Improvements in Calcining Furnaces.
Year: 1899

page_text: Date of Application, 4th July, 1899-Accepted, 2nd Sept., 1899
Improvements in Calcining Furnaces.
A communication by WALTER B. DEVEREUX, of Glenwood Springs Colorado,
in the United States of America, Mining Engineer.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester,
both in the County of Lancaster, 118, New Street, Birmingham, in the County
of Warwick, and 322, High Holborn, in the County of Middlesex, Civil Engineer,
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:―
This invention relates to improvements in calcining furnaces and more particu-
larly to that class of calcining furnaces in which the ore is stirred by rakes and
gradually pushed along the surfaces of the roasting hearths until finally delivered
at one end of the furnace in a calcined or desulphurized condition, and it is
purposed to provide a simple and effective means of operating the rakes which stir
and advance the ore along the hearths of such furnaces and to protect this
mechanism from the action of the heat of the furnaces. The great difficulty
experienced in these furnaces has arisen from the fact that any mechanism by
which the rakes are operated must be exposed more or less to the great inuer
heat of the furnaces. In order to protect this mechanism as far as possible from
this heat and at the same time provide a simple and effective mechanism for
operating the rakes, the following plan has been devised and this invention
consists essentially in enclosing the mechanism by which the rakes are operated
in hollow metallic channels, which channels are built into the walls of the
furnace over the hearths on each side of the ovens, and form integral parts of
such walls. These metallic channels are cast of one piece in the shape of oblong
boxes capable of supporting masonry, and have narrow slits throughout their
length on their inner side and preferably in the upper corner thereof, opening
into the interior of the furnace to admit of the free action of the operating
mechanism, but in no part of their length do they come into direct contact with
the interior of the ovens but are separated therefrom by some portion of the brick
work which forms the furnace proper, while their entire outer surface on one
side is in contact with the air. In these metallic channels are placed rollers
which support the rakes, and by means of which they are operated. By this
means and by keeping a constant flow of water through the various parts it is
believed a simple and effective means of operating the rakes is provided, and
that the mechanism is effectively protected from the injurious effect of the inner
heat of the oven.
This invention will be best understood by reference to the accompanying four
sheets of drawings forming part of this specification, in which Figure 1 is a plan
view of a calcining furnace embodying this invention; Figure 2 is a cross sectional
view on the lines 22 of Figure 1; Figure 3 is a longitudinal sectional view

page_text: on the lines 3 3 of Figure 1; Figure 4 is an enlarged cross sectional view of a
detail, and Figure 5 is a side view of the furnace complete. Similar letters refer
to similar parts throughout the several views. In the drawings. B represents
an ordinary calcining furnace built of brick or other suitable material. A are
upright beams enclosing, the furnace proper. These are placed at convenient
intervals in pairs on both sides. of the furnace and are connected by the rods A
and nuts N. G are ovens, of which there can be any desired number. A furnace
provided with three has been shown. Care the hearths and D the rakes by
which the ore is stirred and advanced: These rakes D are hollow and extend
across the ovens over the hearths and are provided with hollow teeth 1. It is
preferred to construct these teeth of porcelain or similar material and to have
them made hollow in order that the water passing through the rakes may also
circulate through these teeth. The rakes are attached at both ends to the rods L,
by which they are operated. These rods extend out beyond the furnace and are
connected by cross pieces P2 and operated by any convenient.power which can
give them a reciprocating motion as the cylinders. P and the piston rods P¹.
