AU781202B2 - System for attaching diaphragm - Google Patents

System for attaching diaphragm Download PDF

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Publication number
AU781202B2
AU781202B2 AU24895/01A AU2489501A AU781202B2 AU 781202 B2 AU781202 B2 AU 781202B2 AU 24895/01 A AU24895/01 A AU 24895/01A AU 2489501 A AU2489501 A AU 2489501A AU 781202 B2 AU781202 B2 AU 781202B2
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AU
Australia
Prior art keywords
diaphragm
fastening
frame
fastening strip
strip
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
AU24895/01A
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AU2489501A (en
Inventor
Matti Servo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Valmet Fabrics Oy
Original Assignee
Tamfelt Oy AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from FI20000531A external-priority patent/FI109365B/en
Application filed by Tamfelt Oy AB filed Critical Tamfelt Oy AB
Publication of AU2489501A publication Critical patent/AU2489501A/en
Application granted granted Critical
Publication of AU781202B2 publication Critical patent/AU781202B2/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25CPROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/04Diaphragms; Spacing elements

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

Description

AUSTRALIA
Patents Act 1990 Tamfelt Oyj Abp
ORIGINAL
COMPLETE SPECIFICATION STANDARD PATENT Invention Title: System for attaching diaphragm The following statement is a full description of this invention including the best method of performing it known to us:- 1/1 The invention relates to a method of attaching a diaphragm to be used in an electrolysis process to a frame, in which method a diaphragm sheet corresponding to the size of the frame is cut from an electrolytic fabric, the sheet being attached from its edges to a fastening groove of the frame by means of a fastening strip, whereby the diaphragm and the frame enclose a space where an electrode can be arranged.
The invention also relates to a diaphragm element comprising a sheet-like diaphragm formed of an electrolytic fabric.
The invention further relates to a fastening strip which is intended for attaching a diaphragm to a frame.
Electrolysis is known to be used as one stage in the manufacturing process of metal. Electrolysis takes place in a basin where an electrolyte as well as positive and negative electrodes, i.e. anodes and cathodes, are arranged. Depending on the occasion, either cathodes or anodes are arranged inside a frame provided with a porous diaphragm. Conventionally, a bag sewn from an electrolytic fabric is arranged around 15 a U-shaped frame. The fastening of bags, however, has proved to be difficult, due to varying dimensions of bags and frames. An untight bag will bulge, come into contact S°with the electrodes and be damaged. Further, an untight diaphragm reduces the power o of the electrolysis process and impairs the quality of the end product. Moreover, to sew the bags and fix them to their places is cumbersome. Another problem is that although i 20 only one side of the bag were damaged, the entire bag has to be replaced. A lot of electrolytic fabric will thus be wasted.
In US publication 4,455,209, a diaphragm is attached to a frame by means of a rubber strip. In this case, both sides of the frame are provided with fastening grooves to which the edges of diaphragm sheets are tensioned by means of the rubber strips to 25 be pressed into the grooves. A disadvantage of this solution is that it is difficult to attach the diaphragm tightly, because the diaphragm becomes pleated at the corners of the frame, i.e. where the fastening groove curves between the vertical and the horizontal bar of the frame. Furthermore, it is slow and difficult to attach the diaphragm in this way.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
According to a first aspect the present invention provides a method of attaching a diaphragm to be used in an electrolysis process to a frame, in which method a diaphragm sheet corresponding to the size of the frame is cut from an electrolytic fabric, the sheet being attached from its edges to a fastening groove of the frame by means of a fastening strip, whereby the diaphragm and the frame enclose a space where an electrode can be arranged, characterized in that a flank surface of the diaphragm is tightly fixed to the fastening strip in a separate stage before mounting it to the frame, and that a diaphragm element formed in this way is attached to the frame by pressing a fastening element of the fastening strip into the fastening groove.
According to a second aspect the present invention provides a diaphragm element comprising a sheet-like diaphragm formed of an electrolytic fabric, characterized in that the diaphragm sheet is tightly attached to a fastening strip and that the fastening strip comprises a fastening element for attaching the diaphragm element to a fastening groove of a frame.
According to a third aspect the present invention provides a fastening strip i 20 which is intended for attaching a diaphragm to a frame, characterized in that the fastening strip comprises a fastening element for attaching fastening strip to a fastening groove of the frame and that the fastening strip has a section transversal to the fastening element, intended for being attached to a flank surface of the diaphragm.
Preferred embodiments of the present invention may provide a new kind of an 25 arrangement for attaching a diaphragm used in an electrolysis process.
In preferred embodiments of the invention a diaphragm sheet of the size of the respective frame is cut from an electrolytic fabric, the sheet being tightly attached to a fastening strip before mounting it to the frame. Thereafter, the diaphragm element provided in this manner is attached as one piece by means of fastening elements of the fastening strip to a fastening groove formed in the frame. This solution provides the advantage that, compared with using a separate sheet and a fastening strip, it is considerably faster to handle the diaphragm element and attach it to the frame.
Furthermore, the joint between the diaphragm and the frame is tight, because the diaphragm fabric is not pleated at the corners of the frame. The fastening strip bent in advance into the form of the fastening groove of the frame is attached to a flank surface of the diaphragm, whereby the entire diaphragm is planar and the joint is tight.
In another preferred embodiment of the invention the fastening strip comprises a broadening transversal to the fastening element, the broadening being at least as wide as a section between the inner edge of the frame and the fastening groove. This solution provides the advantage that the broadening serves as a fastening surface between the diaphragm and the fastening strip, whereby the joint between them is firm and tight. The broadening also prevents metal from stratifying between the frame and the diaphragm element, and a time-consuming cleaning of the frame can be avoided when the diaphragms are replaced. A similar stratification of metal can also be prevented by filling the edge regions of the diaphragm so as to be substantially impermeable.
:*0 ooo o *e e• *o The invention will be described in greater detail in the attached drawings, in which Figure 1 schematically illustrates a principle of an electrolysis process, Figure 2a is a schematic side view of a frame to be used in the electrolysis process and a diaphragm element attached to it, and Figure 2b, correspondingly, views them from the direction of arrow A, and Figures 3a to 3c schematically show details of embodiments.
Figure 1 illustrates an electrolysis process, in this case nickel electrolysis, in a simplified manner. Thus, an electrolytic basin 1 contains a nickel sulphate mixture as an electrolyte 2. In addition, a positive electrode, i.e.
