-eight thousand pounds, more or less. It is provided with a perforated false
bottom for admission and distribution of the steam, and a pair of rails extend
lengthwise of the cylinder. On these rails a series of hooks is run somewhat
similar to inverted rakes, and formed each of metal bars with spaces between for
the circulation of the steam. In charging, one of these hooks, to the end of which is
attached a chain, is placed at the end of the cylinder, and a car or truck filled with
rubber to be treated is run in and its load empted into the cylinder by means of a
follower on the car actuated by apparatus outside of the cylinder.
This is repeated until the cylinder is full to a height of say four or five feet, when
a second hook is introduced, and so on until the cylinder is fully charged and the
rubber fills it solidly from end to end and to within a short distance of the top.
The cylinder is provided with a removeable head which is now swung into place
and secured by bolts. Steam is then turned on and the valves adjusted to maintain
a pressure of say from 100 to 120 pounds. Under these conditions the hydrocarbon
oil combines with the rubber, and the sulphide of calcium removes the free sulphur.
combining with it to form persulphide of calcium. This is to a large extent, removed
in the water of condensation.
According to the present invention there is a constant circulation of steam through

page_text: the devulcanizer, the steam passing through the perforations in the false bottom (by
which it is diffused uniformly through the mass of rubber) and escaping through a
suitable pipe which leads to a condenser.
After the operation has continued a sufficient time, say for thirty-six hours. the
cylinder is blown off from the top and bottom valves, and, so soon as the pressure is
reduced to the normal, a vacuum pump is connected with a suitable pipe opening
preferably into the bottom of the cylinder, drawing air (for say about an hour) through
the mass of rubber from top to bottom. This is a very important step in the process,
since thereby much time is saved in drying, to effect which the residual heat of the
devulcanizer is thus utilized, and the latter moreover is partly cooled down.
The next step is the removal of the devulcanized rubber, which is effected by
drawing out successively the several hooks, each hook carrying in front of it a mass
of rubber, which is immediately broken up and passed through disintegrating, rolls.
The use of the perforated false bottom and the uniform distribution of the heat
thereby effected, is particularly advantageous in that it prevents unequal expansion
and contraction of the devuclanizer, which in a vessel of such dimensions it is of
great importance to avoid. Moreover as the steam is constantly passing in and out,
the temperature of the devulcanizer at the top is practically the same as at the
bottom.
After devulcanization is effected the process may be completed by drying the rubber
in an artificially heated atmosphere, and then sheeting by means of rolls, and a good
commercial product is obtained in this way. But my foreign correspondent has
discovered that a very remarkable effect upon the appearance. quality and properties of
the product is obtained by passing the rubber through rolls while in a moist condition.
that is to my directly after its removal from the devulcanizer. Not only is a very
important improvement thus effected, but the time consumed in drying (say twelve
hours) is saved. the apparatus used therefor is rendered unnecessary, and valuable
floor space in the factory is economized.
The rubber produced by this process is remarkable for its homogenity, and its
uniformity throughout. beine free from hard lumps and inequalities that are con-
spicuous in the ordinary product. Further, the rubber made by the new process is
characterized by great strength and elasticity and by a smooth and velvety surface.
which characteristics distinguish it from restored rubber as ordinarily produced.
It is not possible to obtain the same effect by simply moistening rubber after it
has once been dried, and then sheeting. which is probably due to the fact that the
moistening of the stock in the devulcanizer is effected under a very high pressure.
and therefore the moisture is forced into all the interstices and brought into intimate
contact with every particle of the mass of rubber.
It is essential therefore in carrying out this invention, that the moisture be applied
under such conditions as to permeate effectually every part of the mass of rubber.
The required condition of moisture may, of course. be obtained by the use of water
under pressure: but steam is preferred.
To produce the very best result it is desirable to continue the rolling and sheeting
by passing the rubber between successive rollers. or a number of times between the
same rollers. until perfectly dry; but it is not always convenient or expedient to do
this, and it suffices to make an excellent grade of rubber. to give the rubber three
or four passes while yet moist, and then spread it to dry.
To form a perfect sheet by continuous rolling of the moist rubber requires about
sixteen passes, making the sheeting process somewhat longer and more difficult than
in dry sheeting. The rubber begins first to assume a powdery, then a filamentary
appearance, and then the filaments unite presenting a veil-like form which gradually
develops into a fine sheet of uniform texture, having a smooth velvety surface pre-
senting a marked contrast to the usual product. During all the rolling, moisture and
considerable refuse exude from the mass, and any hard and gritty substances that
may remain are also removed. The drying is assisted by the heat of the rolls due
to the great friction, which heat, in this process of moist rolling, becomes a useful
factor, instead of being detrimental and injurious as in the process of dry sheeting

page_text: The ordinary sheeting mill consists of a single pair of rolls, and while this part of
the process can be practised with it, it is preferred to employ a mill of special con-
struction comprising a number of rolls arranged in series one above another, and
adapted to give the rubber as many squeezes as there are rolls less one.
The rolls
in this mill are supported by castings having in each edge recesses in which the
journal boxes of the rolls rest, and in which they have a horizontal adjustment to
regulate the space between the rolls. Other castings confine the journal boxes in
these recesses and carry adjusting screws.
To produce a devulcanized rubber powder, which is a new commodity, the above
moist rolling process is arrested when the rubber is in the powdery stage, and the
powder is then dried keeping it constantly stirred up or in motion, to preserve the
pulverulent condition.
Dated this 17th day of December 1889.
J. H. JOHNSON & Co.,
Agents.
COMPLETE SPECIFICATION.
Improvements in and Apparatus for the Treatment of Waste Rubber
Goods to Recover the Rubber therefrom, and the Production of
a New Product by such Treatment.
I, JAMES YATE Jonsson. of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, do hereby declare the nature of this Invention (which has been com-
municated to me from abroad by Nathaniel Chapman Mitchell, of Philadelphia. in
the State of Pennsylvania, United States of America, Manufacturer) and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement:-
This Invention has reference to recovering rubber from waste rubber goods, that
is to say separating the rubber from foreign matters associated with it, and restoring
the rubber itself to such condition that it can be re-used in the manufacture of
rubber goods.
The invention embraces the various steps or operations performed upon the stock
as well as the machinery or apparatus which has been devised for use in carrying
out the process and also a new article of restored rubber produced thereby.
The bulk of the waste stock available for treatment in accordance with this
invention, consists of old boots and shoes, which may be taken as a fair sample of
the articles to be treated. When collected by junk dealers. this stock contains
much dirt and sand, not only on the surface but ground into the fabric. The rubber
has a backing of fibrous material, sometimes cotton. and sometimes wool, upon which
it has been vulcanized, and to which it therefore adheres tenaciously, the fibre being
to some extent impregnated with rubber which is desirable to recover. It also
contains much metal in the shape of buckles. nails, stiffeners and the like. All
these and other foreign substances, which are unavoidably mixed with the stock in
great quantity, have to be separated and removed from the rubber. and the latter
must be treated in a special way to bring it again to a condition resembling crude
gum, susceptible of vulcanization.
By long continued effort and experiment my foreign correspondent has succeeded
in developing a process whereby this waste stock can be treated with certainty, and
in an economical manner, removing all foreign matters from the rubber, without
appreciable loss thereof, and resulting in a uniform and satisfactory product.
The mode of procedure is as follows.
After the stock is picked over and sorted. and what is unfit for treatment thrown
to one side, the available stock is reduced to fragments of a size convenient for
further treatment. This is the first step of the process. and it is preferably effected
by means of a cracker mill of special construction and which forms a part of this
Invention.
The cracker mill consists of several (say three) pairs of rolls, between which the

