Pressure Hydrogen Reduction of Nickel, Cobalt and Copper from Their Aqueous Systems

摘要

The paper describes the hydrogen reduction processes of nickel, cobalt and copper in aqueous systems (solutions or suspensions), from both theoretical and practical points of view. The history and the developments of the hydrogen reduction processes are briefly outlined. The production processes of nickel, cobalt and copper powders from various aqueous systems are generally introduced. The thermodynamics of the reduction reactions are discussed according to the relationships between the electrode potentials, and the pH values or the concentrations of metal ions. In addition, the influences of various parameters on the reduction thermodynamics are reviewed. The reduction mechanisms and kinetics are described in detail from the experimental results of many researchers, including the effects of various factors on the reduction kinetics. More pages are given to the control of the physical characteristics of the metal powders so produced. And the effects of the operating conditions and a variety of additives on the physical properties and the morphology of the powders are broadly discussed.