-United States Patent [19]
Goens et al.
[11] 3,972,795
[45] Aug. 3, 1976
[56] References Cited
UNITED STATES PATENTS
756,328 4/1904 Christy 204/275 X
[54] AXIAL FLOW ELECTROLYTIC CELL
[75] Inventors: Duane N. Goens, Golden, Colo.;
James L. Lake, Lakewood, Ohio
[73]
[22]
[21 ]
[52]
[51 ]
[58]
Assignee: Hazen Research, Inc., Golden, Colo.
Filed: Sept. 11, 1974
Appl. No.: 505,029
U.S. Cl•................................ 204/269; 204/270;
. 204/275; 204/284
Int. CI,2 C25C 3/08; C25e 7/00
Field of Search ..; 204/267,269,275,284,
204/290 F, 149, 152, 153,278,270
3,701,724 10/1972 Entwisle et al... 204/290F
3,778,307 12/1973 Beer 204/290 F X
Primary Examiner-John H. Mack
Assistant Examiner-A. C. Prescott
Attorney, Agent, or Firm-Sheridan, Ross & Fields
[57] ABSTRACT
There is provided a membrane-free axial flow electrolytic
cell in which the anodes and cathodes are perforated
and lie transversely of a conduit through which
an ion containing and conducting medium is pumped.
This device is especially useful in the electrolytic recovery
of metal values from acid leach solutions from
low grade ores, e.g., copper, and for the carrying out
of electrochemical reactions such as the production of
sodium hypochlorite or sodium chlorate from NaCl.
16 Claims, 8 Drawing Figures
10
o
>-I)
N
en g-
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~
I-'
..w.
\0
-.J
..N.
-.J
\0
Ul
Fig_2
42 11111' 1m ~.
.CI.:l
~
!a (D
/0 IIII 'rmlI~1 -r /6'1-'·,'<~9d\ :=1
f""t-
>c::
<!Cl
w
I-'
\0
-..,J
0\
38
40
50~
52 56
Fig_4
66
Fig_l
Fig_3
24
26~;llliLlcOC rflI rBl ~~
24U ~1;lrl ~
QJ.1,llltf II Jj CQ'J lf1l .
u.s. Patent Aug. 3, 1976 Sheet 2 of 2 3,972,795
..J"
~
",.
l/
~
~,
~
10.0
~8.0
:.J g
-6.0
W~
~4.0
o
>
..J2.0
..J
W
U
4.0 0 50 100. 150 200 250 300
CURRENT DENSITY I
ASF
Fig_6
2.0 3.0
COPPER CONC.,
gIL
Fig_5
1.0
\;50 ASF 100 ASF ....200 ASF
\ I,:" \ - - -
IV ~ ~ ....
If , fj"
J b ;y " I J V
QIf J / Cu S04 - VARIED
P V V H2S04 -5 gil
Fe2 (S04)3 - 0 -5 gil
0 / V FLOW - 60 ft Imin.
'"y
,
o
100
-0
~80
i:>
Z
WSO
U
lL.
!t40
IZ
w20
0.::
0.::
::::> u
/4
TO LEACH
5
CURRENT
DENSITY-IOOASF
v Cu CONC. giL
,15-.20
5
0 --....
" 5 I
~
2
~o
-2 >UZ
~I
U
LL Itl
IZ
W
0.::
0.:: a o 20 40 60 80 100
LfNEAR VELOCITY,
ft Imin.
