Note: Descriptions are shown in the official language in which they were submitted.
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~L~T~OD~ CONTAIN~R F~R ~L~CTR~LYTIC C~LLS
TECENIC~L FI~D
This invention relates to electrolytic depo~ition of metals
~rom aqueous solutions, in general and, more particularly, to an
improved electrode con~ainer or box.
ACRGROUND OF TE2 ART
The recovery of met21s such as nickel, copperl lead~ zinc
and silver by an aqueous electrolytic process has been successfully
practiced on $he commercial scale for many years.
Reducing the process down to its barest essentials, a
cathode and anode are inserted into a suitable aqueous electrolyte
and an electrical current is pas0ed between the two. The metal to be
recovered is plated out at the cathode, while a variety of proces~es
may take place at the anode. Anode processes could be dissolution of
the anode or liberation of a gas such as oxygen or chlorine.
In some cases, it i8 necessary to separate the cathode and
anode by a membrane or diaphragm permeable to the electric current.
For example, in recovery of nickel from impure nickel anodes, a
diaphragm permeable to the electrolyte is necessary to prevent impure
electrolyte from reaching the cathode where the impurities, such as
copper, lead or ~inc could plate out and contaminate the pure nickel
plated at the cathode. The interposition of a diaphragm between anode
and cathode has co~monly been accomplished by enclosing each cathode
~ith a "cathode box" which consists of a rigid wooded frame supporting
a cloth membrane. In order to prevent back-diffusion of impure electro-
lyte into the box, a positive flow of purified electrolyte is maintained
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from the cathode compartment to the anode compartment, by holding a
positive head of electrolyte in the cathode compartment. The box
frame serves the important function of maintaining the membrane taut
to resist its tendency to bulge out towards the anode by virtue of
the electrolyte Elow.
In other cases, it may be necessary to surround both the
cathode and anode by separate diaphragms, as described in Can. Pat.
No. 463,573. The wooden electrode container described in this
aforementioned patent i5 still commonly used and a similar structure
made from polypropylene is described in Can. Pat. No. 981,212. In
both these devices, two permeable diaphragms are tautly stretched
over each face of an open rec~angular frame. The edges of each
diaphragm are forced into a continuous groove formed within each leg
of the frame. A caulking rope or rod is forced into the groove
(over the diaphragm) to ensure the integrity of the diaphragm/groove
seal and to hold the cloth taut~
This type of electrode container suffers from a number of
shortcomings. In order to secure the diaphragm within the groove,
heavy manual hammering is required. This labor intensive job is a
major cause of wear to the box and is fatiquing for the worker. ~he
need to maintain the diaphragm in tension, restricts the cloths,
which can be succes~fully caulked, to heavy cloths with a rough
finishO This e~cludes many otherwise excellent diaphragm fabrics,
such as polye~ter and polypropylene.
For such a structure made from wood, further shortcomings
are that the metal to be recovered may tend to be deposited on the
wooden frame. As the dendritic growth continues, short circuits may
develop between an adjacent cathode and anode, resulting in lower
current efficiency and damage to the diaphragm. Moreover, organic
impurities may leach from the wooden frame into the electrolyte.
Another disadvantage of the wooden frame is the amount of
labor necessary to build a box. As any one with woodworking experi-
ence knows, building a sturdy wooden frame (especially in light of
the heavy service conditions in an electrolytic facility) having
joints, requires skill and time.
3~i
A further disadvantage shared ~y wcoden containers is -that due to
their inherent buoyancy, they will -tend to floa-t in electrolyte. This m~kes
them difficult to sink in the plating cell and hold securely in position.
Accordingly, substantial means are required to immobilize the box in the tanks.
SUMM~RY OF THE INVENTICN
Accordingly, there is provided a container -for recovering metal frcm
an electrolyte, the container ccmprising two polymeric memhers, the members
forming a three sided open faced structure, a bag permeable to the electrolyte
enveloping the structure, and polymeric spreading means disposed between the
members for maintaining the bag in a taut condition about the structure.
BRIEF DESCRIPTIoN OF THE DRAWINGS
Figure 1 is an elevation of the invention.
Figure 2 is an elevation of a component of the invention.
Figure 3 is a top plan view of a component of the invention.
Figure 4 is a view of Figure 3 tc~ken along lines 4 4.
Figure 5 is a partial perspective view of the invention.
