close

Вход

Забыли?

вход по аккаунту

?

Патент USA US3062740

код для вставки
Nov. 6, 1962
F. o. READ ETAL.
3,062,738
GRANULAR ION EXCHANGE PROCESS FOR PULP TREATMENT
Filed Jan. 15, 1959
2 Sheets-Sheet 1
5
/
n.9n- ;_-.
wv
q
{1-4lrh|uIn}vELi
/w
w/
I|ItlIIIJ.
| lIr!I|l7
w
2|"HalI_F1| IC| Il l
00_4/
/0
Z
02
.
50L.
50!;
=
w
2. v
VIa‘NTlt Tl._I Dl lW
w
5%
w
E
Y.
_,. V
m
g9?1.
. A
.f
V
.v
“Mm
my”
?I
m
H
g7
Nov. 6, 1962
F. o. READ ETAL
3,062,738
GRANULAR ION EXCHANGE PROCESS FOR PULP TREATMENT
Filed Jan. 15, 1959
2 Sheets-Sheet 2
/23456789
/0
//
192.5.
0 0.0
07
0 66
0
5
0
O
V
.
[23456789/0/1
EXC/IAA/GER NUMBER
.?/vEA/mes
E€ 4 /l/( d . F5791)
United States Patent G?hce
3,002,733
Patented Nov. 6, 1962
2
under and illustrated in the accompanying drawings, in
3,062,738
GRANULAR llGN EXCHANGE FRO<CE§S FUR
PULP TREATMENT
Frank 0. Read, Ernest H. D. Carman, Harry E. Cross,
and Alexander Thompson Moir, all at .iohannesburg,
Transvaal, Republic of South Africa, assignors, by
which
FIGURE 1 is a diagrammatic side view of apparatus
suitable for carrying out the processes of the invention,
FIGURE 2 is a section of the line 2——2 of FIGURE 1.
FIGURE 3 is a plan view of a convenient lay-out
alterenative to FIGURE 1,
mesue assignments, to The Consolidated Goid Fields
FIGURES 4 and 5 are graphs illustrating a speci?c
of South Africa Limited, London, Engiand, a company
example of the invention.
of the United Kingdom
The apparatus shown in FIGURE 1 comprises a series
10
Filed Jan. 13, 1959, Ser. No. 786,575
of twelve Pachuca tanks 101, 102 to 113, each of which
Claims priority, application Republic of South Africa
.
.Ian. 31, 1958
comprises a conical base 100 with an air inlet 201, 202
11 Claims. (Cl. 210-24)
to 213, and a central column 301, 302 to 313 adjustable
in height, in the well-known manner. Adjacent pairs of
This invention relates to ion exchange processes.
It has been proposed to eitect ion exchange between 15 the Pachuca tanks 101, and 102 and so on are connected
pulps and ion exchange materials in granular form by
contacting the pulp with ion exchange material and then
removing the granules of ion exchange material from the
pulp.
together by means of separators consisting in inclined
pipes 401, 402 to 412. These pipes are connected to one
Pachuca tank of the pair at a high level and the other of
the pair at a low level. As shown in FIGURE 2, the pipes
In one proposal granules of ion exchange resin are 20 401, 402 communicate with the tanks 101, 102 through
small apertures 98 and 99. At the top of each pipe 401
made to settle out of a mixture while decanting the pulp.
In a second proposal ion exchange resin is contained in
baskets which are immersed in the pulp. In yet another
to 412 there is a conduit 501 to 512, which leads upwardly.
Below the conduit there is a small pipe 601, 612 through
which air is introduced.
proposal the resin is contained in a column through which
Consider the ?rst tank in FIGURE 1, that is the one
the pulp is caused to ?ow upwards.
on the extreme left. Pulp is introduced at the top through
In all these processes operation is only possible with
pipe 97. It is agitated in the well-known manner in the
very low density watery pulps from which substantially
Pachuca tank 101. Ion exchange material is introduced
all the +325 mesh Tyler fraction has previously been
through the conduits 501, 502 into each tank from the
removed and washed by means of a series of classi?ers
next
succeeding tank. The ion exchange material and
30
or cyclones and thickeners working in counter-current.
