Improvements in Grinding Apparatus, more especially applicable for use in Grinding and Amalgamating Ores Containing Gold and Silver.
Year: 1889

page_text: Date of Application, 23rd Dec., 1889
Complete Specification Left, 12th July, 1890-Accepted, 16th Aug., 1890
PROVISIONAL SPECIFICATION.
Improvements in Grinding Apparatus, more especially applicable
for use in Grinding and Amalgamating Ores Containing Gold
and Silver.
I MIDDLETON CRAWFORD of 3 Oxford Street, Liverpool, in the County of
Lancaster, Engineer do hereby declare the nature of this invention to be as
follows:-
The object of my invention is to provide an apparatus which will very efficiently
and rapidly grind ores for the separation therefrom of gold and silver in such a way
that whilst the subsequent amalgamation of the gold and silver is greatly facilitated
the sulphur and sulphur compounds and other impurities are automatically separated
and expelled.
According to my invention I provide a circular grinding path consisting of two
main portions, an inner portion which rotates, and an outer portion which is stationary.
Between the two portions is a space leading to a space underneath the rotating
portion of the grinding path containing a well or trough for mercury and provided
with an inlet for water. In this grinding path grinding balls are placed, so that when
the inner portion of the grinding path is rotated these balls grind material between
themselves and the grinding path. The grinding path and balls are enclosed by a
casing in which there is an inlet for the materials to be operated upon-this inlet
preferably consisting of a funnel shaped piece leading down to within a short distance
of the rotating portion of the grinding surface. Around this funnel shaped portion
is a space leading to an outlet at the upper part of the casing-this space being
preferably divided up into several sections.
When the apparatus is in operation the material fed in at the hopper passes to
between the balls and grinding surface and is there ground. Water is passed
into the space beneath the rotating portion of the grinding bed and up between the
space between this portion and the stationary portion and between the grinding balls
and the grinding surface into the casing above and eventually out by the aforesaid
outlet in the said casing. The space in the casing between the balls allows the water
to separate the gang and impurities and pass them away at the outlet, whilst the
heavier portions likely to contain precious metal return to between the grinding
surfaces for being further acted upon. I may heat the water and mercury by means
of a steam chamber underneath the bed.
The apparatus may be used for grinding various materials by supplying an air
current through the spaces in place of water.
Dated this 23rd day of December 1889.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in Grinding Apparatus, more especially applicable
for use in Grinding and Amalgamating Ores Containing Gold
and Silver.
I, MIDDLETON CRAWFORD of 3 Oxford Street, Liverpool in the County of
Lancaster Engineer, 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 principal object of my Invention is to provide an apparatus which will very
efficiently and rapidly grind ores preparatory to the separation therefrom of gold
and silver the grinding being effected in such a way that whilst the amalgamation of

page_text: the gold and silver is greatly facilitated the sulphur and sulphur compounds and other
impurities are automatically separated and expelled.
According to my Invention I provide a circular grinding path consisting of two
main portions an inner portion which rotates and an outer portion which is stationary.
Between the two portions is a space constituting a passage leading to a cavity under-
neath the rotating portion of the grinding path containing a well or trough for
mercury and provided with an inlet for water or other liquid. On this grinding path
free or loose grinding balls are placed the said balls being unconfined by cages or the
like so that when the inner portion of the grinding path is rotated these balls grind
material between themselves and the grinding path. The grinding path and balls are
covered in by a casing in which there is an inlet for the materials to be operated
upon this inlet preferably consisting of a funnel shaped piece leading down to within
a short distance of the rotating portion of the grinding surface. Around this funnel
shaped portion is a space leading to an outlet at the upper part of the casing this
space being preferably divided up into several sections. I may heat the water and
mercury by means of a steam chamber underneath the bed.
And in order that the said Invention may be fully understood I shall now proceed
more particularly to describe the same and for that purpose shall refer to the several
Figures on the accompanying drawings the same letters of reference indicating
corresponding parts in the several Figures.
Figure 1 represents in vertical section and Figure 2 in plan with the upper casing
removed an apparatus constructed according to my Invention and Figure 3 is a
horizontal section taken along the line 1-2. Figure 1 through the ore feeding and
refuse delivering passages. A is a case or chamber preferably of cast iron which may
conveniently be supported on pillars B and which contains the grinding surface or
path C. C. The part C of the grinding surface is fixed in the casing A and is
consequently stationary and the part C2 is rotatory it being keyed onto or otherwise
removeably secured to the upper end of a vertical shaft or spindle D supported at
the lower end in a footstep bearing E and at the upper part in a bearing and stuffing
box E in the bottom of the case A. The grinding surface or path CC2 is concave
and on it are placed a number of free balls F which effect the grinding operation
between themselves and the grinding surface or path CC2. Between the parts ()
and C2 of the grinding surface or path, a space G is left communicating with an
annular trough or recess H formed in the bottom of the casing A to contain mercury.
The bottom of the casing A and of the part C are preferably inclined as at a a to
allow any mercury which may find its way between them to return to the trough.
A space I is provided between the bottom of the casing A and the portion C2 of the
grinding path for the passage of water (or other liquid) admitted thereto under
pressure by a pipe K. The case A is provided with a hood or cover L to which the
feeding hopper M and the discharge passage or passages N for the refuse are
connected.
The shaft D and portion C2 of the grinding path are rotated from any suitable prime
mover by any suitable gear or driving device such as by means of a driving strap
passing round a driving pulley fast on the shaft D or by means of gear wheels P as
shewn.
When the apparatus is in operation the material fed in at the hopper M passes down
the pipe or passage M² to between the balls F and grinding surface (2 and is
there ground. Water or other liquid under pressure is passed by the pipe K into
the space beneath the rotating portion C2 of the grinding surface the water or liquid
passing thence up through the space G and between the grinding balls and the
grinding surface into the space enclosed by the casing Labove and eventually out
by the outlet or outlets N over the upper edge of which outlet it flows into an
annular trough R and is conducted thence by the spout R2 away from the apparatus.
The space in the casing between the balls and the hood or cover L allows the water
to separate the gangue and impurities which pass away with the water or liquid at
the outlet whilst the heavier portions likely to contain precious metal return to
between the grinding surface CC and the balls F to be further acted upon.