PREFERRED MODE FOR C~RP~YING OUT THE INV~rICN
Referring to Figure 1, there is shown an electrode container or
bo~ 10. Although cathQdes are more co~monly disposed within such boxes, it
should be understood the instant box 10 may be utilized for anodes as well.
The box 10 includes a permeable bag 12 tightly suspended over a
frc~me 14. The frame consists of two, hinged, polymeric me~bers 16A and 16B.
The members 15A and 16B form a three-sided open support structure 32. It is
preferred to utilize a polymeric hinge 18. The members 16A and 16B rotate
through an arc A.
A spreader bar 20 exerts a tensile force on the tw~ m~mbers 16A and
16B to provide tautness to the bag 12. The b~r includes two nubs 22A and 22B
that fit into channels 24A and 24B
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respectively. The bar 20 further includes a plurality of grooves 26
formed therein. A fastener, such as string 28, circumscribing the
upper edge of the bag 12 via bag loops 34 and serpentinely threaded
through the grooves 26, is utilized to securely hang the bag 12 from
the bar 20 and prevent it from dislodging from the box 10. The bar
20 includes a pair of extensions 30A and 30B for hanging the box 10
in a complçmentary groove ~ormed within an electrolytic tank (not
shown). See Figures 2, 3 and 4.
Referring to Figure 5~ the string 28 may be affixed to the
bag 12 by a plurality of loops 34. The loops 3~ are registered
against a hem 38 ~hich circumscribes the upper edge of the bag 1~.
Both the loops 34 and the hem 38 may be affixed to the bag 12 by
suitable stitching 36.
The invention and the`manner of applying it may be bPtter
understood by a brief discussion of the principles underlying the
invention.
The b~x 10 is an apparatus ~or containing an electrode and
separating purified electrolyte from impure electrolyte. The
electrode is suspended within the box 10 by kno~n means. Purified
electrolyte is fed into the box 10 to maintain a slightly positive
head over the impure electrolyte circulating outside the box 10
within the tank (not shown).
It is pre~erred to utilize reaction injection molded high
modulus polyurethane for the members 16~ and 16~ and the bar 20.
For added strength and durability, the members 16A and 16B and bar
20 may be reinforced with a fiberglass bar extending therein.
Polystyrene and polypropylene have been employed in other prototypes
but it was found through experience that the dimensional stability
~warping and creep) and strength of the box 10 did not meet
expectations. Polyurethane appears to deliver good service and can
be readily handled on a mass production basis while simultaneously
exhibiting good physical properties. The dense polymer prevents the
bo~ 10 from floating within the tank. Accordingly, the prior art
technique of securing the box 10 to the tank has been obviated.
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Since the bag 12 no longer has to ~e made from a rough
material, it may be made from commonly available slick materials
such as polyester or polypropylene since the hammering and caulking
regui~emants have been eliminated. Moreover, since the members 16A
and 16B and the bar 20 may be easily and quickly molded, the labor
intensive prior art te~hnique of making the boxes 10 from wood has
been also eliminated.
A method of making the box 10 is now quickly described.
The two ~ember3 16A and 16B are joined together by the hinge 18 in a
known manner. The box 10 is hinged so that the bag 12 may be
expeditiously installed over the box 10. The bag 12 is simply
slipped over the box 10. After it has been positioned properly, a
stretching tool (not shown) expands against ~he t~ members 16~ and
16B, forcing the members 16A and 16s apart thereby stretching ~he
bag 12. While the members are forcibly separated making the bag 12
taut over the hox 10, the spreader bar 20 is inserted into the t~o
channels 24A and 24B to maintain the tensile force on the me~bers
16~ and 16B and the bay 12. The tool is then released and removed.
The string 28 is then looped through the grooves 26 to ensure the
registration of the bag 12 against thè members 16A and 16B.
The disclosed invention overcomes the shortcomings of the
prior art. The metal to be recovered will not grow on the plastic
members and spreader bar. Organic impurities do not leach from the
polymeric bo~ as they will from a wooden box. ~oreover, the
polymeric box will not float in the electrolyte nor will it require
extensive labor for fabrication.
While in accordance with the provisions of the statute,
there areillustrated and described herein specific embodiments of
the invention. Those skilled in the art will understand that
changes may be made in the form of the invention covered by the
claims and that certain features of the invention may sometimes be
used to advantage without a corresponding use of the other features~
