Rafiu Bale - Academia.edu (original) (raw)

Papers by Rafiu Bale

Journal of African Earth Sciences, 2020

Using sociocultural and poststructuralist theoretical lenses, this study examines the narrative c... more Using sociocultural and poststructuralist theoretical lenses, this study examines the narrative construction of language-learner identity across time and space. We applied cross-narrative methodologies to analyze language-learning autobiographies and interview data from three English users who had recently transitioned to a U.S. context for graduate studies. We found that learners' narratives and identity constructions are shaped in unique ways by the narrators' present and distant interactions, which can be understood by identifying points of transition (PsoT) in their stories. PsoT revealed how learners made sense of their ever-changing identities across time and space, viewed inconsistencies and conflict, and linked these conflicting identities with imagined futures. Our study contributes to research about learner identity and agency as we offer a narrative exploration of how L2 users construct identities and give meanings to these constructed identities by linking the influences of time and space in their language learning narratives.

Rare Metal Technology 2018, 2018

Treatment of secondary/waste to recover rare earth metals (REMs) is gaining importance due to its... more Treatment of secondary/waste to recover rare earth metals (REMs) is gaining importance due to its increasing global demand, lack of availability of high grade natural resources and huge generation of secondaries. Present paper reports the critical review on available processes for recovery of REMs from secondaries viz. manufacturing scraps, e-waste, industrial residues such as red mud, fly ash, waste water, etc. Hydrometallurgical processes with combination of Beneficiation/Pyro-/Electro techniques are discussed to recover REMs effectively. The recommended processes require less energy to deliver high purity yield which is one step towards green environment. Salient findings on various methods are reported with recommendations which will be helpful to researchers working in the area of REMs extraction.

Communications Faculty Of Science University of Ankara Series B Chemistry and Chemical Engineering, 2018

A study on the preparation of porous silica from a Nigerian talc ore by acetic acid leaching was ... more A study on the preparation of porous silica from a Nigerian talc ore by acetic acid leaching was investigated. The initial and leached talc products were characterized by Energy Dispersive X-ray fluorescence (EDXRF), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive spectroscopy (EDS) and the N2 adsorption techniques. The influence of acetic acid concentration, reaction temperature and particle size on the ore leaching kinetics were examined. The results of the dissolution rates were found to be significantly influenced by leachant concentration, temperature and decreasing particle size. The dissolution mechanism process followed the diffusion control shrinking core model with the calculated activation energy of 34.53 kJ/mol supporting the proposed mechanism. The leached product has a specific surface area increased to 2.056 m 2 /g from the initial ore surface area of 0.15 m 2 /g. At optimal leaching conditions, the pore size distribution calculated by Barret-Joyner-Halenda (BJH) method based on N2 gas isotherms showed the presence of peaks from micropores and mesopores formation, indicating the porous nature of the leached product.

Journal of African Earth Sciences, 2016

Abstract The basal unit of the succession in the Illela borehole belongs to the Dange Formation c... more Abstract The basal unit of the succession in the Illela borehole belongs to the Dange Formation comprising thick calcareous and variably coloured dark-greyish shale of 36.30 m thick which is overlain by a 31.44 m thick limestone of Kalambaina Formation with 1.7 m thick shaly-limestone inclusive. The uppermost part of the section belongs to the Gwandu Formation which has intercalation of silty-clay, muddy siltstones with well lithified ironstone capping the borehole section. The limestone/carbonate microfacie as deduced from their salient lithologic, sedimentologic and paleontologic features are comparable to standard microfacie (SMF) types 9 and 10, i.e. bioclastic wackestone/bioclastic micrite and packstone-wackestone respectively. Diagenetically, syndepositional and early diagenesis have taken place particularly cementation and replacement in the carbonate rocks and these have greatly affected the reservoir potential negatively. The matrix/grain relationships indicate a shallow marine environment of deposition. The borehole section is delineated into upper foraminifera and lower ostracod biostratigraphic units as no formal biostratigraphic zonation could be attempted due to low diversity of both benthic foraminifera, marine ostracods and the absence of planktonic foraminifera. The similarity of the ostracod assemblages between this study area, Illela borehole, West Africa, North Africa (Libya), Mali and Niger Republic) and South-Western Nigeria (West Africa) suggests that a marine connection exists between the Gulf of Guinea and the Sokoto Basin via the area occupied by the River Niger during the Paleocene.

