Improvements in Roasting Furnaces.
Year: 1896

page_text: Date of Application, 15th July, 1896-Accepted, 22nd Aug., 1896
COMPLETE SPECIFICATION.
Improvements in Roasting Furnaces.
I, BENJAMIN THOMAS LACY, of 21 Fremont Street, San Francisco, California,
United States of America, but at present residing at 7 Craven Street, Strand, London,
in the County of Middlesex, 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 :-
My invention relates to certain improvements in mechanical furnaces for roasting
ores of that class in which travelling rabbles are employed for stirring and advancing
the ore through the furnace, such a furnace being illustrated in Figs. 1 to 5 inclusive
of the accompanying drawings, in which
Fig. 1 is a transverse vertical section through x-x of Fig. 2.
Fig. 2 is a horizontal section through ww of Fig. 1.
Fig. 3 is a transverse vertical section through y-y of Fig. 2.
Fig. 4 is a transverse vertical section through z-z of Fig. 2.
Fig. 5 is a longitudinal vertical section on line 5-5 Fig. 4.
My improvements are shown in detail on a larger scale in Figs. 6 to 9 inclusive
of the accompanying drawings, in which
Fig. 6 is a side elevation of one of the travelling trucks which carry the rabbles.
Fig. 7 a plan view of same partly in section,
Fig. 8 an end view of Fig. 6, and
Fig. 9 is a transverse section through the chamber in which the trucks travel.
Referring to Figs. 1 to 6 inclusive
A represents the roasting chamber having a hearth B and an arched top C.
The hearth B has a central longitudinal slot D made through it as shown. In the
present case the hearth proper is supported upon suitable iron or other plates B
which are turned upwardly in the centre leaving a slot between them, the height
being sufficient to prevent the ore from falling down through this slot:
Beneath the furnace is an open chamber E, within which one or more (preferably
four) four-wheeled trucks F are adapted to travel one pair of wheels of one of
such trucks being exposed and the other shown by dotted lines in Fig. 2. From
this truck an arm G extends upwardly through the slot in the hearth, and across
its upper end is a supporting bar H from which the rabbles or stirring teeth
project. This truck preferably runs on tracks in the chamber beneath the furnace,
and these tracks are continued exterior to the furnace at each end and pass round
in a curve so as to return parallel with the furnace and exterior to it.
JJ are sheaves which serve to guide and also transmit power to a cable K
which is attached to the car at opposite ends, one of the sheaves J' being a grip
sheave adapted for the purpose of pulling the rabbles through the ore
hearth B of the furnace.
on the
When the car is in motion, it is drawn along by the movement of the cable
passing beneath the furnace, and by means of the upwardly projecting bar and the
rakes carried by it, the ore is stirred and moved along through the furnace at any
desired rate of speed. After leaving the furnace the car passes around upon the
track exterior to the furnace and during its passage and return to the point of
commencement it becomes sufficiently cool and ready to again enter the furnace.
Each time that the stirring apparatus enters the furnace, an automatic mechanism
is put into action which delivers a suitable proportion of the raw material into
the furnace from a hopper or receptacle above. This mechanism is shown in
°

page_text: Fig. 5 and comprises a shaft M belted to a driven shaft M' with a tappet m which
engages a lug o on the lower side of a slide O¹ in the bottom of the hopper O.
The open ends of the furnace may be closed by flexible or swinging doors L of
metal, asbestos, or other suitable material so that when the car reaches either of the
doors it will be displaced to allow the car to pass and again close after the passage of
the car.
Referring now to Figs. 6 to 9 inclusive which illustrate my improvements in detail
I find it advantageous to arrange hinged doors P at any suitable points in the chamber E
along which the trucks F travel, such doors opening in the direction of the line
of travel of the trucks and the extent of their opening being preferably adjustable,
by which means I am able to regulate the quantity of air desired to be admitted
into the furnace, which passing through the slot D in the hearth B of the furnace
helps to prolong the life of the cast iron sides that protect and form such slot.
As the curved end portions of the tracks on which the trucks F travel are of
comparatively small radius I find that the employment of flanged wheels for such
trucks is objectionable as such flanges are subject to great wear and tear and
further that there is a tendency for the trucks to jump the tracks in rounding
such curves, and in order to overcome these disadvantages I mount the trucks on
plain wheels F¹ and mount a frame or arms Q on the frame in which the wheels FI
are carried, such frame Qbeing provided with horizontal wheels or rollers Q¹
which are capable of revolving and which bear on the inside edge of the head of
the rails forming the track.
The arm G connected to the trucks F and to the upper end of which the
rabble arms are secured is preferably fitted with a roller R at each end which
projects up into the slot D in the hearth of the furnace so as to reduce the friction
when the truck is travelling through chamber E.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed I declare that what
I claim is :-
In roasting furnaces of the class hereinbefore described.
1. The employment of doors P in the passage or chamber E through which the
trucks carrying the rabbles travel, so as to regulate the admission of air to the
furnace, substantially as and for the purpose specified.
2. Mounting the trucks carrying the rabbles on plain wheels and providing
horizontal wheels or rollers to bear on the inside edge of the rails constituting
the track along which such trucks travel, substantially as and for the purpose
specified.
3. Fitting a roller at each end of the arm connected to the trucks and to the
upper end of which the rabble arms are secured, such rollers working in the slot
in the hearth of the furnace for the purpose of reducing the friction when the
truck is travelling through the chamber in which it runs, substantially as specified.
Dated this 15th day of July 1806
ALLISON BROS.,
Agents for the Applicant.