Interaction mechanism of magnesium ions with cassiterite and quartz surfaces and its response to flotation separation

Abstract

• The interaction mechanism of magnesium ions with cassiterite and quartz surfaces was proposed. • Magnesium ions suppressed the floatation of cassiterite and activated the flotation of quartz, and it was related to pH. • Magnesium ions considerably affected the adsorption of oleate species onto cassiterite and quartz surfaces. • Magnesium ions interacted with the mineral surfaces via specific adsorption of hydrated Mg(OH) + and Mg(OH) 2 . The interaction behavior and mechanism of magnesium ions with cassiterite and quartz surfaces and their effects on flotation separation of cassiterite from quartz were investigated by micro-flotation tests, surface adsorption experiments, zeta potential measurements, solution chemistry calculation, and X-ray photoelectron spectroscopy (XPS) analysis. The micro-flotation tests showed that solution pH significantly affected the floatability of cassiterite and quartz in the absence and presence of magnesium ions, and the preferred flotation separation of cassiterite from quartz was obtained at pH 6.8–8.2. Adsorption experiments and zeta potential measurements indicated that magnesium ions significantly affected the adsorption of sodium oleate on the mineral surface. The effect gradually aggravated with increasing pH due to the specific adsorption of hydrated Mg(OH) + and Mg(OH) 2 on the mineral surface. The adsorption mechanism of magnesium species onto the mineral surface was ascertained by XPS measurement. Magnesium species were adsorbed onto the mineral surface through interaction with the O sites of cassiterite and quartz particles, and a strong interaction occurred in the solution with high pH.