Journal of Applied Sciences and Environmental Management, 2015

The Akiri vein copper mineralization was investigated for its carbon and oxygen isotopic composit... more The Akiri vein copper mineralization was investigated for its carbon and oxygen isotopic composition to determine the characteristics of the mineralizing fluid. Carbon and oxygen isotope analyses of Akiri siderite range between δ 13 C values (-1.05 to-1.71‰) and δ 13 O values (-14.94 to-15.18) respectively. δ 13 C isotopic composition is comparable to values expected for Cretaceous marine carbonates. The 18 O depletion in the vein siderite indicates dominant meteoric water sources involved for carbonates precipitation. This significant depletion between the δ 18 O compositions of Akiri siderite compared with carbonates from other parts of the basin probably indicate differential formational temperature or fluid composition. © JASEM

NRIAG Journal of Astronomy and Geophysics

Scientific African

Mineral deposits show an intrinsic relationship with hydrothermal alteration and structures featu... more Mineral deposits show an intrinsic relationship with hydrothermal alteration and structures features which may be invaluable for regional scale exploration survey using spaceborne data. Within the Kaiama sheet, spatial data such as Landsat 8 OLI and ASTER digital elevation model were processed by enhancing hydrothermal alteration and geological lineaments. Image processing techniques such as band ratio and principal component analysis were used for alteration mapping, while Fry analysis and distance correlation analysis were applied for evaluating the structural attributes of gold and cassiterite mineralization. Evidence from image processing suggests the presence of clay and iron alterations within zones of known mineral deposits, while structural studies by application of the Fry and distance correlation analysis suggests gold and cassiterite occurrence is effectively controlled mainly by a NE-SW tectonic trend. The proximal association of gold and cassiterite mineralization with geological structures and hydrothermal alterations may be invaluable for defining a digital exploration criterion for the Kaiama sheet.

African Journal of Pure and Applied Chemistry, Oct 31, 2009

A study of the lixiviation of Manganiferrous Aluminosilicate Mineral in hydrochloric acid has bee... more A study of the lixiviation of Manganiferrous Aluminosilicate Mineral in hydrochloric acid has been undertaken. Experiments on quantitative lixiviation of the mineral showed that its dissolution rate depends on hydrogen ion concentration, reaction temperature and particle size. The activation energy calculated from the experimental data was 34.19 kJ/mole and this suggests a diffusion controlled mechanism. A reaction order of 0.2 with respect to the acid concentration was also found. With 8.42 M HCl at 80°C, about 69.27% of the 10 g/L of the manganiferrous mineral was dissolved within 120 min using < 0.09 mm particle diameter.

Canadian Metallurgical Quarterly, 2017

This study involves the leaching of the beryl ore with sulphuric acid (H 2 SO 4) solution for pre... more This study involves the leaching of the beryl ore with sulphuric acid (H 2 SO 4) solution for predicting optimal beryllium extraction conditions with the aim of assessing the importance of leachant concentration, reaction temperature and particle size on the extent of dissolution. A kinetic model to represent the effects of these variables on the leaching rate was developed. It was observed that the dissolution of beryl ore increases with increasing H 2 SO 4 concentration, temperature, decreasing particle size and solid to liquid ratio. At optimal leaching conditions, 89.3% of the ore was reacted by 1.25 mol/L at 75°C temperature and 120 minutes with moderate stirring, where 1612.0 mg/L Be 2+ , 786.7 mg/L Al 3+ , 98.1 mg/L Fe 3+ and 63.4 mg/L Ag + were found as major species in the leach liquor. The unleached products constituting about 10.7% were examined by X-ray diffraction (XRD) and found to contain primarily, siliceous compounds such as Xonotlite, Antigorite, Chrysolite and Kaolinite. RÉSUMÉ Cette étude implique la lixiviation du minerai de béryl avec une solution d'acide sulfurique (H 2 SO 4) pour la prédiction des conditions optimales d'extraction du béryllium afin d'évaluer l'importance de

A study was carried out on leaching of Nigerian kaolin ore by Oxalic acid (C2H2O4.2H2O). The raw ... more A study was carried out on leaching of Nigerian kaolin ore by Oxalic acid (C2H2O4.2H2O). The raw kaolin ore from Share, North central Nigeria was characterised by EDXRF (X-ray fluorescence) and major constituents were SiO2, Al2O3, and minor amounts of K2O, Na2O, CaO, TiO2, along with colour-imparting Fe2O3 and MnO that need to be remove to upgrade the kaolin suitability for industrial usages. The effects of parameters such as C2H2O4 concentration, temperature, and particle size were investigated. Under the standard leaching conditions of −75+63 μm particle size, 75 °C and 0.15 mol/L C2H2O4, about 78.5% of kaolin ore was reacted within 120 minutes. Comparison of the EDX analysis of the raw and leached kaolin showed removal efficiency of 97.1% for the iron at optimal leaching conditions. Energy of activation of 17.65 kJ/mol was obtained in the study supports the proposed diffusion control mechanism for the dissolution process.