the pulp are thus intimately mixed. Part of this mixture
This in itself is a comparatively expensive process and
over?ows continuously into the separators 401, 402
some soluble losses of the metal being recovered are in
through apertures 99, and, under quiescent conditions,
evitable.
ion exchange material floats in the separators 401, 402
Apart from the above proposals it is conventional to
reaches conduits 501, 502. Flow of ion exchange
?lter pulps prior to the ion exchange process. If ?ltration 35 and
material is assisted by the air introduced through the
is resorted to, there is a loss of the dissolved material in
pipes 601, 602.
the ?ltering step. This loss may be as high as 5% in
Pulp from which ion exchange material has been re
uranium recovery plants. To this must also be added
passes into the second tank 102, where it is mixed
the loss due to the ine?iciency of the ion exchange process, 40 moved
with ion exchange material introduced at the top from the
which may be 1%. The capital cost of the ?ltration step,
next succeeding separator 403, and so the process goes
particularly if the pulp is acid, may be very high.
on. Any number of tanks may be provided. In the draw
An object of the invention is to provide a process
ings twelve are illustrated. The number will depend on
which is simple and comparatively cheap to operate and
various
conditions, which will be apparent to the persons
which will be low in capital outlay. In the invention both
skilled in the art. At the end of the series there is a
?ltration and desanding are dispensed with and soluble
Pachuca tank 113 which serves as a level controller with
losses outlined above are avoided while loss of ion ex
the aid of an adjustable pipe 96. Fresh ion exchange
change material is low.
material may be introduced into the tank before the
A process according to the invention consists in mixing
over?ow regulating tank 113, or into the tank preceding
a pulp with a granular ion exchange material having a
that one. As shown a pipe 95 feeds tank 112.
speci?c gravity less than that of the pulp, allowing the
Obviously if the tanks 101, 102 are arranged in one
mixture to separate into fractions and removing the lighter
line, the line may become inconveniently lengthy. For
fraction of the separated mixture containing the ion ex
this reason a lay-out such as that shown in FIGURE 3,
change material.
In a preferred form of the invention the pulp and ion
may be convenient.
Here the tanks 101 to 113 are ar
ranged in two staggered rows with the connecting sepa
exchange material are continuously introduced at the top 55
of a mixing vessel, such as a Pachuca tank. The mixture
over?ows at a high level in the vessel into a separator,
rators 401, 412 between the two rows as shown.
In an example of the invention a pulp obtained from. a
typical uranium recovery plant we treated with an anion
where under quiescent conditions the ion exchange mate
exchange resin to recover dissolved uranium. The details
rial ?oats, and the residual pulp is withdrawn from
of this example are as follows:
60
below.
Plant.—-The plant consisted of 12 mixing tanks and
Conveniently the vessel and the separator are so ar
one additional tank for level controlling.
ranged that the head of pulp in the vessel causes the
The contents of each of these tanks was agitated by
ion exchange material in suspension in the removed frac
introducing air through pipes corresponding to the pipes
tion to flow up a column formed at the top of the sepa
201, 202. The tanks were interconnected by means of
rator. A series of vessels and separators may be ar 65 inclined separators such as 401, 402', each of which formed
ranged to treat the liquid continuously with the ion ex
change material ?owing in counter-current to the liquid.
Where the speci?c gravity of the resin is between 1.1
an angle of 20 degrees with its respective tank, Each
separator was provided with a resin withdrawal pipe, such
as 501, 502 and an air jet such as 601, 602 to elevate the
and 1.2 it is preferred that the speci?c gravity of the 70 separated resin. Internal pipes such as 301, 302 were
provided so as to prevent air used for agitation from
liquid be kept between 1.4 and 1.5.
entering the base of the separators and also to maintain
An embodiment of the invention is described here
3,062,738
3
4
a quiet degree of agitation in the agitators. An ad
mixture of resin and pulp up the conduits. The speci?c
gravity of this resin-pulp mixture was approximately 1.43
justable over?ow was provided in the level controlhng
tank.
