FI108546B - Method for making cathode suspension rod - Google Patents

Description

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METHOD FOR MANUFACTURE OF A CATHODE SUSPENSION BAR

This invention relates to a method for manufacturing a suspension cathode rod used in electrolysis of metals, wherein the suspension rod 5 is formed of a rigid metal outer sheath and a highly conductive core attached thereto. The joint brings the outer jacket and core into intimate contact with one another and the joint is pulled, knocked or cast.

10 For a long time, the electrolysis of metals has used the method of: .j .: using seed plates first grown on mother plates • · *. Use of such seed disks as a cathode which are of the same metal:. “Than metal precipitated by electrolysis, such as copper, is falling behind, especially when it comes to investing. The construction of the new 15 electrolysis plants has moved to the use of permanent cathodes, and the plate-like part of the cathode is usually made of either acid-proof steel or titanium.

Durable cathodes have been manufactured in many different ways, the main difference being ". ··. The structure of the 20 cathode suspension rod and the attachment of the plate member to the suspension rod.

<·· '·. . ·. Attaching the suspension rod structure and plate member to the bar makes it difficult to supply sufficient copper to the plate member to conduct a large electrical current to the plate member, since the acid-proof steel is: Y: poor conductor and thus not an exclusive material for the suspension rod .

There are a number of prior art methods for solving the connection of copper and another metal in the manufacture of hanging bars. The commercial market is mainly dominated by two forms. In the first of these embodiments, a full copper hanging bar is used to weld the stainless steel plate using a welding wire made of special alloy »» · I · »» j 2 '' J 8 5 4 6. One disadvantage of this option is the softness of the suspension rod, which is entirely copper, which causes the rod to dip easily, especially if higher cathode weights are used. Shortening of the temperature due to short circuits further aggravates this problem.

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Another disadvantage of a full copper suspension bar is that it is difficult to attach sufficiently to the separate lifting lugs above the suspension bar required by the present advanced material handling. The third disadvantage is that the special alloy welding required to connect the copper • · 10 hanging bars and the stainless steel plate is not as corrosion resistant as the other parts of the cathode • I *. The advantages of this design are that it is quick to make such a permanent cathode, does not require major investment and does not require any | the location of the production line. In addition, there is a benefit to the large copper cross-sectional area 15 in the suspension rod, which results in low resistance and consequently low power loss in the permanent cathode structures.

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In another, much-used embodiment of the permanent cathode suspension bar, a tubular suspension bar core is formed of stainless or acid-resistant steel 20, into which the stainless steel plate portion is welded to the materials normally used.

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'with welding wire. After connection, the hanging bar and the top of the board where the welds are located are · electrolytically plated with copper to provide sufficient electrical conductivity. Copper also protects the welding points from the environmental impact. Such a method has been described e.g.

British Patent 2,040,311.

The major disadvantage of the above-described process is that the electrolytic plating requires a long time, several days, resulting in: the turnaround times of the manufacturing are considerably increased and the plating requires a large investment in equipment. Due to electrolytic plating, the production line must be in the immediate vicinity of a functioning electrolysis plant. The copper cross-section in this structure is smaller than, for example, the structure described above, where the hanging bar is made of whole copper. In turn, this results in that the self-constructions of the permanent cathode described herein have a slightly higher resistor and a higher power loss than that of a full copper hanging bar. The advantage of the steel core suspension rod is its high strength, which allows the permanent cathode to retain its shape well even at high cathode weights, and even short circuits do not cause problems with cathode duration. It is also much easier to attach the aforementioned separate lifting lugs to such a structure. The lifting lugs are welded to the steel rod of the bar before electrolytic copper, which gives the structure a strong and durable appearance. In this embodiment, all welding takes place between the steel parts and the welding remains under copper so the joints are strong and long lasting.

U.S. Patent No. 4,647,358 further describes a permanent cathode with a suspension rod. the outer part is made of a steel tube which is welded to the plate part.

