Niobium and tantalum are chemically similar and are associated with each other in nature which makes it very difficult to separate. For many years, the separation of tantalum from niobium involved the fractional crystallization of potassium heptafluorotantalate away from potassium oxypentafluoroniobate monohydrate, this method has been supplanted by solvent extraction from fluoride-containing solutions by the use of solvent extractants such as Octanol, bis(2-ethylhexyl)phosphoric acid (DEHPA), Alamine 336, methyl isobutyl ketone (MIBK), tri-nbutyl phosphate (TBP) or cyclohexanone. A detailed review of the various processes involved in the breakdown treatment of niobium and tantalum primary sources, extraction and separation and newer processes of extraction as well as the various technique involved were discussed.

Chalcopyrite ores are usually processed by means of hydrometallurg ical or pyro metallurgical processes, but due to environmental aspects and the possibility of increased exp loitation of mixed and lower grade ores and relat ively small isolated deposits, there has been a worldwide upsurge of interest in the hydrometallurg ical processes of this ore as compared to pyrometallurgy. The different concentrates obtained through differential flotation in pyro metallu rgy are usually of poor quality with low metal recovery. This further makes pyrometallurgical processing of chalcopyrite very difficult and costly and rendered them difficult to commercialize. As a result, the metal value is preferab ly extracted directly fro m low grade ores through hydrometallurg ical process. A detailed review of chalcopyrite deposits, production and consumption, min ing, ore processing, steps involved in the pyrometallurgical and hydrometallurgical processing of copper as well as the dissolution kinetics and microbial studies of chalcopyrite ore were discussed.

In this study, bamboo impregnated with nanoscale zero-valent iron (nZVI) and nanoscale manganese (nMn) were prepared by the aqueous phase borohydride reduction method and characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and PIXE analysis. The synthesized nMn-bamboo and nZVI-bamboo composites were subsequently applied to the sorption of methylene blue (MB) dye from aqueous solution. The adsorption of MB dye was investigated under various experimental conditions such as pH, contact time, initial concentration of MB dye and adsorbent dosage. The results showed that the synthesized nZVI-bamboo composite was more effective than nMn-bamboo composite in terms of higher MB dye adsorption capacity of 322.5 mg/g compared to 263.5 mg/g of nMn-bamboo composite. At a concentration of 140 mg/L MB dye, 0.02 g of nZVI-bamboo and nMn-bamboo composites resulted in 79.6% and 78.3% removal, respectively, at 165 rpm, contact time of 120 min and at a solution pH of 7.6. The equilibrium data was best represented by Freundlich isotherm model and the pseudo-second order kinetic model better explained the kinetic data for both nZVI-bamboo and nMn-bamboo composites.

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Hydrometallurgy is the most suitable extractive technique for the extraction and purification of manganese as compared to all other techniques including biometallurgy and pyrometallurgical processes. In the hydrometallurgical processing of manganese from its ore, the leach liquors often contain divalent ions such as iron, manganese, copper, nickel, cobalt and zinc along with other impurities which make manganese very difficult to separate. The processes employed for solution concentration and purification in the hydrometallurgical processing of manganese include precipitation, cementation, solvent extraction and ion exchange. Solvent extraction also proves more efficient and it plays vital roles in the purification and separation of the manganese as compared to all other techniques. A detailed review of the various steps involved in the hydrometallurgical manganese processing, concentration and purification processes and newer processes of extraction of manganese from ores and waste materials were discussed.

This work reports the adsorption of crystal violet (CV) dye onto magnetic zeolite (MZ) nanoparticles, synthesized by direct fusion of fly ash (FA) and magnetite particles. The synthesised MZ showed high capacity for CV dye adsorption, removing 95% of the dye at an equilibrium adsorption time of 10 min and 25˚C. The effects of adsorbent dosage, dye concentration, and pH, on adsorption were evaluated. Adsorption data were best described by the Langmuir adsorption isotherm (R 2 = 0.9986), while the adsorption kinetics was best fitted by the pseudo-second-order kinetic model (R 2 = 0.9999). Application of the MZs synthesised from inexpensive resources such as FA could ensure the sustainability and cost effectiveness of treating industrial effluent containing basic dyes, especially effluent from the textile industries.

In this study, fly ash was obtained from Matla power station and the physicochemical properties investigated. The fly ash was characterized by x-ray fluorescence, x-ray diffraction, scanning electron microscopy, and inductively coupled plasma mass spectrometry. Surface area, particle size, ash and carbon contents, pH, and point of zero charge were also measured. The results showed that the fly ash is alkaline and consists mainly of mullite (Al6Si2O13) and quartz (SiO2). Highly toxic metals As, Sb, Cd, Cr, and Pb as well as metals that are essential to health in trace amounts were also present. The storage and disposal of coal fly ash can thus lead to the release of leached metals into soils, surface and ground waters, find way into the ecological systems and then cause harmful effect to man and its environments.

Studies on the kinetics of dissolution of a Nigerian lateritic soil in acids media including hydrochloric, nitric and sulphuric acids have been undertaken. The elemental and mineralogical characterization, loss of mass on ignition, moisture content and pH of the material suspension in water were determined. The effects of acid concentration, process temperature, stirring rate and particle size on the dissolution rate were investigated. Experimental results indicated that laterite dissolution was greatly influenced by hydrogen ion concentration and the leaching data fitted a diffusion model. The linear dependence of the rate constant k on 1/r o 2 supported the proposed kinetic model. Values of 60.23 kJmol -1 , 64.31 kJmol -1 and 67.53 kJmol -1 were obtained for the activation energies of laterite dissolution in hydrochloric, nitric and sulphuric acids respectively; and the order of reaction was approximately one with respect to each of the three acids.Laterite finds its applications in building houses and road construction. Solid lateritic gravel is also used in aquaria where it favours the growth of tropical plants. Intensive laterization results in the formation of aluminium-rich laterite (Bauxite) and laterization of igneous rocks often results in a considerable nickel and cobalt concentration [1,3,4]. Cobalt and nickel have found numerous applications in chemical and manufacturing industries. The strategic nature of cobalt has made it imperative to search for cobalt-enriched laterites, which constitutes one of its primary sources. As there is no comprehensive study on kinetic dissolution of laterites in Nigeria, except the one reported by Olanipekun (2000) [5] on the dissolution of laterite in HCl medium. The present study represents a more comprehensive study on a Nigerian laterite.The present investigation was therefore aimed at establishing the conditions for the leaching of a Nigerian lateritic soil in hydrochloric, nitric and sulphuric acids, followed by a comparative analysis of the kinetic data. EXPERIMENTALS MaterialLateritic soil used for this study was collected from a mining site in Ilorin, Nigeria. Elemental analysis and mineralogical characterization were respectively carried out by X-ray fluorescence model 12045B4/3 and Philips PW1800 X-ray diffractometer, with CuK α (1.54 Å) radiation generated at 40 kV and 55 mA.All reagents used were of analar grade and were all products of BDH. Doubly distilled water was used for all the analytical preparations. Physico-chemical Characterization Loss of mass on ignitionThe loss of mass on ignition was carried out gravimetrically at 600 °C using ASTM method until a constant weight was obtained. The process was carried out in triplicate. Moisture content determinationThe moisture content determination was carried out gravimetrically by heating 1.0 g of laterite in the oven at temperature of 105 ºC for 5 hours. pH determinationThe pH of 10.0 g suspension of laterite in 30 ml distilled water was measured by the use of a pHep ® HANNA pH meter. The measurement was ...