Improvements in Grinding Mills.
Year: 1889

page_text: Date of Application, 14th Sept.. 1899
Complete Specification Left, 5th Nov., 1889-Accepted, 7th Dec., 1889
PROVISIONAL SPECIFICATION.
Improvements in Grinding Mills.
I, ROMULUS NORWOOD, of 127 Pomeroy Street, New Cross Road, in the County
of Surrey, Manufacturer, do hereby declare the nature of this invention to be as
follows:-
--
My invention relates to grinding mills and is designed to improve the construction
of the same.
My said invention relates more particularly to grinding mills of that kind or class
described in the specification accompanying former Letters Patent granted to Philip
Middleton Justice dated 13th June 1882 No. 2767.
In mills of the kind or class described in the former Letters Patent above referred
to, the material is ground or reduced between stones the lower one of which is adapted
to be rotated and is formed with its face perfectly plane from its centre to its skirt or
periphery, and the upper one of which is dished or formed concave from its eye or
centre to its skirt or periphery.
Now it has been found in practice, more especially in fine grinding, that is to say,
in reducing substances to an impalpable powder, that better results are obtained by
so forming the upper or stationary stone that the dishing or concavity extends only
throughout a portion of the distance from the centre to the skirt or periphery of the
said stone, a plane annular surface of greater or less width being provided around the
dished portion or concavity.
In carrying my said invention into practice I prefer to make the said upper or
stationary stone with the dished or concave portion extending from the eye or centre
of the stone to about half way between the said eye or centre and the skirt or
periphery of the said stone. The remainder of the grinding face of the said stone
is formed flat or plane.
In cases in which it is desired to reduce the material that is being operated upon,
to an impalpable powder this plane or flat surface is very advantageous for effecting
the speedy reduction of the said material.
I can if desired vary the extent of the said dished or concave portion and con-
sequently that of the flat or plane portion surrounding it according to the material
to be operated upon, or the degree of fineness required.
Dated this 14th day of September 1889.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Grinding Mills.
I, ROMULUS NORWOOD of 127 Pomeroy Street, New Cross Road, in the County of
Surrey, Manufacturer, 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 :-
My invention relates to grinding-mills and is designed to increase the efficiency
of such mills without adding to the cost of their manufacture or working.
My said invention relates more particularly to grinding-mills of the kind or class
described in the specification of formner Letters Patent granted to Philip Middleton
Justice and dated 13th June 1882, No. 2767.
In mills of this kind or class, the material is ground or reduced between stones
which are arranged one above another and the lower one of which is adapted to be

page_text: rotated and is formed with its entire upper surface flat or plane from its centre to its
skirt or periphery, whilst the upper stone, which is held stationary, is dished or formed
concave from the eye or centre to its skirt or periphery.
Now I have found in practice, more especially in fine grinding, that is to say, in
reducing pigments and other substances to an impalpable powder, that better results
are obtained by so forming the upper or stationary stone that the dishing or concavity
extends only throughout a portion of the distance from the eye or centre to the skirt
or periphery of the said stone, a flat or plane annular surface of greater or less width
being provided around the dished portion or concavity.
In carrying my said invention into practice, therefore, I make the upper or
stationary stone in this manner. I prefer to make the said stone with the dished
or concave portion extending from the eye or centre of the stone to about mid-way
between its eye or centre and its skirt or periphery, the remainder of the grinding
face of the stone being made flat or plane. The dishing or concavity should have a
maximum depth at the eye of the stone of say from one-eighth to one-fourth of an
inch, more or less, the depth being increased or lessened as may be best adapted to
the material to be ground. The dressing or face-cracking of the stone may be
carried out in any suitable manner.
I find that, by constructing a grinding-mill with an upper stone formed as above
described, I adapt the said mill for reducing pigments and similar substances more
rapidly and effectually than heretofore.
In cases in which it is desired to reduce the material to an impalpable powder, the
above described formation of the upper stone is very advantageous and ensures the
speedy and uniform reduction of the said material.
I can, if desired, vary the extent of the said dished or concave portion and con-
sequently that of the flat or plane portion surrounding it, according to the nature of
the material to be operated upon or the degree of fineness required.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I wish it understood that
I claim -
In a grinding-mill such as I have hereinbefore referred to, an upper stone the
operative surface of which has a dished or concave portion surrounded by a flat or
plane portion, and which is arranged to operate in combination with a lower stone
having its entire operative surface flat or plane, substantially as bereinbefore described,
and for the purpose specified.
Dated this 5th day of November 1889.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.