Selective flotation of silicates and Ca-bearing minerals: The role of non-ionic reagent on cationic flotation

Flotation of pure minerals was performed to characterize the conditions for separation of silicates (palygorskite, quartz, orthoclase, albite, biotite, and muscovite) and Ca-bearing minerals (calcite, apatite and gypsum). These minerals constitute a large portion of gangue in some low-grade ores of industrial and rare metals (such as rare earth element REE, uranium, tantalum and niobium). The costs associated with pyro- and hydrometallurgical-processing of low-grade ores of strategic REE are prohibitively high due to huge consumptions of energy and reagents. Froth flotation can be applied to beneficiate the ores prior to application of extractive processes. Batch experiments were performed in order to generate scientific knowledge about zeta potentials and flotation characteristics of pure silicates and Ca-bearing minerals. The paper discusses the effects of mixing cationic collectors (amines) with non ionic reagents on the selective flotation of silicates and Ca-bearing minerals. The most important information from this study is about selective flotation of palygorskite from a family of silicates using a mixture of primary amine (Cataflot, 5 × 10−5 M) and non-ionic reagent (PX4826, 5 × 10−5 M) at pH 8. Also, the paper discusses a strategy for reducing the consumption of amine collectors by adding non ionic reagents. Synergistic effects of primary amine and non-ionic reagent in terms of calcite and apatite recoveries by flotation at pH 8 were observed.

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► Flotation of pure minerals constituting the gangue of rare metal low grade ores was performed.
► Mixed collector synergetic effects confirmed for silicates and Ca-minerals flotation.
► Selective separation of palygorskite from silicates and Ca-minerals is achieved at pH 8.
► Reagents consumption lowered with addition of non-ionic reagent for biotite–muscovite flotation.