Electrolysis: processes – compositions used therein – and methods – Electrolytic material treatment – Metal or metal alloy
Reexamination Certificate
2000-04-03
2001-10-09
Gorgos, Kathryn (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electrolytic material treatment
Metal or metal alloy
C204S269000, C134S008000
Reexamination Certificate
active
06299756
ABSTRACT:
The present invention relates to a separating member for separating the bottom of an electrolytic tank from the rest of the tank in connection with removing the solids created in the electrolytic tank.
In an electrolytic process, there are precipitated metals such as copper, nickel and zinc onto the surface of cathodes provided in an electrolytic tank, either starting from metal anodes that dissolve in the electrolyte present in the electrolytic tank, or from metal ions already dissolved in the electrolyte. However, all solids are not precipitated onto the cathode surfaces; these are for example precious metals and solid impurities contained in the electrolyte. Therefore, along with a metal refining process, on the bottom of the electrolytic tank there are accumulated various solids that must from time to time be removed from the tank, for instance because the solids contain valuable ingredients, such as precious metals, or because a thicker solids accretion threatens the purity of the cathode obtained from the electrolytic process.
Generally the solids accumulated in an electrolytic tank are at least partly very finely divided and only slightly heavier than the electrolyte, wherefore it is difficult to separate the solids from the electrolyte. In the course of the electrolytic process, it is extremely harmful if the solids start circulating from the electrolytic tank bottom, because then the chance that the solids end up on the cathode is particularly great, and this would result in a substantial drop in the purity of the metal to be produced.
Generally the removal of solids accumulated on the bottom of an electrolytic tank requires that the whole electrolytic process must be interrupted, which reduces the efficiency per unit of time, i.e. the productivity of the electrolytic plant. Thus the removal of solids must be made part of the replacing process of the electrolytes, i.e. anodes and cathodes, which makes the replacing complicated and slow and restricts the solids removal to take place in a rhythm determined by said replacing exchange process. Moreover, a remarkable amount of electrolyte must first be removed from the tank and then returned therein, which generally has harmful effects on the electrolyte quality and causes a lot of extra work. In the solids treatment system, there also is conducted a remarkable amount of electrolyte, which must be replaced with a new one and may be harmful in the further processing of the solids. In addition to this, the manual washing of the electrolytic tanks makes the process clearly more labor-intensive and subjects the employees to various health hazards, for instance owing to the effect of splashes sprayed from the tank and of the ingredients contained in the spray. Likewise, owing to the number of employees needed in the manual washing of the tanks, it is often nearly impossible to automate the handling of the electrolytes, which further increases the need for labor in the electrolytic plant.
The object of the present invention is to obviate some of the drawbacks of the prior art and to realize an advanced separating member suited in electrolytic tanks in order to separate the electrolytic tank bottom from the rest of the tank, so that the removal of solids from the electrolytic tank bottom can be carried out without essentially disturbing the electrolytic process. The essential novel features of the invention are apparent from the appended claims.
According to the invention, in an electrolytic tank, advantageously in the electrolytic tank walls, there are installed support members which, in addition to providing support, also guide the path of the separating member to be installed in the electrolytic tank. Said separating member is arranged in the tank, substantially along the whole length thereof, essentially near to the tank bottom, for the duration of the removal of solids found on the tank bottom, so that the separating member separates the liquid electrolyte from the solids that are settled onto the electrolytic tank bottom that are meant to be removed.
The separating member according to the invention is manufactured of flexibly connected structure elements which form an essentially sealed surface, but which can also be bent in relation to each other. Thus the separating member can be installed in the electrolytic tank without any particular aperture made in the tank, simply by conducting the separating member onto the surface of the liquid electrolyte, and further under the surface, substantially near to the rear wall of the electrolytic tank.
When the need arises to remove the solids accumulated onto the electrolytic tank bottom, the separating member according to the invention is first conducted to above the electrolytic tank, into a space located in between the rear wall of the electrolytic tank and the electrode located nearest to said rear wall, so that one end of the separating member advantageously is substantially near to the electrolyte surface. When the separating member is started to be conducted from the transport member into the electrolytic tank, to underneath the electrolyte surface, the passage of the separating member in the electrolyte is controlled by means of support and control members attached in the electrolytic tank, advantageously in the electrolytic tank walls. Said support and control members form the trajectory of the separating member in the electrolytic tank. The support and control members attached in the vicinity of the electrolytic tank bottom are installed in the tank at such a height with respect to the electrolytic tank bottom that when moving the separating member at a speed determined by the transport member, the solids found on the electrolytic tank bottom cannot start circulating due to the motion of the separating member, and thus the solids are prevented from remixing with the liquid electrolyte.
Owing to the mutual flexibility of the structural elements of the separating member, the proceeding direction of the separating member can be changed from a substantially vertical direction in the vicinity of the rear wall of the electrolytic tank to a substantially horizontal direction in the vicinity of the side walls of the electrolytic tank, when installing the separating member in the tank. Thus the support and control members of the separating member can be arranged essentially near to both rear walls of the electrolytic tank, so that the separating member can advantageously be inserted in the electrolytic tank through a space in the vicinity of one rear wall and removed therefrom through a space in the vicinity of the other rear wall.
When the separating member according to the invention is placed in an electrolytic tank, the separating member separates the part of the tank that is located near the bottom from the rest of the tank, and simultaneously it separates the solids found on the electrolytic tank bottom from the electrolyte needed in the electrolytic process. Consequently, the space left in between the separating member and the electrolytic tank bottom can be cleared of solids without the solids getting a chance to be mixed into the liquid electrolyte present in the rest of the tank. Thus the removal of solids can be carried out while the electrolytic process is in operation, and completely separately from the electrode treatment step. When the solids have been removed from the electrolytic tank bottom, the separating member is removed from the tank by utilizing the support and control members attached in the electrolytic tank, and shifted onto a separating member conveyor provided outside the tank; said conveyor transfers the separating member to another electrolytic tank, where a corresponding removal of solids from the electrolytic tank bottom must be carried out.
The separating member according to the invention can be placed in the electrolytic tank so that in between the separating member and the opposite rear wall, there is left a substantial clearing, so that the separating member does not impermeably separate the solids located underneath the separating member from the
Gorgos Kathryn
Nicolas Wesley A.
Outokumpu Oyj
Smith-Hill and Bedell
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