Synergetic effect of a mixture of anionic and nonionic reagents: Ca mineral contrast separation by flotation at neutral pH

•Effect of mixed collector system on Ca-mineral selectivity was elucidated by flotation data.•Mixing of anionic and nonionic reagents enhance the calcite/francolite separation.•Using nonionic reagent allows sodium oleate consumption decreasing by 5-fold. Ca mineral flotation was performed to characterise the separation conditions of calcite, francolite, fluorite and gypsum at neutral pH. These minerals constitute the gangue of metallic or sedimentary ores. The separation of Ca minerals is difficult because of their similar surface properties. Thus, the effect of using different electrolytes on francolite zeta potential measurements was studied. Batch experiments were performed to generate scientific knowledge of Ca mineral flotation behaviour at neutral pH. This paper discusses the effect of mixing anionic collectors (sodium oleate, hydroxamic acid, D2EHPA) with nonionic reagents on the selective separation of Ca minerals. The most interesting observation is the separation of gypsum from other Ca minerals using a mixture of sodium oleate and nonionic reagents. Additionally, this paper discusses the enhancement of separation contrast between calcite and francolite by adding nonionic and anionic reagents.