The present invention relates to a method for removing a particulate contaminant material from a particulate mixed lithium metal phosphate material, comprising the steps of providing a particulate mixed lithium metal phosphate material, including a particulate contaminant material and a fine particulate mixed lithium metal phosphate, having the mass x*m, feeding the particulate mixed lithium metal phosphate material into a fluidizing stage containing particulate mixed lithium metal phosphate material of mass m, and fluidizing it in the fluidizing stage, feeding the fluidized particulate mixed lithium metal phosphate material to a sifting stage and passing it through the sifting stage, discontinuing the feed of the particulate mixed lithium metal phosphate material into the fluidizing stage after 10 to 100 times of the mass m have been fed into the fluidizing stage, fluidizing and sifting the material present in the fluidizing stage after discontinuing the feed, until the mass of the material present in the fluidizing stage becomes 10% to 100% of the mass m, and removing the remaining material from the fluidizing stage, wherein the sequence of steps b) to f) is repeated until the total mass x*m has been processed.