Improvements in Gold "Saving" and Mineral Washing Machines.
Year: 1887

page_text: Date of Application, 22nd Dec., 1887
Complete Left, 9th Apr., 1888
Complete Accepted, 11th May, 1888
Improvements in Gold "Saving" and Mineral Washing Machines.
I CHARLES MITCHELL of Johannesburg South African Republic at present
residing at 3 Brunswick Street, Stamford Steet in the County of Surrey Engineer
do hereby declare the nature of-this-invention-to-be-as follows:-
This Invention relates to a peculiar construction and arrangement of machinery or
apparatus for more expeditiously effecting the "saving" of gold from auriferous
deposits whether Reef Alluvial or Conglomerate and partly applicable as a mineral
washer for precious stones and consists as arranged for gold "saving" of one or more
rotating circular copper plates or pans of a slightly conical or dished form coated
with amalgam or charged with free quicksilver to enable the separated gold to
adhere as is well understood-These plates are mounted on a rotating shaft which
is inclined more or less from the vertical and revolves in suitable bearings capable
of lateral adjustment according to the desired inclination of the plate or plates and
to the nature of the substance to be treated. The said plates are supplied with water
from one or more spray pipes or they may if desired work submerged in water in a
suitable tank.
When using say three plates or pans they should be set at different angles
alternately and be capable each of separate angular adjustment to the shaft, and
each plate is provided with an adjustable raised discharge pipe so as to retain a
sufficient amount of free quicksilver. For alluvial washing the first or top plate
may be made of iron or of wood if desired. The crushed quartz or the alluvial
auriferous soil is supplied by a shoot or otherwise onto the top plate which being set
at the proper angle gives an inward motion towards the centre to the substance
under treatment by its revolution and causes the fine gold and refuse to be delivered
through an opening onto the second or next plate below near the centre thereof the
rough quartz being removed by a rake or otherwise. The water spray drives back
.
073

page_text: the rougher and light quartz and allows the heavy gold to be caught by the amalga-
mated plate This second plate which takes in its feed of quartz near the centre
is set at such an angle that its rotation will impart an outward movement to the
quartz which it throws off at the periphery and deposits outside as rough tailings.
It is also provided near its outside edge with one or more discharge openings to
allow the remainder or fine quartz and gold to fall onto the bottom or third plate
which is inclined so as to carry the same to near its centre where it is provided
with an adjustable raised discharge pipe retaining the free quicksilver and gold
whilst allowing the refuse to escape.
When intended simply as a washer for precious stones the rotating conical
plates or pans whether one or more be employed may be of wood or iron supplied
with water in the same manner as described with reference to the gold "saving'
machine.

page_text: Fig. 1 is a front elevation of a gold "saving" machine constructed according to my
invention shown as provided with three plates or pans in section.
Fig. 2 is a side elevation thereof.
Fig. 3 is a plan of one of the conical or dished plates or pans shewing the adjustable
discharge pipes in connection therewith.
Figs. 4 and 5 are details shewing arrangements by which the height of the inlet
apertures of the discharge pipes may be regulated.
Similar letters indicate corresponding parts in all the figures.
A is the main framing of the machine, B the inclined rotating shaft working at its
lower extremity in the footstep bearing C and supported above by the bearing D
which is capable of lateral adjustment in order that the angle or inclination of the
shaft B.and consequently, of the plates mounted thereon may be adjusted as required:..

