IMPROVEMENTS IN ORE GRINDING AND AMALGAMATING MACHINES
Year: 1881

page_text: LETTERS PATENT to Thomas Allison Readwin, of Bloomsbury Square, in the
County of Middlesex, for an Invention of "IMPROVEMENTS IN ORE GRINDING
AND AMALGAMATING MACHINES."
PROVISIONAL SPECIFICATION left by the said Thomas Allison Readwin
at the Office of the Commissioners of Patents on the 22nd August 1881.
THOMAS ALLISON READWIN, of Bloomsbury Square, in the County of Middlesex.
"IMPROVEMENTS IN ORE GRINDING AND AMALGAMATING MACHINES."
This Invention has reference to that kind of machine used for grinding ore and
amalgamating gold or silver with mercury, wherein by an arm carried round by a
vertical spindle suitably driven a pestle is caused to rotate about its own axis, and
to roll obliquely on the inner surface of a circular pan whose half vertical section
approaches the form (as seen in corresponding section) of the rounded surface of the
pestle.
In machines of this kind as heretofore usually constructed considerable wear
takes place in the bearings of the vertical spindle (to which neither oil nor grease
can safely be applied); also in the pestle axis; also in the mercury cup at the
bottom of the pan. Considerable loss of time arises owing to the irregularity due.to
the hand feeding, and there is no efficient provision against unauthorised with-
drawal of the contents of the pan.
Now according to my Invention to obviate or mitigate these defects the bearings
of the vertical spindle are formed of hard wood or asbestos, and water is used as a
lubricant. The pestle axis (heretofore usually made in one piece with or cast in
the pestle body) is made of hardened steel and removeable from the pestle body,
and is fixed therein in such a manner that it can be shifted lengthwise or renewed
at pleasure. The pan is bored out or recessed at the bottom, and hollow cylin-
drical hardened steel cup is fixed in the recess to receive the lower end of the
pestle axis which works therein. A long trough is provided that runs the entire
length of each set of pans; in this trough an archimedian screw is caused to revolve
so as to gradually propel any material placed in it from one end of the trough
Price Rd1

page_text: towards the other; opposite each pan there is an aperture in the trough through
which, as the material travels along the trough, some of it falls; each of these
apertures is provided with a chamber of specific capacity having inlet and outlet
doors or valves which are opened and shut at regular intervals by screws or
gearing actuated by the driving shaft placed over the machines; or instead, I |
produce the same effect by means of a boss carrying a cup or cups which shall dip
into the material and discharge the required quantity into a shoot in a specified
time.
The mercury cup is provided with an eyed tap screw, a wire or bar (which may
be composed of wires stranded together) is put through the eye of each tap screw
in a series, and is secured by means of a lock and key, or the bar may be hinged
to the tap screws in a series instead of passing through eyes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Allison Readwin in the Great Seal Patent Office on the
21st February 1882.
THOMAS ALLISON READWIN, of Bloomsbury Square, in the County of Middlesex.
“IMPROVEMENTS IN ORE GRINDING AND AMALGAMATING MACHINES."
This Invention has reference to that kind of machine used for grinding ore and
amalgamating gold or silver with mercury, wherein by an arm carried round by a
vertical spindle suitably driven, a pestle is caused to rotate about its own axis and
to roll obliquely on the inner surface of a circular pan, whose half vertical section
is of a form resembling that (as seen in corresponding section) of the rounded
surface of the pestle.
In machines of this kind as heretofore usually constructed considerable wear
takes place in the bearings of the vertical spindle (to which neither oil nor grease
can safely be applied); also in the pestle axis; also in the mercury cup at the
bottom of the pan. Moreover, considerable loss of time arises owing to the irregu-
larity due to hand feeding, and there is no efficient provision against unauthorized
withdrawal of the contents of the pan.
Now according to this Invention to obviate or mitigate these defects the
bearings of the vertical spindle are formed of hard wood or asbestos, and water is
used as a lubricant.
