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Nov. 5, 1946.
2,410,637 -
Filed June 23, 1944 _
Patented Nov. 5, 1946
George M. Darby, Westport, Conn, assignor to
The Dorr Company, New York, N. Y., a corpora
tion of Delaware
Application June 23, 1944, ‘Serial No. 541,760
5 Claims. (01. 209-454)
This invention relates to the sizing or classi
that controls the size separation.
Where the
fying of /'suspended solids to separate-them into
particles to be so sized or fractionated into groups
groups or fractions according to particle size,
with a'minimum of both under-size or over-size
in each fraction. More particularly, the inven
tion is applicable to the treatment, in this man
ner, of particles of minute sizes where differences
of micron accuracy are important, as exempli?ed
in the sizing of very ?ne abrasives.
of sized particlesare of screen-mesh sizes, the
velocity is substantial which means that the di
ameter of the ori?ces in the constriction plate
nance of a controlled density of the bath is im
portant, means are made use of which automati
of as small as can be conveniently drilled there
are of appreciable size.
But, when it comes to
sizing particles where the difference between the
particles to be overflowed and those particles to
be discharged through the bottom differ by say a
This invention proposes to make use of hin 10 few microns, then two troubles are encountered.
First, it is impracticable to drill holes small
dered settling in a pool or bath of suspended
enough in the constriction plate, and second,
solids that are in teeter due to hydraulic water
however small the holes are that can be drilled,
being passed upwardly through such a bed
they are so large relative to the solids that the
through a constriction or ori?ced plate that lies
beneath the bed. Feed material is continually 15 descending solids being as small as they are, pass
through the ori?ces in the plate which they
passed to the bath, and ?nely sized solids are
should not do. Therefore, an important object
continually overflowed therefrom, while the
of this invention is to solve this problem.
coarser solids are discharged from the bottom
The problem is solved by using a composite con
of the bath. Since the density of the feed ma
terial may vary somewhat, and as the mainte 20 striction plate with ori?ces in one section there
through and then beneath is disposed a diffusion
or dispersion section of pervious material, such
cally control the density of the bath to maintain
as porous tile. Tile alone cannot be used be
it practically constant. In such an environment,
the invention has for its object the provision of 25 cause too much water will go through it and
the water that does pass therethrough cannot be
a constriction plate coupled with the flow of hy
concentrated in spots as is necessary in a con
draulic water or other classifying liquid; under
striction plate. So the net result is that all the
conditions to maintain the bath of suspended
bene?ts of the constriction plate can be enjoyed
solids being classi?ed with a certain void ratio
that assures the maintaining of all of the sus 30 using larger ori?ces than otherwise, but solids
cannot pass downwardly through the ori?ces be
pended solids being classi?ed in teeter and thor
cause they are blocked by the tile that is in close
oughly mobilized so that substantially none can
subjacent contact with the plate. Thus, this
come to rest on the constriction plate.
composite water-controlling partition has the
The velocity of the hydraulic water passed up
attributes of avoiding the necessity of too ?ne‘ ori
wardly through the ori?ced‘constriction plate 35 ?ces;
of preventing descent of solids through the
controls the dividing line of particle size below
larger ori?ces used; and of reducing the velocity
which particles are swept upwardly from the
through the larger ori?ces due to the diffusing
teetered bed by the hydraulic water ?owing
and ?ow-retarding action of the previous section
therethrough and overflow from the apparatus,
while those particles that are larger than that 40 of the plate.
The best embodiment of this invention now
size descend against the up?owing water and are
known, is shown in the accompanying drawing
discharged from the bottom of the bed. There
but it is to be understood that form is used for
fore, one function of the velocity of the hydraulic
illustrative purposes only, for obviously the in
water ?owing through the plate is to control the
line of division’ of particle size. But a feature 45 vention is} capable of other manifestations. For
instance, the, invention may be practiced in a
of operation of this invention is that not only
single pocket-classi?er or sizer.~
must the velocity of the hydraulic water be con
trolled (which is well known) but the volume
In the drawing, Figure 1 is a perspective View.
of a multi-pocket sizer embodying this invention.
ratio of water on the one hand to water and 50 Fig. 2 is a transverse vertical sectional View taken.
along the line 2—2 of Fig. 1, looking toward the
solidson the other hand so that the volume of
feed end of the apparatus. This illustrates howv
the water present in the bed is not less than .60
a representative pocket is made and how it works,
of the volume of water and solids present.
must be controlled in order to maintain ‘the void
vIt‘is the velocity of the hydraulic water passing
upwardly through the ori?ced constriction plate
either as a complete unit or as one of a number
55 of such pockets in a machine like that of Fig. 1.
