ABSTRACT
Studies of physico-chemical characterization, and chemical speciation of sulphur of seven Nigerian coal samples have been undertaken. The seven coal samples originated from South-east, North-central and North-east of Nigeria where there are proven economic deposits of this mineral. Moisture content, bulk density, percentage ash and loss of mass on ignition of all the coal samples were determined. The ultimate analysis of the raw coal, the corresponding coal ash as well as sulphur content of all samples were carried out with the aid of X-ray fluorescence technique (XRF). The major elements were Fe, Ca and S while the minor metals were K, Sc, Zn, Ni, Ti and Zr. Other metals including Ga, Cu, Mn, Cr and V were found in traces. The Nickel/Vanadium ratio which is a means of providing information on the source rock depositional environment ranged between 8.8 - 32.9. Three different source rock depositional environments were deduced for the coals from their nickel/vanadium ratios, while the calculated values of V/(V+Ni) suggested that they were all formed under oxic condition. The three chemical species of sulphur, sulphate, pyritic and organic sulphur in the seven coal samples were determined using the ASTM method.