Green flotation depressats of typical salt and silicate gangue minerals in froth flotation – a comprehensive review

Abstract

Salt and silicate gangue minerals are widely present in various actual ores. To achieve efficient utilization of valuable minerals, it is usually necessary to precisely separate them from gangue first. Flotation is the preferred method for efficiently removing salt gangue and enriching useful minerals. Since the floatability of these gangue minerals is similar to that of valuable minerals, selective flotation reagents such as depressants, collectors and frothers must be added to increase the difference in their floatation. Some traditional inorganic depressants (phosphates, silicates and fluorides) pose environmental risks due to the generation of refractory wastewater. Green depressants have received extensive research attention due to their eco-friendliness and excellent inhibitory performance. This paper systematically reviews and comments on the crystal structure characteristics and flotation response mechanisms of typical salts (carbonates, sulfates, and halides) and silicate gangue minerals, with a focus on analyzing the efficacy, environmental friendliness, and application progress of green depressants in the targeted depression of the above minerals. The research status of green depressants has been systematically sorted out and classified based on four criteria: source, associated waste, inhibitory efficacy and degradability. Finally, the typical applications of green depressants in the flotation of common salt and silicate gangue minerals are systematically reviewed, and their development trends and existing challenges are summarized and prospected. This review aims to provide theoretical support for the design and optimization of green depressants and reduce the environmental load brought about by some traditional inorganic depressants.