The rods are hollow and constructed so as to allow a constant flow of water
through them and the rakes. D with the teeth E. The rods L are adjustably
connected with rakes D. by the elbows T, and at their opposite extremities the
rods on one side of the oven are connected with the bottom of the water tank W,
by means of the flexible pipes S, and the rods on the other side of the oven with
top of the tank W by the return pipes S. F are the metallic channels in which
the mechanism which operates the rakes is enclosed. These channels are cast
of one piece, in the form shown and are hollow oblong boxes having slits through-
out their length, in their upper inner corners opening into the furnace, and having
openings on their outer sides at stated intervals of sufficient size to admit the
placing therein of the rollers H. The upper parts of the channels, over the slits,
project beyond the sides of the channels, thus forming shelves upon which the
masonry rests. These channels form integral parts of the side walls of the
furnace and are intended to displace the masonry of the ovens at the points
where inserted, and to support the masonry above them. The outer walls of
the channels form the exterior walls of the furnace and so are in direct contact
with the outer air. There are two metallic channels in connection with each
hearth, and they are placed on either side of the hearths and preferably slightly
above them. The metallic channels in no place are in direct contact with the
interior of the furnace but at all points are separated therefrom by some portion
of brick work. As the tops of these channels form ledges which support the
masonry, the space here between the interior of the oven and the metal is
necessarily somewhat narrow, but this is more than compensated for by exposing
the entire outer wall of the channel to the air. What is claimed as this inven-
tion is the idea of providing such hollow metallic channels of such construction
that they will protect the nicchanism which operates the rakes, from the heat
of the furnace and at the same time form integral parts of the walls of the
furnace and be exposed to the outer air. The mechanism for operating the rollers
and giving them a continuous reciprocating movement is enclosed in these
metallic channels and consists of rollers H and the rods L sliding upon them.
These rollers H are placed at whatever intervals may be found suitable and are
provided on one side with axles R, by means of which they rotate. These axles
are enclosed in the boxes I in which they rotate and are held in place by the
nuts O. The boxes I are cast in the shape shown, being made sufliciently thick
to exactly enclose the axles of the rollers H which rotate in them. They are cut
away on their outer edges and fit into the openings in the outer walls of the
metallic channels to which they are attached by the bolts J. This construction
permits of the easy removal of the rollers, whenever for any purpose it may
become necessary.
For oiling the axles R of the rollers, the wells W are provided. % is the feed
hopper; X the chimney of the furnace; Y the flue leading from the fire chamber;

page_text: gg and the passages connecting the various ovens and the car by which
the ore in its final calcined state is removed.
The operation is as follows:
The ovens are constructed as shown with the metallic channels forming integral
parts of the side walls. The rollers H are inserted in the openings in the side
walls and bolted in place as described. The rakes D are then inserted and
attached at both ends to the extremities of the rods L, by the adjustable elbow T.
The ends of the rods L rotate loosely in the elbows T, as shown in Figure 4, as a
result of which construction there is a partial rotation of the arms of the rake
at the end of each stroke caused by the weight of the teeth when the latter cease
to be in contact with the mass of ore on the bed. The outer extremities of the
rods L. are then connected with some source of power and a reciprocating motion
is imparted to the rods and thus to the rakes and the ore stirred and gradually
advanced along the hearth. A continual flow of water is secured from the wator
tank W, through the pipes S, the rods L on the left of the furnace, the rakes D
and the teeth E, and as the water is heated in passing through the rakes it will
return in the line of least resistance by the rods L on the right of the furnace
and the return pipes S' into the top of the water tank W, where it will be again
cooled and the operation continued.
The ore is introduced through the chutes Z and stirred and raked over the
first hearth C. It then falls through the passage g to the second hearth C where
a similar operation is undergone, and the process continues until the ore in its
final calcined state is dumped into the car 7.
Having now particularly described and ascertained the nature of this said
invention and in what manner the same is to be performed as communicated to
me by my foreign correspondent, I declare that what I claim is :-
1. The combination with the side walls and the roof of a calcining furnace,
of a hollow metallic girder having three sides closed and the fourth side divided
by a continuous slot extending throughout its length, set longitudinally into
the wall of the furnace, with its outer face set in the plane of the exterior wall
of the furnace and forming the exclusive support for the side walls and roof
above said channel, and with the slot opening into the interior of the furnace
throughout the length of the bed.
2. The combination with the side walls and the roof of a calcining furnace,
of a hollow metallic girder, having three sides closed and the fourth side divided
by a continuous slot extending throughout its length, set longitudinally into the
wall of the furnace, with its outer face set in the plane of the exterior walls of
the furnace and forming the exclusive support for the side walls and roof above
said channel and exposed to the outer air throughout its length, and with the
inner wall not in direct contact with the interior of the furnace, and the slot
opening into the interior throughout the length of the bed, and arranged to
replace the masonry for which it is substituted.
