Contrasting Cation Distributions in Spinels of Similar Composition

Chromite mined from the Great Dyke in Zimbabwe is used for the production of about 180 000 tonnes of ferroalloy per annum, equivalent to about 6% of the world’s supply. The chemical and physical characteristics of the ores, which vary even within the same seam, affect the carbon content of the ferroalloys and hence their commercial value. The purpose of this study is to examine some of the differences between two extremes of chromitites, sheared and unsheared, used in the ferroalloy industry in Zimbabwe to provide a better understanding of the factors that influence the composition of the alloys as a basis for process mineralogy.The ores consist of chromium spinels (MgAlCrFe)3O4 with a lattice of alternating non-equivalent planes of tetrahedrally coordinated A sites and octahedrally coordinated B sites. The distribution of five major cations (Mg2+, Al3+, Fe2+, Fe3+ and Cr3+) was examined by the technique of electron channelling.</jats:p

Investigation of challenges to the utilization of fuel cell buses in the EU vs transition economies

In the urban environment, residents' health is damaged seriously due to fossil-fuel combustion, among the pollutants most are created from transport vehicles. Fuel cell buses fuelled by hydrogen appear to be a promise solution to environment, energy and public health problems that we face today. Studies worldwide point towards the technical feasibility of hydrogen as an energy carrier in the transport and stationary sectors, but several non-technical barriers need to be overcome or removed before hydrogen can be deployed in energy systems. This paper expounds a previous country-specific analysis by contrasting the challenges arising at EU level and those faced by transition economies, using China and Brazil as case-studies to identify the key barriers and potential impact on hydrogen fuel cell buses applications. The evaluation criteria used are described. Lessons on the critical conditions for a successful introduction of fuel cell buses and hydrogen into society and the establishment of a hydrogen infrastructure arise from the above analyses.Fuel cell buses Non-technical barriers European union Transition economies