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Патент USA US2293033

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Aug. 18, 1942.
H. 1.. MEAD ETAL '-
2,293,033
API’ARA'I'US AND rnocnss For: mzsnnqne momnon FEED
’
Filed April 5, 1940
‘
2 Sheets-Sheet 1
INVENTORS
law/FRY
4 . M540 ,
LOP/V4197‘ u. M4057‘
ATTORNEY.
Aug. 18, 1942. I
H. L. MEAD EI'AL _
-
2,293,033.
APPARATUS AND PROCESS FOR DESLIMING FLOI'ATION FEED
Filed April 5, 1940
Z-Sheets-Sheet 2'
I
y
..x..
.
‘
INVENTORS'
H4??? A . M6740 ,
‘ATTORNEY.
v Patented Aug. '18,‘ 19.42,
' r 2,293,033‘
‘UNITED? STATES PATENT OFFICE
APPARATUS AND rnocsss FOR nasrmmo
morarron mans
'
‘ Barry L. Mead and Ernest J. Maust, Brewster,
Fla., assignors to American Cyanamid Com
pany, New York, N. Y., a corporation of Maine
. Application April 5, 1940, Serial No. 327,948
'
6 Claims. (cpl. 209-454)
This invention relates to the desliming of
E
?otation feed in the ore dressing art and more
_‘ particularly it relates to an improved apparatus
of the hindered settling type for desliming the
?nest fraction of ?otation feed.
~
Recent improvements in the ?otation art have
required that ?otation feeds be very thoroughly
deslimed,v that is to say, more completely than
the desliming produced in the use of free settling
tanks. This is particularly true inv connection 10
with the ?otation of silica from phosphate rock
using the so-called cationic ?otation reagents as
even very small quantities of slimehave a dele
terious effect on the promoter action of the
tion is conducted in one tank where a small
amount of water and a small area' does work
equivalent to that accomplished by a series of
large settling tanks employing much larger
quantities of water. This improved apparatus is
useful‘i‘or desliming very ?ne ?otation feed of
any ore material but it is particularly useful in
the non-metallic ?eld, especially the ?nest frac
tion of phosphate ?otation feed ranging from
-48 mesh down to 325 mesh.
In carrying out our invention use is ‘made of
the density of a teetering mass of ?ne ?otation
feed to keep the light slime from-entering the
denser body of material in suspension. A density
reagents.
‘
in excess of that of water is induced in the
In our copending application Serial No. 320,121
pockets of the hindered settling deslimer due ‘to
?led February 21, 1940, we have described an
the particles being held in teeter by means of
improved process for the simultaneous sizing and
the hydraulic water passing through the con
desliming [of phosphate ore ?otation feed in a
striction plate in the bottom of the compart
hindered settling classi?er, which is a much 20 ment. Hence, in addition to the tendency for
more eiiicient method than the ordinarily em
a rising column of water to carry off slime, the
ployed desliming, operations, the process, how
density of the material in suspension also tends
ever, deals only with the desliming of the larger
to aid in slime removal. In our improved bin
particlefractions of the phosphate material and
dered‘ settling deslimer water is added at such
does not result in slime removal from the very
a rate that only about 6 gallons per minute per
?ne fraction of phosphate material to which
square foot of over?ow area is used. In the
the present invention relates.
‘
_
The ordinary'methods of desliming very'?ne
?otation feed in the past have ,not been found
‘ordinary hindered settling classi?er water in ex
cess of this amount must be used to keep the
‘particles in suspension and thus ?ne ?otation
to be entirely satisfactory. The prior methods 30 feed-is over?owed. This water limitation at a
of desliming very ?ne ore material usually con
point of not over about 6 gallonsper minute per
sists of passing the material into a series of large
square foot of over?ow area is made possible and
settling tanks with the addition of large volumes
teeter still maintained by ?aring the hydraulic
of fresh water to each of the series of settling
chamber at a point above the teeter column.
