IMPROVEMENTS IN FURNACES FOR TREATING ORES
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Joseph Emerson Dowson at the Office
of the Commissioners of Patents on the 15th May 1877.
JOSEPH EMERSON Dowson, of 3, Great Queen Street, in the City of Westminster.
Civil Engineer. "IMPROVEMENTS IN FURNACES FOR TREATING ORES."
:-
The improvements are as follow I construct a hollow shaft or tower, vertical
or nearly so, and attach thereto near the bottom one or more calcining or reverber-
atory chambers, Also near the bottom and on the outside of the shaft one or more
fires, or one or more gas generators. The flue or flues from the fire or fires, or gas
generator or generators, I build up against the shaft and arrange said flue or flues that
the heated gases and currents of air passing from or over the fire or fires, or gas
generator or generators, are made to ascend to near the top of the shaft, and then to
pass through an opening into the shaft, when by means of a properly regulated
draught these heated gases and currents are drawn down the shaft and passed either
under or over the floor or floors, or along a side or sides of one or more calcining
chambers into a condensing flue or tower, or directly into a stack.
The ore to be treated in the furnace above described is first pulverized and then
showered down the shait from the top or elsewhere, as may be preferred; but to
lessen the velocity of its fall, and more particularly to ensure the presence of
sufficient oxygen to effect the changes desired in the condition of the metals, blasts
or currents of air are forced into the shaft in a horizontal or an upward or downward
direction, or partly in one direction and partly in another. Air blasts or currents
may also, if required, be forced into the calcining chamber or chambers.
The air blasts or currents can be driven by one or more rotary fans or other
mechanical contrivance placed outside the furnace, but it is desirable that the
currents of air should be heated before they pass into the shaft. This can be done
by forming air flues or passages under the floor or floors of the calcining chamber
or chambers, and in the walls of the shaft, or partly in the walls of the shaft
and partly in the flue leading from the furnace fire or fires, or gas generator or
generators.
The number of air blasts or currents, and the quantity of air to be forced into the
shaft or calcining chamber or chambers, must be regulated according to the nature
of the ore to be treated, and the condition to which it is desired all or any of the
metals should be brought. The roasted ore which falls to the bottom of the shaft,
is raked down an incline into one or more calcining chambers, and there further
roasted or treated as may be required.

page_text: In some cases an additional fire may be required for the calcining chamber or
chambers, and if so, this can be attached to the lower part of the shaft, or direct to
the calcining chamber or chambers.
It is an advantage to have more than one calcining chamber, for while finished
ore is being drawn out, the chamber in which it is can be dampered off, and the
work of the shaft proceeded with uninterruptedly, and without loss of heat owing
to doors being open.
It may also be desirable in some cases to have more than one shaft, down which
the ore can pass, and one or more calcining or reverberatory chambers attached to
each shaft.
The most convenient plan is to have two chambers for each shaft, side by side,
separated by a partition wall, and with dampers at each end. These chambers can
have one or more floors.
The space underneath the floor or floors should be enclosed so that the finished
ore can be raked into it through holes in the chamber floor, and there kept hot and
dry till required for lixiviation or other treatment.