Improvements in Machines for Separating Light and Heavy Substances, chiefly designed for the Purification of Semolina and Middlings, and the Extraction of Wheat from Stones.
Year: 1890

page_text: Date of Application, 29th July, 1890
Complete Specification Left, 29th Apr., 1891-Accepted, 25th July, 1891
PROVISIONAL SPECIFICATION.
Improvements in Machines for Separating Light and Heavy
Substances, chiefly designed for the Purification of Semolina
and Middlings, and the Extraction of Wheat from Stones.
I, JAMES HIGGINBOTTOM, of 32 Scel Street, Liverpool, in the County of
Lancaster, Milling Engineer, do hereby declare the nature of this invention to be
as follows:-
:-
This invention relates to apparatus for separating by means of air suction or
exhaust, light and heavy substances and it is chiefly intended for application to
the semolina and middlings sieve purifier and apparatus for which I have obtained
Letters Patent No. 14711 of October 13th 1888.
A series of plates or covers impervious to the draught, made of wood, metal or
other material are applied to the surface of the sieve, either above or below it, or
in both positions, or the sieve cloth itself can be made impervious at intervals.
The parts made impervious in any of these ways are preferably immediately
beneath the channels or spaces between the nozzles, and are employed for the
purpose of preventing the passage of the air through the meshes of the sieve at
these points, and thereby for the further purpose of intensifying the inrush of the
air through the meshes of the uncovered portions of the sieve from the space
below the sieve to the exhausted chamber above the sieve.
I prefer to place the covers longitudinally on or under the sieve, but in some
cases they may be placed across the sieve, or even both longitudinally and
transversely across the sieve.
The tray of nozzles as described in the Patent No. 14711 of 1888, may be
arranged to serve the purposes of the cover plates by adding projecting pieces
below the channels touching the sieve, or the portion between the nozzles, or the
bottom of the channels is placed immediately on the sieve surface, and in some
cases the contour of the nozzles or of the outside surface of the channels is
continued below the sieves in a second grid until the two contours meet in a
rounded point.
The cover plates may be made either wider or narrower than, or equal to, the
acting sieve surface spaces between any two contiguous cover plates as may be
found desirable according to the nature of the material being treated as a general
rule the cover plates should be made narrowest at or towards the head of the
sieve, and widest towards the tail of the sieve. The cover plates can be parallel
in their length or they may be made to taper, if desired, in which case their
narrow ends would be preferably placed towards the head or feed end of the
sieve.
The action of the invention is as follows:-
The exhaust air chamber above the sieve has a partial vacuum maintained
therein by fans or other exhaust apparatus as is well understood by millers. The
air rises naturally through the meshes of the sieve to supply such vacuum and in
so doing, the lighter substances are prevented from falling through the meshes of
the sieve.
It is desirable to use as small an amount of uprising air as possible, and to
arrange so that the air currents rising through the meshes of the sieve should be
more rapid at the tail end or other parts of the sieve, than at the head end or other
parts of the sieve. This invention accomplishes these desirable objects, because
the air, which would have passed upwards to supply the vacuum through all the
uncovered meshes of the sieve is by the use of the non-pervious covers constrained

page_text: to pass through the lessened quantity or number of meshes of the uncovered parts
of the sieve and in so doing the air moves at an increased velocity.
Further, by placing the cover plates in a suitable manner such increased velocity
may be obtained at any desired part of the sieve.
66
In some cases the grids are arranged to give the well known shape known as
."
vena contracta to the passage through the sieve. The grids are preferably
attached in such manner as to be removable for cleaning and examination
purposes.
Dated this 28th day of July 1890.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Machines for Separating Light and Heavy
Substances, chiefly designed for the Purification of Semolina
and Middlings, and the Extraction of Wheat from Stones.
