Raman Spectroscopy in the Hydrometallurgical and Materials Engineering World

Autoclave processing of arsenical sulphide feedstocks from which precious metals (Cu, Co, Zn, Ni, Au) are extracted from employs high temperatures (150-225°C) which produces Fe-AsO4-SO4 crystalline phases [1-2]. In 1994, four phases were reported to form for the high temperature (150-225°C) Fe-AsO4-SO4 system [2] but confusion arose in 2007, as the discovery of two new phases were reported [3]. Therefore it was evident that these phases had not been fully identified in terms of arsenate speciation, in spite of the fact that some of these phases are used and advocated in arsenic disposal [2-3]. In the second case, attempts to increase the throughput (extraction of Zn) of an industrial leach autoclave, a massive scale formation never before observed resulted in halting of production. The final case deals with the binding mechanism between the highly commercialized N719 molecule and nano-crystalline anatase (TiO2) as a semiconductor in the DSSC field which has been highly investigated over the last decades [4-5] as a result of the high efficiencies they produce.