Eco-friendly and economical preparation of permanent ferrite magnet with ultrapure magnetite concentrate: Focus on the action mechanism of silicon and aluminum impurities

•Ultrapure magnetite concentrate (UMC) with a purity of 99.5% was obtained via a reverse flotation separation.•The feasibility of UMC substituting iron oxide red (IOR) for permanent ferrite magnet (PFM) preparation was confirmed.•A comparison between UMC and IOR for PFM preparation was studied.•The action mechanisms of Si and Al impurities in UMC on its magnetic powder were explored.•The effects of Mn and Cl in IOR on its PFM products were investigated.