Improved Method of Separating and Collecting Very Fine Powders and Substances, either During or After Grinding or Disintegrating, and Apparatus therefor.
Year: 1894

page_text: Date of Application, 7th May, 1894
Complete Specification Left, 1st Feb., 1895-Accepted, 2nd Mar.. 1895
PROVISIONAL SPECIFICATION.
Improved Method of Separating and Collecting Very Fine
Powders and Substances, either During or After Grinding
or Disintegrating, and Apparatus therefor.
We, FELL CHRISTY, and JAMES ALFRED NORRIS, of Broomfield Road Iron
Works, Chelmsford in the County of Essex, Engineers, do hereby declare the
nature of this invention to be as follows:
The object of this invention is to obtain extremely fine powders or substances
from materials which are ground.
It has been usual in the past to obtain these powders or substances by means of
an upward spout or trunk so constructed and fixed that the current of air produced
by the disintegrator or grinding mill or by any other means shall carry the fine
particles into a room or settling chamber.
We find, however, that relatively coarser particles are frequently carried up,
either due to the higher velocity of the wind in the centre of the trunk or by
being rolled up the sides of the trunk.
In carrying our invention into effect we arrange 2 trunks in such a way that the
material is blown by the current of air due to the action of the disintegrator or
other means up or along one spout and down or along the other and back to the
disintegrator continuously until sufficiently fine to pass out through one or more
specially arranged outlets in the downward or return trunk.
The outlet or outlets in the downward or return trunk are arranged in several
ways, one way being as follows:-
The downward or return trunk which may be round, square, or any convenient
shape, is constructed in 2 pieces with a break between them, the lower end of the
top piece in the case of a vertical or oblique trunk being supported over the upper
end of the lower piece which is enlarged or funnel shaped.
There is an inlet near the centre of the disintegrator, and the action of the
disintegrator causes the current of air which has the powder in suspension to be
at a slightly higher pressure than the surrounding air and results in a portion of
the current air escaping at the outlet or outlets described above.
We find that the velocity in the downward or return spout is sufficient to ensure
the grosser particles being carried forward in an approximately straight line past
the outlet and back to the disintegrator, and only the finest particles can turn back
and escape at the outlet, which may be situated in a suitable settling chamber, dust
collector, or other suitable arrangement for collecting the powder, or is connected
to a settling chamber by a suitable spout. The air after passing through the
settling chamber may either be discharged into the atmosphere or returned to the
mill.
Another way is to arrange the downward or return spout without a break, but
with one or more side outlets connected at an acute angle.
We regulate the quantity of air and powder which escapes at the outlet or
outlets in several ways, riz. by regulating the size of the air inlet at either the
centre or feed hole of the disintegrator, or by partially closing the lower end of
the downward or return spout, or by altering the angle of the outlet, or by
assisting the outlet with an exhaust fan, or by increasing the pressure in the circuit
of air by blowing air or gases into it, or by fitting the lower end of the upper

page_text: portion of the down or return trunk with a telescopic arrangement so that its depth
into the lower portion can be varied.
Dated this 7th day of May 1894.
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Chartered Patent Agent,
For the Applicants.
COMPLETE SPECIFICATION.
Improved Method of Separating and Collecting Very Fine
Powders and Substances, either During or After Grinding
or Disintegrating, and Apparatus therefor.
We, FELL CHRISTY, and JAMES ALFRED NORRIS of Broomfield Road Iron
Works, Chelmsford in the County of Essex, Engineers, 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:-
The object of this invention is to obtain extremely fine powders or substances
from materials which are ground.
It has been usual in the past to obtain these powders or substances by means of
an upward spout or trunk so constructed and fixed that the current of air produced
by the disintegrator or grinding mill or by any other means shall carry the fine
particles into a room or settling chamber.
We find, however, that relatively coarser particles are frequently carried up,
either due to the higher velocity of the wind in the centre of the trunk or by being
rolled up the sides of the trunk.
In carrying our invention into effect we arrange two trunks in such a way that
the material is blown by the current of air due to the action of the disintegrator or
other means up or along one trunk and down or along the other and back to the
disintegrator continuously until sufficiently fine to pass out through one or more
specially arranged outlets in the downward trunk.
To clearly explain our invention reference is made to the accompanying
diawings in which an apparatus for carrying same into effect is illustrated and in
which
Fig. 1 is a sectional elevation of a settling chamber having our invention applied
thereto and
Fig. 2 is a section of Fig. 1 on the line x-x.
In the drawings a is the upward trunk from the disintegrator b and c is the
downward trunk which may be round, square or of any convenient shape. This
downward trunk c as shown is constructed in two parts with a break or outlet
between them, the lower portion d being of larger diameter and the upper portion
being supported or terminating on a line with, below or even slightly above the
break between the two trunks.
There is an inlet e near the centre of the disintegrator, and the action of the
disintegrator causes the current of air which has the powder in suspension to be
at a slightly higher pressure than the surrounding air and results in a portion of
the current of air escaping at the outlet or break described above the course it
takes being indicated by the arrows.
We find that the velocity in the downward trunk c is sufficient to ensure the
grosser particles being carried forward in an approximately straight line past the
outlet and back to the disintegrator, and only the finest particles can turn back
and escape at the outlet, which as shown is situated in a suitable settling chamber
or dust collector for other suitable arrangement for collecting the powder, or is
connected to a settling chamber by a suitable spout. The air after passing through
the settling chamber may either be discharged into the atmosphere or is preferably

