Recovery of magnesite from silicate gangue minerals via reverse flotation using a novel alkyl ether amine collector

Magnesite (MgCO 3 ) has wide applications in industries including refractories, building materials and environmental remediation. However, magnesite applications may be limited due to common association with gangue minerals such as quartz and other silicate minerals (talc) which need to be removed in order to produce a high-grade magnesite concentrate. The removal of silicate gangue minerals is a long-standing challenge in magnesite ore beneficiation, particularly using froth flotation and collectors display mediocre selectivity. In the quest for more efficacious collector for flotation to separate quartz (SiO 2 ) and talc (Mg 3 Si 4 O 10 (OH) 2 ) from magnesite, a novel alkyl ether amine collector was studied in a three-stage reverse flotation process. Specifically, the effects of pH and collector concentration on the flotation performance were investigated. Subsequently, Fourier-transform infrared (FTIR) spectroscopy, Atomic Force Microscopy imaging (AFM) and zeta potential measurements were employed to understand the interfacial reaction between the collector and magnesite, talc and quartz, respectively. The reverse flotation tests results showed that the optimal conditions for separating silicates from magnesite were pH 10 using a collector concentration of 120 g/t. Optimal conditions (pulp pH 10 and 120 g/t alkyl ether amine collector) in a continuous reverse flotation process improved Mg concentrate grade from 22.9 % to 24.5 % while reducing silicon (Si) content from 3.8 wt% to 1.1 wt%. The zeta potential analysis showed that, at pH 10, the collector exhibited stronger adsorption on quartz than on magnesite. Complementary FTIR analysis confirmed adsorption was not restricted to quartz but also affected talc in the feed sample. These results indicate the collector could be effectively utilized in a dual reverse flotation process to reduce Si content by removing both quartz and talc. The findings contribute to advancing metallurgical processing in the concentration of magnesite ore, which could be further processed for Mg production.