Fig. 3 is a partial vertical sectional view of an
enlarged detail of the composite constriction plate
of this invention.
Referring to Figure 1, for the moment, 2| in
dicates a tank having a bottom 24, with the tank
being narrower at the inlet end It‘ where feed I 'n'
enters, and wider at the other end 29 from which
over?ow 39 discharges. The tank is divided into
pockets having submerged divisional walls 25,
shown in dotted lines, and there is a sight-glass
22 for each pocket. Each pocket has an over
?ow weir-edge it over which liquidv over?ows
from the pocket into a side launder 3| which
slopes as shown toward the overflow end 30; {8
indicates a pipe for conducting hydraulic liquid
such as water to each pocket through the valve
l9, the pipe 20 and the manifold 23. From the
manifold 23, there is a branch pipe 21 leading to
each pocket, controlled by a pinching valve 28
for controlling the volume and velocity of hy
draulic liquid passing from the manifold into
each packet. 26 represents a sands discharge
from each pocket.
Each pocket is also provided with a super;
elevation‘ indicator ID, a discharge valve-stem
II, a motor operator l2 for the valve-stem, and
a diaphragm-equipped controller 13 for the mo‘
t‘or. Each pocket is greater in width succes
sively as it is more distant from the feed inlet
I'Lbut all are of ‘equal depth.
Referring now to‘ Fig. 2, the motor controller
I3.‘ is wired‘ to‘ the motor operator l2 through a
conduit 49, and the superlelevation ‘indicator
pip'e I0‘ is connected with the controllerv !3; by
means of a pipe 41. The valve-stem or rod II
is ‘connected with a conical valve 42 that is
adapted to“ close the valve seat 43 located in a
constriction plate 44 that is provided with one
?'ces 45'. ‘Between the constrictionv plate and the
bottom 24 of the'tank is formedea hydraulic liquid‘
chamber‘ ‘136' fed with‘ such liquid through pipe
21, with‘ its valve control 28 leading from the
manifold 23'. When unsea'ted, the‘ valve‘ 42: pere
Inits suspended solids from the bath or bed B
thereof in the pocket to pass out“ therefrom
through the conduit 41w discharge as“ 25; 48
indicates a drain plug‘- for the hydraulic chame'
ber 48'. This construction and its operation is
shown and described in the U. ‘S. A. patent ap-'‘
This is done in the practice of the
Haagensen invention by controlling the valve 42
automatically to maintain the density of the
bath constant, irrespective of ?uctuations in the
rate of feed, or other variables that affect
density. If the density of the bath rises, the
column of clear water in the super-elevational
tube I0 that is balanced by the bath‘ of'suspended
solids, rises above the ?xed liquid level of the
bath, to an elevation high enough to ?ow through
the pipe 4| into the controller I3 where pressure
thereof‘ presses upon a diaphragm (not shown)
whose consequent movement operates an elec
trical circuit‘ that starts motor-operator [2 to
raise or unseat the valve 42 from its seat 43 and
let out enough sands until the density falls back
to normal.» When this happens, the column of
clear water in the pipe l0 falls back to normal,
the motor-controller I3 returns to normal, and
this in turn stopsthe motor I 2 to leave the valve
just enough on its seat to provide proper dis
charge of sands through the valve seat“; Thus,
the valve is normally open and o? its seat, but as
density rises, the valve’ is raised further 011' its
seat, and if the density gets too low, the valve
is seated until the correct operating density is
The classi?ed ?nes continue to' over
?ow the weir edge continually, while the sands
continually discharge through the pipe 41, except
when the valve is actually seated-which is rare.
However, the discharge of sands may ?uctuate
in quantity depending upon the distance that the
valve is off its seat, as a result of its operation
by the motor l2. The valve may be said to go
. through a‘hunting action of rising and falling
when the density changes, but minutes or some
timeshours may go by without the‘ valve chang-'
ing its position, if the density is not disturbed
byv?uctuat'ions in quantity of feed, or its density.
