Flotation separation mechanism of rutile and chlorite using CMC as depressant

Abstract

In ores containing rutile, chlorite is the most common silicate gangue mineral. However, the flotation separation of rutile and chlorite has yet to be thoroughly studied. In this study, carboxymethyl cellulose (CMC) was used to depress chlorite when sodium oleate (NaOL) was used as the collector of rutile. The selective depression and its mechanism were investigated through micro-flotation experiments, zeta potential analyses, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and particle video microscopy (PVM). Single mineral flotation showed selective depression of chlorite by CMC appeared at pH 7, NaOL concentration of 20 mg/L, and CMC concentration of 10 mg/L, when 88.39 % recovery difference between rutile and chlorite was obtained. The most effective concentration of CMC for the artificially mixed ore test was 15 mg/L, resulting in rutile recoveries and grades of 87.78 % and 75.28 % respectively. The results of Zeta, FTIR, and XPS tests indicate that the adsorption of CMC on chlorite surface is attributed to chemical and hydrogen bonding interactions, wherein the OH– and COOH– groups in CMC interact with hydroxyl groups of Fe²⁺ and Al³⁺ complexes, thereby diminishing chlorite floatability and impeding subsequent NaOL adsorption. PVM image further elucidates that hydration-repulsion interaction potentials between CMC-absorbed chlorite particles and gas bubbles deter particle adhesion. This markedly reduces chlorite ore carryover on bubble surfaces while minimally impacting rutile. This study can provide a theoretical basis for separating rutile and other vein minerals under the NaOL system.