Improvements in Stones or Equivalent Devices for use in Machinery for Grinding Quartz and other Substances.
Year: 1889

page_text: Date of Application, 13th Apr., 1889
Complete Specification Left, 15th Oct., 1889-Accepted, 21st Dec., 1889
PROVISIONAL SPECIFICATION.
[Communicated from abroad by ALFRED ADAIR, Gold Assayer and Amalgamator,
and JOHN GEORGE CRUICKSHANK, Engineer, both of Johannesburgh, South
African Republic.]
Improvements in Stones or Equivalent Devices for use in Machinery
for Grinding Quartz and other Substances.
JOSEPH ADAIR mineowner Egremont Cumberland-do hereby declare the nature
of this invention to be as follows:-
I replace the stones in ordinary mills for grinding flour by discs of cast iron or
steel, they can be worked either horizontally or vertically.. Grooves are left in the
casting corresponding to the places of the grooves in stones but much deeper, they
are of the depth to which it is intended the disc to wear down to.
These are
afterwards filled with soft metal, cement, or other substance which is easily cut away
as often as is required to provide for feeding and ventilation. In some cases
I prefer to cast a permanent frame into which the wearing parts are fitted leaving
grooves or spaces to be filled with soft metal or cement or other substances when
worn out these can be easily removed and new ones substituted.
COMPLETE SPECIFICATION.
Improvements in Stones or Equivalent Devices for use in Machinery
for Grinding Quartz and other Substances.
I, JOSEPH ADAIR, Mine Owner, Egremont, Cumberland, do hereby declare the
nature of this invention (which has been communicated to me from abroad by Alfred
Adair and John George Cruickshank, both of Johannesburg, South African Republic)
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 stones or equivalent devices for use in mills for the fine
grinding of quartz cement and other minerals or substances.
According to one part of this Invention the stones used in ordinary mills, for
grinding flour for instance, are replaced by complete, or built up, discs of hard
metal, such as cast iron or steel. Grooves or recesses are left or formed in the
metal and they may be situated in places corresponding to the places at which the
grooves in ordinary stones are situated but they are made much deeper than
the ordinary grooves, being of the depth down to which it is intended the grinding
surfaces to wear. They may extend right through the metal if desired. These
grooves or recesses are filled with soft metal, cement, or other substance softer than
the grinding surfaces, which soft metal, cement or the like, is easily cut away as
often as is required to provide for feeding and ventilation. It is preferred to make
the said grooves at an angle to the axis of the grinding device so that the angles
at the leading edges of the grinding surface separated by the grooves or recesses,
have an obtuse angle.
According to a further part of the Invention there is cast, or otherwise formed,
a permanent frame or holder into which the portions of the stone or grinding
device are fitted the said portions being of segmental shape by preference the
grooves or spaces to be filled with soft metal, cement, or other softer substances
being situated between the adjacent segments and preferably being so shaped that
the softer surfaces made by the material contained in the said grooves or recesses.
present a larger area as they approach the centre of the stone or grinding device.
[Prins 21

page_text: I will more particularly describe the Invention with reference to the accompanying
drawings.
Figure 1 is a plan and Figure 2 is a side view of a metal grinding device made
according to this Invention showing one made up of separate pieces or segments A
with grooves or recesses B between them and with grooves or recesses B2 in them
the said grooves or recesses all extending down through the metal and being
inclined as shewn in Figure 2 so that the leading edges have an obtuse angle which
remains the same as the surface wears down and gives an edge over which the
substance being ground rides so as to be properly received between and acted upon
by the grinding surfaces.
The grooves or recesses B B2 are filled in with softer material as hereinbefore
described. The segments are secured in place by the rimmed frame tray or
support C by projections on the segments fitting into the spaces c and also by the
band D. The support C may be perforated as at c to lighten it.
Figures 3 and 4 shew in plan and side view respectively a stone with the sides
of the recesses in planes parallel with the axis of the stone. As in the preceding
arrangement the grinding surfaces of the segments A are cut away so that the
recesses at B have an area increasing as the centre is approached. The leading
edge of the segments may have a strip E of material harder than that in the
grooves B but not so hard as that of the segments A so that objectionable hollows
are not formed at this part and therefore the material being operated upon is
efficiently fed between the grinding surfaces of the segments A. The material at E
may be in the form of slabs or plates situated at the sides of the segments A.
The parts may be secured as in Figures 1 and 2 by a support C and band D. In
this case I have shewn ribs on the support which ribs enter the lower parts of
the grooves.
Figures 5 and 6 shew an arrangement generally of the kind hereinbefore described
but without the material E the sides of the segments being inclined so as to present
an obtuse angle leading edge as hereinbefore described. The stones or grinding
devices may be used either vertically horizontally or in any desired position. Both
of the stones or grinding devices may be made as described or one only may be so
made and it may be either the upper or the lower one but generally it is preferred
to make both as described. Owing to the increase of the surface of the softer
material towards the centre of the stone or grinding device and the corresponding
decrease of the grinding surface the stones or grinding devices made as described
wear down much more equally than do the stones ordinarily used in mills. The
grinding surfaces may be white iron or steel or equivalent hard metal or they may
be of hard stone such for instance as quartz or granite or a hard composition such
as emery composition and the softer material may be plaster of Paris or plaster of
Paris and sand or lime, sand, clay or mixtures thereof, or wood, soft metal, or the
like, or where the segments are of metal the filling for the grooves or recesses
may be say of soft malleable iron. The strip E of medium hardness may be of
Portland cement, porcelain or earthenware, but I do not limit myself to the use of
the precise materials enumerated.
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 :-
1st. A grinding device consisting of discs or segments of hard metal such as cast
iron or steel with spaces filled in with a softer material presenting an increasing
area towards the centre of the stone and correspondingly reducing the area of the
grinding surface towards the centre substantially as hereinbefore described.
2nd. A grinding device consisting of a stone or the like with its parts or segments
presenting an obtuse angle at the leading edges substantially as and for the purpose
hereinbefore described.
3rd. The metal grinding device made substantially as hereinbefore described and
shewn in Figures 1 and 2 of the accompanying drawings.

page_text: 4th. The stone or grinding device made substantially as hereinbefore described and
illustrated in Figures 3 and 4 of the accompanying drawings and also the modification
with the inclined. obtuse angle at the leading edge of the segments as explained
with regard to Figures 5 and 6.
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