page_text: The said shaft may be driven by gearing as shewn or otherwise and by any
suitable power and carries the conical or slightly dished plates or pans E, E¹, El,
coated with amalgam or charged with free quicksilver and provided with flanges F,
and attached to the bosses G secured adjustably by set screws or otherwise, for
facility of removal, to the shaft B. ffaro apertures in the flanges F, which
should be above the level of the free quicksilver in the plates, through which the
smaller lumps of the substances under treatment such for instance as alluvial earth
may be discharged by the rotation of the plates. H, H¹, H", are the adjustable
discharge pipes for conveying the substances operated upon from one rotating plate
to another. The inlet portions h h of these discharge pipes which pass through
the plates near the centre are preferably threaded externally and provided with
adjusting nuts as shown, in fig. 4 by which the height of their mouths above such
plates may be regulated, so as to retain a sufficient quantity of free quicksilver,
or the said portions hh may be threaded internally and provided with an
externally threaded adjustable pipe as shewn in fig. 5. The other extremities
of the discharge pipes are preferably situate near the circumference of the plates
so as to discharge close to the periphery of the plate below. The said pipes H
should also be so arranged as shewn in fig. 3 that when the inlet portions h h
are brought to their lowest position by the rotation of the inclined plates the
discharge ends ₁₁ will still have about one quarter of a revolution to make
before reaching their lowest position, the object of this arrangement being to cause
such pipes to commence their discharge quickly. J J are the pipes for delivering
water to the respective plates, and K. K the feed and discharge shoots respectively.
The action of the apparatus when employed for washing alluvial earth for example,
for gold "saving" is as follows:
The alluvial oarth is supplied by the shoot K or otherwise to the top plato E which
being set at an angle as shewn gives an inward motion towards the centre to the
substances therein by its rotation, the water from the pipe J drives back the earth
and allows the gold to be caught by the amalgamated plate, the larger lumps of the
substance under treatment are then removed by the attendant by means of a fork rake
or other convenient implement and the smaller lumps are thrown off through the
openings ff in the flange F. The refuse together with the gold not caught by the
first plate.now passes through the discharge pipes H onto the second amalgamated
plate E which is also inclined so as to give the substances an inward motion towards
the centre, the above mentioned operations are then repeated except that there are no
lumps requiring removal by hand and the refuse and gold not caught by the second
plate pass through the discharge pipes H therein onto the third inclined amalgamated
plate E where the same operations are again repeated the refuse passing out of the
adjustable raised discharge pipes H therein which like the other discharge pipes are
elevated sufficiently to prevent the heavy gold and free quicksilver from escaping, and
from thence is delivered by a shoot K¹ or otherwise as required. The inlet apertures /
of the pipes H, H¹, H", should when the machine is employed for washing alluvial
earth or other substances which may contain lumps be preferably furnished with
wire meshes or suitable strainers to prevent clogging and render the discharge
free.
.
When the machine is employed for washing crushed quartz or other substances that
have been pulverized or reduced to a fine state, the holes in the flanges may be
dispensed with and also the strainers to the inlets of the discharge pipes and of course
there are no lumps requiring removal by hand as before described.
The same machine may be equally well employed for washing minerals for precious
stones the action being the same as before described with reference to Alluvial earth,
but amalgamated plates not being required, plates of wood iron or other suitable
material may be substituted therefor.
It will be readily understood that various modifications of the above might be
employed, for instance one plate alone of larger diameter in proportion might be used
or two four or more plates might be employed with an equally good result. Also the
discharge pipes might discharge near the centres instead of near the peripheries of.the

page_text: plates below in which case a different angle or inclination would have to be given to
each plate in order to cause the substances falling thereon to pass over the entire
surfaces thereof.
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
1 claim is :-
:-
1. The application and use for the purpose of gold "saving" and mineral washing
of one or more rotating plates or pans set at an angle to the horizontal plate and
mounted upon an axis, provided each with a suitable discharge pipe or pipes
substantially as described.
2. In a machine for gold "saving" and mineral washing the combination and
arrangement of rotating plates or pans set at an angle to the horizontal plane mounted
upon an inclined axis or shaft working in adjustable bearings and provided with a
suitable discharge pipe or pipes the inlet apertures of which are capable of vertical
adjustment and supplied each with water from a suitable pipe or otherwise substantially
as specified and illustrated by my drawings.
3. The combination and arrangement of apparatus for gold "saving" and mineral
washing substantially as specified and illustrated.
Dated this 23rd day of March 1888.
A. E. ALEXANDER, Fel. Inst. P.A.,
Agent.