page_text: stock is ground. It is found in using such rolls that it is very desirable to keep
them full to prevent lashing, and breaking; but that on the other hand the strain
resulting when the rolls are kept full from end to end. produces speedy deterioration.
These difficulties are overcome by the use of a guide block or guide blocks, arranged
to confine the stock in the surface of the rolls on one side of the said block or
blocks, and to cut off the rest of the rolls by shifting these blocks from time to
time, new acting surfaces are obtained uniformity of wear is secured and the time
during which the rolls can be used is greatly increased.
A further improvement consists in feeding the rubber to the last pair of cracker
rolls over 1 sereen through which the fragments which are already sufficiently
reduced may pass. while the larger fragments are fed on between the final rolls
and further reduced.
The stock contains much iron and steel in the form of nails, buckles, stiffeners
and the like which it is very desirable to remove before acting on the stock with
acid to corrode the fibre.
According to this invention the stock is conveyed by an elevator from the reducing
rolls and fed continuously through a magnetic separating apparatus, consisting of
a series of plates, one beneath the other. magnetized by permanent magnets, and
finally through the field of electro-magnets, the particles of stock being constantly
shifted in falling from one set of magnets to the next, so as to expose all parts
of the mass to the magnetic attraction. The combination of permanent and electro-
magnets is found to act very efficiently for the purpose.
This portion of the operation is preferably conducted in a close chamber at the
top of which is a pipe provided with an exhaust fan which draws out much of the
dust that is freed from the falling mass of rubber.
The stock, freed from all magnetic substances. falls upon an endless belt or
convevor which travels above a series of receivers. and preferably terminates
The belt
immediately above the last of the receivers so as to discharge into it.
is provided with a series of clearers, or dischargers, one for each receiver except
the last, and with means for operating each clearer or discharger independently of
the others, so that, at the will of the operator the stock carried by the belt may
be discharged into any one of the receivers. These dischargers are preferably air
pipes having their orifices above the belt and combined with a mechanical blower.
Another air pipe directed against the underside of the belt keeps it clear of dust.
These receivers communicate with the cooking tank or vessel. wherein the stock
is treated with acid and steam or by other suitable agents, to corrode and disintegrate
the fibre. This treatment with acid and steam is not new in itself, and is included
only as a step in the process. The cooking tank is provided with a discharge gate
of peculiar construction having a non-corrodible lining, and held fast by a clamping
bar detachably mounted on a removable support. This gate prevents leakage and
waste of acid, and being readily removable it permits the contents of the vessel to be
discharged directly into the washing tub, to assist in which a properly directed
stream of water is employed. Heretofore the cooking vessel has been commonly
emptied by hand, using copper buckets, which was a very laborious and disagreeable
operation.
The washing tub, which is cylindrical in shape, is provided with a large conical
roller. such as is commonly employed in apparatus for washing rags and other
materials. To the beam which draws this roller around the tub, are attached
ploughs or stirrers, adjustable both vertically and radially, which stir up the stock
from the bottom of the tub. In this apparatus the stock is washed with repeated
waters. until all soluble matters such as mud. decomposed fibre, and other foreign
substances, which can be carried off in this way, are removed: when this is effected
the ploughs are turned at such an angle as to urge the stock towards the periphery
of the tub, the discharge gate in the side of the latter is opened, and by a few turns
of the shaft the tub is emptied. the stock falling into an elevator cot, whence it is
conveved to a rotatory washer and sand separator.
This latter apparatus is employed to sift out the sand and grit and all fine

page_text: impurities. It is a foraminous cylinder of large diameter, preferably inclined from
its feed end downward, and arranged over a tank or receptacle. As the cylinder
rotates a stream of water is directed into it obliquely striking against the stock
with violence as it is raised by the longitudinal ribs with which the cylinder is pro-
vided. The agitation which the stock receives in passing through the cylinder shakes
off most of the moisture so that the rubber is discharged in practically a dry
state.'
A. small quantity of the rubber is in particles sufficiently fine to pass through the
perforations of the cylinder with the sand and water, and this rubber is of a very fine
quality. To recover it the refuse collected in the tank under the cylinder is carried by
connecting pipe to the bottom of an apparatus which may be termed a specific gravity
separator. It has inclined walls and vertical partitions, and an overflow or discharge
spout at one side. The partitions form a stagnant. portion in the middle part of the
vessel so that sand and heavier matters settle to the bottom, while the lighter particles
of rubber are carried by the water over the side of the vessel and are arrested by a
very fine screen.
The main portion of the rubber stock may be treated in a similar way to remove
gravel, brass buckles, rivets, eyes and many other foreign substances.
The next step is the devulcanization and desulphurization of the rubber. In
carrying out this part of the process, the rubber is exposed to the action of heat,
preferably steam heat, in a devulcanizer of special construction.
The steam acts mainly to soften the rubber and has but little effect in removing the
sulphur. My foreign correspondent has discovered that desulphurization may be
effected by mixing with the rubber a small quantity of sulphide of calcium previously
to the treatment with steam. When calcium sulphide is used alone it requires a very
high degree of heat to effect desulphurization, which high degree of heat dries the
rubber to an injurious extent. It is therefore desirable to mix with the calcium
sulphide some substance which will keep the rubber in a moist condition. For this
purpose it is preferred to use heavy petroleum. Seven pints of the mixture of
petroleum and sulphide of calcium to two hundred pounds of rubber scrap will
generally be sufficient and seven pints of the fluid contains one quarter of a pound of
the sulphide. Heavy petroleum alone has been used prior to the invention, and
its use broadly is not claimed.
The devulcanizer in which the operation is carried on, as well as the method of
and apparatus for charging and discharging the same, constitute special features of this
Invention.
It has heretofore been a very tedious and difficult operation to fill the devulcanizer
with a full charge of rubber, and a still more difficult one to remove the charge after
ireatment, inasmuch as the rubber becomes compacted and set by the action of the
steam. It has been customary to introduce the rubber in pans or vessels, which
resis upon a wagon or truck rolled into the devulcanizer, but by this means, in
addition to the difficulty of handing it is impossible to utilize anything like the full
capacity of the devulcanizer, or to direct the steam through all parts of the mass.
It is an object of this Invention to effect devulcanization in bulk, that is to say,
with the rubber charged directly into the cylinder and resting on the bottom thereof,
which I believe has never before been accomplished.
By so doing a more thorough and uniform distribution of the sieam can he
effected, and when it is desired to draw air through it, as presently described, this
can be accomplished without difficulty. It would be obviously impracticable to
maintain such a circulation through all parts of a mass contained in pans, and the
result would not be uniform.
The devulcanizer emploved in the process is a long cylinder disposed horizontally
and say about five feet in diameter and having a capacity of say from sixteen thousand
to twenty eight thousand pounds, more or less. It is provided with a perforated false
bottom for admission and distribution of the steam, and a pair of rails extend length-
wise of the cylinder. On these rails a series of hooks is run somewhat similar to
juverted rakes, and formed each of metal bars with spaces between for the circulation