3. In a calcining furnace the combination of a hollow metallic channel, con-
structed in and forming an integral part of the wall of a calcining furnace, with
its outer face set in the plane of the exterior wall of the furnace and forming
the exclusive support for the side walls and roof above said channel, and opening
into the interior of the furnace through the length of the bed; mechanism for
stirring the material on the furnace bed, and means substantially as described,
within the channel, for supporting and moving the stirring mechanism over the'
furnace bed.
4. In a calcining furnace, the combination of a suitable hearth; two hollow
metallic channels, constructed in and forming integral parts of each side wall
of such furnace, on each side of the hearth, each with its outer face set in the
plane of the exterior wall of the furnace and forming the exclusive support of
the side walls above said channel, and each opening throughout its length into
the interior of the furnace; mechanism for stirring the material on the furnace

page_text: bed, and means substantially as described, within each channel, for supporting
and moving the stirring mechanism over the furnace bed.
5. In a calciuing furnace the combination of a suitable number of hearths;
two hollow metallic channels, one of which is constructed in and forms a part
of each side wall of the furnace above each hearth, each with its outer face, sel
in the plane of the exterior wall of the furnace and forming the exclusive support
for the side walls and roof above said channel; and each opening throughout
its length into the interior of the furnace above each hearth; mechanism for
stirring the material on the furnace bed; means, substantially as described, within
each channel for supporting and moving the stirring mechanism over each hearth
of the furnace; and means for actuating the devices, substantially as described.
6. The combination of a hollow metallic channel, constructed in and forming
an integral part of the wall of a calcining furnace with its outer face forming
the exclusive support for the side walls and roof of the furnace and opening into
the bed of the furnace throughout its length; a rake, provided with suitable
teeth, moving over the furnace bed having arms extending through the opening
in the metallic channel; rollers in the channel; upon which the arms of the rake
slide and means, substantially as described, for giving a reciprocating motion
to the rake.
7. The combination of a hollow metallic channel, constructed in and
formning an integral part of the wall of a calcining furnace, with its
outer face forming the exclusive support for the side walls and roof
of the furnace and opening into the bed of the furnace throughout its
length; a hollow rake, provided with suitable hollow teeth, moving over the
furnace bed, having arms extending through the opening in the metallic channel;.
and flexible water connections whereby water may be supplied to the interior
of the rake continuously, for the purpose of cooling the same; and means, sub-
stantially as described, for giving a reciprocating motion to the rake.
8. The combination of a hollow metallic channel, constructed in and forming
an integral part of the wall of a calcining furnace, with its outer face forming
the exclusive support for the walls and roof of the furnace, and opening into
the bed of the furnace throughout its length; a hollow rake, provided with
suitable hollow teeth, moving over the furnace hearth, having arms extending
through the opening in the metallic channel; rollers in the channel upon which
the arms of the rake slide; flexible connections whereby water is admitted to
the interior of the rake for the purpose of cooling the same; a circulating tank.
to which said connections are attached, whereby a constant circulation of water is
effected through the rake; and means, substantially as described, for giving a
reciprocating motion to the rake.
9. The combination with each hearth of a calcining furnace, of two hollow
metallic channels, one of which is constructed in and forms a part of each side
wall of the furnace, above each hearth, each with its outer face forming the
exclusive support of the walls and roof of the furnace, and each opening through-
out its length into the interior of the furnace, above each hearth;
a hollow
rake, arranged to slide horizontally over each hearth, and provided with suitable
hollow teeth, having arms extending through the opening in the metallic channel;
rollers in each channel upon which the arms of the rake, moving over the
particular hearth with which said channel is connected, slide; flexible connections
attached to each rake whereby water is admitted to its interior for the purpose
of cooling the same; a circulating tank to which the connections of each rake
are attached, whereby a constant circulation of water is effected through each
rake; and means, substantially as described, for giving a simultaneous recipro-
cating motion to each of the rakes.