Insights into the influence of temperature on the adsorption behavior of sodium oleate and its response to flotation of quartz

Abstract

Temperature affects the flotation of quartz in the calcium/sodium oleate (NaOL) system, while there is a lack of understanding of its potential mechanism. Therefore, in this work, the flotation response of quartz to temperature was investigated via micro-flotation experiments, interface property analyses, and theoretical calculations. Flotation results demonstrated that increasing temperature contributed to higher flotation recovery of quartz, which enhanced the removal of quartz from hematite. Surface tension results revealed that higher temperatures lowered the critical micelle concentration (CMC) and surface tension of the NaOL solution, and thus enhanced its surface activity. Solution chemistry calculations and X-ray photoelectron spectroscopy (XPS) measurements confirmed that the increased content of Ca(OH)+ achieved by increasing temperatures enhanced the adsorption amounts of calcium species (acting as activation sites) on the quartz surface. Dynamic light scattering (DLS) measurements verified that the association degree of RCOO− to form (RCOO)22− was strengthened. Furthermore, adsorption density measurements and molecular dynamics (MD) simulations confirmed that increasing the temperature facilitated NaOL adsorption toward the surface of the quartz, which was attributed to the stronger interaction between NaOL and the calcium-activated quartz surface at higher temperatures. As a result, quartz flotation was improved by increasing temperatures. Accordingly, a possible adsorption model was proposed.