page_text: of the steam. In charging, one of these hooks, (to the end of which is attached. a
chain) is placed at the end of the cylinder, and a car or truck filled with rubber to be
treated is run in and its load emptied into the cylinder by means of a follower on the
car actuated by apparatus outside of the cylinder.
That is repeated until the cylinder is full to a height of say four or five feet, a
second hook being then introduced, and so on until the cylinder is fully charged and
the rubber fills it solidly from end to end and to within a short distance of the top.
The cylinder is provided with a removeable head which is now swung into place
and secured by bolis. Steam is then turned on and the valves adjusted to maintain a
pressure of say from 100 to 120 pounds. Under these conditions the hydrocarbon oil
combines with the rubber, and the sulphide of calcium removes the free sulphur,
combining with it to form persulphide of calcium. This is to a large extent, removed
in the water of condensation.
According to the present invention there is a constant circulation of steam through
the devulcanizer, the steam passing through the perforations in the false bottom (by
which it is diffused uniformly through the mass of rubber) and escaping through a
suitable pipe which leads to a condenser.
After the operation has continued a sufficient time, say for thirty-six hours, the
cylinder is blown off from the top and bottom valves, and, so soon as the pressure is
reduced to the normal, a vacuum pipe is connected with a suitable pipe opening
preferably into the bottom of the cylinder, drawing air, (for say about an hour)
through the mass of rubber from top to bottom. This is a very important step in the
process, since thereby much time is saved in drying, to effect which the residual heat.
of the devulcanizer is thus utilized, and the latter moreover is partly cooled down.
The next step is the removal of the devulcanized rubber. which is effected by
drawing out successively the several hooks each hook carrying in front of it a
mass of rubber, which is immediately broken up and passed through disintegrating
rolls.
The use of the perforated false bottom and the uniform distribution of the heat
thereby effected. is particularly advantageous in that it prevents unequal expansion
and contraction of the devulcanizer, which in a vessel of such dimensions it is of great
importance to avoid. Moreover as the steam is constantly passing in and out, the
temperature of the devulcanizer at the top is practically the same as at the bottom.
After devulcanization is effected the process may be completed by drying the
rubber in an artificially heated atmosphere, and then sheeting by means of rolls, and
a good commercial product is obtained in this way. But my foreign correspondent
has discovered that a very remarkable effect upon the appearance, quality and
properties of the product is obtained by passing the rubber through rolls while in a
moist condition, that is to say directly after its removal from the devulcanizer. Not
only is a very important improvement thus effected, but the time consumed in drying
(say twelve hours) is saved, the apparatus used therefor is rendered unnecessary, and
valuable floor space in the factory is economized.
The ordinary sheeting mill consists of a single pair of rolls, and while this part of
the process can be practised with it, it is preferred to employ a mill of special con-
struction comprising a number of rolls arranged in series one above another, and
The rolls in
adapted to give the rubber as many squeezes as there are rolls less one.
this mill are supported by castings having in each edge recesses in which the journal
boxes of the roll rest, and in which they have a horizontal adjustment to regulate the
space between the rolls. Other castings confine the journal boxes in these recesses
and carry adjusting screws.
To produce a devulcanized rubber powder which is a new commodity the above
moist rolling process is arrested when the rubber is in the powdery stage and the
powder is then dried keeping it. constantly stirred up or in motion, to preserve the
pulverulent condition.
T
In the accompanying drawings which form part of this specification Figures I to IV
illustrate the cracker mill Figure I being a plan view Figure Il a view in longitudinal
section showing the screen and the second and third pairs of rolls and Figures III

page_text: and IV views in vertical cross section and front elevation respectively showing the
third pair of rolls provided with an oscillatory screen.
Referring more particularly to Figures I and II the three sets of rolls marked.
respectively 1, 2 and 3 are arranged in any convenient relation as shown in Figure I.
Set No. 1 has a smooth roll a and a coarsely corrugated roll a¹. No. 2 has a roll b
with fine corrugations and another b¹ with coarse corrugations and No. 3 has two
rolls ce both with fine corrugations. The rolls are supported in bearings in suitable
supporting frames A. and provided with driving gears C. the journal boxes of one of
each pair of rolls being provided with set screws B as usual for regulating the space
between the rolls.
Upon the top of side frames A of each pair of rolls are bolted angle plates which
support the two guide rods e extending parallel with the axis of the rolls and from
end to end thereof. The rods e pass through and support the guide blocks E which
can he moved lengthwise of said rods to any position. The rods e are screw-threaded
and a jam nut is placed on each side of each block E to hold it in place. The shape
of the blocks E is clearly shown in Figures II and III.
In practice the blocks E are set about 16 or 18 inches apart and the rubber stock.
is fed in between them. Adiustment of blocks E when desired can be very quickly
effected. One of the blocks E may be removed altogether and the other set near the
middle of the length of the rolls so as to utilize only the portion of the rolls between
it and one of the side frames A. The construction and arrangement of the guide
blocks is the same for all the rolls.
The stock after being partially reduced by the rolls of mill No. 1 is delivered by
hand or by any suitable mechanical appliance to the rolls of No. 2 mill for further
reduction. The result of the action of these two pairs of rolls is that part of the stock.
is already in fragments sufficiently small for the further operations for recovering the
rubber whereas part of it requires still further reduction which is effected bymill No.3.
After passing between the rolls of No. 2 the stock slides down an inclined guide G
(Figure II) to the lower end of the screw conveyor H by which it is raised and fed
onto the upper end of an inclined screen I which leads to the rolls ce¹ of No. 3 mill.
Any suitable mechanical lifter would be the equivalent of the conveyor II and it may
even be omitted altogether and the stock thrown onto the screen by hand without
departing from the spirit of the invention.
C
As the stock slides by gravity down screen I the smaller fragments pass through it
and fall upon an inclined guide-way K which delivers it under the roll c¹ directly to
the elevator boot L (Figure 1). A guide or deflector is placed under the screen I
to prevent the fragments passing through the latter from being caught by the roll c¹.
The larger pieces of the stock are delivered by the screen I between the rolls e e¹
and after being further reduced by these rolls they fall upon the guide-way K and are
conveyed thereby to the elevator boot L.
The screen I is provided with guide-strips k to convey the stock between the blocks E.
These strips are pivoted at 7 to the upper end of the frame of the screen I so that when
the position of the blocks E is changed the strips can also be adjusted properly.
The screen I in Figures I and II is stationary. As shown in Figures III and IV
it is arranged to oscillate transversely. This screen at its upper end rests upon a
crosspiece m and at its lower end has a tongue n which is mortised in a groove in the
stationary strip which forms a continuation of the screen. To one side of the screen
frame is bolted an arm which carries two small friction rollers q. Between these
rollers is a star-shaped cam on a shafts to which motion is communicated through
a pulley t. By means of the cam ra rapid oscillatory motion is communicated to the
screen I whereby the operation of sifting out the smaller fragments of the stock is
performed more effectually.
The elevator L lifts the ground stock and delivers it to the magnetic separating
apparatus shown in Figures V and VI the former being a central vertical section
through the apparatus and the latter a front elevation partly in section.
A represents the casing forming a chamber in which the apparatus is set. L. is the
elevator by which the stock reduced to small fragments is fed into a chute C. From