----+""'-(-)
(+)---+---
Fig_7 /2
STORAGE
VESSEL
PUMP
FROM
LEACH
1
3,972,795
2
AXIAL FLOW ELECTROLYTIC CELL BRIEF STATEMENT OF THE INVENTION
Briefly stated, the present invention is in an axial flow
BACKGROUND OF THE INVENTION AND PRIOR electrolytic cell which comprises in combination an
ART 5 electrically non~conductivetubular conduit having end
Electrolytic refining and recovery of metal values closures for each end of the conduit, and each of the
from leach solutions is well known. The principal activ- end closures having an opening therethrough for pasity
in this area has been, however, in the better grades sage of an ion containing and conducting medium. A
of ore. Where the primary metal to be recovered is in plurality of electrodes is provided in axially spaced
too low concentration, e.g., in the case of copper less 10 relation within the conduit and transversly disposed
than about 0.5 percent by weight, it is uneconomical to across the conduit, each of the electrodes being prorecover
the copper and such ore is frequently passed vided with macro openings extending therethrough.
over as worthless. Too much material must be handled First bus bar means are provided which electrically
connect alternate ones of the electrodes. Second bus
for current prices to justify the effort. The prior art has 15 bar means isolated from the first bus bar means also are
reported it to be all but impossible to extract the last of provided for electrically connecting the remaining
the copper electrolytically at a profit. (See U.S. Pat. electrodes. When fluid is pumped through the tubular
No. 1,195,616, Column 3, Line 28). device and the alternate electrodes are connected to
Ordinarily in electroplating by electrolysis, the manu- opposite poles of a source of direct current, rapid flow
facture of the chlorine by electrolysis, and such other 20 of the ion containing and conducting medium through
electrochemical reactions it is desirable to have maxi- the apparatus with minimum pressure drop may be
mum current density for the most rapid exchange of achieved and quite surprisingly, in such an arrangeelectrons
and hence electrochemical reaction. How- ment the current drain is most heavy in the initial porever,
the intensity of the current used or the current tion of the apparatus where the concentration of the
density is directly proportional to the concentration of, 25 desired ion, for example copper ion, is found, and gradfor
example, the metal being recovered from the ion ually decreases in the direction of flow of the ion concontaining
and conducting medium. As the ion con- taining and conducting medium as the concentration of
taining and conducting medium is depleted of the metal the desired ion decreases. It is believed that this phebeing
plated, for example, the efficiency of the cell nomenon is observed because the ion containing and
decreases rapidly. It has, therefore, been common 30 conducting medium is moved through all of the e1ecpractice
to use a given cell at maximum current density trodes alternating between positively and negatively
until a predetermined concentration of the desired ion charged electrodes in the course of its axial movement.
has been reached or efficiency has materially de- The flow is essentially turbulent flow in order to minicreased,
and then transfer the partially spent ion con- mize the effects of build up of ion concentration adjataining
and conducting medium to another ceIl where a 35 cent the electrode surfaces which concentrations tend
lower current density is being applied. Alternatively, to reduce the efficiency of the electrode. Because of
the current density in a cell such as that first described the parallel arrangement of the alternating positive and
may be manually adjusted as the desired metal ion is negatively charged electrodes, the control of the voltdepleted
from the ion containing and conducting me- age at which the desired plate reaction occurs is reladium
so as to correspond more nearly to the strength of 40 tively simple, and the current drain along the circuit
that medium. This is impractical. Thus, it has been becomes a function of the concentration of the desired
common practice to utilize a series of individual cells ion in the ion containing and conducting medium.
using decreasing current densities in succeeding cells In a more specific embodiment of this invention,
until the ion being recovered is finally depleted at the there is provided an axial flow electrolytic cell in which
end of the series of cells. 45 an ion containing and conducting medium flows axially
The present invention solves these problems by pro- through perforated electrodes of alternating polarity at
viding an apparatus in which the current drain auto- flow rates normally greater than 5 ft./minute and which
matically decreases in an axial direction as the concen- comprises in combination a rigid electrically noncontration
of the desired ion in the ion containing and ducting tube of uniform circular cross section. Electri50
cally nonconductive end closures are provided for each conducting medium also decreases. In like manner end of the tube, each of the enclosures having an openwhere
an electrochemical reaction is being carried out ing therethrough preferably tapped to receive a suitas
the concentration of a desired product increases, able conduit for the passage of an ion containing and
and the demand for conversion of the raw material conducting medium into and out of the ceIl respecdecreases,
also the current drain will automatically 55 tively. A plurality of circular expanded metal elecdecrease.