However, where‘ it is important to realize the
advantage of accuracy of sizing, toward which
thekemphasis of this invention is directed, at
tenti'on should be paid to assuring that the sus
pended solids in the bed, bath or pool bemain-'
tained in mobilized condition with ‘substantially
none of them at rest. In order to assure a still
further speci?c optimum- condition of teeter,
there must be established and maintained a re-'
lationship within the bath, whichv is a pulp or
plication of Haa‘gensen‘; Serial No‘. 501,841: f > 50 mixture of solids and liquid, whereby the volume
The operation thereof may be brie?y described
of- the liquid present‘ bears a particular ratio to
as‘, follows: theret'is'van ever‘ichanging pool‘, bed‘
the‘total volume of the liquid and solids of‘ the
or'b'ath B of suspended solids‘ in the-pocket, pass=
pulp. Such ratio is‘ that the volume of liquid
ing from one pocket to a nextsucceeding one‘
present should equal 60% of the total volume
over the submerged.v partition 25 between adj'aé'
of the liquid and solids present, ‘in which case‘
centrpockets. Hydraulic liquid; such as water,
the volume of- suspended solids'willequal 40% of
is supplied to the bath through the manifold 23‘
the total volume of liquid and solids.» The‘ ratio
and pipe 21 into the‘ hydraulic chamber 46- from
of the volume of liquid to total volume of‘liquid
whence it ?ows upwardly through the constricfe
and solids may rise- as high as’ 90%; but“ 60% is‘
tion plate 44 at a velocity and in a volume will 60 critical and a‘ less percentage should be avoided,
cient to‘maintain the suspended- solids 'in the
if possible.- Latitude‘i's' allowed up to 90%1 but
bath thoroughly mobilized and in: teeter. The‘
as the percentage- rises above 60% decreased‘
velocity of the up?owing hydraulic water de'e
e?q'ciency is experienced. This _percen'tage'~ of
termines the‘ particle size less than‘ which‘ par-4
liquid may be referred to as “void ‘randrnamleiy
ticles over?ow the Weir edge l4 into the‘ launders
the ratio of space‘ occupied by'nonesolidsi‘ com3| and flow to discharge as ?nes‘. _ Particles of- a
pared with the‘ space taken‘ up bythe' liquid?
size larger than thosede‘sired to’ over?ow‘; die
solids mixture of pulp. It is- eXpe’die?t for dale
scend and pass- out from‘ vthe bedor bath‘ B
cul'ation purposes,’ however, to use’ decimals
rather than percentages; so we may say" that the
through‘ the valve-seat Mlv (the valve 42 being
normally unseated) and~ the conduit as dis.
charged sands.
However, the efficiency of this classification of
particles into an over?owedfraction or" ?nes
and “into a discharged fraction of sands, ‘depends
upon maintaining constant the‘ density' of the‘
“void-ratio” should be .60' of the volume of the
pulp (the solids ram being .4001? the volume of
‘the pulp), although latitude‘ is permitted up to
.90 of the volume of the pulp (with the ‘solids
ratio .10). Therefore; void ratio" is", that" ?g
are Obtained by dividingw'the‘volum?é of the liquid’
spacing thereof is arranged .to cut down the
bythe volume of the pulpor bath. For example,
.ajcvoid' ratio of ‘.60 (solids ratio .40 with 3.2
speci?c gravity solidswould give a speci?c gravity
pulp of 1.88 if taken just above the bottom of the
pulp or bath. The calculation thereof is as fol:
velocity of the hydraulic. wateri passing ‘there
through to that required. by thesize classi?ca-._
tion or fractionation to be effected. Other con
striction plates can beused so long as the per
viouslayer or section is liquidvdiffusingvand has
pores so small thatsolids will. not pass there
through, while the upper layer is ‘ori?ced with
liquid impervious blank areas between the ori-v
lows: 3.2 times .40 (ratio of solids) equals 1.28.
To :this is added '.60 which is the sum ‘of the
speci?c gravity of water (100) timesthe .60 ratio.
Thus 1.28‘plus'.60 equals the speci?c gravity of
the pulp, namely 1.38. ‘With avoid ratio of .70 10 ?ces. 'Another type. of such plate is a metal or
metallized plate having small discs of pervious
(solids ratio .30) the-calculation is: 3.2 times.30
material seated therein through which hydraulic
-(ratio of solids) equals .96. The speci?c gravity
liquid can ?ow upwardly.