Operation-Warm uranium~bearing pulp was fed into
and on a volumetric basis contained approximately 130
mls. wet settled resin per litre of mixture. The resin-pulp
‘the ?rst tank of the series at constant rate of 3.9 litres 5 mixture withdrawn was discharged into the next preced
per minute. Su?icient air was bubbled into each tank to
ing tank, through the conduit,_ and so on along the series;
provide homogeneous mixing of the pulp.
and ?nally the resin-pulp m1xture discharged from the
Relevant details regarding the pulp used are as follows:
?rst conduit was screened through a 60 mesh Tyler screen
.
.
8
and the pulp returned continuously to the second tank
Speci?c gravity of Pulp ------ "_-------------- '7 1'4 10 of the series, The resin removed was washed and eluted
Speci?c gravlfy of suspe_nded Sohds ------------ " 2'7
by conventional methods and eventually returned to the
Speci?c gravity of solution ___________________ __ 1.03
circuit
Percent solution m pulp __________________ “ 50'0
The tank and separator preceding the level-controlling
TABLE I
tank were provided in order to recover any traces of resin
.
.
which might not have been completely recovered in t e
Grading of Suspended Solids
15 preceding separator. All the pulp discharged was screened
Tyler mesh:
+60 ________________ “Percent by Weight“
—60+90 _______________________ _-dO--_—90+200 ______________________ __d0____
—200+325 _____________________ "do-n-
through a 30 mesh Tyler screen to determine the amount
Nil
of resin lost due to entrainment. This loss Was found to
0-6
be of the order of 1 ml. of wet settled resin per 8 hours.
24‘4 20
After 24 hours of continuous operation, samples of
20.4
resin and pulp were removed from each agitator, sepa
—325 __________________________ __do____ 54-6
Agitator No.
rated by screening and ?ltering and analysed for U308.
TABLE III
Feed
101
Soln. U308, g.p.l-_____ .741
.480
.238
.133
.098
.060
wet settled resiIL--- ____ -_ 26.2
15.2
9.06
7. 04
4.06
50
40
44
40
39
Resin U305, g.p.l.
Temperature, ° 0-.-- .... .-
58
102
Analysis of solution in feed pulp:
103
104
105
100
107
108
100
110
111
.040
.027
.017
3. 44
2.74
2.14
35
34
32
31
After
Elution
.012
.008
.005 ______ .
1.68
1.44
1.10
0.50
31 ...... _.
The results shown in Table III are graphically illus
Fe++ ___________________ "grams/litre“ 1.70
trated in FIGURES 4 and 5.
Fe+++ ______________________ __d0____ 1.26 35
As can be seen, the e?‘lciency of ion exchange is
H2804 ________________________ __do____ 3-90
99.33% which compares favourably with conventional ion
Si02 __________________________ __do____ 2-07
exchange processes. As there has been no ?ltration there
U308 _________________________ __do_-__ 0.741
are no ?ltering losses. Furthermore, the pulp from the
N03 __________________________ __do___.. 0.372
pH value _____________________________ __
leaching step has not been excessively diluted, and the
1.42 40 normal ratio of one part of solids to one part of liquid
Pulp ?owed through the interconnecting separators and
is mbore or less mamtamed’ no prehmma?’ triiatment h.aV'
eventually over?owed into the ?nal Over?ow pipel By
ingween necessary to remove the coarse raction of solids.
adjusting the height of this pipe the pulp levels in the
tanks could be varied at Wm
1 if aim. .
.
. .
_ . n 1011 exchange process consisting 1n m1x1ng a pulp
For this particular test the level of the ?nal over?ow 45 wlthf lgranFial ltgntexfcltlgnge lmatinal.ha‘tllllng a. speclitic
pipe was so adjusted as to provide a combined volume
.
.
.
.
of approximately 80 litres in each stage, 1.e. tank plus
separator of each pair. The average retention ‘time of the
gray! y 6.58 an .a o
'3 Pu 13’ 2.‘ Owmg. 6 mixture. 0
separate into fractions and removing the lighter fraction
of the Se arated mixture containin the .0 ex ha 6
material p
g
1 n
c ng
glugutgsl aach stage was’ therefore’ approxlmately 20 50
Initially 1.6 litres of wet settled resin in the nitrate form
' was added to the pulp in each tank.