Fountain Journal of Natural and Applied Sciences, 2013

Dam water and sediment were collected from ten different locations on Owalla dam to evaluate the ... more Dam water and sediment were collected from ten different locations on Owalla dam to evaluate the quality of the water. The average values of most physical-chemical parameters, the pH, temperature, total dissolved solid (TDS), NO3-, total hardness (TH) were within World Health Organization (WHO) and United State Environmental Protection Agency (USEPA) guidelines for drinking water. There was correlation between the results of Biochemical Oxygen Demand (BOD), sulphate and phosphate which were higher than the USEPA, Standard Organization of Nigeria (SON) or Canadian standard for drinking water. This is an indication of high load of organic pollutants. The dam sediments are texturally immatured coarse sands dominantly comprised of sub-angular to sub-rounded quartz, alkali feldspars with clay and iron-oxide coatings. The sediments geochemical composition is essentially silica, alumina and iron oxide. Toxic trace elements including Cd and Pb occur in very minor to insignificant concentrat...

The increasing demands for metals with gradual depletion of un-renewable resources warrant the ne... more The increasing demands for metals with gradual depletion of un-renewable resources warrant the need for industrial metals recovery from secondary sources including zinc–carbon batteries. The recycling from wastes is important as cost of safe disposal of its hazardous components is quite high compared to the amount of waste produced-cum-limited storage capacity. For instance, sub-Sahara African countries’ including Nigeria has been found to have dominance of non-rechargeable spent batteries containing precious metals content. These metals which may be toxic are valuable industrial elements if re-processed. In this work, combinations of acid leaching, solvent extraction and precipitation techniques were utilized in processing spent Tiger Head Zinc–carbon batteries assaying majorly 41.30 wt% ZnO, 4.30 wt% Fe2O3 and 2.69 wt% MnO2. At optimal conditions, the leach liquor was selectively treated to achieve 96.7% zinc recovery efficiency by Cyanex®272 extractant prior to its beneficiation ...

Journal Of Chemical Society Of Nigeria, 2013

Indian Chemical Engineer, 2020

The purification of Al(III) to alumina by bis(2,4,4-trimethylpentyl)phosphinic acid commonly call... more The purification of Al(III) to alumina by bis(2,4,4-trimethylpentyl)phosphinic acid commonly called Cyanex®272 in kerosene diluent from aqueous aluminium leach liquor was investigated. The influences of parameters such as equilibrium pH and extractant concentration on the extent of Al(III) extraction were accordingly examined. After appropriate optimisation, an extraction efficiency of 98.6% Al(III) by 0.25 mol/L Cyanex®272 in kerosene diluent at 27 ± 2°C in the equilibrium pH range of 3.0-3.5 was achieved from an initial biotite-rich kaolinite leach liquor containing 1864.7 mg/L Al, 123.4 mg/L Fe, 70 mg/L Mn and 17.6 mg/L Ti as a major constituents. Other metal ion species detected including Ca and Mg was found to occur from low to trace amounts (≤1 mg/L). Total stripping of Al(III) from the loaded organic phase was carried out using 0.1 mol/L H 2 SO 4 solution at an aqueous: organic (A:O) phase ratio 1: 1. The thermodynamic feasibility of extraction process to obtain high-grade alumina (Al 2 O 3 : 14-387-9021, melting point = 2056°C) gave the apparent standard enthalpy (ΔH), entropy (ΔS) and Gibb's energy (ΔG) of 3.87 kJ/mol, 10.57 J/K mol and −3177.6 J/mol respectively at 27 ± 2°C.

Transactions of the Indian Institute of Metals, 2018

The increasing global demands for pure manganese in steel production and manganese compound as di... more The increasing global demands for pure manganese in steel production and manganese compound as dietary additives, fertilizer, pigment, cells and fine chemicals production cannot be overemphasized. Thus, continuous efforts in developing low cost and eco-friendly route for purifying the manganese ore to meet some defined industrial demands become paramount. Therefore, this study focused on reductive leaching and solvent extraction techniques for the purification of a Nigerian manganese ore containing admixture of spessartine (O 96.00 Mn 24.00 Al 16.00-Si 24. 00) and quartz (Si 3.00 O 6.00). During leaching, parameters such as leachant concentration and reaction temperature on the extent of ore dissolution were examined accordingly for the establishment of extraction conditions. At optimal leaching conditions (1.5 mol/L H 2 SO 4 ? 0.2 g spent tea, 75°C), 80.2% of the initial 10 g/L ore reacted within 120 min. The derived dissolution activation energy (Ea) of 35.5 kJ/mol supported the diffusion reaction mechanism. Thus, the leachate at optimal leaching was appropriately treated by alkaline precipitation and solvent extraction techniques using sodium hydroxide and (di-2-ethylhexyl) phosphoric acid (D2EHPA) respectively, to obtain pure manganese solution. The purified solution was further beneficiated to obtain manganese sulphate monohydrate (MnSO 4 .H 2 O, melting point = 692.4°C: 47-304-7403) of high industrial value. The unleached residue (* 19.8%) analyzed by XRD consisted of silicileous impurities (SiO 2) which could serve as an important byproduct for some defined industries.

