Improvements in Screening Ores, and Apparatus therefor.
Year: 1894

page_text: Date of Application, 27th Mar., 1894
Complete Specification Left, 27.h Dec., 1894-Accepted, 2nd Feb., 1895
PROVISIONAL SPECIFICATION.
Improvements in Screening Ores, and Apparatus therefor.
We, NATHANIEL GREENING, Managing Director of N. Greening & Sons,
Limited, of Warrington, in the County of Lancaster, Wire Manufacturers, and
CHARLES RALEIGH, of Johannesburg, in the South African Republic, Milling
Engineer, do hereby declare the nature of this invention to be as follows
This invention relates to improved means for screening ores crushed or pulverized
by stamps or other reducing machinery.
In the reduction of ores by gravitation stamps, the partially crushed ore is
thrown against screens or sieves by the action of the falling stamps, the fine
particles passing through the meshes whilst those which have not been sufficiently
educed are arrested and subjected to further treatment.
During this process a portion of the meshes of the wire gauze or other screening
material become blocked or choked by wedge-shaped particles, the larger ends of
which are unable to pass through and which are only to a moderate extent removed
by the manual application of a brush; the result being a rapid diminution in the
efficiency of the screen.
Our invention consists in the application of mechanical meaus for keeping the
screen or sieve thoroughly clean and open in the meshes, by the obstructions being
dislodged before they become immovably fixed.
According to one mode of carrying out our invention, we employ a mechanically
driven brush or agitator which travels backwards and forwards regularly or inter-
mittingly, with a horizontal, vertical or diagonal motion, across the surface of the
screen or sieve whilst in use. The brush or agitator may be of the fixed or
revolving type, may be flat and move rectilineally or may be cylindrical and
partake of a rotative motion, and it may be applied continuously or intermittingly.
For operating the brush, we mount a revolving shaft in bearings carried by
brackets attached to the timbers of the stamp battery. The shaft may impart a
traversing motion to the brush by means of a screw-thread. The brush may be
caused to rotate by a feather and feather-way. The range of travel may be
regulated by movable tappets, which, acting on clutch wheels, reverse the motion
at the end of each traversing movement. A to-and-fro traversing motion may,
however, be imparted to the brush by the well-known mechanism embracing a shaft
screw-threaded in opposite directions, the threads crossing one another.
The requisite pressure of the brush against the screen or sieve may be maintained
by means of a dead weight or a spring, and the brush is preferably of steel wire or
fibre arranged spirally.
The brush may be applied to the reverse surface of the screening material, and
may partake of a rolling as distinguished from a rubbing motion.
With certain classes of ore, the apparatus may be advantageously arranged to
operate with a beating or striking action, the result being that at regular or
irregular intervals the screen or sieve is beaten, struck or flicked by one or more
fixed or traversing beaters. In this case also the beating action may be applied to
the reverse surface of the screening material.
Dated the 27th day of March 1894.
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Chartered Patent Agent.

page_text: Improvements in Screening Ores, and Apparatus therefor.
We, NATHANIEL GREENING, Managing Director of N. Greening & Sons,
Limited, of Warrington, in the County of Lancaster, Wire Manufacturers, and
CHARLES RALEIGH, of Johannesburg, in the South African Republic, Milling
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 :-
This invention relates to improved means for screening ores crushed or pulverized
by stamps or other reducing machinery.
In the reduction of ores by gravitation stamps, the partially crushed ore is
thrown against screens or sieves by the action of the falling stamps, the fine
particles passing through the meshes whilst those which have not been sufficiently
reduced are arrested and subjected to further treatment.
During this process a portion of the meshes of the wire gauze or other screening
material becomes blocked or choked by wedge-shaped particles, the larger ends of
which are unable to pass through and which are only to a moderate extent removed
by the manual application of a brush; the result being a rapid diminution in the
efficiency of the screen.
Our invention consists in the application of mechanical means for keeping the
screen or sieve thoroughly clean and open in the meshes, by the obstructions being
dislodged before they become immovably fixed.
According to one mode of carrying out our invention, we employ a mechanically
driven brush or agitator which travels backwards and forwards regularly or inter-
mittingly, with a horizontal, vertical or diagonal motion, across the surface of the
screen or sieve whilst in use. The brush or agitator may be of the fixed or
revolving type, may be flat and move rectilineally or may be cylindrical and
partake of a rotative motion and it may be applied continuously or intermittingly.
For operating the brush, we mount a revolving shaft in bearings carried by
brackets attached to the timbers of the stamp battery. The shaft may impart a
traversing motion to the brush by means of a screw-thread. The brush may be
caused to rotate by a feather and feather-way. The range of travel may be
regulated by movable tappets which, acting on clutch wheels, reverse the motion
at the end of each traversing movement. A to-and-fro traversing motion may,
however, be imparted to the brush by the well-known mechanism embracing a shaft
screw-threaded in opposite directions, the threads crossing one another.
The requisite pressure of the brush against the screen or sieve may be maintained
by means of a dead weight or a spring, aud the brush is preferably of steel wire or
fibre arranged spirally.
The brush may be applied to the reverse surface of the screening material, and
may partake of a rolling as distinguished from a rubbing motion.
With certain classes of ore, the apparatus may be advantageously arranged to
operate with a beating or striking action, the result being that at regular or
irregular intervals the screen or sieve is beaten, struck or flicked by one or more
fixed or traversing beaters. In this case also the beating action may be applied to
the reverse surface of the screening material.
In the accompanying drawings, which show by way of example the manner in
which our invention may be carried out,
Fig. 1 is a front elevation of a stamp battery furnished with a rotating and
travelling brush.
Fig. 2 is a cross section on the line x-x.
Fig 3 is n rear elevation of the driving gear at the back of the battery.