This improves the efficiency of the overaIl trodes of one sign is provided in axially spaced relation
cell. to each other and circumferentiaIly engaging the side-
Also, the a~ial flow type ceIl of the present in~ention waIls of the tube, each of the electrodes of the said one
enables effiCient recovery of low concentratIOns of sign having terminal means radially extending theredesired
ions from the ion containing and conducting 60 from and projecting through the wall of the conduit. A
medium which concentrations were prior to this time first bus bar externaIly of the tube and electrically conthought
to be uneconomicaIly recoverable. The im- necting all of the terminal means of the one sign is
proved ceIls of the present invention have the advan- provided. Also, a plurality of circular expanded metal
tage in that a single ceIl utilizing an axial flow principle electrodes of the opposite signs are provided in axially
for the ion containing and conducting medium replaces 65 spaced and alternating relation with the electrodes of
the multiple cell procedure previously described, as the one sign. These electrodes of the opposite sign also
weIl as those where the electrolyte foIlowed a tortuous circumferentiaIlY' engage the sidewall of the tube and
path between and around a stack of electrodes. have terminal means radiaIly extending therefrom and
3,972,795
4
electrodes. There is thus provided a tubular conduit 10
formed of an electrically nonconducting material. Any
suitable material may be used for this purpose, the most
economical being a plastic material such as polyethylene,
polypropylene, polystyrene, polymethylmethacrylate,
or the like. Such resinous material may be
transparent, transluscent or opaque so long as it serves
as an electrical insulator. The conduit 10 may be of any
suitable length and may under certain circumstances be
flexible or formed in a spiral or circuitous path for the
purpose of conserving space. For most purposes, a
straight-through tubular member will be found satisfactory.
The tubular conduit lOis provided with end closures
12 and 14, and each having openings such as the opening
16 extending through the end closure 12. This is
conveniently internally threaded to receive a conduit
for passage of fluid through the end closure 12. A similar
drilled and tapped opening is conveniently provided
in the end closure 14. Enclosure 12 is provided with a
circular groove 18 dimensioned to receive one end of
the conduit 10. A suitable compressible gasket 20 or
seal 20 may be provided. As best shown in FIG. 2 the
end closure 12 is also suitably drilled preferably at 90°
intervals as at 22 to receive compression rods 24 which
are conveniently threaded at each end and provide in
combination with nuts 26 and washers 28 a suitable
means for compressively retaining the end closures 12
and 14 in sealing engagement with the extremities of
the conduit 10.
As previously indicated, the cell is provided with a
plurality of transversely disposed electrodes. As shown
in FIG. 1, a series of first electrodes 30 are provided at
uniformly spaced intervals, these electrodes being of
35 circular configuration as best shown in FIGS. 3 and 4
and desirably formed of expanded titanium metal. The
periphery of the electrodes 30 closely approximates the
internal periphery of the conduit 10, there usually
being provided a slight clearance 32 for ease of assem-
40 bly. Each of the electrodes 30 is provided with a radially
projecting terminal member 34 which extends
through the sidewall ofthe conduit 10 in a suitable bore
36. The outer or distal end of the terminal 34 is conveniently
threaded as at 38 to receive a nut 40 useful for
45 both the purposes of retaining the electrode 30 in
proper position within the cell body 10 and for providing
electrical contact with a bus bar 42. The clearance
between the opening 36 and the terminal 34 is conveniently
filled with a hardenable sealant 44 (FIG. 3). In
50 the embodiment shown in FIG. 1, seven electrodes 30
are provided. Depending upon the manner in which the
electrodes are ultimately connected, the electrodes 30
may be either cathodes or anodes. In like manner there
are provided in alternating relationship with the elec-
55 trodes 30 a plurality of second electrodes 46. The electrodes
46 are of similar design, construction and dimension
to the electrodes 30. Accordingly, the electrodes
46 are provided with radially outwardly extending
terminals 48 extending through bores 50 in the
60 sidewall of the conduit 10. The distal ends of the terminals
48 are threaded as at 52 to receive retaining nuts
54 for the purpose of securing the electrodes 46 to a
bus bar 56 of opposite polarity to the bus bar 42 when
the cell is connected in an electric circuit not shown.
