Bio-based nonalcoholic frothers for cleaner mineral flotation separation - a comprehensive review

Froth flotation is the most common upgrading technique for the beneficiation of low-grade minerals and finely liberated materials. The growing complexity of mineralogy and the decreasing grade of resources have increased flotation reagent consumption. Environmental concerns and regulations require mineral concentrators to use bio-based, eco-friendly reagents and to adopt cleaner production practices. The crucial role of frothers in flotation is well recognized, particularly in generating fine, uniformly dispersed, and stable bubbles (froth), essential for efficient mineral recovery. However, among various flotation reagents, they have historically received less attention. Nonalcoholic frothers, including alkoxy hydrocarbons and polyglycol-based compounds, are used in various flotation circuits. Recent studies have highlighted the potential of bio-based and nonalcoholic (low-toxic) frothers derived from natural sources, reporting notable improvements in flotation efficiency, reduced reagent consumption, minimized health risks, and a clear step toward environmentally responsible mineral processing. This review comprehensively examined natural nonalcoholic frothers derived from renewable resources, thoroughly evaluating their chemical structures, functional properties, applications in flotation processes, and performance compared to conventional synthetic frothers, which are often hazardous. Interestingly, several studies have shown that these natural frothers can exhibit unexpected functionalities, such as acting as collectors or even depressants, thereby influencing the overall separation process in unpredictable ways. Despite encouraging results, numerous research gaps persist when it comes to nonalcoholic frothers. This review highlights gaps and technical challenges by consolidating current knowledge and existing trends. It outlines clear research directions to accelerate the development and widespread adoption of nonalcoholic biofrothers in mineral flotation systems.