Copper anode in copper cyanide bath

What kind of copper anode I have to use in copper cyanide bath? Is it necessary to use copper free oxygen? If positive, why free oxygen is important? If negative what kind of contaminant is it necessary to analyse?

I work in a company that electroplating copper an copper/tin to make coins in steel substract and in our process we use anode of copper free oxygen .

Oxygen free copper anode corrode more uniformly, thus produce fewer particles. They also are more pure than oxygen containing copper. Thus less contamination of the plating solution. Before oxygen free anodes were available, people used electrolytic "slab" anodes. Both types must be bagged. I found that oxygen free were less expensive because there was much less waste.