page_text: Fig. 4 is a view corresponding with Fig. 2, but illustrating the beater which we
prefer to employ for acting on the screen instead of a revolving brush.
The revolving brush A is secured to a spindle A' contained in a hollow shaft A'
provided with a bevel-pinion A and mounted to rotate in a cylinder B furnished
with arms B and B. A bevel-pinion C is provided with a flanged sleeve c
mounted in a bearing in the end of the arm B'. This sleeve slides on the rotating
screw-threaded shaft D and has a feather engaging with a feather-way d in that
shaft, and consequently the pinion, though free to slide upon the shaft, rotates with
it. The pinion C gears with the pinion A³. In the arm B2, a flanged sleeve c¹ is
fixed; this sleeve having an internal screw-thread engaging with the thread on the
shaft D. A plain distance-piece 2 is placed between the two sleeves c and c'.
The shaft B³ serves as a guide for the cylinder B and its appurtenances. This
shaft is mounted in brackets B and B hanging from the shaft D. These hanging
brackets permit the brush A and the parts to which it is connected, together with
the shaft B, to be lifted up out of the way, as indicated in dotted lines in Fig. 2.
The hooks B6 and B7, which are caused to engage with the shaft B³, serve for
holding the parts in the raised position. The shaft D is mounted to rotate in
bearings D and D₁ bolted to the framework of the battery. Between the
bearing D and the hanging bracket B* there are two bevel-wheels D2 and D³ loose
on the shaft D and formed with clutch-teeth. These bevel-wheels gear with and
are driven by a bevel-wheel D¹ on one end of a shaft D' rotating in a bearing D'.
On the other end of the shaft D there is a spur-pinion D driven by a spur-
wheel E, which is keyed on the end of a shaft passing through the framework of
the battery and supported in suitable bearings; the other end of the shaft having
keyed to it a bevel-wheel E'. This bevel-wheel is driven by a bevel-pinion E
and pulley E. On a rod F, the ends of which pass through holes in the ends of
arms projecting from the brackets B and B, are fixed two tappets F1 and F.
A double clutch F on the shaft D between the bevel-wheels D2 and D³ is
connected to a weighted lever F4 pivoted at F' to the framework. This lever is
coupled by a link F to the rod F. The clutch F3 can slide on the shaft D, but
is caused to rotate with it by means of a feather and feather-way. G is the screen.
The brush A instead of being spiral in form may be of any convenient shape.
Instead of the brush, a flapper with two or more wings may be employed.
The
The action is as follows:-The shaft D is caused to rotate by the pulley E³
acting through the pinion E³, the bevel-wheel E¹, the spur-wheel E, the spur-
pinion D', the bevel-wheel D₁, the bevel-wheel D³ and the clutch F³.
brush A is caused to revolve by the pinion C through the pinion A³ and the
shaft A2; the brush with its appurtenances being moved along the screen G owing
to the engagement of the sleeve c¹ with the shaft D. When the brush has arrived
at the end of its travel, the eye b projecting from the cylinder B strikes the
tappet F, thus causing the lever F to throw the clutch F³ out of engagement
with the bevel-wheel D³ and into engagement with the bevel-wheel D2, whereupon
the shaft D rotates in the opposite direction and brings the brush back until the
eye b strikes the tappet F1 and again throws the bevel-wheel D³ into gear.
The shaft B³ may be clamped in such a position as to cause the brush A to bear
against the screen G with the requisite pressure, and the clamping devices
employed may be adjustable. It will, moreover, be understood that other parts of
the mechanism can be made adjustable if desired, and that the details of the
mechanism may be altered in various ways without departing from the principle of
our invention.
Instead of the brush A, we, however, prefer to employ a traversing beater such
as illustrated in Fig. 4. A star-pinion A is fixed on the end of the spindle A¹.
A flexible arm H is secured to the cylinder B, and is furnished with a projection H¹
and a block of wood or other suitable material H². This block may be faced
with a brush if desired.
As the spindle A' rotates, the teeth of the star-pinion A' coming successively
into contact with the projection H' impart a vibratory movement to the arm

page_text: and cause the block H³ repeatedly to strike the screen G, with the result that
obstructions in the meshes of the screen are dislodged. We have found that about
620 vibrations per minute of the beater H give a highly satisfactory result. The
block H2 is carried to and fro from end to end of the screen precisely as previously
described with regard to the revolving brush A.
Having now particularly described and ascertained the nature of our invention
and in what manner the same is to be performed, we claim :-
1. The improved means substantially as herein described for screening ores
crushed or pulverized by stamps or other reducing machinery.
2. In screening ores crushed or pulverized by stamps or other reducing
machinery, the employment of a brush or flapper operating substantially as herein
described.
3. In screening ores crushed or pulverized by stamps or other reducing
machinery, the employment of a beater operating to vibrate the screen, sub-
stantially as described with special reference to Fig. 4 of the accompanying
drawings.
4. In screening ores crushed or pulverized by stamps or other reducing
machinery, causing the screen to vibrate substantially as herein described.
Dated the 27th day of December 1894.