Gangue Entrainment in Olivine Flotation: Effect of MIBC Dosage on the Mitigation of Lizardite Recovery

摘要

Background: Olivine is an important industrial raw material especially for metallurgicalapplications like foundry sand, refractory, slag conditioning, etc. Loss On Ignition(LOI) value (>1%) is the main specification of olivine ore/concentrate for those areastogether with the chemical specifications.Objective: This flotation study was conducted in natural pH condition with Na-oleate ascollector to clarify the effect of frother (MIBC) dosage on the LOI value of olivine concentrate.Methods: Characterization of ore sample for this study was made by XRD, XRF and petrographicanalyses. Lizardite, a serpentine group mineral, was found to be a hydrated softfraction of ore sample in addition to hard olivine and pyroxene minerals constituting ore.Results: Finely ground soft lizardite adversely affected the olivine flotation in a way of entrainingmechanically into concentrate. LOI value of concentrate was observed mainly tobe froth volume depended issue, and therefore, mainly water recovery dependent. LOI valueincreased proportionally with water recovery at longer flotation time and MIBC dosagesindicating the entrainment of lizardite as the suspending hydrophilic component of waterphase. Certain rate of the hydrated lizardite mineral was thought to be recovered via hydrophobization,which was clearly seen especially at the initial stages of flotation period inthe presence of excess frother. This experimental finding was attributed to similar chemicalcomposition of minerals constituting ore, and accidental activation of lizardite.Conclusion: Lizardite recovery in froth was explained with accidental activation and/orweak attachment of locked particles onto froth bubble although main recovery mechanismwas determined to be mechanical entrainment. Olivine concentrate obeying the specificationsof metallurgical applications could be obtained at suitable MIBC dosage and flotationtime.