IMPROVEMENTS IN APPARATUS FOR REDUCING OR PULVERIZING MINERALS AND METALLIC ORES
Year: 1882

page_text: LETTERS PATENT to Richard John Cunnack of Helston in the County of
Cornwall Merchant, for an Invention of IMPROVEMENTS IN APPARATUS FOR
REDUCING OR PULVERIZING MINERALS AND METALLIC ORES
"
PROVISIONAL SPECIFICATION left by the said Richard John Cannack at
the Office of the Commissioners of Patents on the 5th August 1882.
RICHARD JOHN CUNNACK of Helston in the County of Cornwall, Merchant.
IMPROVEMENTS IN APPARATUS FOR REDUCING OR PULVERIZING MINERALS AND
METALLIC ORES."
The apparatus consists mainly of two horizontal rubbers of similar dimensions
of which the lower is applied with its upper surface in a level position while the
upper rubber is moved upon it in the manner hereinafter described. Apertures
are made in and around the centre of the upper rubber through which a small
stream of water carries in the stuff to be treated.
Motion is given to the upper rubber by means of an upright shaft fitted to
revolve in a strong frame, over the centre of the lower or fixed rubber and driven
by any suitable gear, (with rubbers which may be about 4 feet diameter, and
about 30 to 40 revolutions per minute is found to be a suitable speed of rotation
but the size and rate may be varied according to the character of the material
treated.) At the lower end of the shaft is a crank of a length (generally from two
to five inches) suited to the size of the rubbers; the crank pin (which is made
sufficiently long to allow for the wear of the rubbers) working in a hole made over
the centre of the movable rubber in a metal plate applied across it for that
purpose.
On the shaft being turned the upper rubber will thus be moved excentrically
over the lower one the unequal friction on its opposite circumferences causing it at
the same time to revolve on its axis about the crank pin. (This revolution about
its axis may be increased or varied by suitable gearing attached to the rubber and
frame, but these additions are not essential to the performance of the machine,

page_text: although they in some cases increase the good effect.) The double motion thereby
produced not only increases the grinding effect, but it also keeps the two surfaces
in a uniformly effective condition.
The whole is surrounded by a shallow pan of any suitable material, over the
edge of which the ground substance is expelled by a flush of water in the usual
way. The fineness or coarseness is regulated by increasing or diminishing the
quantity of water in the pan.
The wearing portions of the rubbers may be made separate from the other parts
of the machine so as to admit of renewal as they become worn away. These
renewable parts or 'shoes" may be of any convenient thickness (generally about
3 inches but this may be greatly varied) and they should be of very hard metal.
They may be either solid or with holes or openings throughout their substance
with a view of producing numerous cutting edges, as the upper plate revolves
over the lower one, this being found most effective in treating very hard material.
In many cases it is advantageous to fill up the holes or perforations with a softer
material, such as wood, cement or other similar substance, (leaving such intervals
as are necessary for feeding) to prevent the material under treatment from passing
through too quickly.
When separate rubbers or "shoes" are used, a bed plate is fastened to a proper
loading or foundation at the base of the machine, having hollows in its upper
surface into which projecting studs on the back of the "shoes" fit. The upper or
moving portion is made in the shape of a shallow circular pan into which weights
may be put having also openings in the bottom corresponding to the projecting
studs on the back of the "shoes" 'so as to admit of the ready insertion of the latter.
A bar is fixed across the top of the pan, in which, directly over the centre of the
latter is bored the hole for receiving the crank pin giving motion to the whole.
The fed materials flow into the pan and from thence through openings in and
about its centre, to the grinding surfaces.
In some cases the rubbers may be advantageously made of hard stone or slag.
I construct these by building them with cement within iron rings, taking care that
the grain (if any) of the stone fragments is as far as possible set at right angles
to the grinding surfaces. Cast iron centres may be built in the rubbers so
constructed to provide for feeding through and to support the bar containing the
hole in which the driving pin of the crank works.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Richard John Cunnack in the Great Seal Patent Office on the
5th February 1883.
RICHARD JOHN CUNNACK of Helston in the County of Cornwall Merchant
IMPROVEMENTS IN APPARATUS FOR REDUCING OR PULVERIZING MINERALS AND
METALLIC ORES
"
The apparatus consists mainly of two horizontal rubbers of similar dimensions of
which the lower is applied with its upper surface in a level position while the
upper rubber is moved upon it in the manner hereinafter described. Apertures are
made in and around the centre of the upper rubber through which a small stream
of water carries in the stuff to be treated.
Motion is given to the upper rubber by means of an upright shaft fitted to
revolve in a strong frame over the centre of the lower or fixed rubber and driven
by any suitable gear (with rubbers which may be about 4 feet diameter about 30
to 40 revolutions per minute is found to be a suitable speed of rotation but the
size and rate may be varied according to the character of the material treated)
At the lower end of the shaft is a crank of a length (generally from two to five
inches) suited to the size of the rubbers the crank pin (which is made sufficiently
long to allow for the wear of the rubbers) working in a hole made over the centre
of the movable rubber in a metal plate applied across it for that purpose.
On the shaft being turned the upper rubber will thus be moved eccentrically
over the lower one the unequal friction on the opposite parts of its circumference
causing it at the same time to revolve on its axis about the crank pin. This
revolution about its axis may be increased or varied by suitable gearing attached
to the rubber and frame but these additions are not essential to the performance of
the machine although they in some cases increase the good effect the arrangement
preferred being a wheel having internal teeth fixed to the frame gearing into a
toothed pinion attached to the rubber and turning with it on the crank pin. The
double motion thereby produced not only increases the grinding effect but it also
keeps the two surfaces in a uniformly effective condition.
"
The whole is surrounded by a shallow pan of any suitable material over the edge
of which the ground substance is expelled by a regular or intermittent flush of
water in the usual way. The fineness or coarseness is regulated by increasing or
diminishing the quantity of water in the pan.
The wearing portions of the rubbers may be made separate from the other parts
so as to admit of renewal as they become worn away. These renewable parts or
shoes" may be of any convenient thickness (generally about 3 inches but this
may be greatly varied) and they should be of very hard metal. They may be
solid but preferably they should be made with holes or openings throughout their
substance with a view of producing numerous or extensive cutting edges as the
upper plate revolves over the lower one, this being found most effective in treating
very hard rough material.
In many cases it is advantageous to fill up the whole or a portion of the holes
or perforations (more especially towards the outer edges) with a softer material
such as wood, cement or other similar substance (leaving such intervals as are
necessary for feeding) to prevent the material under treatment from passing
through too quickly.
When separate rubbers or "shoes" are used a bed plate is fastened to a proper
loading or foundation at the base of the machine, having hollows in its upper
surface into which projecting studs on the back of the "shoes" fit. The upper or
L

