An Improved Method of Calcining Pyrites and other Gold Bearing Ores.
Year: 1888

page_text: COMPLETE SPECIFICATION.
An Improved Method of Calcining Pyrites and other Gold Bearing
Ores.
I, DAVID HUTTON, of Alfred Chambers, Currie Street, Adelaide, in the Province
of South Australia, Machinist, 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:—
The object of my Invention is to provide a method for the more perfect dis-
integration of the matrices containing Gold by a process of carbonization and
oxidization of the foreign matters enveloping the gold pellicles such as Iron, Arsenic,
etc. By my method nearly all the gold any ore may contain can be saved in the
form of free gold through being brought in contact with quicksilver in the ordinary
way.
In caleining pyrites by the methods usually adopted, the ore has first to be
reduced to a fine powder; and this, from its refractory nature, involves much labor
and expense.
In my invention, the pyrites are treated as received from the dressing
floors, and after calcination, are reduced to powder by crushing rolls for treatment
by, any suitable gold saving method or apparatus.
.
My improved process of calcination consists in the injection of steam or of water,
and in some cases of a strong solution of Chloride of Sodium for the generation of
steam, into the kiln or furnace. By this means, a more complete carbonization and
oxidization of the pyrites is effected, and the ore is removed from the kiln or furnace
in masses which are friable and can be easily reduced to any required degree of
fineness; so that the gold, however finely divided, need not be lost.
My invention consists primarily in the injection of steam or aqueous vapours at
a sufficient pressure; but where such, from any cause, are not available, water, or
with some
ores a strong solution of Chloride of Sodium, may be injected.-Care
must then be taken that the fluid is only supplied in such quantities as will be
readily converted into steam or vapor or the full benefits of my process will not be
obtained. Steam or aqueous vapours may be injected into the kilns or furnaces by
any suitable methods; but an appliance for the purpose is shewn in the accom-
panying drawings, in which Fig. 1, is an elevation of a square kiln; Fig. II, is a

page_text: plan of the floor of the same. A₁ Fig. I. is an ordinary kiln twelve feet square.
B₁ air-tight cover or lid. C₁ outlet door. D₁ safety valve in cover B₁. E, steam
supply pipe. F₁ Fig. II. brick gutter or perforated pipes on floor of kiln.
G₁ diagonal perforated pipes radiating from a central four-way joint and with F₁
connected with the main supply pipe E.
The kiln or furnace A, is charged in the usual way with ore, or pyrites. intermixed
with suitable fuel in such proportions as the class of ore to be treated may require.
The kiln is then fired and the contents hoated to redness or such other degree as
may be necessary. Upon the required heat being attained, the cover of the kiln
is closed down so as to exclude the outer air and steam or aqueous vapours injected
from the supply pipe E, through the gutter F₁ and the diagonal pipes G₁. The
injection is continued until the steam ceases to be decomposed during its passage.
through the charge of the kiln and is thrown off in moderate volumes through the
safety valve. On this being perceived the supply of steam or fluid is stopped. The
kiln is kept closed until the charge has sweated down and cooled. The latter is then
removed, and after, being exposed to the atmosphere for such period as may be
required, is ready for crushing and after treatment.
It will be found that during the process of calcination the ores have become
thoroughly carbonised and oxidised, and that in consequence they are so friable as to
be reduced to the finest powder with little labor.
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
First The method of obtaining the more perfect carbonization and oxidisation
of pyrites and other ores, such process consisting of the injection of steam or aqueous
vapours under pressure, or of fluid for the formation of such vapors, during the
period of calcination, and, after rendering the kiln or furnace airtight, of allowing
the charge to sweat down or cool, afterwards exposing it to the action of the
atmosphere, substantially as herein described.
Secondly In the process of calcinating pyrites and other ores, the injection from
underneath of steam or aqueous vapors during the period of calcination, substantially
as herein described.
Tao
1
P T 1
1000