AN IMPROVED METHOD OF SEPARATING METALLIC ORES FROM THEIR GANGUE APPLICABLE ALSO FOR OTHER MINERALS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Thomas Sanden Godman Kirkpatrick
at the Office of the Commissioners of Patents on the 31st July 1882.
THOMAS SANDEN GODMAN KIRKPATRICK of 38 Eccleston Square in the County
of Middlesex "AN IMPROVED METHOD OF SEPARATING METALLIC ORES FROM THEIR
GANGUE APPLICABLE ALSO FOR OTHER MINERALS
17
My Invention relates to an improved method of separating metallic ores from
their gangue, and is more especially valuable in its application to the separation and
treatment of ores containing the precious metals, whether free or in combination.
It is also applicable to coal and other minerals.
Many attempts have been made to effect the separation of minerals from their
accompanying gangue by means of water and also by means of air, but up to the
present time and more especially in the case of gold and gold sulphides, whether
treated by water mercury or other processes either the percentage of loss in the
operation has been very large or the expense very considerable; but by the method
of my Invention I am able to produce a result in the case of ores containing gold
and gold sulphides equal to or within a fraction of the result obtained by fire-assay
of the sample of raw mineral treated and at a very trifling cost.
My invention consists in a peculiar and improved method of "winnowing" the
ore for the purpose of separating particles of different densities, the peculiar
feature of this method being that the ore is caused by its own gravity to be
repeatedly presented in thin loose streams, to a steady and continuous ascending
current of air drawn through the descending or falling ore by exhaustion and of a
strength regulated at will to suit the character of the minerals under treatment,
whereas all previous attempts to separate the ore from the gangue by means of air
have been based on "jigging" the ore on sieves by varying or intermittent puffs of
air compressed or otherwise forced through a comparatively large and dense bulk
of crushed ore reposing on screens or sieves.
In carrying my invention out in practice the ore is dry-crushed by any suitable
mechanical process, and is separated by sieves into three or more sizes according
to the quality of the ore and the character of the matrix. Each parcel of different
sized ore is then ".winnowed" separately, by being passed through a machine so
constructed as to repeatedly present the ore in thin loose streams falling by gravity
into upwardly directed currents of air which separate and carry off the less dense

page_text: worthless particles, leaving the metallic constituents of the ore to be collected, as
the operator may determine, in one two or several parcels, if there be a sufficient
variety and quantity of base metals present in the ore to render such a separation
worth while; the machine being capable of being regulated with great exactitude
by a simple mechanical contrivance to suit the class of ore or gangue in each
particular case, and the whole process being conducted automatically at a minimum
cost.
I would observe in passing that it is better to under-, rather than over-, dress
the ore, as the presence of a small amount of gangue in the product is of far less
importance than the loss of valuable mineral dust which might be carried away to
the exhaust by too fine dressing.
The ore after being concentrated as above described is treated by any approved
method for the extraction of the metals it may contain.
In the case of some minerals the lighter portion is the more valuable (coal for
instance of which millions of tons are annually left for waste in consequence of
mixture with heavier gangué) and the principle of this Invention is equally
applicable.
The machine for winnowing the ore is provided with means for receiving
screening feeding and distributing the crushed ore for the purpose of submitting
it to the air current and it is constructed principally of a successive series of
vertically or upwardly directed exhaust passages, whereinto the ore is caused to fall
in thin loose streams, being conducted from one to the next by suitable shoots and
openings and in which it is met by upwardly directed currents of air produced by
the suction of an exhaust fan. The machine can be so regulated as to treat each
separate sized parcel of sieved ore and is provided with a settling chamber having
a number of compartments in which the more or less fine but dense particles
which may be partially separated by the current of air, are deposited, such
compartments being provided with an automatic delivery of the concentrated
produce into receivers which can be kept locked and thus secured under the
absolute control of the operator or manager, a point of the first importance in the
manipulation of ores containing the precious metals.