Patent Application
20060091004
This invention relates generally to refining processes and more particularly to cathode construction as used in electro-deposition processes.
Spurred by the introduction of electro-plating in 1840, the electro-deposition process has been used for the refining of many minerals including copper. Copper is extracted from the ore using large metal sheets made of titanium or stainless steel. These sheets are suspended in tanks containing the copper ore, a 5%-10% solution of sulfuric acid, plus other chemicals.
Low voltage/high amperage direct current electricity is applied, using lead as the anode, and the titanium/stainless steel plate as the cathode. The copper is electro-deposited (plated) on the metal to a pre-determined time/thickness.
Removal of the deposited copper requires the “peeling” of the copper from the cathode using a “knife” arrangement. Should the copper become deposited around the edge of the cathode, then its removal is significantly encumbered.
There is a significant need to provide for a mechanism which curtails depositing of the copper into a defined area. To this end, a variety of techniques have been developed including the use of various edge strips of CPVC, HDPE, Sponge/Spring combinations, etc.
All too often though, the edge strips break due to rough handling, copper getting underneath the strips, impact, age, etc. Protection such as wax, silicone, etc., must be re-applied each cycle; these are messy and create occupational and safety hazards, increase production costs.
Another problem associated with traditional edge strips is that when they are exposed to the high temperatures of their working environment, the materials used in the edge strip tend to degrade or unduly expand; this creates gaps in the seal between the edge protector and the cathode (allowing copper to be deposited in these gaps).
Gaps in the seals are also created during the grinding process to clean the cathode for subsequent uses. This narrows the width of the cathode; hence, the edge protector (designed for a particular width cathode) does not seal as well as it previously did.
When the edge strips break or fails to form a proper seal around the edge of the cathode, removal of the deposited copper is a major problem.
It is clear that there is a need for an improved method for controlling the deposit of ores onto cathodes.
The present invention creates an improved edge protector for an electrode found in the electro-winning process. As noted earlier, the edge protector is placed around the edges of the cathode to keep electro-winning from occurring along the edges of the electrode.
To this end, the protector uses an inner core configured to accept an edge of the electrode. The inner core is configured substantially as a “U” to encircle the edge of the electrode and extend a short distance along the opposing faces of the electrode.
This inner core is made from a first material which is chosen because of its ability to withstand high temperatures. One such material is Acrylonitrile Butadiene Styrene (ABS) commercially available from GE Plastics Inc. Those of ordinary skill in the art readily recognize other materials which are suitable for this purpose.
A seal along the faces of the electrode is provided using a pair of pliable lips which are secured to the inner core. The pliable lips are made from a resilient material chosen due its flexible nature, thereby creating a satisfactory seal with the edges of the electrode.
While those of ordinary skill readily recognize a variety of materials which serve this function, the preferred embodiment uses a Flexible Polyvinyl Chloride (FPVC) commercially available from GE Plastics Inc.
The inner core is covered by a resilient skin made from a third material which protects the edge protector from physical damage. The skin forms a layer of protection for the electrode from physical damage created during the handling and movement of the electrode.
The preferred embodiment of the invention uses an Acrylic Polyvinyl Chloride (APVC) for the skin. Those of ordinary skill in the art readily recognize a variety of materials which are useable in providing this protective skin. One such product is commercially available from Viking Inc. and has a Heat Deflection Temperature in excess of 175 degrees Fahrenheit.
The electrode created by this invention is extremely durable and capable of withstanding the high heat associated with the electro-winning process. Further, because of the excellent seal created, electro-deposition along the edge of the electrode is minimized.
The invention will be more clearly described by the accompanying drawing and the following descriptions thereof.
The length of the edge protector is chosen to meet the specific needs of the electrode. Ideally, the edge protector covers three edges of the electrode and are sealed where the pieces connect. In an alternative embodiment, two edge protectors are used, one for each side of the electrode.
The edge protector has an inner core 11 in which channel 14 is formed. Channel 15 is configured to accept the edge of the electrode (not shown) and still have slots 13 which permit a key (not shown) which has been secured to the electrode. Slots 13 are slid around the key to secure edge protector to the electrode, or injected filled with plastic.
Those of ordinary skill in the art readily recognize a variety of “keys” which serve in this fashion.
The material which forms inner core 11 in the preferred embodiment is acrylonitrile butadiene styrene (ABS) which has been shown capable of withstanding the high temperatures normally associated with the electro-winning process.
The electrode extends past lip member 10 which forms a seal along the opposing faces of the electrode to keep slurry from becoming electroplated with the edge protector. In the preferred embodiment, lip 10 is made of a Flexible Polyvinyl Chloride (FPVC) which is less dense than the ABS of the inner core.
By being less dense, lip 10 more readily molds to the face of the electrode to form a more efficient seal than the ABS of the inner core 11.
Further protection for the edge protector is provided by skin 12, which is formed from an acrylic polyvinyl chloride (PVC) in the preferred embodiment. This material is more dense than the material of the lips or the inner core.
This denser skin 12 protects the inner core 11 from “bumps” during the handling of the electrode during the electrodes placement and withdrawal from the electro-winning tanks as well when the electro-deposited material is being pulled from the electrode. Skin 12 absorbs and deflects physical damage to the edge protector.
It is clear from the forgoing that the present invention creates a highly improved edge protector.