page_text: this it falls into a hopper D provided with an inclined throat plate d adjustable by
means of thumb screws a so as to regulate the size of the discharge outlet of the
hopper. The plate, d is supported by a spring so that it is capable of yielding to
the pressure, of the mass passing through the outlet. In this outlet is, arranged a
futed rollere driven by a belt whereby, a regular feed of the stock is maintained:
The stock passes by gravity across the inclined plate fof iron or steel which is rendered
magnetic by a series of permanent horseshoe magnets g so that this plate will arrest
a portion of the magnetic particles contained in the niass. !
Above the plate and parallel therewith is an endless, belt mounted on rollers' 7.
Notion is communicated to the shaft of one of these' rollers by means of bevel
gears from the shaft of the fluted roller c. The belt carries wipers which travel
across the magnetized plate f and carry off the particles that adhere thereto dropping
them into a chute E. The machine as thus far described is of known construction.
The stock which passes the plate f falls into another hopper D' similar in construction
to the hopper D and a farther elimination of magnetic particles is effected, by a
plate f magnetized by magnets g
1!
A third separator F identical, in construction with the first and therefore requiring
no particular description is arranged beneath the others. Passing from this the stock.
strikes against a platem inclined nearly at a right angle to the plane of motion of
the stock through the first three separators. A fluted roller n at the lower end of
this plate feeds the stock through a throat plate o similar to that above described and
the mass slides by gravity across a magnetic plate which is magnetized by a series
of electro-magnets G in circuit with a dynamo or other source of electric energy.
This arrangement of permanent and electro-magnetic separators in series as described
is found to act very efficiently in eliminating all magnetic particles from the, stock
which particles are all collected by the wiper, mechanism with which each separator
is provided and deposited in the chute E. In passing from one separator to another
and particularly in passing to the last of the series the stock is somewhat shaken up
and its particles are shifted among themselves so that each separator of the series acts
upon a different part of the mass from the next preceding.
"
At the upper end of the chamber A is arranged a large. pipe. H provided with an
exhaust fan and having a flaring mouth K which overhangs the series of separators.
A gentle exhaust is maintained by the fan I which sucks out the fine dust a great
quantity of which is liberated from the mass under treatment, as it falls from one
separator into the next.
1
The arrangement of the exhaust pipe described and shown is found to be of great
importance. If the suction, apparatus were arranged to act directly upon the hopper
of one of the separators it would entail great loss of rubber particles as experience as
shown but by enclosing the series of separators in a close chamber and placing the
exhaust pipe at the upper part thereof with its mouthoverhanging the several separators
a great quantity of dust and dirt is carried away without removing any of the rubber.
From the electro-magnetic separator P the stock falls upon a belt L' which forms
part of the conveying and distributing mechanism, illustrated in Figures VII and
VITE of which the former is a side elevation partly in section and the latter a top view.
At the left of Figure VII. is shown the separator J in which the rubber is treated
to remove particles of iron and steel and which may be such as just described or of any
suitable construction.
Beneath the outlet of this separator is the feed end of; the endless belt or conveyor L
By which the rubber particles as they fall on to it are carried forward. This belt
turns on pulleys K Kand is supported at suitable intervals by friction rollers. The
shaft of pulley K is journaled, in adjustable bearings m and set screws » are provided
fór tightening the belt when necessary.
Beneath the belt L' near the discharge end thereof are receivers or reservoirs L, M, N.
Three are shown, but a greater or less number may be used as occasion may require.
The pulley is directly over the last receiver N so that all particles carried, to the
end of the belt will fall into it.
"At O'is placed a small fan or blower, which is kept in continuous action and from it

page_text: are led the air pipes 1, 2 and 3.
Pipe 1 has its discharge orifice opposite the
receiver L and directly over the belt while the orifice of pipe 2 is similarly,
arranged over the receiver M. If it be desired to fill the receiver L while the contents
of M and N are being withdrawn the valveo of pipe 1 is open while the valve of
pipe 2 is closed, hand levers p being provided to operate these valves. Fan Other
causes a steady current of air to play upon the 'belt L' carrying off all the particles of
rubber into the receiver Luntil sufficiently full. "A vertical screen or curtain P is
arranged alongside of the belt and the particles striking against it are deflected into
the receiver below. The air pipe 3 is conducted from the fan to the underside of the
return portion of belt L' and its function is to keep the belt clear from particles of
dust that may settle upon it.
The receivers L, M, N are provided with discharge gates operated by means of
handles through which outlets they may be emptied as desired into the cooking vessel
or tub for treating the stock for removal of fibrous matters.
This cooking tub is shown in Figures IX to XII, Figure IX being a longitudinal
vertical section of a cooking tank Figure X a vertical section at right angles to
Figure IX Figure XI a detail in horizontal section. illustrating the discharge gate and
Figure XII a vertical section of the same.
A represents the cooking tank or vessel made of wood with the usual lead lining and
provided with a flue or uptake B for the escape of vapours. The vessel A has a cover C
composed of several panels which can be readily removed when it, is desired to fill
the vessel from the receivers described above where the stock is accumulated one of
which receivers is shown at L (Figure, IX). D represents a steam pipe from which a
number of branch pipes dare led into the vessel the steam escaping through perfora-
tions in the lower horizontal part of the pipes d.
The discharge gate E is best shown in Figures XI and XII. It is composed of
wood metal or any suitable material and provided with, a lining e of Ajax metal so
called which as experience shows is well adapted to withstand the action of the acid
used in treating the rubber stock but other non-corrodible material-may be substituted.
The gate is hinged at its upper side to a rod F supported by harsh. The lining e has
a counter-sunk groove in which is a packing or gasket adapted to make a tight joint
with the shouldered frame G surrounding the outlet to the vessel, A.
On each side of the gate-way is a stout bar H bent at a right angle to its inner end
which passes behind the wall I. At their outer ends the bars H are provided with
hooks against which rests the cross bar K. The latter is provided with a threaded
opening or socket k at its centre and with a shoulder at each end which shoulders
engage the hooks on the bars H. A rod M having a threaded portion m which
engages the threaded opening & bears at its inner end in a step on the gate E. The
rod M has a hand wheel N for turning it by which sufficient pressure can be kept on
the gate E to make it perfectly tight and prevent leakage while the operation of
defiberizing the rubber is being carried on in the tank A.
When this operation is concluded the screw rod M is loosened and it and the cross-
bar K can be at once removed out of the way, so as not to be exposed to contact with
the acid in the vessel. The gate E is then raised and suspended by eye pupon
hook P the latter being attached to the end of chain 0. The contents of the tank A
at once begins to discharge itself being carried by gravity down the chute S and
water being turned on from a pipe Q the tank is completely flushed out.
This operation requires but a few minutes time and is attended with little difficulty.
The gate can be quickly replaced and secured and the tank can at once be filled with
another charge from one of the receivers L.
The stock when washed out of the cooking tank is discharged into the washing tub
illustrated in Figures XIII to XVI Figure XIII being a plan view Figure XIV a
sectional elevation and Figures XV and XVI details of the ploughs or stirrers.
The washing tub and its roller are such as commonly used in paper mills and other
factories and no novelty is claimed therein the invention consisting in the combination
with such old apparatus of the co-operating ploughs- or stirrers for loosening the mass

