IMPROVEMENTS IN FURNACES OR APPARATUS FOR BURNING CALCINING OR ROASTING SULPHUR ORES SPENT OXIDE OF IRON AND OTHER MATERIALS AND IN APPARATUS FOR SEPARATING DUST AND SOLID IMPURITIES FROM THE GASES OBTAINED
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Isaac Shimwell MoDougall at the
Office of the Commissioners of Patents on the 24th February 1883.
ISAAC SHIMWELL MCDOUGALL of Irk Vale, Chadderton, near Manchester, in the
County of Lancaster " IMPROVEMENTS IN FURNACES OR APPARATUS FOR BURNING
CALCINING OR ROASTING SULPHUR ORES SPENT OXIDE OF IRON AND OTHER
MATERIALS AND IN APPARATUS FOR SEPARATING DUST AND SOLID IMPURITIES
FROM THE GASES OBTAINED
"
My Invention relates principally to furnaces or apparatus for burning calcining
or roasting sulphur ores, spent oxide of iron or other materials and is especially
adapted for producing sulphurous acid gas for conversion into sulphuric acid or for
other purpose.
The apparatus consists of a series of superposed chambers or floors furnished
with rakes or agitators and feeders by means of which the materials under
treatment are fed continuously through the series of chambers whilst being
submitted to the burning calcining or roasting process. The said rakes or agitators
and feeders are fixed to a main shaft passing through the chambers which are
provided with openings or passages from chamber to chamber alternately at the
centre and at the side so that the materials are passed by the said rakes across
each floor and from chamber to chamber throughout the series of chambers con-
stituting the furnace until the said materials are finally delivered out of the said
furnace. The said shaft and the said rakes when made of cast iron and exposed
to great heat are liable to warp and break when strained. To obviate this I make
the said shaft and rakes hollow and provide them with wrought metal pipes fixed
in their interiors and forming an inner wrought metal lining to the cast metal.
In order to render it possible to replace the shaft without removing the floors of
the chambers I provide the shaft at each place where the rakes are to be fixed
thereto with shoulders and the rakes with a forked inner end which embraces the
shaft. A pin or cotter is passed through the forked ends of the rake to secure it
to the shaft and by withdrawing this cotter the rakes may be readily removed

page_text: from the shaft which can then be withdrawn from the furnace for renewal or
repair.
In order that the shaft may be readily removed for repairs or other purpose
after the rakes are removed as hereinbefore described (without the necessity for
breaking the floors) on each alternate floor where the material passes through a
passage at the side I furnish the centre floor box through which the shaft passes
with a flanged movable cover resting on a flange on the floor box and fitting
round the shaft by which arrangement the shaft can readily be removed through
the floors and out at the top of the furnace.
A loose piece of hard steel may be fixed to the bottom of the shaft working on
a loose steel disc so that the said loose pieces take the wear and when worn can
be readily replaced without necessitating the renewal of the shaft.
In order to adapt the furnace for use for treating various kinds of materials
requiring submission to the heat of the furnace for a longer or shorter period I
provide in addition to the feeding hopper at the top other hoppers communicating
with floors at different levels through which the different materials may be fed at
the same time according to the number of the chambers through which they are
required to pass. In order to dry the materials (where desirable) before they are
fed into the chamber I provide a floor outside the roof of the top chamber and I
furnish this floor with a rake so that the material being fed on to the said
floor is dried thereon and then by the operation of the said rake is fed therefrom
into the top chamber.
My Invention relates further to the provision of means for freeing the gases
from-dust and solid impurities immediately after leaving the furnace and before
they pass to the chambers or vessels in which their utilization or chemical com-
bination or treatment takes place. These means consist of a chamber divided by
a series of plates or baffles having holes or perforations therein. The holes in the
one plate or baffle are not opposite those in the adjacent plates or baffles so that
The dust and solid impurities are impeded by the said plates as the gases pass
through the holes and the said dust and solid impurities fall to the lower part of
the chamber. The bottom parts of the said plates or baffles are without holes and
a damper is provided between each plate or baffle which on being moved into
position closes in the space between the lower unperforated parts of the said
plates or baffles and cuts off the enclosed space so that the gas has not access
thereto. These dampers are for the purpose of thus being placed in position to
allow of the dust and solid impurities being removed from between the plates
without permitting access of air to the gas. The said Chamber can be made to
answer the purpose of a nitre oven by providing bearing bars and other parts
within the said chamber for supporting the nitre pots and suitable doors for the
charging and removal of the nitre pots.
The vertical shaft may be rotated by any convenient gearing from the source of
motive power and connections may be made from the said gearing for operating
charging pistons for pushing the material from the hopper or hoppers on to the
drying floor or into the chambers of the furnace.
Each chamber may be provided with a manhole or manholes for gaining access
thereto when required.