tanks. Adequate settling area in this case must 35 It is an advantage of the present invention
be provided in each tank to settle all of the plus
that the ?nest fraction of phosphate ?otation
250 mesh material each time that it enters a
feed which cannot be deslimed ,in the ordinary ‘
tank. As some. slime always tends to settle,
hindered settling classi?er (-48 mesh down to
with true particle size material, the amount .of
325 mesh) is readily deslimed using our im
slimesettling in each tank of \a series is a de 40 proved apparatus. A very thoroughly deslimed
creasing amount, but is never entirely removed
product is produced, which deslimed feed when
as mathematically this is impossible. Hence,
subjected to froth ?otation concentration by
in previous methods ‘it was not economically
either the silica ?otation process or the fatty
practical to obtain the high degree of desliming
acid phosphate ?otation process results in a
that is attained in the hydraulic hindered set 45 higher grade product and permits more e?lcient
_
operation.
tling deslimer of this invention. The settling
tanks of the prior methods might be cylindrical
_ ‘The present invention has many advantages
tanks with ?at bottoms, conical tanks, or rec
tangular tanks with bowl attachments wherein ’
the settled material was raked out of-the bath.
_In accordance with the present invention a
process is provided in which very ?ne fractions
of ?otation feed can be thoroughly deslimed. An
over the prior desliming processes such as those
using a series. of settling tanks or cones, drag
classi?ers and the like. Some of these outstand
ing advantages are low ?rst cost of equipment,
small floor space. and economy of about 60%
to 70% in the use of water over the free set
tling desliming. When compared to a desliming
improved apparatus of the hindered settling type
is provided in which the entire desliming operas .55 process using a series .of these cones it was found
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2,298,083
2
of the tank is not suf?cient, however, to support
that only’ll/a as much water was needed in our
improved hindered settling deslimer and at the
the ore particles and they fall back into the pock
vsame time ‘the initial cost was only about 5/5
as much to produce a better deslimed product.
,The invention will be more readilyunderstood
_by referring to the following drawings of our
jected to hydraulic water at a velocity di?erent
from that in pocket ‘I. This process is repeated
improved hindered settling deslimer apparatus
in which:
Fig. 1 is a longitudinal sectional view;
ets. The feed passes from the pocket ‘I into the
pocket 8 by means of the slot I5 and ishere sub
as the feed passes from pocket to pocket, addi
tional quantities of slime being removed in each
pocket until the thoroughly deslimed feed col
10 lects in the last pocket I3, from which it is sub
Fig. 2 isv a top plan view; and
sequently discharged by operation of the dia
Fig. 3 is a transverse ‘sectional view taken
phragm actuated through the changes of spe
along the lines 3-3 of Figs. 1 and 2_and looking
ci?c gravity in pocket I2 to open the plumb bob
in the direction of the arrows.
valve seated in the feed discharge opening I9.
‘ The deslimer comprises atank I having the
is no opening in the ba?le I4 separating
?aring sides 2. The lower half 01' the tank is 15 There
pocket
I2 from pocket I3 and the velocity of the
divided into a plurality of pockets or compart
hydraulic
water in I3 is just enough less than
ments as illustrated. These pockets are num
that of pocket I2 so that the feed passing over
bered from ‘I to I3 inclusive. A hydraulic water
the top of baille It into pocket I3 will settle or.
compartment 3 is located beneath the pockets
collect at the bottom.
20
and separated therefrom by the perforated con
We have found that a very ?ne fraction of.
striction plate 4 through which hydraulic water
phosphate ?otation feed can be very thoroughly
may be ?owed. Any number of pockets may be
deslimed in accordance with the above operation,
used, the number being optional and limited only
by which even the 250 mesh material may be
to a practical size over which water may be uni
retained using an apparatus in which approxi
formly distributed through'the holes of the con- mately 2000 gallons per minute for 50 long tons
striction plate in the hydraulic water compart
per hour of feed were being processed. Among
ment 3. Hydraulic water inlets 22 are shown
the important features which appear to be in a
leading into the various portions of the hydraulic
general measure responsible for the improved re
water compartments 3 in such a manner that
of this apparatus are the ?ared sides of
varying amounts of water and at different veloci 30 sults
the
tank
which increase the area‘ and reduce the
ties may be forced through the constriction plate
velocity of the uprising currents of water so
6 into each oi‘ the pockets ‘I to I3 inclusive. A
that the slimes are carried over the top and the
baiile plate I4 divides each of the pockets from
ore materials fall back and can be collected.