65 As in the case of the first electrodes 30, there is provided
a plurality of electrodes 46 in alternating relation
with the electrodes 30. In the embodiment shown six
electrodes 46 are provided. The total number of re-
3
projecting through the wall of the tube. A second bus
bar electrically isolated from the first bus bar and lying
externally of the tube electrically connects all of the
terminal means of the opposite sign.
In the further discussion of the present invention 5
reference will be had to an "ion containing and conductingmedium".
This is commonly and perhaps inaccurately
frequently referred to as an electrolyte. It is
believed to be more correctly defined as a medium
which conducts ions or allows for ion transport and a 10
medium which also contains such ions. For example,
water, neglecting for a moment the slight degree of
dissociation of pure water, is an ion conducting medium.
Until it contains ions of a desired nature, e.g.,
copper ions, it is not an ion containing and conducting 15
medium.
Reference will also be had to the electrodes as being
"macro" porous. This is to distinguish the electrodes of
the present invention from the micro porous electrodes
which are formed from pressed graphite or from pow- 20
dered sintered metal and in which the pores are extremely
fine. In the present invention the electrodes are
conveniently formed of expanded metal, e.g. titanium
metal, in which the minor dimension is approximately
3/16 of an inch and the major dimension is approxi- 25
mately 5/16 of an inch. The effective surface area of
such an expanded metal electrode is nearly 80 percent
of a solid plate and yet it has an open area of at least
50%. Any other perforated means may be used, e.g.
drilled or punched openings through the electrode 30
which will provide a large amount of electrode surface
with minimum resistance to the flow of liquid therethrough.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention may be better understood by
having reference to the annexed drawings wherein:
FIG. 1 is a side elevation, partially cut away, of an
axial flow cell in accordance with the present invention.
FIG, 2 is a top plan view of the cell shown in FIG. 1,
and showing the bus bar connectors radially extending
from either side thereof.
FIG. 3 is a fragmentary cross sectional view of the
apparatus shown in FIG. 1 as it appears in the plane
indicated by the line 3-3 in FIG. 1.
FIG. 4 is across sectional view of the apparatus
shown in FIG. 1 as it appears in the plane indicated by
the line 4-4 in FIG. 1 and showing a circular expanded
metal electrode circumferentially engaging the sidewalls
of the conduit.
FIG. 5 is a graph showing at different current densities
the relationship between current efficiency and the
concentration of copper at very low concentrations of
the metal.
FIG. 6 is a graph showing the relationship of cell
voltage to current density.
FIG. 7 is a graph showing the effect of flow rate on
current efficiency at very low copper concentration.
FIG. 8 is a schematic diagram of a copper recovery
system utilizing an axial flow electrolytic cell in accordance
with this invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring now more particularly to FIGS. 1 and 2,
there is here shown a preferred embodiment of the
present invention, FIG. 1 being partially cut away to
show the internal construction and arrangement of the
3,972,795
5 6
spectiveelectrodes is immaterial insofar as the present sulfuric acid and in the cases indicated with sodium
cell structure is concerned, but seven first electrodes sulfate. This solution was pumped through the appara-
30 and six second electrodes 46 has been found satis- tus such as shown in the annexed drawings, the temperfactory.
ature of the ion containing and conducting medium
In order to maint';lin the electrodes 30 in suitably 5 noted, the amperage and the time over which the curspaced
relationship to the electrodes 46 of opposite rent was applied. The voltage was determined and reelectrical
charge there is provided a plurality of spacing corded.
