The Role of Solids Characterisation Techniques in the Evaluation of Ammonia Leaching Behaviour of Complex Sulphides

Abstract

This paper presents the state of art of some experimental techniques that are useful for identification of the various mineral phases of raw materials, leach residues and for determination of reaction mechanisms for the oxidative ammonia leaching of sulphide minerals and Cu-Zn-Pb bulk concentrates. Techniques discussed include microscopy, X-ray diffraction (XRD), thermal analysis (TA), surface area measurements, chemical phase analysis and electrochemical measurements. These provide supportive evidence in studies on leaching of multimineral sulphides. Under the experimental conditions used, a multidisciplinary approach ensures elimination of various uncertainties and provides better analysis of kinetic data. This is discussed in the light of raw material characteristics, experimental variables, solution analysis, nature of products formed, etc. Uncertainties usually associated with the analysis of kinetics data are also briefly discussed. Lean grade complex sulphide ores are chosen for a case study because they have assumed a worldwide significance as potential future resources of both nonferrous and precious metals.

Keywords::

• Multi-mineral sulphides
• characterisation
• microscopy
• X-ray diffraction
• thermal analysis
• chemical phase analysis
• surface area measurements
• galvanic interactions
• solid – solution aqueous ammonia chemical equilibria
• leaching kinetics