Improvements in Roasting Furnaces more especially intended for Roasting Pyrites or the like for the Direct Production of Sulphuric Anhydride from the Gases Evolved.
Year: 1899

page_text: Date of Application, 26th Jan., 1899
Complete Specification Left, 4th Oct., 1899 -Accepted, 11th Nov., 1899
Improvements in Roasting Furnaces more especially intended for
Roasting Pyrites or the like for the Direct Production of Sulphuric
Anhydride from the Gases Evolved.
I, GEORGE WILLIAM JOHNSON, of 47, Lincoln's Inn Fields, in the County of
London, Patent Agent, do hereby declare the nature of this invention (which has
been communicated to me from abroad by the "Verein Chemischer Fabriken" of
Mannheim, in the German Empire) to be as follows:
This invention has for its object to provide an improved roasting furnace more
especially intended for use in roasting pyrites or the like for the direct production
of sulphuric anhydride from the evolved gases and I will describe it in that
connection. In a furnace according to this invention the air necessary for roast-
ing the materials (which I will refer to as pyrites) is first passed through an
apparatus wherein it is dried by means of concentrated sulphuric acid and is
then conducted to the roasting chamber or chambers, and the gases issuing from
the said roasting chamber or chambers are passed through a space or spaces
containing contact material, which space or spaces may be situated either above
or below the pyrites to be roasted the said gases traversing it either in the upward
or in the downward direction and maintaining the contact material at the
requisite temperature. Access of external undried air is as far as possible pre-
vented by providing the necessary apertures with means by which they can be
closed air-tightly and the structure as a whole is protected by armouring prefer-
ably consisting of iron plates.
I describe two forms of furnace according to this invention by way of example.
The closing doors of all the working apertures are provided with devices by
which they can be tightly closed. These may be screws and bars resembling
those of retort lids, the joints being packed with asbestos cardboard pressed
against the faced surfaces when the said screws are tightened up.
The air requisite for roasting enters sulphuric acid drying towers and after
passing through them, the said air is conducted to underneath the bars of the
roasting chambers.
The roaster gases enter the chambers which contain the contact material which
may be the burnt ore, the heat of the said gases being sufficient to maintain the
said contact material at a red heat, as the gases pass through these chambers
the reaction whereby the sulphurous acid is converted into sulphuric anhydride
takes place.
The roaster gases having undergone the reaction, are conducted to the con-
densers or absorbers wherein the sulphuric anhydride which has formed is absorbed
by concentrated sulphuric acid.
The entire furnace is cased with iron armour, so as to prevent access of air
through the structure thereof notwithstanding the powerful resistance offered to
the passage of the gases by the contact material.
Fresh contact material is admitted through a charging device the spent material
being removed by the revolving grates,