collars 58 of similar axial dimension and dimensioned In the course of the electrolytic reaction, using copfor
close sliding fit within the internal diameter of the per sulfate as the ion yielding material, copper would
conduit 10. The spacing collars 58 are also formed of a lO be deposited from the cathode as small particles of
nonconducting material which may be the same as or copper powder, a substantial portion of which remains
different from the nonconducting material used in fab- suspended in the ion containing and conducting mericating
the conduit 10. dium as free metal. Some of the copper, however, ad-
It should be noted that in the preferred embodiment hered to the electrode or became trapped within the
the spacing between the electrodes of opposite charge, 15 structure. In order to remove this electrode deposited
e.g. electrodes 30 and 46, is uniform throughout the copper, a solution of NH4C03.NH4 was circulated
axial length of the cell. Prior art structures have sought through the cell to dissolve metallic copper. Since this
to improve cell efficiency by varying the distance be- copper has also been recovered· by electrochemical
tween the electrodes in order to accommodate various 20 reaction from the solution, it was determined and
concentrations of the desired ion. This is not necessary added to the quantity of metallic copper separated
in the present structure and therefore renders more from the spent ion containing and conducting medium.
simple and less expensive the construction of the de- The following table tabulates the results of tests carvice.
ried out under varying conditions and with varying
In like manner the terminals 48 are suitably sealed 25 amounts of copper in the ion containing and conductagainst
escape of liquid through the bores 50. The jng medium at the start. The "total Cu" is the summaterminals
such as terminals 34, are suitably secured to tion of the amount of copper powder collected in grams
the expanded metal electrodes, e.g. electrodes 30, by and the amount of copper recovered from the
welding or soldering as at 60 in order to ensure ade- NH4C03.NH4 solution in grams.
quate electrical connection. As indicated above, alter- 30 The axial flow cell used in the following tests innate
electrodes 30 and 46 extend through opposite
sides of the cell defined by conduit 10. The terminals cluded nine cathode plates and eight anode plates. The
34 and 48 also extend through bores 62 and 64 in bus cell body was formed of 2 inch internal diameter by 1fs
bars 42 and 56, respectively. The bus bars 42 and 56 in inch wall Plexiglass tube with slots milled for the electhe
embodiment shown in the drawings, lie along oppo- trode peripheries and holes drilled for the terminals. 35
site sides of the conduit 10 and are out of electrical The end caps were formed of V2 inch Plexiglass with an
contact with each other. These are conveniently ce- annular groove for the end of the conduit and sealing
mented as by hardening cement strips 66 and 68 re- ring and drilled and tapped for Y:! inch pipe in the censpectively
to the external surface of the conduit 10. ter thereof. The bus bars were formed of copper and
The laterally extending portions of the bus bars 42 40 suitably drilled to receive the electrode terminals. The
and 56 may be secured by any suitable means not anodes were formed of expanded titanium. The cathshown
to the opposite poles of a source of direct cur- odes were formed of perforated titanium punched and
rent. ground to the proper size and having titanium termi-
In operation, an ion containing and conducting mate- nals. The cell was approximately 10 inches between
rial containing for example copper ions in solution, is 45 end caps, and the electrodes were spaced V2 inch apart
introduced to the cell through the end plate 12 and a alternating cathode-anode-cathode, etc. and terminatsuitable
conduit threadedly engaged in the threaded ing with a cathode.
bore 16. This material is pumped quite rapidly (at ve- The present cell has also been used to recover copper
locities normally greater than 5 ft./minute) in an axial from aqueous acid leach solutions of copper ore condirection
through the perforated electrodes 30 and 46. 50 taining copper in very low concentration, e.g. from
Where the concentration of the copper ion is at its about 0.1 to about 2 grams per liter. In such a case, the
highest adjacent the end cap 12, the demand for elec- ore which is at approximately 325 mesh is slurried with
trical current generated by the electrodes 30 and 46 the acid leach composition, and the slurry pumped
first encountered will be at the highest. As the ion through the axial flow cell of the present invention.
