Physicochemical,mineralogy,and thermo-kinetic characterisation of newly discovered Nigerian coals under pyrolysis and combustion conditions

In this study,the physicochemical,microstructural,mineralogical,thermal,and kinetic properties of three newly discovered coals from Akunza(AKZ),Ome(OME),and Shiga(SHG)in Nigeria were examined for potential energy recovery.Physicochemical analysis revealed high combustible but low levels of polluting elements.The higher heating values ranged from 18.65 MJ/kg(AKZ)to 26.59 MJ/kg(SHG).Microstructure and mineralogical analyses revealed particles with a rough texture,surface,and glassy lustre,which could be ascribed to metals,quartz,and kaolinite minerals.The major elements(C,O,Si,and Al),along with minor elements(Ca,Cu,Fe,K,Mg,S,and Ti)detected are associated with clays,salts,or the porphyrin constituents of coal.Thermal analysis showed mass loss(ML)ranges from 30.51%to 87.57%and residual mass(RM)from 12.44%to 69.49%under combustion(oxidative)and pyrolysis(non-oxidative)TGA conditions due to thermal degradation of organic matter and macerals(vitrinite,inertinite and liptinite).Kinetic analysis revealed the coals are highly reactive under the oxidative and non-oxidative conditions based on the Coats-Redfem Model.The activation energy(Ea)ranged from 23.81 to 89.56 kJ/mol,whereas the pre-exponential factor(kQ)was from 6.77×10^(-4)/min to 1.72×10^(3)/min under pyrolysis and combustion conditions.In conclusion,the coals are practical feedstocks for either energy recovery or industrial applications.

Mineralogy,physicochemical and oxidative thermal analyses of Cretaceous coals from the Benue Trough,Nigeria

The erratic supply of electricity in Nigeria has renewed interest in the utilisation of coal for energy selfsufficiency and diversification of the national energy mix.In this study,selected coal samples from three regions of the Benue Trough Basin were examined through pore water chemistry,X-ray diffraction(XRD),and thermosgravimetric analysis(TGA).The low pH observed for the Lower Benue Trough(LBT)coals indicates the release of sulphur and acids during oxidation.Mineralogical analyses reveal quartz,kaolinite,montmorillonite,albite,pyrite,gypsum and sodium chlorate in the coal samples.The genetic kaolinite species identified in Imeagha(IMG)coal are detrital kaolinite and the highly crystalline neomorphic kaolinite.Gypsum and jarosite minerals occurred in minor quantities in Garin Maiganga(GMG),whereas significant amount of pyrite was detected in Enugu(ENG)coal.Oxidative thermal degradation resulted in the residual mass(RM)ranging between 4.35%and 56.96%and mass losses(ML)between 43.04%and 95.65%due to the drying,devolatilization,and coke formation in the samples.The most reactive coal examined was GMG coal,whereas the least reactive was IMG coal.Lamja(LMZ),GMG,and OKB coals are suited for electricity generation,whereas ENG and IMG coals can be utilised for cement production.

Investigating the Industrial Potentials of Some Selected Nigerian Clay Deposits

One of the most important useful and widely abundant industrial minerals in the world is the clay minerals. Their applications in various industries are dependent on their properties. In this study, the mineralogical and physico-chemical properties of RahinSho (RC), Major Porter (MP), Wereng camp (WC), Kwi (KC) and Naraguta (NC) clay deposits in Plateau State, Nigeria were investigated to evaluate their potentials for some industrial uses. The x-ray diffraction studies revealed the kaolins as the dominant clay minerals in all the samples. The non-clay minerals found were quartz and muscovite. The chemical analyses by x-ray fluorescence also indicated that the silica (SiO2) values of the samples ranged from (41.20 - 62.26)% while the alumina (Al2O3) range was (17.25 - 37.15)%. Some considerable amounts of impurities found were Fe2O3 (0.43 - 27.52)%, TiO2 (0.05 - 3.28)%, K2O (0.13 - 3.01)%. The oxides of Na, Ca and Mg were within acceptable limits in the clays for most purposes. The loss on ignition ranged from 4.30% - 12.43%. The physical properties investigated were particle size distribution that contained heavy clay-size materials ranging from 67.88% - 91.88%, plasticity index had range of values from 15.90% - 33.68%, and drying and firing shrinkages were 1.10% - 2.22% and 1.65% - 4.49% respectively. All the samples attained a temperature of 1500°C without fusion except Naraguta clay that fused at 1300°C. At the temperature of 1200°C, RC, MP and WC clays retained their natural colours of white and near-white respectively, while KC and NC clays changed colours from orange pink and light brown to moderate pink and moderate reddish brown respectively. These results compare very well with several clays elsewhere. Based on these characteristics, the clays were observed to be potentially suitable for the production of paints, tiles, ceramics, refractories, sanitary wares and clay bricks. Minimal processing will increase the potential of RC and MP to meet up with specification for paper, fertilizer and/or pharmaceutical uses.