page_text: after it has once been compressed by the roller so that it can again become permeated
with moisture before the roller passes over it and for bringing up fresh portions of
the stock from beneath. The nature of old rubber stock is such that without such
ploughs or stirrers the washing operation is very slow.
A represents the tub or vat which is circular in form. At the centre is the upright
shaft driven by a pinion a which engages the gear wheel near the upper end of
said shaft. To the shaft B at a level slightly above the top of the tub is firmly
secured the cross-beam C.
D represents a large and heavy conical roller having a periphery formed of wooden
slats or bars set a slight distance apart. This roller rests by its own weight upon
the bottom of the tub. Its spindle d is attached at its inner end to the shaft B and ai
its outer end is connected to the cross-beam by a link so that the roller follows
the motions of the beam C around the tub.
Two traps E F are arranged alongside the tub which communicates with them by
means of gates ef. Each trap is covered by a fine perforated screen (Figure XIV)
which arrests particles of rubber but permits water mud and fine particles of sand and
the like to pass through. Most of the mud and other matters washed out of the
rubber settles in the trap while the water runs off to the sewer by an overflow pipe G
(Figure XIV).
To the cross-beam Care bolted several castings constituting hangers. In each
hanger are the journal boxes h¹ for a vertical spindle H and the several hangers also
have bearings for a worm shaft i, which extends parallel to the beam and carries
worms. Each spindle H has a worm wheel which engages one of the worms on
the shaft . At the lower end of each spindle H is a plough or stirrer I. These
ploughs may be set at any angle by properly turning the worm shaft by means of
the crank handle m.
Each plough shaft F is provided with a feather 7 by means of which the worm
wheel is keyed onto the shaft. The shaft is held in position by means of a collar q
secured to the shaft by a set screw the collar resting upon the upper journal-box
of the hanger. On loosening this collar the shaft can be vertically adjusted to any
desired position. This provision for vertical adjustment is of some importance in the
operation of the apparatus it being frequently desirable to adjust the ploughs to
penetrate to a greater or less depth in the mass of stock in the tub.
N represents a water pipe provided with a cock n. O is a discharge gate for
removing the stock P an elevator for raising it to the elevated receptacle or
trough and R is a screw conveyor for carrying it to the rotatory washer and sand
separator S.
a
In operation the stock to be washed is discharged into the tub A through
chute T. The shaft B is then set into motion the ploughs being set at a proper
angle to stir up the stock constantly exposing different portions thereof to the action
of roller D. The latter by its weight squeezes out the mud decomposed fibre etc.
from the rubber this action being facilitated by the construction of the periphery of
the roller with open spaces.
A sufficient quantity of water is kept in the tub from
the pipe N and from time to time the gates ef are opened and the muddy water
drawn off. The rubber arrested by the screens g is thrown back into the tub A.
The
When the operation has proceeded so far as to remove all the impurities that can
practically be gotten rid of by this means the discharge gate is opened.
ploughs are then set obliquely to the beam C in such manner as to urge the stock
from the centre towards the periphery of the tub. At each revolution of the beam a
portion of the stock is thus pushed through the gate O and is carried by the elevator P
to the receptacle Q the water in the tub aiding to float off the rubber. From the
receptacle the stock is delivered by the screw R to the rotatory washer which will
now be described in connection with Figures XVII and XVIII which illustrate the
apparatus in longitudinal section and plan respectively.
A represents the rotatory cylinder which is inclined sligthly downward towards its
dicharge end. Its periphery for the greater portion of its length is composed of
perforated sheets a of brass or other suitable material. The perforations are preferably

page_text: of different sizes being largest at the upper or feed end of the cylinder and finest at
its discharge end.
The sheets a are supported on ribbed rings band the latter are carried by arms c
radiating from a central rod B. The cylinder is provided with three hoops or tires C,
one at each end and one in the middle. These rest on friction rollers D by which the
cylinder is supported. At the middle of the cylinder is a toothed gear E which is
engaged by a pinion F on a shaft G receiving motion through bevel gears g from a
shaft H which carries the fast and loose pulleys hh. By these devices a rotatory
motion is imparted to the cylinder A when in operation.
Beneath the cylinder A is a tank or receptacle I for receiving the water and all
matters passing through the shell of the cylinder. To protect the gear E and the
supporting rollers 1) the cylinder is provided with guards which overhang these
parts and divert the water sand etcetera. therefrom and into the receptacle I beneath.
At the upper or feed end of cylinder A is the hopper K into which the stock is fed
by the screw conveyor L.
At this end is a
pipe M for hot water when required and
another pipe N for cold water. The latter pipe passes through the hopper and its
discharge end enters the cylinder obliquely so as to direct the stream of water against
the side thereof.
The cylinder A is provided with longitudinal ribs 0 attached internally to its shell.
These ribs when the cylinder is in motion carry the stock up until their inclination
to the vertical permits it to fall back to the bottom of the cylinder.
The tank is provided with a drain pipe P which carries off the water with the
particles of sand and other matters that pass through the perforations of the cylinder.
In this mass is a comparatively small quantity of rubber in a very fine state of division
to recover which the pipe Pis led to the bottom of a separator Q entering it at p.
The vessel has walls 7 which diverge from either side of the inlet and has vertical
partitions which enclose a space in the centre of the vessel. Vessel discharges
from a spout & upon a screen S sufficiently fine to arrest all particles of rubber that
are carried by the water. Pipe P is provided at t with a sand trap.
The operation of the apparatus is as follows:-
Motion being imparted to the cylinder A rubber stock to be cleansed is fed into
the hopper K which delivers it into the upper end of the cylinder whose ribs O carry
it round with the cylinder and let it fall when near the top. A strong stream of
water is kept discharging through pipe N. This strikes with violence against the
mass of stock in such direction as to shake out much sand and dirt at the outset
carrying such matters through the perforations at the upper end of the cylinder. As
the latter continues to rotate its inclination gradually carries the stock forward
causing it to traverse the entire length of the cylinder. During all this time however
it is repeatedly taken up and let fall being thus thoroughly shaken up with the water
so that by the time it issues from the discharge end into the elevator boat. T practi-
cally all the impurities or foreign substances which are capable of passing through
the perforations have been eliminated. The bits or pieces of metal or other matters
of a larger size are removed by other means. By the time the stock reaches the
lower end of the cylinder the agitation it has received has freed it almost entirely
from moisture so that it is delivered to the elevator in practically a dry state.
Much of the sand settles in tank I but a considerable quantity of it and all the fine
rubber particles which are much lighter than the foreign substances are carried by
pipe Pand delivered into the bottom of the vessel Q. This is always full of water
up to the overflow spout s. The body of water enclosed by the partitions is almost
stagnant consequently all matters of greater specific gravity than water which may
enter it will settle down. Moreover this still body of water forces the incoming
current to keep up the inclined sides of the vessel which current carries off all the
fine particles of rubber onto screen $ whereas the sand and heavier impurities
remain in the vessel Q and sand trap t whence they may be removed from time to
time.
The rubber arrested by the screen S is very fine and pure and it is added to the
main body of the stock when about to be vulcanized.