1, JAMES HIGGINBOTTOM, of 32 Seel Street, Liverpool, in the County of
Lancaster, 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 certain improvements in machines or apparatus for
sieving, separating or purifying granular, pulverulent or other like material, or for
separating grain or seeds from stones by means of a vibrating sieve or sieves, up
through which a current (or currents) of air is caused to pass by means of a blast
or exhaust device.
The invention is, however, chiefly intended to be applied to semolina and
middlings purifiers having cach a vibrating sieve and air exhaust device, and
especially to those semolina and middlings purifiers.and sieving machines which are
provided immediately above the sieve with a flat collecting tray covered with a
series of hollow tapering nozzles, as described in the Specification of my Letters
Patent No. 14711 of. 1888.
The objects of my improvements are to reduce to as small an amount as possible
the quantity of air required to be passed through the sieve and also to provide simple
means whereby the air currents may have a greater velocity at one part of the
sieve as for instance at the tail end thercof-than at another part-such, for
example, as the head thereof.
The invention may be described by reference to the accompanying drawings, in
which-
Figures 1 and 2 are longitudinal section and plan respectively of the sieve and
sieve frame of a middlings purifier furnished with one form of my improvements,
the collecting tray and nozzles being removed.
Figure 3 is a section, on an enlarged scale, taken transversely to the sieve and
showing one form of my invention, namely, that with covers above the sieve, and
also showing a portion of the collecting tray and two of the nozzles in section.
Figure 4 is a section on line xa, Figure 3.
Figure 5 is a similar view to Figure 3 showing a slightly different form of the
invention.
Figure 6 is a similar view to Figure 3, showing another modified form of the
invention.
Figure 7 is a similar view to Figure 3, showing the two forms of my invention,
namely with covers above and below the sieve.
Figure 8 is a section on line yy, Figure 7.
A is the frame of the vibrating sieve, and B is the sieve cloth formed in the
usual manner, in sections, as shown, having different sizes of mesh. C is the flat
collecting tray placed as close as practicable to. the sieve surface and vibrated

page_text: therewith, and D are the tapering nozzles aforesaid which are preferably provided
with hoods d as in Figures 3 to 8.
The air below the sieve is caused, by a suitable exhaust device, to rise up
through the sieve and the material thereon, and through the nozzles D into a
partially exhausted depositing chamber above the nozzles, and in passing into said
chamber, the air is so expanded or dispersed that the dust and other light material,
carried off by it from the material on the sieve, is separated and deposited on the
tray C and the upper surfaces of the nozzles.
In order to intensify the velocity of the air passing through any desired section
or sections of the sieve, I apply to the surface of the said section or sections,
either above or below it (or both above and below), a series of impervious plates
or covers EE or (and) E¹, E', which may be made of wood, metal or other
suitable material. I prefer to place the covers longitudinally on the sieve, as
shown, but in some cases, when applied to the under surface of the sieve, they
may even be placed transversely thereto, or both longitudinally and transversely
thereto.
The impervious covers or plates, in whatever way they may be arranged, are
employed for the purpose of preventing the passage of the air through the meshes
of the sieve at the parts covered, and thereby intensifying the velocity of the air
passing up through the adjacent uncovered portions F into the superposed
depositing chamber. In most cases I apply the impervious covers to the tail
section or sections, as shown in Figures 1 and 2, as it is generally the tail end of
the sieve which requires an intensified air current.
The cover plates E may each be made either wider or narrower than, or equal
to, the active sieve surface space F which lies between any two of the cover plates,
as may be found desirable according to the nature of the material being treated.
As a general rule, the cover plates should be made narrowest at or towards the
head of the sieve, and widest at or towards the tail of the sieve, as seen in
Figure 2. The cover plates can be parallel in their length or they may be made
to taper, in which case their narrow ends would be preferably placed towards the
head end of the sieve.