the adjoining pockets from ‘I to I2 inclusive. All
By restricting the over?ow at a point where
of the pockets except I3 are connected through a . =
the
material is to be removed, we provide a
suitable opening or slot I5 in the battles I4. While
positive ?ow of a small amount of remaining
the slot I5 is shown extending only part way up
slime in a direction opposite to that of the pas
the ba?les I4, it may, if desired, be extended to
sage of feed. This is an important part of the
the top. A standpipe I1 is shown positioned in
invention. Another important part of this in
the pocket I2, in such a manner that changes
vention is the restricting of the ?ow rate of
of speci?c gravity in this compartment cause
water- in the cell in which the material is dis
water to rise in the pipe actuating a diaphragm
20 operatively connected to the top of the stand
pipe. This diaphragm may be 'of the ordinary
?exible‘ rubber type but is preferably a bellows
diaphragm. When the diaphragm is forced up
wardly by water pressure the plumb bob valve I8
which is seated in the discharge opening IS in
the bottom of pocket I3 is raised a su?icient
height to permit the deslimed feed to pass out
through the opening I9. Each of the pockets ‘I
to I3 inclusive may for convenience have obser
vation windows 23 which will permit the oper
' charged to a point low enough to settle all 01
' the plus 250 mesh ?otation feed. As water is
added in excess of this amount in the other
cells, limiting the velocity of upward ?ow to a
point below 6 gallons per minute per square foot
of over?ow area at the over?ow point, the ?nest
of the ?otation feed could not settle into the bot
tom of these pockets to be discharged. Hence,
in the pocket through which the material is dis
charged the velocity of the rising current of water
is maintained at a point below 6 gallons per min
ute per square foot of area. As the ?ne ma
ator to view the passage of the feed through
these compartments. A feed opening 2I is so 55 terial is not agitated suf?ciently at this low ?ow
rate to actuate a diaphragm discharge mecha
arranged in conjunction with the baf?e I6 that
nism, this mechanism is operated from the super
when feed is introduced it passes directly into
elevation water in the adjoining pocket to dis
the compartment 1. An over?ow area at the
charge the deslimed‘feed in the discharge com
top of the flared portion of tank 2 is provided by
means of the weir 5 by which water and‘ slime 60
In a preferred embodiment of our apparatus a
are over?owed into the over?ow launder 6. The
diaphragm actuated device working through su
weir 2| prevents over?ow at the most distant
perelevation of the material in teeter in a pocket
portion of the tank from the feed entrance.
In operation a very fine ?otation feed, as for
of the machine to discharge the material, from
partment.
'
_
.
example in the case of phosphaterock ranging
an adjoining pocket is employed. The deslimed
in particle size from —48 to 325 mesh, is fed into
feed might also be discharged by means of a
the feed opening 2I and thence into the com
hand operated valve, a centrifugal pump or a
partment ‘I, whereupon the rising currents of
simple spigot, without violating the basic fea
hydraulic water passing through the construc
tures of the‘ invention. ,There are many ad
tion plate .4 carry the ?ner slime particles into 70 vantages however, which result from the use of
the ?ared portion of the tank. Here the up
‘the teeter column .actuated diaphragm pump,
ward velocity of the water decreases due to the
among which are: it is automatic in operation
increased area. The velocity is, however, sum
and does-not require the attention or an oper
cient to carry the slimy Particles over the weir 5.
ator,
it is easily adjusted for any variance in the
The velocity of the water in the ?ared portion 75
2,293,033
type of feed, amount of feed or other operating
conditions.
-
.
In utilizing our improved apparatus no sizing is
attempted unless we differentiate between col
loidal slime and true particle size of about‘250
mesh. The rising velocity of the hydraulic water
is regulated in‘ such a manner that it is su?icient
to ?oat away the colloidal slimes while at the
same time it is approximately equal .to or less
than the free settling rate of 250 mesh sand.
When the velocity of the rising water is thus
regulated the 260 mesh sand and, ofcourse, the
material "larger than 250 mesh readily separates
out and is completely free from the colloidal
slimes.