page_text: is shown a small
In the ordinary
Extending down the centre of the space enclosed by partition's
water pipe R having its outlet near the bottom of the vessel Q.
operation of the apparatus this pipe is not needed but it is sometimes desired to treat
masses of refuse removed in other operations by magnetic separation for example and
which may contain small quantities of rubber. In such cases the mass to be treated
is poured into the middle part of vessel and water turned on through the pipe R.
The action is the same as above described. By the use of this apparatus the fine
particles of sand and gritty substances generally which are present in old rubber stock
in great quantity and which have always been very troublesome in the operations of
recovering rubber from waste articles may be effectually removed and separated from
the rubber without any appreciable loss of the latter for the separator Q acts with
such efficiency and economy as to make it profitable to treat large quantities of sand
in which the rubber particles are so few in proportion as to be scarcely observable
upon examination.
The main body of the stock is or may be treated by a specific gravity separator to
remove gravel and other foreign matters. The rubber is then mixed with petroleum
and calcium sulphide in about the proportions herein before given after which it is in
condition for devulcanization which is carried on with the aid of the apparatus illus-
trated in Figures XIX to XXIII. Figure XIX is a side elevation of a devulcanizer
the cylinder being partly broken away to show the interior. Figure XX is a plan
view thereof. Figure XXI is a cross-section Figure XXII illustrates in elevation
the removable head of the cylinder and Figure XXIII which is drawn to a much
larger scale than the other figures is a perspective view of one of the discharge
books.
A represents the devulcanizer. It is provided with a head B which instead of
being hinged to the vessel is preferably entirely separate therefrom and during the
process of loading and unloading can be swung out of the way by means of an
overhead carrier D which runs on a track D'. The head is secured in place during
the process of devulcanization by means of a series of bolts which are let into radial
slots in the periphery of head B and corresponding slots in the flanged end of
cylinder A.
f
Rails are laid lengthwise of the cylinder and between them is the perforated false
bottom for distributing the steam which is supplied from the boiler by a pipe
which runs under the bottom d from end to end of the cylinder (see Figure XX).
A car or truck C is arranged to run on the rails into the interior of cylinder A
and by means of this car or truck the operation of charging is carried on.
The car C is provided with a follower f extending lengthwise across the body
thereof and adapted to push off the load of rubber from the forward end.
The follower is attached to a rod g which passes through a guide hole in the tail
board of the car. To the outer end of the rod g is attached a rope which passes
over a pulley on the car C and then over a pulley P being attached at its end to a
windlass (not shown in the drawing) by means of which the follower can be pushed
forward for discharging its load of rubber scraps into the devulcanizer.
The
The construction of the discharging hooks G is shown in Figure XXIII.
hook is somewhat similar in form to an inverted rake. It is composed mainly of
stout bars of wrought iron about half an inch thick and two inches wide. The rear
or upright portion of the hook is formed of bars & beni into U-shape. These are
firmly braced by cross-bars which are secured to the vertical bars by angle
irous P. The tongue mis bolted at its rear end to the uprights and at its forward
end has an eye to which is attached a draft chain n. The side pieces are bolted
at one end to the outer uprights and at the other to the shank of tongue_m.
Additional oblique braces and are provided to strengthen the structure. The
bottom pieces P also constitute runners for sliding the hooks over rails . The whole
structure is open so as not to interfere with the circulation of the steam and while
comparatively light and occupying small space within the devulcanizer has ample
strength for the work required:
The method of charging the cylinder A is clearly shown in Figure XIX, The

page_text: nrst Hook & being placed in position in the extreme end of the cylinder the space
over and in front of it is filled by means of the car C for a distance lengthwise of
the cylinder of say five feet. Another hook is then placed in position and the
charging proceeds as before. When the cylinder is charged to its utmost capacity
the rubber filling it in a continuous mass from end to end, the platform I at the mouth
of the cylinder is removed the head is swung into place and securely bolted to
the cylinder.
Steam is then turned on through the pipe
admitted to the space beneath false bottom and by the perforations in the latter it
e by means of the cock y and is
is diffused through all parts of the mass of rubber. The steam exit pipe c is
always open so that the steam is constantly circulating through the cylinder instead.
of remaining stagnant therein. This is found to be an important improvement
and renders the operation of devulcanization much more thorough.
reduces the amount of condensation in the cylinder. The water of condensation
formed therein is collected in the space beneath the perforated bottom which spaco
is constantly drained by the pipe swhich is provided with a steam trap to prevent
the escape of steam. To facilitate the drainage the cylinder is preferably slightly:
inclined towards its forward end.
Morcover it
When the operation of devulcanization is complete the pipe e is closed and the
exhaust pipes and are opened blowing off the steam at both top and bottom.
When the pressure gauge indicates zero the pipe which leads to the bottom of the
cylinder and is connected with steam pipe e is opened and a vacum pump put into
operation by means of which heated air is drawn into the cylinder through pipe m
leading to the top thereof.
The air is drawn through the mass of rubber from top to bottom, removing, a
great portion of the moisture. When it enters the cylinder which is at a very
high temperature within, the air is still further heated thereby performing its work
more efficiently. In addition to the utilisation of the residual heat of the devulcanizer
to dry the rubber this operation is advantageous in that it reduces the temperature
of the latter to such an extent that when the head B is removed the workmen can
at once proceed to withdraw the hooks G.
Prior to the adoption of this plan it required about five hours to blow off the
cylinder and even then when the head was removed considerable steam remained
and the heat was so intense that the operation of discharging could not begin for
some time.
Now the whole operation subsequent to the shutting off of the steam
requires only two hours and a half.
11.
When the head B is removed the movable platform I is again rolled to the mouth
of the cylinder, the draft chain of the first hook is hooked on to a chain attached to
the windlass and the hook drawn on to the platform carrying with it the mass of
rubber in front of its prongs. The mass is a compact lump which is broken up into
smaller pieces and removed by trucks to the cracker rolls for disintegration.
The next hook is drawn out in like manner and so on with all the others until the
cylinder is empty.
A good commercial product may be obtained by drying this devulcanized rubber
in an artificially heated atmosphere, and then running into sheets between sheeting
rollers.
A special feature of the Invention however is the production of a new article of
restored. rubber very different in its appearance and characteristics from ordinary
rubber. by passing the rubber through rolls directly after treatment with live steam.
while vet in a moist condition that is to say, without first drying it, as has heretofore
been done. The rubber produced by this process is remarkable for its homogeneity
and its uniformity throughout, being free from hard lumps and inequalities that are
conspicuous in the ordinary product. Further the rubber made by the new process
is characterized by great strength and elasticity and by a smooth and velvetv
surface. which characteristics distinguish it from restored rubber
produced.
as ordinarily
It is not possible to obtain the same effect by simply moistening rubber after it has

