Year: 1895

page_text: Date of Application, 3rd May, 1895-Accepted, 13th July, 1895
I, EDWARD AUBREY MARTIN 42 Oak Road Horfield Bristol, Mining
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 improvements in the process of roasting sulphide ores
more especially in connection with that operation which is known as the chlorinating
process, but is also applicable to other methods of treating ores and has special
reference to that part of the process which appertains to roasting the ore previous
to subjecting it to chlorination or other processes.
Where sulphide ore is roasted in vertical furnaces it often happens that through
defect of roasting the last trace of sulphur is not removed and from well understood
chemical reasons sulphur even in minute quantities presents an obstacle to the
complete chlorination of gold in oriferous ores but my invention relates to a process
and means for overcoming this defect in eliminating the ultimate trace of sulphur
to a greater extent than has been possible with the method of roasting in vertical
furnaces hitherto in use.
But I do not confine myself to using this improvement in furnaces to roasting
gold ores, it is also applicable to the roasting of all sulphide ores.
I carry my invention into practice in manner as follows:-
In that class of roasting furnace which is termed the vertical type and where the
sulphides of the ore are exposed to the roasting process by being blown in by
steam or air from the top and being ignited and more or less oxidised as they
descend through the furnace to the bottom, I utilise the heat contained in the
resulting sulphurous acid and the burning sublimed sulphur which in the present
method of roasting in vertical furnaces now goes to waste.
The gases escaping from the mouth of the furnace are drawn off at or near the
mouth of the furnace, and conducted through certain channels to a reverberatory
furnace, during the passage of the heated gases through the channels or
immediately prior to the introduction of gases into the reverberatory furnace and
before the further combustion of the sublimed sulphur takes place there is mixed
with the said gases a suitable quantity of air heated or otherwise to enable a
better and more perfect combustion of the sublimed sulphur to take place in the
reverberatory furnace the now utilised gases are used for the purpose
re-roasting the already partially roasted ore which has been passed through the
vertical furnace.
of
This partially roasted ore is placed on the bed of the reverberatory furnace and
the flame from the recovered gases and burning sublimed sulphur directed on and
over the ore which ore is manipulated whilst in the reverberatory furnace in any of
the usual and well known methods.
It will now be found that after being thus roasted in the reverberatory
furnace, the last trace of combined sulphur is entirely eliminated from the ore.
In order that my invention and the manner of carrying it out may be more
clearly understood, I append hereto two sheets of explanatory drawings which are
to be read and taken as part hereof.
In the drawings like letters refer to like parts.
Figure 1. is a horizontal transverse section of the arrangement of furnaces.
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page_text: Figure 3 is a vertical section of furnace.
A. is the shaft of the vertical furnace at the top of which the ore is introduced
at O.
B is the firebrick lining and walls of the vertical furnace.
C. is the bottom on which the partially roasted ore falls, and D is the aperture
through which the said ore is withdrawn on to the bed I of the reverberatory
furnace.
Near the top of such furnace an aperture and flue E communicating with the
vertical shaft A and a flue F which carries the gases down to the bed of the
reverberatory furnace I.
Air is admitted by an aperture HI to mix with the recovered gas which now is
enabled to be freely burnt and the flame of which completes the roasting of any
ore deposited on the bed I of the reverberatory furnace such ore having been
previously partially roasted in the vertical furnace A or prepared for roasting or
any other process it is desirable to subject ores to heat.
K is a fire place in which a supplementary fire may be burned to heat or roast
any ore placed on the bed I of the reverberatory furnace. L are doors in the
walls of the reverberatory furnace through which the ore can be manipulated,
during the process of roasting, M is a damper to shut off the heat and flame from
the fire place or furnace K from the reverberatory furnace bed I when and as
required.
O is the aperture at the top of the furnace through which the ore is passed into
the furnace.
The method of working the furnace is as follows:-
The vertical furnace A having been sufficiently heated either from the fire place K
or by other means powdered ore is introduced through the opening at the
mouth of the vertical furnace in falling through the previously heated furnace A
the combined sulphur contained in the ore is ignited, the heat flame and other
products are driven off through channel or opening E and thence down flue F
into reverberatory furnace of which I is the bed air having been previously
admitted into flue F at hole H to assist in the combustion of the sulphur.
P are openings in the side of the furnace to dislodge ore adhering to sides of
furnace.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed I declare that what I
claim is :
1. A form of vertical roasting furnace in which the heat evolved in roasting
sulphide ores is utilised for supplementary roasting in the manner and method as
hereinbefore described and set forth.
2. A process of eliminating the last trace of sulphur from sulphide ores that
have been previously roasted in a vertical furnace in a powdered or finely ground
state by means of a furnace or furnaces constructed in the manner hereinbefore set
forth and described.
3. A form of vertical roasting furnace which is combined with a reverberatory
furnace in such a manner that a fire may be used in connection with the
reverberatory furnace so that the partially roasted ores from the vertical furnace
may be readily removed to the reverberatory furnace for further treatment
substantially in the manner herein before set forth and described.
Dated this 2nd day of May 1895.
.
W. M. LLEWELLIN, C.E.,
15 King Square, Bristol, Agent for Applicant.