_
>
We claim:
1. A-method of desllming withoutclassifying
slimy ore feed containing ?ne particle sizes which
comprises introducing the feed into a rising col
umn of water the velocity of said rising column
being such as to cause the coarsest particles of
the feed to remain in suspension, subjecting said
stream of water to deceleration to a velocity at
which the ?nest ore particles settle but slime
rises, over?owing a portion of the water at said
velocity to remove slime, causing said deslimed
materials to pass into a zone of rising water the
tank-the upper portion of which has ?ared sides
‘and an overflow area for slimes, a series of
pockets located in the lower portion of the tank,
means for introducingyore material into one of
the pockets, means for discharging the coarser
ore material in a pocket located at the opposite
end of the series from the one into which the
feed is introduced, means for introducing water
upwardly into each of the pockets at a variable
velocity, means for restricting over?ow above
the pocket from which the deslimed feed is dis
charged which causes the excess water to flow
in a direction opposite to that of the passage of
feed water in order to over?ow from the tank,
said pockets in the series communicating with
one another through‘ restricted openings in the
‘sides thereof with the exception that there is
no communicating opening in the wall of the
discharge pocket‘ and the preceding'pocket.
5. A hindered settling deslimer comprising a
tank‘ the upper portion of which has ?ared sides
and, an over?ow area for slimes,'a series of
pockets located in the lower portion of the tank
and having perforated bottoms, means for intro
ducing ore material into one of the‘ pockets,
means for discharging the coarser ore material
in a ‘pocket located at the opposite end of the
velocity of which‘is such that the particles just
series from the one into which the feed is intro
duced, means for introducing water through the
settle in ‘a discharge zone and discharging the
settled ore particles from said discharge zone at 30 aforesaid perforated bottoms into each of the
a rate determined by sensing means located in a ~ '
zone 'preceding the discharge zone.
a
2. A method of desliming without classifying
slimy phosphate ore feed containing very ?ne
pockets at a variable velocity, means for restrict
ing over?ow above the pocket from which the
deslimedieed is dischargedv which causes the
excess water to ?ow in a direction opposite to
particle sizes, which comprises introducing the 35 that of the passage of feed water in order to
feed into a rising column of water the‘ velocity
over?ow from the tank, said pockets in the
series communicating. with one another through
of said rising column being such to cause the
restricted openings in the sides thereof with the
coarsest particles of the feed to remain in sus
exception that there is no communicating open-‘
pension, subjecting said stream of water to de
celeration to a velocity at which the ?nest ore 40 ing in the wall of the discharge pocket and the'
preceding pocket.
‘
particles settle but slime rises, overflowing a por
6._ A hindered settling deslimer comprising a ,
tion of the water at said velocity to remove slime,
tank the upper portion of which has ?ared sides
causing said deslimedmaterial to pass into a zone
and an overflow area for slimes, a series of
of rising water the velocity of which is such that
the ?nest ore particles just settle in a discharge 45 pockets located in the lower portion of the tank
and having perforated bottoms, means for in
zone and discharging the settled ore particles
troducing ore material into one of the pockets,
from said discharge zone at a rate determined by
sensing means located in a zone preceding the
means for- discharging the coarser ore material
a diaphragm mechanism
discharge zone.
, which; comprises
3. A method of desliming without classifying 50 actuated by density changes‘ in one pocket to
operate a feed discharge opening in the bottom
slimy phosphate ore feed containing very fine
particle sizes, ranging from ~48 to+325 mesh
ot another pocket located at the opposite end
which comprises introducing the feed into a ris
of the series from the one into which the feed
is introduced, means for introducing water
ing column of water the velocity of said rising
column being such to cause the coarsest particles 55 through the aforesaid perforated bottoms into
each of the pockets at a variable velocity, means
of the feed to remain in suspension,‘ subjecting
for restricting over?ow above the pocket from
v said stream of water to decelartion to a'velocity
which the deslimed feed is discharged which
at whichthe ?nest ore particles settle but slime
causes the excess water to ?ow in a direction op
rises, over?owing a porion of the water at said
velocity to remove slime, causing said deslimed 60 posite to that of the passage of feed water in
order to overflow from the tank, said pockets
material to pass into a zone of rising water the
\ velocity of which is such that the ?nest ore, 250
mesh, particles just settle in a, discharge zone
in the series communicating with one another
vthrough restricted openings in the sides thereof
and discharging the settled ore particles from
with the exception that there is no communicat
said discharge zone at a rate determined by sens-‘ 65 ing opening in the wall of the discharge pocket
and the preceding pocket.
ing means located in a zone preceding the dis
charge zone.
.
-
4. A hindered settling deslimer comprising a
.
'
_
HARRY L. MEAD.
ERNEST J. MAUST.
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