Inside the steel tube of the hanging bar is a hollow copper tube which is. , either longer than the steel tube or at least partially opened at its ends 20, the current passing through the copper inner tube of the suspension rod.

, I (t; The inner diameter of the steel tube is close to the outer diameter of the copper tube so that, «*» Γ '': the tubes are in close contact with each other. According to the patented: / ·· method, the outer jacket is initially open easier to place, and after installation of the inner tube, the outer casing of v · 25 is secured by longitudinal welding of the tube, and at the ends of the rod, the inner tube and outer casing are welded together.

I · · "'The advantages of the method described above can be attributed to the high strength of the rod and the welding of both the cathode plate member and the individual lifting lugs' * 30 directly to the rod housing of the same metal. welding »· 4 1 ϋ 8 S 4 6 and / or punching between the sheath and the core, which makes it difficult to obtain uniform rods in large volumes, and the disadvantage is that the sheath and the core must be welded at the ends to seal and not corrode, since the electrolyte between the sheath and the core is not good for the long-term operation of 5 rods, production therefore requires quite a few and difficult to automate work steps, which results in expensive production and, as mentioned above, maintaining a consistent quality can be overwhelming.

This invention relates to a method of manufacturing a suspension rod for a permanent cathode used in electrolysis of metals, wherein the suspension rod is made of a rigid metal outer sheath in which an electrically conductive core is drawn, either by pulling, bumping or casting. The purpose of the methods is to obtain good electrical contact and 15 tightness between sheath and core without additional work steps. It is most advantageous to provide a metallurgical bond between the bar parts. In this case, after the sheath and the I * core have been joined, it is sufficient that the sheath is machined at least at one end at least partially open to provide good electrical contact between the cathode hanger rod and the pool busbar. The essential features of the invention will be apparent from the appended claims.

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In the text, as a highly conductive core metal, the text is mostly talked about: * ··· copper, but it can also be aluminum. The rigid metal outer sheath is • * v .: preferably made of stainless steel, whereby it can be acid resistant or <I · v * 25 stainless steel.

When the hanging rod is formed by pulling, the rod is electrically electrically conductive »· *; · 'by pulling copper into the finished outer jacket. For example, when the outer sheath is made of stainless steel, it is easiest to make it beforehand because: * 30 stainless steel is difficult to pull. Preferably, this is done by making a * k · copper into a suitable tubular blank inside the steel sheath. The blank »I · • · * I · I · 5::.} 8 5 46 is inserted into the steel sheath and a mandrel is drawn through the hole in the copper blank to force the copper tightly against the surface of the steel sheath. A steel rod can also be used as a mandrel, which is pulled or pressed into a hole in the copper blank and, if necessary, also left inside the finished rod 5. During manufacture, the steel sheath can be supported from outside to prevent deformation, if necessary. Adjusting the temperature to the proper temperature can influence the working of copper and its binding to steel.

The hanging cathode of the permanent cathode can also be made by tapping, whereby a suitable core is inserted into the outer sheath, which, by pressing the ends of the core, makes it possible to extrude the shell well into at least the most important or end regions. Here, as in the case of drawing, the temperature can be adjusted to be favorable for the copper to work. Depending on the temperature used, pulling and bumping can be achieved. , a metallurgical contact between the outer sheath and the core.

When the hanging rod is formed by casting, it is done so that the outer casing formed of the steel tube acts as a mold into which ... 20 copper core is directly cast. Potential adhesion of copper ♦ · to the outer surface of the steel sheath can be prevented by, for example, • the outer surface of the pipe! 1 i · »i 1: ···. with graphite solution or other coatings. Casting copper! i · • · ·. ·. : The most reliable way to create the right metallurgical v ·; y is inside the steel sheath. bond between steel and copper.