containing and conducting medium passes through the 55 Under suitable current density conditions such as those
cell and the copper ion concentration is decreased by set forth in the following table, dendrites of copper
the formation of suspended particles of metallic cop- metal will be formed on the cathodes. These can easily
per, the current demand called for by adjacent elec- be dislodged and recovered.
trodes 30 and 46 also decreases. At the lower end of In order to facilitate recovery of material such as
the cell as shown in FIG. 1 approaching the end plate 60 copper dendrites adhering to the electrodes, it is con-
14, the concentration of the copper ion and the ion templated that the cell shall be divisible into halves and
containing and conducting medium is virtually zero, held together by suitable clamps and seals. When it is
depending upon the length of the cell and the flow rate. desired, then, to clean the electrodes, the half shells
The following data and specific examples show re- may be separated, and the electrodes exposed for results
obtained with an embodiment of the invention as 65 moval of the deposited dendrites of metal. The elecshown
in the annexed drawings and using various ion trode spacing ranges from 0.25 to 1 inch and the voltcontaining
and conducting media. The test .solutions age at which the cell is operated is generally from about
were prepared by dissolving copper in water along with 2 to about 10 volts.
3,972,795
7 8
TABLE I
RUN ION CONTAINING & COND. MEDIUM COMPo FLOW RATE C.D. AMP. TOTAL Cu CATHODE RISE MAT.
NO. H2SO, Fe Na,SO, Cu gm/I gpm asf HRS. gms. EFF TEMP BAL. '7c
Start Finish rk 0c. *
I 5 0 15 0.1'15 0.170 4.6 100 50 1.6 2.6 2 75.6
2 5 0 15 0.1'15 0.141 6.'1 100 50 4.7 8.1 2 87.8
3 5 0 15 0.1 '12 0.130 '1.2 100 50 6.3 10.6 101.0
4 5 0 15 0.2'12 0.085 9.2 200 170 21.5 10.7 8.5 103.9
5 5 0 15 0.288 0.157 '1.2 ;WO 85 '1.8 9.8 5.5 75.0
6 5 0 15 0.2'16 0.073 '1.2 50 47:5 1'1.7 35 1.0 88.5
7 5 0 15 0.2'14 0.235 '1.2 100 25 4.6 16 77.2
8 5 5 0 0.291 0.117 '1.2 50 47.5 14.7 27 0 '18.9
'I 5 0 15 0.278 0.053 '1.2 50 50 22.9 45 101.9"
10 5 5 0 1.890 1.430 '1.2 100 41.7 52.7 '10 2.0 114.6
II 5 0 I.R'IO 1.510 '1.2 200 100 34.6 70 '11.0
12 5 0 0.96'1 0.750 '1.2 50 21 23.7 '16 100.7
13 5 0 1.120 0.921 '1.2 100 21 16.3 66 1.0 82.1
14 0 15 0.'150 0.789 '1.2 100 21 15.7 63.5 1.0 97.7
*Matcrial Balancc '7c = 100 X gms Cu Powdcr + .gms Cu leached
Total Cu In soln.
**Rased on eu Powder recovered alone
In conventional copper electrowinning current densities
are normally 15-25 ampereslsq ft at copper concentrations
of 30-45 gil. The ratio of ASF to Cu is
25 limited to 0.5 to 1.0 over a wide range of copper concentrations.
Techniques such as directed flow of electrolyte, air
sparging, ultrasonic agitation, and mechanical wiping
have all been used to increase the copper mass trans30
port and thereby permit higher current densities. ASF:
Cu ratios as high as 2-7 have been achieved.
Copper powder has been produced in the axial flow
cell at ASF ratios in the range of 50-70. This ratio is of
significance in the field of copper electrowinning. As
35 will be noted in the following Table II in the electrowinning
of conventional copper per liter, the normal ASFICu
ratio is 0.5 to I. New techniques have improved the
ratio by a factor of up to 7. In the case of the very low
concentrations we are able to use, we are able to realize
ratios of up to 100 times those conventionally obtained
and from 7 to 10 times those of improved techniques.