page_text: once been dried and then sheeting which is probably due to the fact that tie
moistening of the stock in the devulcanizer is effected under a very high pressure,
and therefore the moisture is forced into all the interstices and brought into intimate
contact with every particle of the mass of rubber.
It is essential therefore in carrying out this Invention that the moisture be applied
under such conditions as to permeate effectually every part of the mass of rubber,
The required condition of moisture may of course be obtained by the use of water"
under pressure but steam is preferred.
To produce the very best result it is desirable to continue the rolling and sheeting
by passing the rubber between successive rollers or a number of times between the
same rollers until perfectly dry, but it is not always convenient or expedient to do
this, and it suffices to produce an excellent grade of rubber, to give the rubber three
or four passes while yet moist, and then spread it out to dry.
To form a perfect sheet by continuous rolling of the moist rubber requires about
sixteen passes making the sheeting process somewhat longer and more difficult than
in dry sheeting. The rubber begins first to assume a powdery then a filamentary
appearance and then the filaments unite presenting a veil like form which gradually
develops into a fine sheet of uniform texture, having a smooth velvety surface pre-
senting a marked contrast to the usual product. During all the rolling, moisture and
considerable muck exude from the mass and any hard and gritty substances that may
remain are also removed. The drying is assisted by the heat of the rolls due to the
great friction which heat, in this process of moist rolling becomes a useful factor
instead of being detrimental and injurious as in the process of dry sheeting.
This process is preferably carried on by means of the mill shown in Figures XXIV
and XXV which illustrate the mill in vertical cross section and a front elevation
respectively.
The frame consists of several castings firmly but detachably fastened together. At
each end of the mill there is a front upright casting A and a rear casting B which
are substantially alike except that the upright B is somewhat taller than A. These
uprights have longitudinal strengthening ribs a b. Between the uprights A. B is the
intermediate casting C (one at each end). The shape of the casting C is shewn in
Figure XXIV. It is provided on each side with a series of horizontal arms e forming
between them recesses for the reception and support of the journal boxes I) (dotted
lines Figure XXIV.) of the several rolls, which fit in said recesses. As shown, there
are three of these recesses on the rear side of the mill and two on the front side.
making supports for five rolls, but the construction of the frame work could readily
be modified to support a greater or less number if desired.
The casting C fits snugly between the uprights A B to which it is firmly secured
ly bolts 7. At the top of each side frame is a cap piece E provided at each end with
a downwardly projecting shoulder c. These shoulders fit over the ends of the
uprights A B and prevent them from spreading. The cap-pieces E are fastened to
the casting C by bolts f and the two cap pieces are connected and braced together by
rods F. Other tie rods G connect the uprights A. A and B B.
The rolls 1, 2, 3, 4, 5, are supported in their respective journal boxes D which are
slipped into the recesses in the casting C as already described. The roll 3 is of larger
diameter than the others and from it the other rolls are driven. Roll 3 may be about
18 inches in diameter and the other rolls 16 inches, but these dimensions are variable.
The driving shaft H has a pinion which engages a large spur gear I on the shaft
of the roll 3. At the other end of the mill is a train of gears 6, 7, 8, 9 on the shafis
of the rolls 1. 2. 4 and 5 respectively, and driven from a gear wheel on the shaft of
the roll 3. The direction of rotation of all the rolls is indicated by the arrows in
Figure XXIV. Each roll rotates in the opposite direction to the one adjacent to it.
The gearing should preferably be such that the large roll 3 makes say 25 revolutions
per minute while the smaller ones make 30. This would give to all the rolls the same
circumferential speed.
The position of the rolls is regulated and determined by jack bolts K which are
screwed into threaded bosses k on the uprights A B and bear at their inner ends

page_text: against the journal boxes D of the several rolls. By means of these jack bolts the
position of each roll can be adjusted independently of all the others. Should it bo
necessary to remove any one of the rolls, this can be effected without disturbing any
of the others by first taking off the top pieces or caps E and then unbolting and
removing the uprights A or B as may be required to give access to the desired roll
which leaves the journal boxes of the roll free to be withdrawn horizontally from the
recesses in the supporting castings C.
By the arrangement of the rolls as shown one below the other and with their
axes alternately to the right and left of a vertical plane, several important advantages
are secured.
It enables four pinches or nips to be given to the rubber with five
rolls, or in other words enables five rolls to do the work which heretofore required
four pairs of rolls it makes a very compact machine occupying but little if any more
floor space in the factory than a single mill now takes up and it permits the adjust-
ment of each roll independently of the others so that the space between each roll and
the one adjacent to it (either above or below) can be regulated to a nicety.
Furthermore the described arrangement effects the feed or passage of the
rubber through the machine without special devices for this purpose or manual
interference.
As shown in Figure XXIV the rubber after passing between rolls 1 and 2 falls
upon roll 3 the direction of whose rotation carries it through the space between 2
and 3. After passing the roll 5 the stock falls into an inclined way or chute L from
which it may be gathered and again passed through the mill if desired. Guide
blocks are arranged at the ends of the rolls to prevent escape of the rubber stock
sideways.
This Invention also includes the production of a devulcanized or restored rubber
powder which is likewise a new article of manufacture. To produce such powder I
proceed as hereinbefore described by passing the rubber stock while moist between
smooth surfaced rolls that is to say beginning the rolling operation directly after
removal of the stock from the devulcanizer. The first effect of such rolling is to
reduce the rubber to a powdery condition (which cannot be effected if the rubber be
dry) after which the particles begin to adhere and form filaments. I now arrest the
rolling while the rubber stock is in this pulverulent condition. This moist stock if
dried in the ordinary way would become set and lose its pulverulent form. It is
therefore necessary in order to preserve this condition to dry the rubber while keeping
it constantly agitated or stirred up, so that the particles do not remain in one position
long enough to admit of their adhering together for example the particles may be
fed into a cylinder heated externally and provided in the interior with a stirrer but
other means may be employed to keep the rubber in motion while drying so as to
prevent adhesion of the particles into lumps.
The product of this process is a new commodity being devulcanized rubber in the
form of a coarse powder of great purity unassociated with foreign matters. There
is no such article on the market as a devulcanized rubber powder. Unvulcanized or
crude rubber does not exist in the form of powder. and so far as I am aware could
not without great difficulty be reduced to that condition even if it were an object to
do so whereas ordinary restored and devulcanized rubber as already explained is
necessarily produced in the form either of sheets or lumps.
The only rubber product that exists as a powder is a preparation which is used as
an adulterani or filler in the manufacture of cheap rubber goods. This preparation
is made by grinding old rubber boots and other articles until very finely divided and
then by an air blast blowing off as much of the dust and fiber as can be removed in
that way. Much fiber and other foreign matters necessarily remained attached to or
associated with the rubber particles giving the mass a grayish black colour whereas
the product of my process is deep black in color and free from foreign matters.
What further and most clearly distinguishes the powder produced by this process
from the product above described is that the rubber contained in the latter is
vulcanized. The devulcanized rubber powder, prepared according to the process