‘of water (1.00) times the ratioof voids (water)
As explained in the earlier part of this speci-_
7.70, equals .70. .96 plus .70 equals 1.66 the speci?c
gravityof the pulp-atthebottomof the bath 15 ?cation, the maximum accuracy of this appa-.
ratus is not realized unless the void ratio, namely
thereof. If _a liquid other than water-is made
the ratio of the volume of non-solids, is main-.
use of, naturally the speci?c gravity thereof
' 7
tained at between .60 and .90 of the total volume
should be used in the calculations instead of that
of the pulp or bath, it being understood that the
of vwater. As the speci?c gravity of the solids
fed to the bath is reasonably constant, afterthe 20 greatest .ef?ciency is experienced when the void
ratio is as close to .60 as is possible to maintain.
?rst setting of the feed of water to the bath, only
If this cannot be maintainedythen the operator
an: occasional sampling of the speci?c gravity of
should err on the side about .60 upto .90, but
the bath or pulp needs to be taken, and the Water
should try to avoid going substantially below- .60.‘,
feed rate adusted, if the void ratio is out of line,
This void ratio determines the condition of
as shown by such sampling.
ef?cient teeter within the bathlanldris a separate
But even when such care is exercised in" main
feature of control from the complex or composite
taining proper conditions of teeter, the accurate
constriction plate of Fig. 3,lbutl this condition of
sizingv or classifying of extremely small solids,
void ratio contributes importantly, to the con-.
such as abrasives, presents another problem,
namely the ori?ces 45,, in; the constriction plate
M, of Fig. 2, cannot be drilled small enough to
prevent the ?ne descending solids from settling
‘against the up?owing hydraulic Water and down
through the ori?ces 545 into the hydraulic cham
ber 46. In other words, the foregoing f‘void 35
ratio” can be made to operate in- classifying
solids according toscreen mesh sizes, but when
classi?cation is attempted of solids differing in
joint operation of the‘ particular constriction
the . hydraulic water led
through pipe 21 into the hydraulic chamber .46,
has a double requirement, namely, it, must, be
su?‘icient in velocity as it passes upwardly
through the composite constriction plateplttlto
bring about the particle size separatior1;;or-class_i-._
?cation desired, ,‘but it must also be inavolurne
sufficient to maintain the criticalvoidratioin
the bath.
diameter by only a few microns, then a new
I claim:
trouble is encountered.
That trouble is solved in the practice of this
1. Apparatus for the sizing of suspended solids,
invention by making the ori?ced constriction
comprising means for establishing and maintain
plate 46 of Fig. 2, in complex or composite form,
ing a pool of suspended solids to be classi?ed by
along the lines illustrated in Fig. 3, wherein me~
hindered settling, means for continually feeding
tallic plate 44 is ori?ced by having holes 45 drilled 4-5 solids thereto, means for continually discharging
therethrough at appropriate intervals, but at
fractionated larger solids from the bottom of the
tached to the metal plate 44 subjacent thereto is
pool, means for continually over?owing from the
a pervious liquid-di?using or dispersing section
upper section of the pool another fraction of
or layer 5|] of porous tile or other pervious ma
terial. By such an arrangement, the ori?ces
need only be as small as they can be made con
smaller solids, means forming a bottom for the
pool including an upper horizontally extending
veniently, for any setting solids that might be
small enough to pass downwardly through the
?at plate of impervious material having ori?ces
for distributively delivering controlled quantities
of water up?owing therethrough under pressure
ori?ce cannot do so because it cannot pass
through the porous tile 50. At the same time,
the hydraulic liquid, such as water, is controlled
and a lower immediately underlying porous tile
downwardly through the pores of which ?ne sol
as to volume and velocity just as well with this
type of composition constriction plate as with a
ids cannot pass but upwardly through which
pores water can be passed for delivery through the
ori?ces of the plate under hydraulic pressure to
simple type. However, in order to get the con
mobilize suspended solids in such pool, means for
trol necessary, it is important that the ori?ced 60 controlling the liquid supplied to the pool so that
metal plate be on top or above the pervious plate
the ratio of the volume of liquid of the pool to
or tile, and not vice versa. By the use of the
the total volume of the liquid and solids content
combination described and claimed herein, sus
of the pool is maintained at not substantially less
pended solids can be classi?ed into fractions
than .60 but which may be as great as .90, means
differing by as little as ?ve microns in diameter, 65 for establishing and maintaining a column of
and solids of twenty microns diameter can be
clean liquid balanced by the density of the pool
separated from solids of ?fteen microns in di
. to a super-elevation above the top of the pool
which super-elevation varies with the density of
The pervious tile is preferably of the type now
the pool due to ?uctuating feed thereto of solids,
on the market called “Porex,” and the tile when 70 a valve-seat in the bottom of the pool, an ad
1/4" thick has proven satisfactory. Standard
justable valve controlling the rate of discharge of
?ow velocity through such a tile is 57 feet per
the solids fraction through the valve seat, and
automatic means for stabilizing-the density of the
hour. This velocity is too great when classify
ing micron sizes of solids so the size of the ori
pool at or near a predetermined normal to ensure
?ces in the metal plate and the center-to-center 75 accurate size classi?cation of solids therein.