2. ‘The process claimed in claim
in which the pulp
a? 21h“)? excfhange- {mammal larei con-tmuously lgtrofiuced
Thereafter eluted
a
.6 Op 0 .a mlxmg V658? ’ he mixture over Owmg at
resin in the nitrate form was fed continuously into the
a l-ngh level m-t-he vessel mm a Separator wh?re under
.
tank the second from the end (the level-controlling tank
' luded) at a constant rate of 0.080 litre wet settled
quiescent conditions the ion exchange material ?oats
to the to
d th
.d l I .t] d
f
b l
P an
ares} ua Pup 1.5 W1 1. raw]? mm c OW‘
mo.
a
.
b R h
y
t
Th
d H
0 m an
_ aas‘
was as follows‘
.
Til
’ e g
d
th t
M
’r 3 d1. 0 ag a1 .
11°
n ysls 0
d
f thi
s r
thn 55
68in
1n the vessel causes the ion exchange material in of
suspen
I
SlOIl in the removed fraction to ?ow up a conduit formed
TABLE H
60
Tyler screen mesh:
Percent by weight retained
+10 __________________________________ __ Nil
—-l0+l6
—16+20
_____________________________ __
—20+30 _
___
~30 _________________________________ __
3. The process claimed in clalrn 2 in which the vessel
at the top of the separator.
4. The process claimed in claim 3 in which the ?ow
of ion exchange material is assisted by a pump.
5. The process claimed in claim 3 in which the ?ow of
11
ion exchange material is assisted by injecting gas into the
76
conduit.
11 65
6. The process claimed in claim 1 in which the speci?c
2
gravity of the ion exchange material is between 1.1 and
1.2 and in which the speci?c gravity of the pulp is between
1.4 and 1.5.
7. An ion exchange process for treating a pulp con
The resin and pulp mixture from each tank over?owed 70 sisting in ?owing a granulated ion exchange material hav
into its associated separator. As no agitation took place
ing a. speci?c gravity less than that of the pulp through
in the separators and due to the difference in speci?c
a series of alternate mixing and separating stages in
'The degree of agitation in each tank was sufficient to
keep the resin homogeneously mixed with the pulp.
gravity between the resin beads and the pulp, the resin
counter-current wtih one another, so that the material -
collected near the extremity of the resin withdrawal pipe.
and the pulp become mixed in the mixing stages, the mix
. Su?icient air was admitted to act as an airlift to lift this 75 tures being allowed to separate into fractions in the sep
3,062,738
5
arating stages, and including the steps of removing the
lighter fraction containing the ion exchange material of
a separated mixture in each separating stage and adding
6
111. The process claimed in claim 9 in which the speci?c
gravity of the ion exchange material is between 1.1 and
1.2 and the speci?c gravity of the pulp is between 1.4
and 1.5.
.
it to the next ‘but one mixing stage in the direction of
5
?ow of the pulp.
References Cited in the ?le of this patent
8. The process claimed in claim 7 in which a pulp hav
ing a speci?c gravity of between 1.4 and 1.5 is treated
UNITED STATES PATENTS
with a granular ion exchange material having a speci?c
., gravity of between 1.1 and 1.2.
2,742,381
9. An ion exchange process consisting in mixing a pulp 10
with an ion exchange material having a speci?c gravity
less than that of the pulp, ?owing the mixture through
an elongated, inclined conduit under quiescent condi
Weiss et a1. __________ _._ Apr. 17, 1956
FOREIGN PATENTS
780,406
Great Britain __________ __ July 31, 1957
OTHER REFERENCES
Chemical Week, 80, #13, pages 73-79, Mar. 30, 1957.
top end of the conduit, withdrawing the ?oating ion ex 15
Chemical and Engineering News, page 80, Sept. 9,
change material at the top of the conduit and removing
1957.
.
pulp at the lower end of the conduit.
Davis et al.: Chem. Eng. Progress, April 1954, pages
10. The process claimed in claim 9 in which the pulp
188—197.
and ion exchange material are mixed vby air injection.
tions to cause the ion exchange material to ?oat to the
Документ
Категория
Без категории
Просмотров
0
Размер файла
464 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа