As outlined above, the Kidd Process did not use wax on its permanent cathodes. This highlighted disadvantages associated with the use of wax by the Isa Process. Cathode copper consumers applied pressure to producers to remove residual wax from the cathode copper, and the use of wax also created “housekeeping” problems for Isa Process operators.
Consequently, MIM commenced a development program in 1997 aimed at eliminating the use of wax. This resulted in a new process called the Isa 2000 technology, which was able to produce single-sheet cathode (as opposed to the Kidd taco shell cathode) without using wax.
This was achieved by machining a 90° “V”-groove into the bottom edge of the cathode. The groove weakens the structure of the copper growing at the bottom edge of the cathode plate because the copper crystals grow perpendicular to the cathode plate from opposite sides of the groove, causing them to intersect at right angles to each other. A discontinuity in the structure is formed at the intersection that results in a weak zone, along which the copper splits during stripping.
Figure 4 is a microscope view of the cross-section a copper cathode growing at the tip of a cathode plate. The yellow lines show the orientation and direction of crystal growth.