An Overview of Process Options and Behavioral Aspects of the Copper Values Recovered From the Copper Bleed Stream of a Copper Smelter Developed at the National Metallurgical Laboratory

Abstract

In the present research, an effort has been made to prepare copper salt=powder from the copper bleed stream generated during the electrowinning of pure copper from the copper anode in a copper smelter. Various approaches have been opted for the complete recovery of copper values such as: evaporation-crystallization, electrolytic process, and direct hydrogen reduction. Physical and chemical properties of copper powder=salt produced from the large-scale experiments from actual plant and model solutions have been evaluated for P=M applications and compared with the standard properties. Thus, mixed crystal suitable for recycling back to the system as a makeup salt containing nickel in a tolerable range could be recovered by evaporation and crystallization of the bleed stream up, to 50%. Copper powder recovery by the electrolysis process at a current density of 700 A=m 2 was about 95%. Scanning electron microscope examination showed that the powder was dendritic in nature. On annealing, the purity of the copper powder was found to be 99.95%. The annealed powder had apparent density of 3.04 g=cc, hydrogen loss 0.72%, and acid insoluble as 0.27%. On compaction of <104-mm sized powder, the green density was found to be 8.7 g=cc. Similarly, the recovery of the copper powder obtained from the model copper solution by the hydrogen reduction process was found to be >99% and the annealed powder had an apparent density of 3.50 g=cc, flow rate 35.6 g=min, hydrogen loss 0.195%, purity 99.8%, and green density of 8.57 g=cc while the powder from the actual plant solution was found to have an apparent density of 3.49 g=cc, flow rate 46.0 g=min, hydrogen loss 0.598%, purity 99.4%, and green density 8.57 g=cc for the powder <100 mm in size. Thus, the properties of copper powder produced by hydrogen reduction and electrolytic route were compared and were found to be suitable for the P=M applications.

Leaching of Oxide Copper Ores by Addition of Weak Acid from Copper Smelters

“…The use of a copper bleed solution (waste streams generated from the electro-purification of copper anodes) as a secondary source to recover valuable species is reported in the literature. This solution contains copper, nickel, sulfuric acid, and traces of Fe, As, and other impurities [31,32]. It is important to note that copper bleed solutions from the electro-purification of copper are very similar to weak acid solutions; thus, the weak acid is a new secondary source for the recovery of valuable species.…”

Copper Refining Electrolyte and Slime Processing - Emerging Techniques

“…While the emerging technologies for improved monitoring and control of impurities in CRE and slime as well as development of salable byproduct recovery (viz., MSO4.nH2O or metal powder/ cathodes) are emphasized [21,59,118,164,[169][170][171][172][173][174] particular emphasis on the homo-/hetero-geneous precipitation is given for impurity control along with slime resource recycling and product development.…”

Iron and Copper Recovery/Removal from Industrial Wastes: A Review

“…Iron is another metal usually present in copper electrolyte. It is well-known that iron causes two undesirable phenomena during copper electrorefining, namely reduction of Fe 3+ to Fe 2+ which consumes current, thus reducing current efficiency and Fe 3+ reacts with the reduced copper causing corrosion of the copper cathode especially at the surface where the Fe 2+ is more apt to be oxidized . This is particularly a problem for cathodes employing copper suspension loops.…”

“…It is well-known that iron causes two undesirable phenomena during copper electrorefining, namely reduction of Fe 3+ to Fe 2+ which consumes current, thus reducing current efficiency and Fe 3+ reacts with the reduced copper causing corrosion of the copper cathode especially at the surface where the Fe 2+ is more apt to be oxidized. 3 This is particularly a problem for cathodes employing copper suspension loops. Therefore, it is desirable to maintain dissolved iron levels to a minimum and to prevent electrolyte oxidation during copper electrorefining.…”