Abstract
A low-grade gold ore from Ilesha-Itagunmodi, south western Nigeria was panned, dried and ball-milled before sieving into fractions. The morphological, mineralogical and chemical composition was studied by optical micro-scopy (Reflected and Transmission), X-ray diffraction (XRD) and Energy Dispersive X-ray fluorescence (XRF), respectively. The sieved fractions were subjected to chemical analysis (AAS). The +106 μm sieve had the highest concentration of the mineral and was then selected for the upgrade through froth flotation using standard reagents. In this paper a report on a 2k factorial experiment that provides an understanding of the impact of operational variables on the quantity of gold mineral obtained from the ore during froth flotation is presented. Analysis results showed that Ilesha-Itagunmodi gold ore is non-refractory with fine grain particles, amenable to froth flotation and contained about 20 other associated minerals, gold had a concentration of about 0.0024%. A com-bination of P-Xanthate and amine glycol collectors at a pH of 9.2 only produced a considerable increase in gold yield. This translated to about 87.13% increase in recovery of gold from the ore. Analysis of variance (ANOVA) was carried out and the model equation obtained was subsequently optimised to obtain a model equation that could be used in predicting the recoverable quantity of gold, indicating that F11,1-values for Collector concentration, Frother concentration, pH and Conditioning time were 156.86, 6.96, 43.81, and 56.77 respectively. A model with an F value of 88.41 was obtained which indicated that the model was significant. The model equation obtained was subsequently optimised to be able to predict the recoverable quantity of gold. A “Pred R-Squared” value of 0.9365 (93.65%) was also obtained and is in reasonable agreement with the “Adj R-Squared” value of 0.9534 (95.34%). It was established that Ilesha placer gold ore is amenable to froth flotation using standard reagents.
Highlights
One of the most striking differences between the ores of gold and those of all other metals lies in the extremely small proportion which the desired material bears to the worthless gangue by which it is accompanied [1]
Chemical and Bulk mineralogical compositions of the sample were studied by X-ray fluorescence (XRF) using a ED-XRFS MiniPAL 4 Model (2005), Xray diffraction (XRD) analysis using Radicon-10 diffractometer and Optical Microscopy was carried out using a Leica Reflected light microscope model number DMRX/MP60 respectively
XRF confirmed the presence of gold in the form of Au2O3 with a concentration of about 0.0024% other minerals of significant concentrations include Ti occurring as TiO2 and Ti2O3 and Fe occurring as Fe2O3 with 36.5%, 0.03% and 35.67% concentrations respectively (Table 5), while the X-ray diffraction (XRD) analysis showed that the gold oxide phase had a range of (32.4606 - 54.0942) for 2Ɵ values (Figure 1) and was sparingly and non-uniformly distributed within its ore [11]
Summary
One of the most striking differences between the ores of gold and those of all other metals lies in the extremely small proportion which the desired material bears to the worthless gangue by which it is accompanied [1]. The gold belt in the southwestern Nigeria is situated within Ife and Ilesha and is reputed to contain about 2 million ounces of gold that can be found to a depth of 3000 meters [3]. This Placer deposits contain low concentrations of gold [4]. The main purpose of this work is to determine the response of Ilesha-Itagunmodi gold to froth flotation using standard reagents. This will be of great economic benefit to the nation if properly exploited
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