TABLE II
25 - 400 ASF
20 - 30°C.
4.6 to '1.2 gal./min.
30 to 50 ft./min.
DSA
Titanium. or stainlcss stccl
0.1 to 2.0 gms/liter as Cu
5 gms/liter
o to 15 gms/liter
5 gms/liter
to one liter
CuSO,
H2S04 Na,SO,
Fe,(SO,h
Water
Anodcs
Cathodc
Current density
Temperature
Flow rate
Typical conditions for electrolysis in the specific
apparatus above described are as follows:
A typical composition for the ion contammg and
conducting medium for recovery of copper at low concentrations
is as follows:
40
In operation, copper forms as a powder on the cell
cathodes. It sloughs off and is carried through the out-
Copper Electrolysis Conditions
Cu H,SO, Current Density
g/I gil amp/ft'
ASF/Cu
Conventional
New techniques
Axial flow
30 - 50
30 - 50
0.2-2.0
150-300
150-300
5.0
15 - 25
30 - 300
50 - 200
0.5 - 1.0
1.0 - 7.0
50 - 70
TABLE III
The axial flow cell design does not permit the convenient
installation of a membrane or diaphragm therefore
it's principal application will be in those situations
where one-compartment cells are satisfactory. There
55 are several of those applications in the minerals industry
and also in the industrial chemicals industry. These
are tabulated in Table III.
let end 14 with the copper depleted ion containing and
conducting medium and collected in a thickener (see
FIG. 8). Overflow from the thickener 11 may be recycled
or directed to the leach bed and ultimately returned
to the system for passage through the axial flow
cell 10 diagrammatically shown in FIG. 8. Oxygen gas
also disengages in the thickener and is available for
recovery.
Experimental results are tabulated in Table I above. 60 _P_r_oc_e_ss_'A_pp_l_ic_a_tio_n E_le_c_tr_o....:ly_te_Sy:....s_te_m _
FIG. 5 illustrates the inter-relationship of copper con- Copper powder recovery Heap or dump leach liquors
centration, current density and current efficiency. In from copper oxide. Electrolyte
strip liquors.
calculating the copper concentration for plotting the Slurry electrolysis of mixed
points in FIG. 5, the average between the inlet copper oxide and sulfide copper.
concentrati.on and the out et cioncent'ration was used. 65 Electrooxidation Ocorveesrylurorfysailnvder,brginoled.fomr orley--
FIG. 6 shows the current density-cell voltage relation- bdenum, rhenium. lead-zinc.
ship. The effect of flow rate on current efficiency at Hypocholn'te generat'Ion sanead wmaetreCrUtrrYe·atment.
very low copper concentrations is shown in FIG. 7. Sewage treatmen!.
3,972,795
9 10
TABLE III-continued b. electrically nonconductive end closures for each
end of said tube, each of said end closures having
Process Application Electrolyte System an opening therethrough for passage of an ion-con-
Sodium chlorate production Sodium chloride brine. taining and conducting medium;
Sodium perchlorate production Sodium chlorate brine. 5 c. a plurality of circular expanded metal electrodes of
one sign in axial spaced relation and circumferentially
engaging the side wall ofsaid tube, each of
What is claimed is: said electrodes of said one sign having terminal
1. An axial flow electrolytic cell comprising in combi- means of the one sign radially extending therefrom
nation: 10 and projecting through the wall of said conduit;
a. anelectrically nonconductive completely closed d. a first bus bar external of said tube and electrically
conduit; connecting all of said terminal means of the one
b. end closures for each end of said conduit each of sign;
said end closures having an opening therethrough e. a plurality of circular expanded metal electrodes of
for passage of an ion-containing and conducting 15 the opposite sign in axially spaced and alternating
medium; relation with said electrodes of the one sign, said
c. a plurality of electrodes in axially spaced relation electrodes of the opposite sign also circumferenand
transversely disposed across said tubular con- tially engaging the side wall of said tube and having
duit, each of said electrodes having macro open- terminal means of the opposite sign radially exings
extending therethrough; 20 tending therefrom and projecting through the wall
d. first bus bar means electrically connecting alter- of said tube; and
nate ones of said electrodes; and f. a second bus bar electrically isolated from said first
e. second bus bar means isolated from said first bus bus bar, external of said tube and electrically conbar
means electrically connecting the remaining necting all of said terminal means of said opposite
electrodes. 25 sign.
