The effect of iron addition (up to 10,000 ppmw) on silicon purification during Al-Si solvent refining is studied in this work. The Al-Si based melts with different iron contents were solidified with different cooling rates. It is found that the iron addition does not affect boron and phosphorus removal rates. Iron distribution in microstructure demonstrates that iron does not have an effect on the diffusion behaviors of boron and phosphorus. The compositions of intermetallic compounds containing iron indicate that there is neither interaction between iron and boron, nor interaction between iron and phosphorus. Besides, the models of interaction between boron and an additive element are proposed. (C) 2016 Elsevier B.V. All rights reserved.