Abstract: A mill roll with a ceramic working surface comprises an annular ceramic formation sleeved upon a hub. In preferred embodiments the ceramic formation is clamped to the hub at angled edge walls so that the formation is held under compression.

Abstract: A cathode for use in the electrolytic refining of copper, comprises a stainless steel hanger bar having a flat undersurface with end portions to rest on supports and electrical contacts, and a flat stainless steel starter sheet welded to the undersurface between said end portions and by one edge so to project perpendicularly from that surface. At least the upright side edges of the sheet are masked to prevent copper deposit thereon, and to improve conductivity from bus-bar to hanger bar and to starter sheet, the hanger bar and that edge margin of the starter sheet welded to it are clad with copper.