Effects of alkali pretreatment on the flotation of spodumene and feldspar.

• Alkali pretreatment could improve the floatability difference between spodumene and feldspar. • The surface dissolution improved the flotation kinetic parameters of spodumene. • Alkali pretreatment changed the mineral surface ions distribution. The surface chemistry and morphology of minerals produced by alkali pretreatment affects their flotation behaviors. This study systematically investigated the impact on the mineral surface dissolution using NaOH as a modifier, which could modify the surface properties of minerals and improve the floatability difference between spodumene and feldspar. Various characterizations including flotation experiments, flotation kinetics analysis, SEM analysis, microcalorimetry analysis, zeta potential measurements, XPS analysis and ICP-MS analysis were conducted. Single minerals and actual ore flotation experiment results were in good agreement, and the flotation grade and recovery of Li 2 O in spodumene concentrates increased by 1.11 % and 6.99 %, respectively, after NaOH pretreatment. The flotation kinetics results demonstrated the cumulative recoveries of spodumene exhibited the best agreement with the first-order kinetic model and the flotation kinetic constant was improved after alkali pretreatment. Microcalorimetric results indicated the absolute values of the reaction heat for spodumene were higher than that of feldspar reacted with collectors after the alkali pretreatment. XPS and ICP results demonstrated the amounts of Al active sites on the spodumene surface was significantly increased after alkali pretreatment compared to that on the feldspar surface, improving the selective adsorption of NaOL. [ABSTRACT FROM AUTHOR]