an anode 3, and a negative electrode, i.e. a cathode 4, are disposed in the basin. For the sake of clarity, the figure shows only a few electrodes, but usually as many anodes and cathodes as possible are arranged closely adjacent 15 to each other in an alternating manner. Plates cast from lead, or so-called soluble anodes, are usually used as anodes. Cathodes, for their part, are thin nickel priming plates, onto the surfaces of which the nickel separated from the :solution or anode stratifies during the process. In the solution shown in Figure 1, the cathode 4 is arranged in the space enclosed by a diaphragm 5. The 20 term 'diaphragm' refers to a porous partition wall which separates the electrolytes and is made of an electrolytic fabric formed for this purpose. The diaphragm is attached to a frame 6, as shown later in Figures 2a and 2b. Nickel is supplied as a nickel sulphate solution into the space enclosed by the diaphragm around the priming plate. Alternatively, the anode can be arranged in the space enclosed by the diaphragm and the cathode, correspondingly, outside the space.
S°The electrolysis process and the related electrochemical reactions are fully known by a person skilled in the art, and therefore it is not necessary to explain them in greater detail herein.
Figure 2a shows a U-shaped frame 6 consisting of two vertical bars 6a and 6b and a horizontal bottom bar 6c. The upper end of the frame can also be supported by a support bar 6d. The frame is made of a material which bears these conditions well. It is advantageous to use a plastic material.
A fastening groove 7 for attaching the diaphragm extends around the frame on its both sides. The diaphragm 5 is attached to a fastening strip 8 in a separate stage, whereby a diaphragm element is obtained. As Figure 2b shows, the 4 elements are attached on both sides of the frame by pressing fastening elements in the fastening strip into the fastening grooves 7.
Figure 3a is a partial cross-section of a structure of a frame.
On both sides of a bar 6a there are fastening grooves 7, whose cross-section at its simplest is rectangular, but, if required, it may also have another shape, for example a shape of a cone. An upper fastening strip 8 comprises a fastening element 8a, which is preferably provided with locking elements, such as bulges or the like, for gripping the fastening groove. The flanks of the fastening groove can be provided with grooves or some other roughening, by which a firm attachment of the fastening strip is ensured. The fastening strip is preferably made of an elastic material, which also improves the attachment and may facilitate the mounting. Compared to the prior art solutions where the diaphragm remains between the fastening groove and the fastening strip, the attachment is firmer. Now the fastening element is in direct contact with the fas- 15 tening groove and the friction between the materials is thus greater. The material and shape of the fastening element are selected such that a sufficient attachment force is achieved. The fastening strip is T-shaped in cross-section, whereupon it comprises a section 8b transversal to the fastening element 8a.
A diaphragm 5 is tightly attached to the outer surface of the transversal section 8b by means of a suitable adhesive, by melting or by sewing, for example. A o diaphragm element can be manufactured by an apparatus which cuts a sheet of a specific size from an electrolytic fabric and simultaneously attaches it to the fastening strip by ultrasonic welding, for instance. Ultrasonic welding is an S. efficient method of attachment in cases where the material properties of the diaphragm and strip are suitable for this. When the diaphragm is attached to S. the outer surface of the transversal section, the diaphragm sheet need not be cut accurately, but the sheet can be bigger than the space defined by the fastening strip, as shown in Figure 2a.
The cross-sectional profile of the lower fastening strip in Figure 3a is L-shaped, whereby the transversal section 8b covers a section between the inner edge 6' of the frame and the fastening groove 7. Such a broadening prevents metal from stratifying between the diaphragm 5 and the bar 6a during the process, which means that when a new diaphragm is mounted, a cumbersome removal of the layers from the surface of the frame can be avoided. The diaphragm 5 is attached to the inner surface of the broadening, whereby the diaphragm remains between the broadening and the frame.
In Figure 3b, the transversal section of the upper fastening strip is only of the size that a diaphragm can be attached to it. In this case, the broadening 9 is formed at the diaphragm 5. Thus, the diaphragm is filled in the edge region to be substantially impermeable such that no harmful stratification of metal occurs. The edges of the fabric can be filled, for example, by painting, injecting or impregnating a predetermined section from the edge of the sheet.
The fabric can be filled by a plastic material, for example. One alternative is to arrange a separate band of a suitable size at the edges of the diaphragm by sewing, welding or by means of an adhesive, for instance. It is also possible that in the edge region, the electrolytic fabric is woven so as to be denser than elsewhere. The above described diaphragms filled at their edges are quite suitable to be used in connection with the solution of Figure 3c, for example.
In Figure 3b, the lower fastening strip is substantially U- 15 shaped and it is arranged between the fastening groove 7 and the inner edge of the frame. Again, the fastening strip thus comprises a transversal section 8b which covers a section between the fastening groove and the inner edge.
The inner branch of the U-shaped strip, for its part, covers a predetermined section of the inner edge 6' of the bar.
20 Figure 3c further shows a solution for attaching a diaphragm.
Therein the profile of the fastening strip 8 is U-shaped, and when it is pressed into the fastening groove 7, it is pressed together like a spring element. In this case, the fastening strip may be of a relatively stiff material. Furthermore, in the section between the fastening groove 7 and the inner edge the frame can comprise a curved bulge 10, by means of which the diaphragm 5 can be tensioned more efficiently. The fastening strip is hammered to the fastening •...*groove, or alternatively it is clamped to its place in one go by means of a plunger tool of a predetermined design. The direction of mounting is shown in the figure by arrow B. Since the tightness of the diaphragm can be adjusted, small variations in the dimensions of the element or frame do not cause problems during the mounting. As the figure shows, the depth of the fastening groove is dimensioned to be deeper than the fastening element, whereupon a required adjustment margin is provided. The deeper the fastening strip is clamped into the groove, the tighter the diaphragm is tensioned in the direction C shown in the figure. Due to the curved bulge 10, the inner edge of the fastening groove 7 is not sharp, and the diaphragm to be tensioned slides over it without getting damaged. The bulge also reduces frictional forces and thus the power required for the tensioning. The diaphragm can also be tensioned afterwards in connection with service operations. When the attachment of the diaphragm is firm and it is kept sufficiently tight, it also stands longer.
Furthermore, it is possible to form a fastening strip directly at the edge of a diaphragm sheet. This can be done, for example, by casting or injection moulding a kind of fastening frame to the diaphragm from a plastic material. The advantage of this solution is that when big production lots are made, the manufacture is rapid.
The drawings and the related description are only intended for illustrating the idea of the invention. In its details, the invention may vary within the scope of the claims. Consequently, the solution of the invention is not restricted in any way to be used only in connection with nickel electrolysis described herein, but it may be applied to all kinds of electrolyses where a diaphragm needs to be attached. Further, the frame can be different from what g is shown as an example in Figure 2a. The cross-section of the bars of the frame, and that of the fastening strip can also differ from what is shown in Figures 3a to 3c.
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Claims (14)

