Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
2000-04-03
2001-07-03
Bell, Bruce F. (Department: 1741)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S288300, C204S297010, C204S297070, C204S297090, C204S297100, C204S297140
Reexamination Certificate
active
06254744
ABSTRACT:
The invention relates to a holder for a mother plate used in the electrolytic refining of metals, such as copper, zinc and nickel, in order to prevent damages in the bottom edge strip of the mother plate during the stripping process stage of the mother plate.
The refining of many metals, such as copper, zinc and nickel, includes an electrolytic stage where harmful impurities are separated from the metal to be produced. The metal produced in electrolytic refining is gathered on the cathode by means of electric current. Usually electrolytic refining is carried out in tanks filled with an electrolyte containing sulphuric acid and, immersed therein, a number of plate-like anodes and cathodes made of some electroconductive material and placed in an alternating fashion. At the top edges, the anodes and cathodes are provided with lugs or bars for suspending them at the tank edges and for connecting them to the power circuit. The metal to be produced is brought into the electrolytic process either as soluble anodes, so-called active anodes, or as dissolved in the electrolyte at some preceding process stage, in which case the employed anodes are insoluble, so-called passive anodes.
The cathode used in electrolytic refining can be produced of the desired metal to be produced, in which case the deposit need not be stripped from the original cathode plate. Usually, however, the cathode, i.e. the mother plate, to be immersed in the electrolytic tank is made of some other metal than the one to be produced. Such materials of the mother plate can be for instance stainless steel, aluminum or titanium. In that case the metal to be produced is gathered on the surface of the mother plate in deposits, which are stripped from the mother plate at defined intervals.
Owing to electric current, the metal produced in electrolytic refining is accumulated in deposits on all electroconductive surfaces of the mother plate, i.e. if the mother plate is completely electroconductive, the metal to be produced covers in a uniform deposit the mother plate in all parts immersed in the electrolyte. Now the deposits of the metal to be produced, accumulated on two sides of the mother plate, are on three sides attached to each other over the narrow edges of the mother plate, and thus the deposits of the metal to be produced are extremely difficult to remove from the mother plate. In order to facilitate the removal of the deposits of the metal to be produced from the surfaces of the mother plate, it is necessary to prevent the metal to be produced from accumulating deposits over the narrow edges of the mother plate, i.e. the edges of the mother plate must be made non-conductive. The best-known way to make the edges of the mother plate non-conductive is to cover the edges with edge strips made of some insulating material. such as plastic. Generally the insulating strips are plastic profiles with a groove-shaped cross-section, and they are pressed onto the edges of the mother plate and remain in place either owing to the pressure created by the transformation, by rivets inserted through the mother plate or due to a combination of these.
The deposit accumulated on two sides of the mother plate is stripped off for instance by using a stripping device described in the U.S. Pat. 4,806,213. In this patent the peeling blades are knifelike blades which are stuck in between the metal deposit and the mother plate on both sides of the plate. During the stripping stage, the cathode to be stripped is generally locked by the supporting bar in a similar vertical position as during the electrolytic stage. The stripping of the deposits is started from that edge of the mother plate which is close to and parallel to the supporting bar. When the stripping of the deposits will continue towards the cathode edge opposite and parallel to the supporting bar of the mother plate, the force caused by the stripping will all the time increase, and the effect of this force will be at the greatest in the outermost point of the deposit from the supporting bar of the mother plate. When this edge opposite to the supporting bar is protected by an edge strip, said bottom edge strip can be destroyed if the stripping is too strong, and the stripped deposit can even take away the bottom edge strip.
The object of the present invention is to obviate some of the drawbacks of the prior art and to produce an improved apparatus for preventing damages during the stripping stage of the mother plate in the edge strip installed on the edge opposite to the edge wherein the supporting bar of the mother plate is fixed. The essential features of the invention are listed in the enclosed claims.
SUMMARY OF THE INVENTION
According to the invention, in order to prevent damages during the stripping stage of the mother plate, in the edge strip installed on the edge opposite to the edge wherein the supporting bar of the mother plate is fixed, the mother plate is supported in a holder, so that in the holder there is at least one pressing member which will substantially tightly press the lower part of the deposit to be stripped against the mother plate. The press effect of the pressing member is thus unharmful for the edge strip installed on the edge opposite to the edge wherein the supporting bar of the mother plate is fixed. During the stripping stage the mother plate with deposits is in a vertical position, and therefore the edge opposite to the edge wherein the supporting bar of the mother plate is fixed, is the lower edge of the mother plate, and the edge strip on that edge is further called the bottom edge strip. In a similar manner, for instance the lower part of the deposit means the part of the deposit which is close to the edge opposite to the edge wherein the supporting bar of the mother plate is fixed.
When an object to be stripped, for instance a cathode from copper, zinc or nickel electrolytic refining, comes to the stripping stage, the cathode has been locked into the stripping device. At the same time the holder of the present invention is positioned so that the lower part of the cathode is pressed by at least one pressing member advantageously on both sides of the cathode. The pressing members are directed so that the contact between the pressing members and the cathode is created in the lower part of the deposit on the mother plate. The position for the contact between the pressing members and the cathode is arranged between 0.5 and 1.5 centimeters above the bottom edge strip.
Depending on the size of the mother plate, it can be advantageous to install in the holder of the present invention more than one pressing member on both sides of the mother plate. The pressing member can advantageously operate hydraulically, pneumatically as well as electrically depending for instance on the place where the holder is used. In one embodiment of the invention, the pressing members on the same side of the mother plate can be connected to each other by a connecting member. The pressing members on the same side of the mother plate can then advantageously be operated simultaneously. It is also advantageous that on both sides of the mother plate, there is provided the same amount of pressing members. Also the pressing members on both sides of the mother plate can advantageously be connected to each other, and they can then be operated substantially simultaneously. The pressing members are then inclinably installed to each other, so that the tilt angle is between 5 and 10 degrees when measured from the vertical position. The pressing effect on both sides of the mother plate is then substantially similar.
According to another embodiment of the invention, each pressing member is operated by a separate actuator of its own. The blank holder can also be operated so that the connecting members for the pressing members on both sides of the cathode can operate separately from each other. Also then the pressing member can advantageously operate hydraulically, pneumatically as well as electrically, depending for instance on the place where the holder of the invention is used.
When a cathode
Bell Bruce F.
Outokumpu Oyj
Smith-Hill and Bedell
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