AMENABILITY ASSESSMENT OF ILESHA LODE GOLD ORE TO FROTH FLOTATION USING CONVENTIONAL AND LOCALLY-SOURCED REAGENTS

Abstract

The preliminary mineralogical study carried out on Iperindo lode deposit in Ilesha gold field showed that gold occurs in finely disseminated quartz veins. This revealed that the ore is not amenable to gravity concentration because a lot of the fine gold paricles are lost into the tailings. The options left for the processing Ilesha gold deposit are cyanidation and amalgamation unfortunately both methods are environmentally unfriendly Hence, the search for suitable method favoured froth flotation. However, the challenge with froth flotation is that the conventional flotation reagents, particularly collectors and frothers are generally scarce and expensive when available. Thus, there is the need to source for local froth flotation reagents to process lode gold ore which can be readily available, affordable and environmentally friendly and also a possible subtitue to conventional reagents: xanthate and methyl iso butyl carbinol. This is the reason why the amenability assessment of Ilesha lode gold ore to froth flotation using locally-sourced reagents was investigated; comparing the recovery efficiency with convectional flotation reagents with a view to replacing the former with the latter. Comminution and characterization of the ore were carried out. Conventional reagents (potassium amyl xanthate and methyl iso-butyl carbinol) were purchased while the locally-sourced (potassium salt of groundnut oil and groundnut oil) were prepared. The pulp was prepared using 20% weight solid particle size of -63+45 μm. The pH of the pulp was adjusted to 9, pulp density of 50 g/cm3, agitation speed of 1200 rpm and agitation time of three minutes. Thereafter, 0.2 g/ton of K+ salt of groundnut oil (soap) as collector was added to the pulp and conditioned for three minutes. After this, 2 ml of groundnut oil was added as frother. The pulp was aerated for three minutes and floated gold concentrate was recovered, dried and weighed. The procedure was repeated at various range; pH of 8.0 to 10, pulp density of 50 to 250 g/cm3, collector concentration of 0.2 to 0.6 g/ton and agitation speed of 1200 to 1400 rpm respectively. The percentage gold concentrates recovered were imputed for both reagents. Composition analysis of the crude sample via Atomic Absorption Spectrometer (AAS) and Energy Dispersive X-ray Fluorescence Spectrometry (ED-XRF) revealed that the crude sample contain 4.10 ppm Au while 32.08% Si and 21.28% Fe are the major elemental constituents of the ore matrix. Chemical analysis of the concentrate samples using ED-XRF after flotation revealed the crude assay 103 ppm at -63+45 m has been successfully upgraded to 530 ppm and 490 ppm Au at a recovery of 92.60 and 85.63% via a pulp density of 50 g/cm3, collector concentration of 0.4 g/ton, pH of 9 and agitation speed of 1350 rpm when potassium salts of groundnut oil and potassuim amyl xanthate were both used as collector while groundnut oil and methyl iso butyl carbinol as frother. Good recovery of the gold concentrate in the diluted pulp was due to less collision between mineral and air bubbles coupled with the weight effect of the mineral which therefore, increases the chance of mineral particles – air bubble adhesion. The locally-sourced reagent is amenable to froth flotation and a potential substitue to conventional reagents. Thus, Ilesha lode gold deposit is worth mining and processing.