Print this pageGeochemistry and Environmental Appraisal of Some Selected Coals from Nigeria
The geochemistry of trace elements and the coal quality parameters of some selected coals from Nigeria were investigated. The samples were collected from seven major existing potential coal mines sites namely: Okpara, Onyeama, Achi, Ezimo, Okaba, Agbogugu, and Ute. Eighteen samples were analyzed using X-ray powder diffraction (XRD), inductively coupled plasma-mass spectrometry (ICP-MS), atomic fluorescence spectrometer (AFS) and scanning electron microscopy (SEM). The concentrations of fourteen potential hazardous trace elements, including Hg, As, Ba, Se, Pb, Cd, Ni, Cr, Co, Mo, Mn, Cu, V, and Zn in coals were determined. To evaluate quality of the proposed analytical method, the GBW standard reference materials; GBW 07312 for sediment and GBW 08401 for coal fly ash were also analyzed. The results obtained with the ICP-MS are in agreement with the GBW certified values.
The mineral matter of the studied coal samples is made up of quartz, kaolinite, and carbonaceous clay minerals. Vertical variations of trace elements observed in two coal mines sites (Okpara and Achi) indicated the distributions of most elements to vary with depth. Compared with average concentration of trace elements in China and Turkey coals, the coals from Nigeria contain a lower concentration. The concentrations of the trace elements are within the range of world coal average. However, most of the elements investigated presented an aluminosilicate and pyrite association and may be harmful to the environment in the process of combustion and utilization.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil