Method for removing aluminum and copper impurities from ferrophosphorus slag after lithium extraction of lithium iron phosphate battery

The invention provides a method for removing aluminum and copper impurities from ferrophosphorus slag obtained after lithium extraction of a lithium iron phosphate battery, and relates to the technical field of lithium ion battery material recovery treatment. According to the technical scheme, the method comprises the following steps: mixing ferrophosphorus slag obtained after lithium extraction of the lithium iron phosphate battery with villiaumite, and roasting to obtain roasted slag containing aluminum and copper fluorides; and mixing the roasting slag with water, carrying out leaching reaction under the condition of a certain pH value, and carrying out solid-liquid separation to obtain a leaching solution containing aluminum and copper complexes and impurity-removed ferrophosphorus slag. According to the method, deep removal of Al and Cu impurities is achieved, and the impurity-removed ferrophosphorus slag meets the requirement for re-preparation of battery-grade iron phosphate and can be used for re-prep