2. An axial flow electrolytic cell in accordance with 14. An axial flow electrolytic cell in which high curclaim
1 in which the conduit is a rigid straight tube. rent densities can be obtained with low metal concen-
3. An axial flow electrolytic cell in accordance with tration electrolytes, comprising: a closed channel of
claim 2 in which the tubular conduit has a circular dielectric material forming the cell body, sealing means
cross section. 30 for sealing the ends of said closed channel to provide a
4. An axial flow electrolytic cell in accordance with completely sealed cell body, a liquid inlet channel in
claim 1 in which the end closures are formed of electri- one of said sealing means and a liquid outlet channel in
cally nonconductivematerial. the other of said sealing means, perforate axially-
5. An axial flow electrolytic cell in accordance with spaced electrodes in said channel supported in an oriclaim
1 in which the electrodes are in substantial pe- 35 entation substantially perpendicular to the long axis of
ripheral engagement with the side walls ofsaid conduit. said chennel, said electrodes being dimensioned so that
6. An axial flow electrolytic cell in accordance with their peripheries extend substantially to the internal
claim 1 in which the electrodes are axialIy spaced at periphery of said closed channel, means for spacing
regular intervals. said electrodes, an electrical terminal for each elec-
7. An axial flow electrolytic cell in accordance with 40 trode connected to the electrode and extending
claim 1 in which the electrodes are nonconsumable. through the wall of said channel, the openings in the
8. An axial flow electrolytic cell in accordance with wall of said closed channel through which said termiclaim
7 in which the electrodes are expanded metal nals extend being sealed against leakage of fluids, first
plates. and second spaced-apart longitudinal bus bars lying
9. An axial flow electrolytic cell in accordance with 45 along the outside of said closed channel, the electrical
claim 8 in which the electrodes are of titanium metal. terminals for alternate electrodes being connected to
10. An axial flow electrolytic cell in accordance with said first bus bar and the electrical terminals of the
claim 5 in which the electrodes are each provided with remaining electrodes being connected to said second
terminal means projecting therefrom for extension 0 bus bar, said bus bars being connected, respectively, to
through the conduit wall. 5 positive and negative sources of electricity so that alter-
11. An axial flow electrolytic celI in accordance with nate electrodes are, respectively, anodes and cathodes,
claim 1 in which the first and second bus bar means are whereby the electrolytic cell which is formed by the
each disposed externally of the tubular conduit. recited structure is completely sealed against the. es-
12. An axial flow electrolytic cell in accordance with 55 cape of liquids and gases from the cell body except at
claim 8 in which the ratio of the effective surface area the inlet and outlet channels.
of the .electrodes to the cross sectional area is at least 15. The electrolytic cell of claim 14 in which said
0.8 to l. closed channel is substantially circular and said bus
13. An axial flow electrolytic cell in which an ion- bars are substantially 1800 apart.
containing and conducting medium flows axially 60 16. The electrolytic cell of claim 14 in which said
through perforated electrodes of alternating polarity at spacing means are spacing collars of dielectric material
flow rates productive of turbulent flow and comprising betweenthe electrodes peripherially abutting the interin
combination: nal surface of said closed channel and closely abutting
a. a rigid, electrically nonconductive tube of uniform adjacent electrodes.
circular cross-section; 65 * * * * *