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 hydrometal...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 hydrometal-lurgical manganese processing, concentration and purification processes and newer processes of extraction of manganese from ores and waste materials were discussed.展开更多
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 mas...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/ro 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.展开更多
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 cryst...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.展开更多
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 ...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.展开更多
文摘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 hydrometal-lurgical manganese processing, concentration and purification processes and newer processes of extraction of manganese from ores and waste materials were discussed.
文摘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/ro 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.
文摘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.
文摘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.
