Reagent optimization across a UG2 plant

Reagent optimization is very important in the recovery of valuable metals from their ore via flotation. This is particularly important for large platinum operations where correct reagent regime and addition system can provide improvement opportunities in recovery and grade. Also reagent optimization can reduce reagent costs for the rougher, scavenger and cleaner flotation units. Reagents were optimized in the flotation of hot floats from the plant at laboratory scale. It was found that in order to save cost, the collector and depressant must be reduced in the roughers and cleaners respectively. This report presents results and some practical considerations that must be taken into account to optimise reagent usage

Effect of pH on the recovery and grade of base metal sulphides (PGMs) by flotation

This study investigated the effect of pH on the recovery and grade of the Platinum Group Metals (PGMs) and base metal sulphides from the UG2 ore of the Bushveld Complex. This was achieved through running a series of test work in a Denver flotation cell at varying pH 6-11 at constant reagent dosage. The UG-2 reef is characterized by two predominant gangue phases i.e. chromite and silicate, that have significantly different physical and chemical properties. The test work was aimed at evaluating which pH gives best recoveries, and finding the effect of the chrome content in these recoveries. A pH of 9 gave the highest recovery compared to other pH ranges. However, the highest PGM grade was attained at a pH of 6 which is slightly acidic. Ideally this trend could be expected since the collectors (xanthates) are more stable in alkaline medium. The higher PGM recovery was also accompanied by higher chrome content as a result of their similar chemical properties

Characterization of Baruten Local Government Area of Kwara State (Nigeria) fireclays as suitable refractory materials

Studies have shown that adequate attention needs to be paid on processing of solid minerals that are potentially available in Nigeria to address its economic problem. Clays from five major towns in Baruten Local Government Area, Kwara State, Nigeria were examined using ASTM guidelines to determine their suitability for refractory applications. The clay samples were classified as Alumino-Silicate refractories due to high values of Al2O3 and SiO2. The results showed apparent porosity (19.4-25.6%), bulk density (1.83-1.90 g/cm3), cold crushing strength (38.7-56.1 N/mm2), linear shrinkage (4.4 – 9.3%), clay contents (52.71-67.83%), moisture content (17.0-23.6%), permeability (68-82 cmsec-1), plasticity (16.7-30.4%), refractoriness (>1300oC) and Thermal Shock Resistance (23-25 cycles) for the clay samples, which were measurable with the established standards for fireclays, refractory clays/brick lining or alumina-silicates and kaolin. Hence, the natural clays could suitably replace imported clays in some refractory applications. Appropriate use of information from this study would improve Nigeria’s industrialization and economic diversification.Keywords: Apparent Porosity, Bulk Density, Clay, Shrinkage and Refractor

Development and Evaluation of an Interactive Instructional Package for Teaching Engineering Graphics Skills

Exposure to modern pedagogical approaches and methods with appropriate instructional media can enhance the development of high-level critical thinking and technical skills. This study examined the development of an interactive instructional software package for teaching engineering graphics and evaluated its relative effectiveness on second-year undergraduate engineering students' academic achievement, skill transfer, and retention. In this study, the quasi-experimental, pre-test, post-test, control group design was employed. 45 research participants were sampled, employing two-stage stratified sampling technique, which comprises the simple random sampling to assign students into three groups from the study population and systematic sampling with k = 3 to select 15 students from each group to a control group and experimental groups A and B. The control group was exposed to conventional classroom instruction (CI), group A to computer-aided instruction (CAI); and group B to conventional and computer-aided instructions (CCAIs). A computer-aided learning package on engineering graphics was developed using the Camtasia software package, which served as the treatment instrument. The pre-test and post-test data used for analysis stemmed from a validated Engineering Graphics Achievement Test instrument. Analysis of covariance and Sidak post hoc test statistical analysis of the groups' performance provided the results on the comparative effects of the treatment conditions. Findings indicated significant differences between the academic achievement, skill transfer, and retention of students, exposed to CCAIs, and CI or CAI strategies. When used together, a significant improvement in students' academic achievement, transfer, and retention of engineering graphics skills occurred than either the CI or CAI strategy used alone

Optimization and characterization of biofuel from waste cooking oil

Abstract: Waste cooking oil (WCO) is regarded as one of the cheapest feedstock for the production of biodiesel. The waste cooking oil used in this study was prepared in the laboratory by adding 5 wt. % of oleic acid into 95 wt. % of soybeans oil. 10 wt. % of titania-supported-magnesium oxide catalyst (MgO/TiO2) used was prepared by incipient wetness impregnation and characterized using XRF and XRD. These materials were tested and used as catalyst for the conversion of waste vegetable oil to biodiesel in the presence of methanol and hexane as co-solvents. Methanol to hexane mole ratio of 1:1 was employed in the transesterification process. The effects of reaction time, reaction temperature and hexane co-solvent on the waste vegetable oil conversion have been established. The 1HNMR analysis was used to estimate the waste vegetable oil conversion and the average molecular formula of fatty acid methyl esters (FAME) produced. It was observed that the oil conversion increased with the increase in reaction time, reaction temperature and use of hexane as co-solvent

Full factorial design approach to carbon nanotubes synthesis by CVD method in argon environment

Whereas meeting product quantity and quality are prime intent in process optimization of materials manufacturing, the application of the more reliable full factorial experiment has not been well-explored in optimization studies of Carbon nanotubes (CNTs) synthesis. In this study, statistical full factorial design of experiment was explored in the parametric studies of CNTs synthesis via acetylene-chemical vapour deposition (CVD). Bimetallic (Feî¸Co) catalyst supported on CaCO3 was employed for the synthesis of CNTs. The dependence of CNTs yield on the growth time (45/60 min), growth temperature (700/750 °C), acetylene flow rate (150/190 ml/min), and argon flow rate (230/290 ml/min) was investigated in the 24 factorial design of experiment. The growth temperature and acetylene flow rate were found to have the most significant effects on the yield of CNTs, and a maximum yield of 170% was obtained at growth conditions of 60 min, 700 °C, 190 ml/min acetylene flow rate, and 230 ml/min argon flow rate. Since acetylene undergoes polymerization or dissolution during non-catalyzed thermal decomposition, the significant effects of temperature and acetylene flow rate as illustrated by the factorial analysis suggests that the selective ability of the Feî¸Co/CaCO3 catalyst towards CNTs growth in the thermal decomposition of acetylene in CVD was mainly thermodynamics-controlled. Characterization of CNTs samples synthesized at different conditions shows that highest-yield conditions do not guarantee best quality properties. Keywords: Optimization, Full factorial design, Carbon nanotubes, Chemical vapour depositio