page_text: In another form of the apparatus the reaction chamber is situated below the
pyrites to be roasted; the roaster gases traversing it in a downward direction,
the layers of pyrites burning downwardly.
The air required for roasting after passing through the sulpliuric acid drying
tower is conducted to the roasting chambers through pipes as before.
The roaster gases generated from the roasting pyrites pass through the layers
of burnt ore or other contact substance wherein the reaction takes place, and
are conducted to the condensers or absorbers.
This apparatus is fitted and has the outer structure covered with armouring
like that first described.
i
Dated this 26th day of January 1899.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.
Improvements in Roasting Furnaces more especially intended for
Roasting Pyrites or the like for the Direct Production of Sulphuric
Anhydride from the Gases Evolved.
I, GEORGE WILLIAM JOHNSON, of 47, Lincoln's Inn Fields, in the County of
London, Patent Agent, do hereby declare the nature of this invention (which has
been communicated to me from abroad by Verein Chemischer Fabriken of
Mannheim, in the German Empire) and in what manner the same is to be per-
formed to be particularly described and ascertained in and by the following
statement:
This invention has for its object to provide an improved roasting furnace, more
especially intended for use in roasting pyrites, or the like, for the direct pro-
duction of sulphuric anhydride from the evolved gases and I will describe it in
that connection.
In a furnace according to this invention the air necessary for roasting the
materials (which I will refer to as pyrites), is first passed through an apparatus
wherein it is dried by means of concentrated sulphuric acid, and is then conducted
to beneath the roasting chamber, or chambers, and the gases, issuing from the said
roasting chamber, or chambers are passed through a space, or spaces, containing
contact material,-which space, or spaces, may be situated either above, or below,
the pyrites to be roasted, the said gases traversing it either in the upward, or
in the downward, direction and maintaining the contact material at the requisite
temperature.
Access of external undried air is as far as possible prevented by providing the
necessary apertures with means by which they can be closed air-tightly, and the
structure, as a whole, is protected by armouring, preferably consisting of iron
plates.
In the accompanying drawings two forms of the improved furnace are repre-
sented by way of example.
Figure 1 is a vertical section and Figure 2 is a horizontal section of one
arrangement.
The roaster gases are generated in the roasting chambers a¹ a² a³ a¹.
The closing doors, (indicated at C), of all the working apertures are provided
with devices by which they can be tightly closed. These may be screws and
bars, resembling those of retort lids, the joints being packed with asbestos card-
board pressed against the faced surfaces when the said screws are tightened up.
The air, requisite for roasting, enters the sulphuric acid drying towers el e³,
at and after passing through them, the said air is conducted by the
pipes ƒ¹ ƒ³ f³ fª to underneath the bars of the roasting chambers]

page_text: The roaster gases from the chambers a¹ a² a³ a enter the chambers g¹ g² which
contain contact material, which may be the burnt ore, the heat of the said gases
being sufficient to maintain the said contact material at a red heat and as the
gases pass through these chambers gig the reaction, whereby the sulphurous
acid is converted into sulphuric anhydride, takes place.
The roaster gases having undergone the reaction, are conducted through
pipes (h) to the condensers, or absorbers, wherein the sulphuric anhydride, which
has formed, is absorbed by concentrated sulphuric acid.
The entire furnace is cased with iron armour, so as to prevent access of air
through the structure thereof notwithstanding the powerful resistance offered to
the passage of the gases by the contact material in the chambers g¹ g³.
Fresh contact material is admitted through the charging device k the spent
material being removed by the revolving grates j.
Figures 3, 4 and 5 shew in vertical sections at right angles to each other and
in sectional plan another form of the apparatus wherein the reaction chamber is
situated below the pyrites to be roasted, the roaster gases traversing it in a down-
ward direction.
aa² are the roasting chambers and 2 the layers of pyrites to be roasted,
CCC are the charging and working orifices fitted with devices for tightly
closing them as aforesaid. The layers of pyrites in this form of apparatus burn
downwardly. The air required for roasting after passing through the sulphuric
acid drying tower d is conducted to the roasting chambers through pipes el e².
The roaster gases generated from the roasting pyrites pass through the layers f¹ f²
of burnt ore or other contact substance, wherein the reaction takes place, and
are conducted through the pipes g g to the condensers or absorbers.
In proportion as fresh pyrites are admitted through the charging orifices C¹ C³
the waste material, which has been used up is removed by the rotary grates ht h².
This apparatus is fitted, and has the outer structure covered with armouring,
like that first described.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1. In roasting furnaces for the purposes described the combination of means
whereby the air required for roasting the pyrites is dried by means of concen-
trated sulphuric acid and is then conducted to beneath the pyrites to be roasted
and of a space or chamber or spaces or chambers containing contact material,
and through which the gases from the pyrites pass (either in an upward or down-
ward direction) so as to maintain the said contact material at the proper tempera-
ture and tightly closable apertures and an armouring or casing for guarding
against access of external undried air all substantially as herein before described.
2. A roasting furnace for the aforesaid purposes constructed as herein before
described and illustrated in Figures 1 and 2 of the accompanying drawings.
8. A roasting furnace for the aforesaid purposes constructed as herein before
described and illustrated in Figures 3, 4 and 5 of the accompanying drawings.
Dated this 4th day of October 1899.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agenis.