The effects of Ca(II) and Mg(II) ions on the flotation of spodumene using NaOL

• Effects of Ca(II), Mg(II) ions on the flotation of spodumene was investigated.
• Added Ca(II), Mg(II) ions change the reactivity of spodumene surface.
• Ca(II), Mg(II) ions could enhance the oleate ions adsorption on spodumene surface.

The effects of Ca(II) and Mg(II) ions on the flotation of spodumene using sodium oleate (NaOL) as the collector were investigated by micro-flotation tests, zeta-potential measurements, absorption measurements, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses. The micro-flotation results indicated that the pH value has a significant influence on the activation of spodumene minerals by Ca(II) and Mg(II) ions. Good floatability of spodumene was obtained with Ca(II) and Mg(II) ions at a pH of 12.5 and 10.0, respectively. In strongly alkaline solutions, Ca(II) and Mg(II) ions readily form hydroxy complexes (CaOH(I) and MgOH(I)) and precipitates (Ca(OH)2 and Mg(OH)2). FT-IR and XPS analyses revealed that the hydroxy complexes and the precipitates adsorbed onto the spodumene surface. These species contributed to the formation of oleate complexes and thus increased the amount of collector adsorption and the floatability of spodumene.

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