Improvements in Mills for Grinding or Crushing Ore and other Materials and for Separating the Dust therefrom.
Year: 1889

page_text: Date of Application, 2nd Dec., 1889-Accepted, 4th Jan., 1890
COMPLETE SPECIFICATION.
Improvements in Mills for Grinding or Crushing Ore and other
Materials and for Separating the Dust therefrom.
We JOHN SNELL CHENHALL of 7 Wolseley Road, Eastville, Bristol Mechanical
Engineer, and JAMES WARNE CHENHALL of Dart Villa, Totnes, Devonshire, Civil
Engineer do hereby declare the nature of our said invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
Our invention relates to the construction of Mills for grinding or reducing ore and
other materials to fine powder, and in means for separating such powder conjointly
with the reduction, the supply of material descending from a hopper to the interior of
the Mill, being automatically regulated.
The main object of our invention is to simplify the construction and working of
ore-crushing and similar machines, the means we employ rendering the operations of
the machine practically continuous, instead of intermittent.
According to our invention we provide a hopper surrounding the upper part of the
Mill, this hopper has a funnel shaped outlet terminating into an annular opening into
the interior of the Mill; connected with an arrangement of arms in the lower part
of the Mill, hereinafter described, is a frustrum of a cone, which either fits closely in
the annular opening of the hopper or leaves a considerable aperture, which may be
regulated mechanically by a ring, through which the material may descend according
to the height of the cone or ring. The rising and falling of the cone is regulated
automatically by the quantity of material in the bottom of the mill, so that where the
quantity is too large, the cone rises and lessens the aperture thus diminishing the
supply, then as the quantity is diminished the cone falls and the supply is increased:
the material is ground or crushed by means of balls which rotate rapidly in an
enclosed or partially enclosed chamber; these balls by their rapid centrifugal action
operate with considerable force on the internal periphery of the chamber, and the
constant succession of blows given by the balls quickly reduces any ore or other
material with which the come into contact to the required degree of fineness, when it
is discharged by the contrifugal action of the balls, aided by air which is sucked into
the mill by the centrifugal action, through openings in the periphery.
To enable the construction of our Mill to be more clearly understood we furnish
the accompanying drawings, in which similar letters are used to indicate similar parts
in all the figures
:-
Figure 1 is an elevation shewing the general arrangement of the Mill. Figure 2
is a section shewing details for the hopper aperture to the chamber, cone, also the
ring for regulating the supply, the balls and the arms for propelling them. Figure 3
is a plan through the line a, b, of Figure 2.
A is the driving shaft with a pulley B fixed thereon. C is a step in the lower
frame or support D, and in which step C the shaft revolves. The upper end of the
shaft passes through the socket E in the conical portion of the pan F. This upper
end of the shaft has a feather for causing the ball carrying frame G to rotate with it,
at the same time permit it to rise upon the shaft for the purpose of checking the
supply of material should the pan F already be overcharged.
The carrier or frame G is provided at its lower part with pockets H in which balls I
are maintained in position said pockets being provided with wedge shaped blocks J
at each side and at top for receiving the impact of the balls when shot towards them
by the larger particles of the material under operation.
The pan F is provided with steel or other bed K in sections which can be adjusted
by set screws L in the required direction and be easy of removal when worn to too
great an extent, the portions between the sections being filled up with wooden strips
to complete the pan proper.

page_text: M, M, are perforated or wire screens through which the dust or powdery particles
of the crushed material can escape they being forced through the meshes partly by
the centrifugal action and the agitation of the balls I. I. and partly by air drawn in
through the apertures N which is sucked from below the socket E into the space
between the frame G and the pan F.
P is the hopper into which the material is first supplied and as it passes down the
shoot Qit falls into the spaces between the pockets H, H, into contact to be operated
on by the balls. The fraine G and pockets H are regulated as to height by the screw
appliances R which rotate with the frame G and shaft A and as the centrifugal action,
coupled with the lifting action of the balls over the material goes on, the frame G has
a tendency to rise so that if the material is very hard and requires a long time to be
reduced the frame rises upon the feather of the shaft A and closes the aperture more
or less between itself and the annular shoot Q, the ring S being first set according to
the diameter or sizes of the pieces of material to be operated on or supplied to the
mill. This ring S is carried by levers T capable of being raised and lowered by the
screw U and hand wheel V. W is a fly wheel.
Instead of the rotating frame G being formed with pockets H a disc shelf may be
arranged to lead the material over the edge, so that the fine dust in falling meets with
the current of air and is forced out through the meshes M.
The operation of the Mill is as follows."
The ore or other material being placed in the hopper, and the vertical shaft with its
attachment set in motion by the means provided, the balls will rotate, and as the
material from the hopper descends, it will be crushed by the balls, but if the supply is
too rapid and the bed of the chamber becomes full, the balls rise and lift the frame G
which checks the supply by partially closing the opening, and when only the proper
quantity is in the chamber the bails will fall and the frame G will enlarge the aperture
and thus automatically regulate the supply and as the operation proceeds the crushed
material is discharged at the outlet or outlets provided.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is
The improved mill for grinding ore or other materials as described and shown, the
essential features of which are:-
a. The automatic arrangement for regulating the supply of material.
H. GARDNER,
166, Fleet Street, London, Agent for the said J. S. Chenhall and J. W. Chenhall.