The pestle axis (heretofore usually made in one piece with or cast in the pestle
body) is made of hardened steel or phosphor bronze, and removable from the pestle
body, and is fixed therein in such a manner that it can be shifted lengthwise or
renewed at pleasure. The pan is recessed at the bottom, and a square tapered
hardened steel or phosphor bronze cup is placed in the recess to receive the lower
end of the pestle axis which works therein.
A long trough is provided to supply the entire set of pans; in this trough a
screw is caused to revolve so as to gradually propel any material placed in it from
one end of the trough towards the other; for each pan there is an aperture, through
which as the material travels along the trough some of it falls and is conducted to
the pans, the quantity supplied to the pans being regulated by suitable means;
according to one arrangement for this purpose each of the apertures in the trough
is provided with a chamber of specific capacity, having inlet and outlet doors or
valves which are opened and shut at regular intervals by screws or gearing operated
by the driving shaft placed over the machines.
Another arrangement to produce the same effect consists of (for each pan) a boss
on the screw shaft carrying a cup or cups which shall dip into the material and
discharge the required quantity into a shoot in a specified time (the apertures in
the bottom of the trough being in this case dispensed with). The arrangement I
consider most advantageous is as follows:-I form outlets at the bottom of the
trough with adjustable shutters, which may be regulated so as to allow the required
quantity of ore to pass through in a given time. The bottom of each pan is
provided with an eyed tap screw, a wire or bar (which may be composed of wires
stranded together) is put through the eye of each tap screw in a series, and is
socured by means of a lock and key.
And in order that my Invention may be well understood I proceed to more
particularly describe the same with reference to the accompanying Drawings,
wherein
Fig. 1 is a side elevation of a grinding and amalgamating machine embodying
my Invention, and comprising a set of ten amalgamating pans fitted with gyrating
Destles.

page_text: Fig. 2 is an end elevation partly in section of the right hand or driving end of
the machine.
Fig. 3 is an enlarged sectional elevation of a portion of the feeding trough.
a is the framing of the machine which supports the pans b, of which ten are
here shewn by way of example and as being a convenient number, but more or
less may obviously be employed; c are vertical shafts driven by gearing d from the
driving shaft e, the gearing & being disconnected when required by shifting the
pinion out of gear along the shaft e by means of the levers d. These shafts c
carry each a hooked arm c¹, in which freely rests the axis or spindle f of the
pestle g so as to carry the pestle round, at the same time allowing it to rotate
about its axis, the half vertical section of the pan approaching approximately the
rounded surface of the pestle, as shewn in section in Fig. 2. The bearings of the
vertical shafts c are formed of hard wood, prepared asbestos, or other material
which will wear well when lubricated with water. The lubricant is supplied to
the bearings through holes formed in the bosses of the large gear wheels d. The
pestle axis f which is made of hardened steel or phosphor bronze is fitted to the
pestle body so as to be easily removable therefrom by means of keys f¹, as shewn
in Fig. 2 (or the spindle may be screwed into the body and secured by a check
nut, or the spindle may be fixed by set screws passing through the top end
of the pestle body), and so that the pestle body can be shifted lengthwise
of it at pleasure. The bottom of each pan is recessed so as to receive a
hardened steel or phosphor bronze cup h, in which works the lower end
of the pestle's axis, and which holds the mercury for amalgamating the gold,
silver, or metal to be extracted as it is reduced or separated from the ore. i, i, are
eyed tap screws screwed into the bottom of the pans to allow when unscrewed of
the mercury or amalgam being run off from the said cups, through which a corre-
sponding bole is bored and tapped to permit of easy removal by a ring bolt. A
wire or bark, which may be composed of wires stranded together, is passed through
the eyes of the screws i, i, and secured thereto by a lock and key, so as to prevent
the unauthorized withdrawal of the contents of any of the pans. is a trough
carried above the pans, and having a screw bladed shaft m, which revolves therein
by means of the wheels n, n, driven from the shaft o, which screw feeds the
crushed ore fed from the hopper p to each of the pans by means of shoots or
spouts q. The regulating tube p' is capable of being shifted up or down, so as to
regulate the supply of crushed ore to the trough L. r, r, are sliding shutters (shewn
in section at Fig. 3), fitted to the bottom of the trough, which doors regulate the
openings r, so as to allow the requisite quantity of ore to pass through in a given
time. 8 is an overflow pipe, which carries off the superfluous ore as it collects at
the further end of the trough, from whence it is returned to the feeding hopper p.
t, t, are overflow pipes to allow the surplus water, together with the baser metals
and gangue in a finely divided condition to escape from the pans by the troughs
t, t, to receivers u. Two or more outlets may be applied to each pan when
required at different levels. v, v, are pipes running the length of the pans, provided
with cocks v³, vl, for supplying water to the said pans.