25. Aii?aratiis for‘ the sizing of su'siiénded: solids;
céiiib?singr?iéans for‘ establishing and maritime
irié'a bop'l of suspended solids to be classi?ed by
hindered- settling,- means for‘ continually feeding
solidsthefe'td fneaiis for continually discharging
4. A?pafatus- according to ‘claim 2, wherein the
ori?ée'd' member has one section pervious both
toniiji?oy'v‘ing' Water and to descending suspended
solids}; am; another‘ section pe'i‘iiious to such we;
fractionated larger solidsfroni the b'ottoin of the
5. Apn'i'atils fof the sizing of suspended Solids,
eomp'nsine means forestablis‘hing and maintain;
mg a pool (‘)?S?S?ehdiid solids to be classified by
pool; means‘ for continually over?owing from the
u?per section of the’
“another fraction _ of
smaller solids, ineansforrning bottom for the
16601 including a horizontally extending ‘member
‘having’ ori?ced' portions providingapertures dis
posed for insuring delivery of controlled quanti
ties of water passing upwardly therefrom and at
the underside of said meinher in the region im
mediately below and extending outwardly beyond 15
the lower edge of the aperture of each ori?ced
portion a porous-tile section through which ?ne
solids cannot downwardly pass but through the
pares of which hydraulic water is passed into and
for delivery from the aperture of the correspond
iiig‘ ori?ced portion under hydraulic‘pressure to
iiiobilize suspended solids in such pool, means/for
establishing and maintaining a column of clean
liquid balanced by the density of the pool to a
tei'biit not to such solids,
hindered settling, means for continually feeding
solids thereto; means ‘for continually discharging
fractionated larger ‘solids from the bottom of the
15001,» means‘ for continually over?owing ‘from the
ubper section of the pool another fraction of
smaller ‘solids,- avcoi'riposite ?ow-constriction ?oor
member einbod’y'rin'gF as an upper portion thereof a
plate of impervious; material having spacedly dis‘
,posed throughout the same up?ow-Ope'nin'gs and
as a contacting lower layer a porous tile imper
violis to the downward passage ‘of ?ne soldiS but
pervious to hydraulic waterinto, through, and
dii'éctly-frointhe pores of which the water passes
into said up?ow openings for upward distribu
tive‘ delivery under- pressure into the overlying
pool whereby to mobilize suspended solids in the
superlelevation above the‘ top of the pool which 25 pool, means for establishing and maintaining a
super-elevation varies with the density of the pool
column of clean liquid balanced by the density of
due to ?uctuating feed'thereto of solids, a valve
the pool to a ‘super-elevation above the top of
seat in the bottom of the pool,v an adjustable valve
the pool which super-elevation varies with the
controlling the rate. of discharge of the solids
density of the pool due to ?uctuating" feed there
fraction through the yalve seat, and automatic 30 to of solids, a valve seat in the bottom of the
means for stabilizing" the density of the pool at or
pool, an adjustable valve controlling the rate of
near a- predetermined normal to ensure accurate
discharge of the solids fraction through the valve
- siz‘e classi?cation of solids therein.
seat, and automatic means for stabilizing the
3;; Apparatus according to claim 2, wherein the
density of the pool at or near a liredetermined
ori?ced? member comprises a porous tile section 35 normal to ensure accurate size classi?cation of
farthest froin the pool andthei‘eabove facing the
pool, a metal section provided with ori?ces and
solids therein.
blanked o? areas of metal thérehetween. 7
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