page_text: returned to the mill or disintegrator by a return trunk g which also passes into
the opening e of the disintegrator.
Another way is to arrange the downward trunk without a break, but with one
or more side outlet pipes connected at an acute angle such outlets communicating
with a settling chamber.
For the purpose of regulating the quality of the powder which escapes at the
outlet or break we may apply to the trunk c a sliding extension piece c¹ and if
desirable apply a similar extension piece d¹ to the trunk d as shown.
These extension pieces may be raised and lowered by means of the screwed
rods respectively such rods passing out of the settling chamber and being
operated by nuts, handles, gearing or in other suitable ways. It will be evident
that the greater the distance the extension c¹ passes into the trunk d or the higher
the extension d' is raised above the outlet of c¹ the greater will be the distance the
powder will have to travel, and therefore the finer will be the particles which
escape, the reverse of the operation allowing of a coarser material being deposited
in the chamber.
Other methods of regulating the quality of the powder which escapes at the
outlet are by adjusting the size of the air inlet at either the centre or feed hole
of the disintegrator or by partially closing the lower end of the downward trunk d
as by the valve h which may be provided with an arrangement for holding it in
any desired position or by altering the angle of the outlet pipes if the outlet
consists of a pipe or pipes placed at an angle to the trunk as previously described.
Or the passage of the powder from the outlet may be assisted by means of an
exhaust fan or by increasing the pressure in the circuit of air by blowing air or
gases (such as steam) into it. Or the return trunk g may be partially closed by
a valve such as i which may also be provided with an arrangement for holding it
in position the effect of thus throttling the trunk g being to increase the pressure
in the settling chamber and thus the fiueness of the material deposited while the
throttling of the trunk d increases the pressure therein and thus allows a coarser
material to pass into the chamber. The settling chamber as shown is provided
with a deflecting plate k and a screw conveyor which moves the settled material
towards the outlet m. The settling chamber may also be provided with divisions
on the floor thereof in order that material of different grades of fineness may be
collected the arrangement of the apparatus allowing of a great range in the
qualities of the material collected.
The process which the material undergoes is in fact allied to levigation and
may he called a process of pneumatic levigation.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is:
:-
1. The method of separating and collecting powders and substances which
consists in passing the material in a current of air through a trunk having an
outlet or break therein through which the finer portion of the material escapes by
reason of the lower pressure outside of the trunk the heavier portion remaining
in the current substantially as described.
2. The method of separating and collecting powders and substances which
consists in passing the material in a current of air through a trunk in a downward
direction said trunk having a break, outlet or outlets therein through which the
lighter portion of the material rises by reason of the lower pressure outside of the
trunk the heavier portions remaining in the current and being returned to a
grinding mill substantially as described.
3. In an apparatus for separating and collecting powders and substances the
employment of a downward trunk through which the material is carried in a
current of air said trunk passing into a second trunk in such a manner that an
outlet is left between the two and means for regulating the quality of material
passing through the outlet substantially as described.

page_text: 4. An apparatus for separating and collecting powders and
Eubstantially as described and illustrated.
Dated this 1st day of February 1895.
substances
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Chartered Patent Agent,
For the Applicants.