In applying my invention to a middlings purifier having a collecting tray and
series of nozzles such as described above, it is preferable to place the impervious
covers E, and E¹, immediately beneath the longitudinal channels or spaces C¹
between the nozzles, as the velocity of the air passing through those portions of
the sieve immediately below said spaces is already reduced to some extent by
reason of the blanking" or retarding effect of the impervious portions of the
superposed tray C. The velocity of the air passing through the nozzles adjacent
to the impervious covers E is thus greatly intensified, beyond what would result
from the shape and arrangement of the nozzles themselves.
The impervious covers E may be arranged in combination with the tray and
nozzles in a variety of ways. For instance, solid strips E, touching the upper
surface of the sieve, may be attached to the underside of the tray C, as in
Figures 3 and 4. Or the covers may be formed hollow, but impervious, as in
Figures 5 and 6, being attached either to the tray or sieve. In the arrangements
shown in Figures 6, 7 and 8, the sides S and S₁ of the covers E are tapered so as
to correspond more or less with the inclination of the inner surfaces of the nozzles,
and the contour of the said tapered sides may be continued below the sieve to the
second series of covers E' whose sides S and S' meet, by preference, in a more or
less rounded point at R, as shown in Figure 7.
vena
In some cases, the opposite sides S and S' of the cover plates EE or E' E' may
be so arranged that the passages between them take the forms known as
contracta." The covers are preferably applied to the sieve in such manner that
they may be readily removed for the purposes of cleaning and examination.
The action of the invention is as follows:-
The depositing chamber above the sieve having a partial vacuum maintained in
it by means of a fan or other exhaust apparatus, the air rises into the chamber

page_text: through the meshes of the sieve, and, in so doing, prevents the lighter portion of
the material on the sieve from falling through the same. Now it is very desirable
to pass as small a volume of air as practicable through the sieve, and to so arrange
the machine that the velocity of such air shall be greater at the tail end (or other
part) of the sieve than at the head end (or other part) thereof. By my invention,
I am enabled to accomplish these desirable objects, as the air, which would
otherwise have passed upwards into the depositing chamber through all the meshes
of the sieve (these being all uncovered), is, by the use of the non-pervious covers,
permitted to pass through only a reduced quantity or number of meshes, namely,
those of the parts left uncovered, so that the amount of air employed is thereby
reduced. Further, the covering over of certain portions of the sieve as abové
described, causes the air passing through the adjacent uncovered parts F to move
with a velocity greater than that of the air which passes through those portions of
the sieve that are not provided with cover plates. Thus an increased air velocity
may be obtained through any desired part of the sieve by furnishing said part with
a suitable arrangement of impervious covers such as above described. In some
cases when dealing with lighter material such as middlings, I use the covers E
placed over the upper surface of the sieve only. When dealing with heavier
material such as semolina and wheat or seeds; or when extracting wheat or seeds
from stones I use the covers E and E¹ placed both above and below the sieve.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is --
1. In a machine of the kind described for separating light and heavy substances,
the application, to one or more sections of the vibrating sieve, either on its upper
or lower surface or both, of a series of impervious cover plates, such as E, and E¹,
so arranged as not to impede the free passage of the material over such section or
sections, whereby the total quantity of air required to be passed through the sieve
is reduced and its velocity is increased through those uncovered portions of the
sieve lying between the cover plates, substantially as described.
2. In a machine of the kind described, the combination, with a vibrating sieve
and a collecting tray above the sieve having a series of nozzles as described, of a
series of impervious cover strips applied at any desired part of the sieve, and
occupying the spaces between its upper surface and certain portions of, the tray
lying between the longitudinal rows of nozzles, substantially as described.
3. In combination with the arrangement of parts set forth in Claim 2, a second
series of cover strips applied to the under surface of the sieve and forming either
wholly or in part a downwardly tapering continuation of the strips above the
sieve, whereby the velocity of the uprising air is increased before passing through
the uncovered parts of the sieve, substantially as described.
Dated this 28th day of April 1891.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Nottingham, and London, Patent Agents.