The Bureau of Mines investigated a hydrometallurgical procedure to recover CO, ni, and cu from an electrolytic zinc industrial copper filter cake. The copper filter cake is presently unmarketable or of low value because economic and environmentally acceptable processing technology is lacking. Research by the Bureau of Mines has developed a multistage process for recovering or recycling over 93 pct of the zn, cd, cu, CO, and ni from this material. The stages involved are (1) wet sizing, (2) h2so4 leaching of undersized material, (3) h2so4-mNO2 leaching of h2so4 leach residue, (4) selective precipitation of as, cu, and co-ni products, and (5) precipitation of manganese for recycling to the leach circuit. The final process residue is only 1.6 wt-pct of the initial cake and consists of lead sulfate.