The operation of the machine is as follows:-The cups h are filled with mercury
(for treating ores containing ingredients injurious to ordinary mercury I use
specially prepared mercury). Water is then run into the pans through the cocks v¹
up to the level of the outlets t. The pestles are then set in motion by throwing
the bevil wheels d into gear, forcing the pestles to revolve in the pans by means of
the arms c². The hopper p being filled with ore crushed to the required size, the
ore falls into the trough at such a rate as may be allowed by the adjustment
of the shutters of the shoot p¹. The screw m being set in motion carries the ore
along the trough, and causes it to pass in a uniform layer over the adjustable
apertures, the screw being so connected with the shaft that it shall revolve at a
proportionate rate with the pestles, supplying the necessary quantity of ore per
minute to each of the pans. The ore, it will be observed, will thus be supplied
gradually and in the proper quantities to the pans, and by the crushing and

page_text: grinding action of the pestles on the pans it will be reduced to a finely divided
condition, in which state it is presented to the mercury in the cups h. The mercury
catches the amalgamable portion of the precious metals contained in the pulverized
ore, and thus forms the required amalgam. During the process the water, together
with the baser metals and gangue, is continually flowing through the overflow
pipes t. When it is required to withdraw the mercury and amalgam the wire rope
or rod k is withdrawn from the eyes of the tap screws i, and the mercury and
amalgam run off as required.
Having described the nature of my said Invention, and explained the manner in
which it is to be or may be carried into practical effect, I hereby declare that what'
I consider to be novel and original, and therefore claim is,-
(1.) In a machine for grinding and amalgamating ore wherein a pestle is caused
to rotate about its own axis, and to roll obliquely on the inner surface of a circular
pan by an arm carried by a driven vertical spindle, the use in combination with
the said spindle of hard wood or asbestos bearings, and water as a lubricant, sub-
stantially as described and for the purpose specified.
(2.) In a machine for grinding and amalgamating ore, wherein a pestle is caused
to rotate about its own axis and to roll obliquely on the inners urface of a circular
pan by an arm carried by a driven vertical spindle, the use in combination with
the said arm and the pestle body of a hard metal pestle axis, so fixed in the pestle
body that it can be shifted end wise to compensate for wear, or removed when
requisite for renewal or otherwise, substantially as described and for the purpose
specified.
(3.) In a machine for grinding and amalgamating ore, the use in combination of
a pan formed with an internal recess at its bottom, and a hard metal cup to contain
mercury for use in the amalgamating process, the cup being such as can be easily
removed and renewed, substantially as described and for the purpose specified.
(4.) In a machine for grinding and amalgamating ore, the use in combination of
a pan formed with an internal recess, and having a hole through its bottom, a hard
metal cup to contain mercury for use in the amalgamating process, such cup having
a tapping hole for withdrawing matters therefrom, a screw closing the said hole in
the pan bottom, such screw having an eye and a wire or equivalent fastening
device passing through such eye, so as to be secured by lock and key to prevent
unauthorized withdrawal of matters from the cup, substantially as described and
for the purpose specified.
(5.) In a machine for grinding and amalgamating ore, the use in combination
with pans and pestles, and means for operating the latter, of a trough with feeding
mechanism, shoots, or spouts, and means for regulating the quantity of ore delivered
in a given time to each pan, substantially as described and for the purpose
specified.
(6.) Constructing and arranging ore grinding and amalgamating machinery,
substantially as described and shewn in the Drawings.
In witness whereof, I, the said Thomas Allison Readwin, have hereunto set
my hand and seal, this Twenty first day of February, in the year of our
Lord One thousand eight hundred and eighty two.
THOMAS ALLISON READWIN. (L.B.)