page_text: Beneath the casing A a cavity or chamber T may be provided into which a heating
agent such as steam may be admitted by a pipe (not shown) for the purpose of
heating the water or liquid and mercury when required. The outlet N is provided
with partitions or baffle plates V to prevent the heavier portions of the material
being carried away with the refuse by undue agitation of the water caused by the
rotating action of the part 2 of the grinding surface. The gold or other precious
metal separated from the ore passes through the space G into the mercury contained
in the trough or recess H whilst the refuse crushed ore is carried away by the water
or liquid through the outlet above as hereinbefore described.
The mercury containing the precious metal is discharged from the trough H
through the pipe W and is treated in the usual manner to obtain the precious metal.
To prevent tampering with the mercury the pipe W may be fitted so that its outlet
end can be turned up and secured by a lock as at w which when the mercury charged
with the precious metal is to be withdrawn can be unlocked so as to leave the pipe W
free to be turned down for discharging the mercury.
X is a pipe which can be closed by a plug or otherwise and by withdrawing this
plug the contents of the mill can be passed off when desired to prevent clogging
for instance when the mill stops. By passing an air current instead of water
through the apparatus it may be used for dry grinding.
Having now particularly described and ascertained the nature of the said Inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
First-The general construction combination and arrangement of parts constituting
a grinding apparatus substantially as hereinbefore described and illustrated by the
accompanying drawings.
Second In apparatus for grinding, free or loose balls which can
come into
contact with each other and which bear only on a lower circular concave grinding
surface consisting of an outer stationary part and an inner rotating part substantially
as hereinbefore described.
Third In apparatus for grinding ores or materials for the separation of precious
metals therefrom the combination with free or loose balls of a concave grinding
track or surface made in two parts one part being stationary and the other part
moveable a space being provided between the two parts for the passage of the
separated precious metal into a trough or recess below containing mercury substan-
tially as hereinbefore described and illustrated by the accompanying drawings.
Fourth-The combination with the subject matter of the last preceding claiming
clause of a cavity or chamber beneath the casing containing the grinding surfaces
for steam or other heating agent to heat the mercury and the water used for
separating the refuse substantially as herein before described and illustrated.
Fifth In apparatus for grinding ores for the purpose of separating precious
metals therefrom the combination of stationary and revolving grinding surfaces
and balls running freely thereon with means for supplying air or water or other
fluid between the grinding surfaces and balls and discharge passages for the refuse
material provided with the herein before described partitions or baffles to prevent
the escape of precious metals with the refuse substantially as hereinbefore described
with reference to the accompanying drawings.
:-
Sixth In apparatus for grinding ores or materials containing precious metals
the combination of a grinding surface and grinding balls with an inlet for air or
liquid from below and a mercury trough or container between the air or liquid inlet
and the grinding surfaces substantially as and for the purposes hereinbefore
described.
DL: 01-
1000
J. H. JOHNSON & Co.,
Agents.