page_text: herein described can be usefully employed for many purposes in the manufacture of
rubber goods for which the powder above referred to could not be 'used:
The foregoing description sets forth a complete system of processes and apparatus
whereby old rubber stock may be treated until all foreign matters are separated from
it the rubber thoroughly devulcanized and desulphurized and finally brought to such
condition that it is available for use in the manufacture of rubber goods of fine quality.
The entire system need not of course be employed but portions of it may be used
separately. The Invention may in parts be modified or altered' and other equivalent
apparatus substituted for or used instead of that described for carrying out the several
steps of the process some of which are not essential. These and other changes may
obviously be made without departing from the spirit of the Invention but to produce
the best results it is deemed advisable to follow the various steps as set forth in the
foregoing description which gives in every instance the best means known for
carrying the Invention into effect.
Having now fully described the said Invention and the manner in which the same is
to be performed what I claim is―
First The herein described process of recovering and restoring old rubber, said
process consisting in first reducing the stock to small pieces or fragments second
removing particles of iron and steel from said fragments third disintegrating or
decomposing the fibrous matters in the stock, fourth further purifying the stock to
remove all foreign substances therefrom and fifth devulcanizing and desulphurizing
the rubber substantially as set forth.
Second The herein described process of recovering and restoring old rubber said
process consisting in first reducing the stock to small pieces second eliminating the
particles of iron and steel by magnetic attraction third destroying the fibers by treat-
ment with acid fourth washing with water to carry away soluble matters, fifth
sifting to separate sand and other fine particles sixth acting on the mass with a
stream of water to float off the rubber from the heavier foreign substances associated
with it and finally devulcanizing and forming the rubber into a sheet or powder
substantially as described.
Third The improvement in cracker or grinding mills for rubber stock consisting
in the application to the feed side of said rolls of a guide block or guide-blocks
constructed and operating to confine the rubber to the portion of the rolls on one
side of the block or blocks. and to cut off the other portion as set forth.
Fourth-The combination with two pairs of rolls of a conveyor for raising the
stock after passing through one pair of rolls to a point above the other pair of rolls.
and an inclined screen either stationary or oscillatory leading to the second pair of
rolls the parts being combined and arranged so that the small fragments pass through
the screen and under the last pair of rolls while the larger fragments pass through
said rolls and are further reduced substantially as described.
Fifth The magnetic apparatus herein described and illustrated in Figures V
and VI said apparatus comprising groups of magnets arranged one above the other
the last group of the series being electro magnets and the others permanent magnets.
the magnets being combined and arranged so that the stock feeds through the several
magnetic fields in succession substantially as set forth..
Sixth-The combination with several groups or series of magnets arranged as
specified in the last preceding claim and enclosed in an air tight chamber of a pipe
having a flaring mouth overhanging the magnets and an air exhausting device in
said pipe substantially as described.
Seventh The conveying and distributing, apparatus herein described and illustrated
in Figures VII and VIII said apparatus comprising an endless feed belt, a series
of receptacles beneath the same and a series of clearers or dischargers preferably
air pipes. adapted to discharge the stock from the belt into either of said receptacles
as set forth.
Eighth The combination with a vessel for defiberizing rubber of a discharge

page_text: gate lined with non-corrodible material a clamping rod for holding said gate in place
and a removable support for said clamping bar substantially as described.
Ninth The combination with the cooking tub of the discharge gate lined with
non corrodible material, the stationary hooks set in the walls of said tub the
removeable cross bar resting against said hooks, and the clamping rod or screw
carried by said cross bar substantially as described.
Tenth The apparatus for washing rubber stock comprising in combination the
circular tub the conical washing roller having an openwork periphery adapted to
compress the stock and squeeze out mud and moisture and the ploughs or stirrers
carried in advance of said roller and constructed to turn up the stock from beneath
loosening the mass and exposing fresh surface to the action of the roller substantially
as described.
Eleventh In a washing apparatus for rubber stock the particular construction of
the ploughs or stirrers hereinbefore described and illustrated in Figures XIII XIV
XV and XVI of the accompanying drawings.
Twelfth The inclined rotatory cylinder having a perforated periphery mounted
above a receptacle and, combined with a water pipe entering the upper or feed end
of the cylinder substantially as described.
Thirteenth The combination of the inclined perforated cylinder provided with
internal longitudinal ribs means for rotating the cylinder and the water pipe entering
the upper end of said cylinder obliquely to the axis thereof as set forth.
Fourteenth The combination with the perforated rotatory cylinder and the tank
beneath the same of the specific gravity separator, and the pipe connecting the tank
with the bottom of the separator, the latter having partitions and an overflow spout
constructed and operating substantially as described.
Fifteenth The combination of the upright vessel having walls sloping inward
towards the bottom, a pipe for conveying water into the bottom of said vessel, an over-
flow spout and vertical partitions enclosing a portion of said vessel above the water
inlet substantially as described.
Sixteenth The use ofcalcium sulphide inthedevulcanization of rubber in connection
with heat and particularly in connection with live steam as set forth.
Seventeenth The use of calcium sulphide and heavy oil in the devulcanization of
rubber in connection with heat and particularly in connection with live steam as
set forth.
Eighteenth The process of devulcanizing rubber by mixing with the same heavy oil
and calcium sulphide and then subjecting the mass to the action of live steam under
pressure substantially as described.
Nineteenth In the devulcanization of rubber the improvement consisting in main-
taining through the mass of rubber in small fragments a constant circulation of steam
as set forth.
Twentieth In the devulcanization of rubber the improvement consisting in first
heating the rubber with live steam under pressure and then causing a current of air
to pass through the mass as set forth.
Twenty first The employment for devulcanizing rubber waste of a cylinder having
a perforated false bottom and a steam inlet beneath the false bottom substantially as
described.
Twenty second-The devulcanizer comprising a cylindrical vessel provided with a
steam inlet beneath a perforated false bottom and with blow off pipes near the top and
bottom of the cylinder respectively substantially as described.
Twenty third The combination with the devulcanizer having rails extending
lengthwise thereof of the loading truck having a discharging follower and means
whereby the follower can be actuated from outside the cylinder substantially as
described.
Twenty fourth-The discharge hooks for unloading the devulcanizer constructed
substantially as herein before described and illustrated in Figure XXIII of the accom-
panying drawings.
Twenty fifth The described method of charging the devulcanizer with rubber wasto

page_text: by filling the same solidly from end to end by means of the loading truck and placing
at intervals as the charging progresses, the openwork discharge hooks as set forth.
Twenty sixth The combination with the devulcanizer having longitudinal rails of
the discharge hooks adapted to run upon said rails substantially as described.
Twenty seventh-The production of restored rubber by rolling the same after
devulcanization while moist substantially as described.
Twenty eighth The production of restored rubber by subjecting the stock to the
action of live steam under pressure and then rolling while in a moist condition as set
forth.
Twenty ninth--The herein described restored rubber in the form of a sheet produced
by rolling the rubber while moist until dry and distinguished by the characteristics
herein before set forth.
Thirtieth The particular construction ofthemillforcontinuous rollinghaving a series
of rolls arranged and supported in a frame substantially as hereinbefore described and
as illustrated in Figures XXIV and XXV of the accompanying drawings.
Thirty first The art or process of producing a restored rubber powder by rolling
the rubber after devulcanization while in a moist condition until it assumes a powdery
form and then drying the powder and at the same time agitating or stirring it to
prevent adhesion of the particles substantially as described.
Thirty second The herein described devulcanized rubber powder.
J. H. JOHNSON & Co.,
Agents.