IMPROVE- MENTS IN FURNACES FOR SMELTING THE ORES OF IRON AND OTHER MINERALS
Year: 1858

page_text: ILU
by the Act.)
PROVISIONAL SPECIFICATION left by George Dalton at the Office
of the Commissioners of Patents, with his Petition, on the 3rd June
1858.
I, GEORGE DALTON, of Lymington, in the County of Southampton,
Gentleman, do hereby declare the nature of the Invention for "IMPROVE-
MENTS IN FURNACES FOR SMELTING THE ORES OF IRON AND OTHER MINERALS,"
to be as follows:-
The blast furnaces in ordinary use for smelting the ores of iron are large and
costly structures, requiring expensive blowing machinery, and the whole of the
fuel employed being charged with the ores and fluxes at the top or mouth of
the furnace, has to traverse the whole body of the furnace before it reaches the
neighbourhood of the tuyeres, where, meeting with the blast, it is converted into
carbonic acid flame, and the requisite smelting temperature attained. But
this carbonic acid flame coming immediately afterwards into contact with
the mass of ignited carbon in the body of the furnace, is converted into
carbonic oxide, and in that condition of imperfect combustion escapes into
the atmosphere, whereby a waste is sustained of fully two-thirds of the whole
fuel employed.
This Invention has for its object an improved arrangement of furnace for
smelting purposes, whereby such waste of fuel may to a great extent be avoided,

page_text: and which from its cheapness of construction, no less than from its economy of
fuel, is especially valuable in localities where rich or fusible ores abound, but
coal and other kinds of fuel are expensive.
In describing the furnaces constructed according to niy Invention I do not
confine myself to the exact details, as the modes of arrangement may be
greatly varied to suit varying circumstances.
The furnace I prefer will be much smaller than the blast furnace in general
use, and the body will be oblong, narrow at the base, gradually enlarging
until the maximum of diameter has been attained, and will then either be
carried up straight or be gradually reduced in area, a good working
rule being to make the breadth at the mouth double that at the base of
the furnace.
The feeding doors should be carefully fitted so as to exclude as much as
possible the outer air, and the mouth of the furnace may be surrounded in the
usual way with a feeding gallery.
Above the feeding doors the furnace may be at once contracted to the
dimensions of a chimney or flue, which may be of any desired form, oval
or oblong being preferred, and such chimney or flue is to be provided with
an exhausting fan or other mechanical contrivance for creating draught.
To supply smelting power, I place on one or both sides of the furnace one or
more fires, such as are commonly used in reverberatory furnaces, and force
air into the ash-pit by a fan blower, or by any other means of mechanical
pressure.
.
Between the fires and the base of the furnace I place a crucible or well to
receive the iron and slag, which is to be tapped or allowed to flow off in the..
usual manner.
At the back of the fire-place I construct an air chamber communicating.
with the fire-place above the bars by several openings. This air chamber
may communicate directly with the ash-pit, or may be closed from the ash-pit
and supplied with air from chambers at the sides of the ash-pit, which is the
arrangement I prefer. Such side chambers may be fronted with cast-iron.
plates, and receive air from a chamber formed under the fire-bridge, with.
openings into the ash-pit. By this arrangement a portion of the air forced.
into the ash-pit circulates through these side chambers, and becomes con-
siderably heated before entering the fire-place to complete the combustion
of the gases from the fuel on the grate bars. The quantity.of such gases
may be advantageously increased by maintaining on the grate bars an unusual
depth of fuel.

page_text: A portion of such heated air may, if desired, be admitted. from the side
chambers to the fuel on the fire-bars. by numerous small openings, and the
quantity admitted from the chamber at the back of the fire-place may be
regulated at will by means of a slide or other similar contrivance.
Having constructed a furnace with arrangements substantially as described,
and having brought it into working condition, it is to be charged from the top
with ores, fluxes, and fuel, in the usual manner, but the quantity of fuel
charged need only be slightly in excess of the amount required to deoxidate the
minerals and to carbonize the iron, the temperature required for smelting the
ores being obtained from the flame of the reverberatory fires.
1
Great economy in the cost of construction and in fuel may be obtained by
other modifications in the form and mode of working furnaces for smelting
purposes. For instance, the chimney or flue at the top of the furnace may be
carried to a sufficient height to draw the flame of the reverberatory fires through
the furnace charge by natural atmospheric pressure, or natural pressure may
be assisted by an exhausting fan or other mechanical contrivance for creating
draught with or without the use of compressed air in the ash-pit. Or the
furnace might be connected at top and bottom with a lofty stack or chimney,
and the flame from the reverberatory fires, caused in part to traverse the
materials at the base of the furnace, and in part to circulate through the body
of the furnace, the proportions being regulated at will by means of throttle
valves or other similar apparatus in the stack and in the flue connecting it with
the top of the furnace.
The mode of arrangement last described would be the more economical,
inasmuch as several furnaces might be conveniently connected with one
stack, and the draught might, if desired, be assisted by some mechanical
contrivance.
Where the ores are unusually fusible, and can only be advantageously
smelted with a very low pressure of blast, a modification merely of the usual
form of blast furnaco may be adopted with advantage, and in such cases I
propose to construct the furnace of greatly diminished dimensions, and I should
prefer to make them oblong and narrow at the base, and instead of reverberatory
fires or the usual tuyere openings for blast pipes, I propose to leave numerous
openings in the masonry at the lower part of the furnace, and to surround the
part of the furnace in which such openings are situated with one or more air-
tight chambers, into which air can be forced by a fan blower or by any other
mode of compression.
The inside of the furnace where such openings are placed, and which may

page_text: be either in one row or in two or morė tiers, may be advantageously recessed,
and the openings may be examined from time to time and cleared of
obstructions by means of small doors or plugged holes in the outside air
chambers.