page_text: "
moving portion is made in the shape of a shallow circular pan (into which weights
may be put if desired, having also openings in the bottom corresponding to the
projecting studs on the back of the "shoes so as to admit of the ready insertion
of the latter. A. cross bar is fixed across the top of the pan in which (directly
over the centre of the latter) is bored the hole for receiving the crank pin giving
motion to the whole.
The fed materials flow into the pan and from thence through openings in and
about its centre to the grinding surfaces.
In some cases the rubbers may be advantageously made of hard stone or slag or
scrap iron or steel. I construct them by building them with cement or wedges
preferably of dry wood within iron rings, taking care that the cleavage planes (if
any) of the stone fragments are as far as possible set at right angles to the grinding
surfaces. Cast iron centres may be built in the rubbers so constructed to provide
for feeding through and to support the bar containing the hole in which the
driving pin of the crank works.
The material to be pulverized should be first crushed to a size to pass through
sieves of froin 9 holes to a square inch or smaller according to the degree of
hardness.
When the apparatus is used for treating gold or silver ores, quicksilver is placed
in the pan surrounding the fixed or bottom grinder (which pan may have a steam
jacket for heating if required) The upper grinder at each revolution will sweep
off the floating particles from the surface of the mercury continually exposing
fresh material to its action without disturbing it so as to cause waste by attrition.
The charge of quicksilver may be drawn off or replaced as often as necessary
without stopping the machine.
Amalgamated copper plates or mercury troughs are set in front of the dis-
charging flush so as to intercept any material that may escape the mercury in
the pan.
The perforations or cavities in the "shoes "or rubbing plates may be of any
shape or dimensions regularly or irregularly distributed throughout the substance
of the plates and as numerous as may be consistent with strength. The object
being to produce the greatest extent of cutting edges. In the case of grinders
built up of fragments, these perforations or cavities are represented by the cement
or wood which being relatively soft wears away more rapidly leaving the edges of
the harder material it encloses free to act.
But that the invention may be the better understood I will by the aid of the
accompanying drawings proceed more fully to describe means employed by me
in carrying the same into effect.

page_text: Figures 2 and 3 represent a section and plan of the movable pan with cross bar
and pinion H. The pinion H is made deep enough to allow for the wearing of the
grinding plates E' E².
Figures 4 and 5 represent a section and a plan of one form of perforated shoes
or grinding plates showing studs F³ at back fitting into the hollows for attachment
to the pan D¹ and bed plate D².
Figures 6 and 7 shew section and plan of the bed plate D².
Having thus described my Invention and means which I adopt in carrying the
same into effect I would have it understood that I do not confine myself to the
precise details shown and described as variations may be made therein without
departing from the peculiar character of my invention But what I do claim is :-
First. The arranging or combining parts of apparatus for reducing or pulverizing
minerals and metallic ores whereby an eccentric motion is given to one of the
rubbing surfaces in relation to the other of them substantially as described.
Second. I claim the arranging or combining parts of apparatus for reducing or
pulverizing minerals and metallic ores whereby the parts constituting the rubbing
or grinding surfaces are provided with perforations or cavities substantially as and
for the purposes described.
In witness whereof I the said Richard John Cunnack have hereunto set
my hand and seal this third day of February in the year of our Lord One
thousand eight hundred and eighty three.
RICHARD JOHN CUNNACK. (L.S.)