Mining, Metallurgy & Exploration, 2019

The increasing demand for pure aluminum and aluminum compounds of industrial quality from kaolini... more The increasing demand for pure aluminum and aluminum compounds of industrial quality from kaolinite ore cannot be overemphasized. Nigeria is one of the African countries endowed with abundant solid mineral resources that have not been sufficiently exploited to assist its indigenous industries. A wide array of applications of pure aluminum and its compounds are available, such as paper filling, refractories, adsorbent, catalysis, and paint additives. In this study, the upgrading of a Nigerian biotite-rich kaolinite ore by a hydrometallurgical route was investigated in oxalic acid media. During leaching studies, the effects of parameters including reaction temperature, lixiviant concentration and particle size on the extent of ore dissolution were examined. At optimal conditions (1.0 mol/L C 2 H 2 O 4 , 75°C), 92.0% of the initial 10 g/L ore was reacted within 120 min. The dissolution curves from the shrinking core model were analyzed and found to conform to the assumption of surface diffusion reaction, and the calculated activation energy of 33.2 kJ/mol supported the proposed model. The unreacted product (~8.0%) analyzed by XRD was found to contain siliceous impurities and could serve as a valuable by-product for certain industries.

Russian Journal of Non-Ferrous Metals, 2017

⎯In the present work, the leaching kinetics of covellite ore in ammonia solution was studied and ... more ⎯In the present work, the leaching kinetics of covellite ore in ammonia solution was studied and the following variables, the solution concentration, reaction temperature and particle size were considered. A kinetics model representing the effects of these variables on the leaching rate was developed and it was ascertained that the leaching rate increases with increasing solution concentration, reaction temperature and decreasing particle size. At optimal conditions, 75.1% of covellite ore was reacted within 120 min and the leaching reaction was diffusion controlled by surface chemical mechanism. The calculated activation energy of 56.98 kJ/mol supported the proposed dissolution process.

Chemical Speciation & Bioavailability, 2010

Abstract: Sequential extraction was carried out to determine the concentrations of some trace met... more Abstract: Sequential extraction was carried out to determine the concentrations of some trace metals (Mn, Cu, Fe, Pb and Cd) in the Kainji lake sediments from seven different locations in four fractions: exchangeable, bound to iron and manganese oxide, bound to organic matters and residual. This was to undertaken to assess the environmental fate of these trace metals. The BCR technique, a modified form of the Tessier method of sequential extraction was used.

Korean Journal of Chemical Engineering, 2017

Hydrometallurgical treatment of copper sulfide ore is increasingly establishing itself as a feasi... more Hydrometallurgical treatment of copper sulfide ore is increasingly establishing itself as a feasible route for the extraction of copper and recovery of associated precious metals value. This is attributed to the merits of this route, which include suitability for low-grade and complex ores, high recoveries, competitive economics, and other operational features. The leaching kinetics of Nigerian complex covellite ore was investigated in ammonia-ammonium sulfate solution. The concentration of ammonia and ammonium sulfate, the ore particle size, and the temperature were chosen as parameters in the experiments. The results show that temperature, concentration of ammonia-ammonium sulfate has favorable influence on the leaching rate of covellite ores; however, leaching rate decreases with increasing particle size. At optimal conditions (1.75 mol/L NH 4 OH+0.5 mol/L (NH 4) 2 SO 4 , −90+75 µm, 75 o C, with moderate stirring) about 86.2% of copper ore reacted within 120 minutes. The mechanism of the leaching was further established by characterizing the raw ore and the leached residue by EDXRF-chemical composition, SEM-structural morphology and XRD-phase identification studies. From the X-ray diffraction analysis, the partially unreacted Cu and S phases were presumed to be CuO, and the iron present in the CuS phase was mainly converted to hematite (Fe 2 O 3 •H 2 O), as the CuS phase disintegrated and remained in the residue afterward.