1. A method of attaching a diaphragm to be used in an electrolysis process to a frame, in which method a diaphragm sheet corresponding to the size of the frame is cut from an electrolytic fabric, the sheet being attached from its edges to a fastening groove of the frame by means of a fastening strip, whereby the diaphragm and the frame enclose a space where an electrode can be arranged, characterized in that a flank surface of the diaphragm is tightly fixed to the fastening strip in a separate stage before mounting it to the frame, and that a diaphragm element formed in this way is attached to the frame by pressing a fastening element of the fastening strip into the fastening groove.
2. A method as claimed in claim 1, characterized in that the diaphragm element is formed of the diaphragm and the separate fastening strip, and that the diaphragm and the fastening strip are joined by welding.
3. A method as claimed in claim 1, characterized in that the diaphragm element is o 15 formed of the diaphragm and the separate fastening strip, and that the diaphragm and 00 :o the fastening strip are joined by sewing.
4. A method as claimed in claim 1, characterized in that the fastening strip is 0 formed at the edge of the diaphragm by casting or a similar manner.
A diaphragm element comprising a sheet-like diaphragm formed of an electrolytic fabric, characterized in that the diaphragm sheet is tightly attached to a fastening strip and that the fastening strip comprises a fastening element for attaching the diaphragm element to a fastening groove of a frame.
6. An element as claimed in claim 5, characterized in that the fastening strip o comprises a portion transversal to the fastening element, and that the portion covers and prevents metal from stratifying on at least a section between the inner edge of the frame and the fastening groove.
7. An element as claimed in claim 5, characterized in that at a predetermined distance, the edge regions of the diaphragm are sealed to be substantially impermeable.
8. An element as claimed in claim 7, characterized in that the structure of the electrolytic fabric is filled in its edge regions.
9. An element as claimed in claim 7, characterized in that a separate sealing band is arranged at the edge of the diaphragm.
A fastening strip which is intended for attaching a diaphragm to a frame, characterized in that the fastening strip comprises a fastening element for attaching the fastening strip to a fastening groove of the frame and that the fastening strip has a 8 section transversal to the fastening element, intended for being attached to a flank surface of the diaphragm.
11. A fastening strip as claimed in claim 10, characterized in that the fastening strip comprises an impermeable portion transversal to the fastening element, and that the impermeable portion covers and prevents metal from stratifying on at least a section between an inner edge of the frame and the fastening groove, the width of the portion corresponding to at least the distance between the inner edge of the frame and the fastening groove.
12. A method of attaching a diaphragm to be used in an electrolysis process to a frame substantially as herein described and with reference to the accompanying drawings.
13. A diaphragm element substantially as herein described and with reference to the accompanying drawings.
14. A fastening strip for attaching a diaphragm to a frame substantially as herein described and with reference to the accompanying drawings. Dated this seventeenth day of February 2005 Tamfelt Oyj Abp Patent Attorneys for the Applicant: F B RICE CO o.*
AU24895/01A 2000-03-08 2001-03-06 System for attaching diaphragm Ceased AU781202B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20000531A FI109365B (en) 2000-03-08 2000-03-08 Arrangement for attaching a diaphragm
FI20000531 2000-03-08

