TABLE OF CONTENTS Before exploring methods for waste processing and resource recovery, it is necessary to characterize the waste, both in terms of chemical and mineralogical composition. Chemical composition is determined by digesting the material in appropriate acids, usually hydrochloric acid and when required nitric acid, and analyzing the solution by atomic absorption spectroscopy. Other methods of solution analysis are also sometimes used depending upon the chemical nature of the material and ease of analysis. They include potentiometric titration, conductometric titrations and colorimetric methods employing spectrophotometer. Details are described in standard instrumental analytical chemistry text books; for example, Willard, Merritt, Dean and Settle (1988).
Chemical analysis provides information on the elements in the material and their percentages, but does not identify the minerals or compounds occurring in it. Therefore, in addition to establishing chemical composition of the material, it is often necessary to know the mineralogical nature of the material. This requires characterizing the specific minerals occurring in the material and how they occur together, to what extent individual compounds are liberated from each other. (Liberation refers to the state where the chemically distinct species are physically separated within a solid, for example, a waste rock. Where the two species are locked together, they are said to be not liberated.) This enables the researcher to select the kind of techniques likely to be most efficient for the separation of economically useful metals or compounds. For example, where the individual species are satisfactorily liberated, separation by one of the physical methods (to...