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Self-casting, for example, occurs by pouring molten core metal into a vertical steel tube *: ·: closed at its lower end. A steel sheath is preferred

Mt preheat vigorously or reheat the entire rod (jacket + core); · <· after melting. It is essential that the sheath is in contact with molten copper long enough to allow time between the sheath and the core,. to form a metallurgical bond. If the jacket tube is not preheated, * »·» I »6 108546, or the entire rod, either during casting or afterwards, no tearing occurs, but the core metal solidifies so rapidly on the inner wall of the cold jacket that no bond is formed.

5 Another way to fill the steel sheath is to immerse it in the copper smelter for a suitable period of time so that preheating may not be necessary at all. Immersion can be done with the tube in a horizontal position, whereby before the steel jacket is immersed, both ends are plugged and a number of openings are made on the side above the tube for feeding copper 10 and removing air. A suitable amount is, for example, one opening at each end of the tube. The tube may also be kept inclined within the molten to ensure filling. Of course, the recess can also be done vertically, whereby only the lower end of the steel sheath is plugged before the recess. For example, about one minute immersion is sufficient to achieve a good 15 result.

As stated above, a contact between electrically conductive metals is desired between the permanent cathode and the busbar for electrolysis so that the current passes with little loss between the cathode and the busbar. Both drawn, cast and cast! * '**. With 20 cores, this is easily accomplished by, for example, removing the steel sheath of a suitable length from the copper core after joining the rod parts i I · · on one side of the rod, either on either side or only on the other end.

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At the same time, the cross-sections of the copper contact of the rod can be shaped to the desired:, v shape, for example convex.

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Separate stainless steel lifting lugs are welded '' directly to the hanging bar steel sheath if necessary. Likewise, the cathode plate section is welded directly to the steel sheath. The plate part and the lifting lugs can be attached to the steel sheath of the suspension rod either before or after the copper core is attached: *: 30.

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Claims (16)

7 08546 A method for making a permanent cathode suspension rod for electrolysis of metals, wherein the suspension rod is made of a S rigid metal outer jacket and an inner, electrically conductive inner part, followed by removal of the outer jacket at least at one end of the rod and the conductive core is brought into intimate contact with one another, whereby the members of the 10 rods are joined to each other by pulling with a mandrel, bumping or casting. Method according to Claim 1, characterized in that the conductive core is copper. 15 Method according to Claim 1, characterized in that the electrically conductive material I is aluminum. Method according to claim 1, characterized in that the core 20 is connected to the outer sheath by inserting the core blank inside the outer sheath and pulling the mandrel through the core blank in a drawing machine. The method according to claim 4, characterized by: , that: '; *; a steel rod is used as a mandrel A method according to claim 5, characterized in that • * ·; the steel rod is left inside a conductive core. * · · Method according to Claim 1, characterized in that the core 30 is joined to the outer sheath by inserting the core blank inside the outer sheath and 8 '08546 by squeezing the core at its ends, whereby the core is extruded into the outer sheath. Method according to Claim 1, characterized in that, in order to provide a metallurgical bond between the outer sheath and the core, the core 5 is joined to the outer sheath by casting it into the outer sheath. Method according to Claim 8, characterized in that the molding takes place when the outer sheath acts as a mold into which the molten core metal is poured. 10 Method according to Claim 9, characterized in that the outer jacket is preheated before casting. The method according to claim 9, characterized in that the outer jacket and core 15 are heated during casting. i ( The method according to claim 9, characterized in that the outer jacket and core are heated after casting. The method according to claim 9, characterized in that:; *: the outer sheath is kept upright closed and the molten core metal t t is poured into the sheath. I | I Method according to Claim 8, characterized in that the v * 25 is cast by immersing the outer sheath in a molten core metal. Method according to claim 14, characterized in that the outer jacket is immersed in a substantially horizontal position in the molten, whereby the ends of the outer jacket are closed and holes are made in the upper part of the jacket; : 30 for defrosting and defrosting. ♦ I »» »t» · 1 Π 8,546 A method according to claim 14, characterized in that the outer jacket is immersed in the molten substantially vertical position, the lower end of the jacket being closed. 5 PATENT LOAD