Influence of iron ions on quartz and apatite flotation behaviour using alkyl ether amine as collector

Alkyl ether amine exhibits significant potential as an efficient collector for silica removal in collophane beneficiation. However, the presence of iron ions often significantly impairs the desilication performance of alkyl ether amines. To elucidate the influence of iron ions on the surface properties and flotation behavior of quartz and apatite particles using alkyl ether amine (EA) as the collector, micro-flotation experiments, solution chemistry calculations, contact angle measurements, zeta potential analyses, and X-ray photoelectron spectroscopy (XPS) were conducted. The findings showed that iron ions considerably decreased the floatability of quartz while having minimal impact on the floatability of apatite. In particular, increasing the concentration of iron ions from 0 to 8.0×10-4 mol/L reduced the quartz recovery rate from 84.6% to approximately 10% at pH 6. Contact angle analysis indicated that the adsorption of iron ions weakens EA's ability to enhance the hydrophobicity of quartz. Zeta potential measurements verified that iron ions modified the EA's adsorption behavior. XPS results further demonstrated that iron ions were chemically adsorbed onto quartz with higher binding affinity than EA, leading to their preferential adsorption on the quartz surface and consequently inhibiting EA adsorption. Therefore, the presence of iron ions reduces the separation efficiency in cationic reverse flotation of quartz from apatite.