Publications (2)

Publication Number Publication Date
AU2489501A AU2489501A (en) 2001-09-13
AU781202B2 true AU781202B2 (en) 2005-05-12

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AU24895/01A Ceased AU781202B2 (en) 2000-03-08 2001-03-06 System for attaching diaphragm

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4455209A (en) * 1982-06-05 1984-06-19 J V Kunststoffwerk Gmbh Electrode frame for the electrolytic recovery of metals
US4886586A (en) * 1988-09-26 1989-12-12 The Dow Chemical Company Combination electrolysis cell seal member and membrane tentering means for a filter press type electrolytic cell
DE4428938A1 (en) * 1994-08-16 1996-03-07 Hoechst Ag Joining unbondable, unweldable polymer to bondable, weldable polymer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4455209A (en) * 1982-06-05 1984-06-19 J V Kunststoffwerk Gmbh Electrode frame for the electrolytic recovery of metals
US4886586A (en) * 1988-09-26 1989-12-12 The Dow Chemical Company Combination electrolysis cell seal member and membrane tentering means for a filter press type electrolytic cell
DE4428938A1 (en) * 1994-08-16 1996-03-07 Hoechst Ag Joining unbondable, unweldable polymer to bondable, weldable polymer

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Publication number Publication date
AU2489501A (en) 2001-09-13

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