Deep recycling method of waste lithium iron phosphate battery

The invention discloses a deep recycling method of a waste lithium iron phosphate battery, which comprises the following steps: crushing positive and negative plates of the waste lithium iron phosphate battery, adding water and concentrated sulfuric acid, stirring to form slurry, carrying out spray oxidation on the slurry in oxidizing gas to obtain an oxide material, adding water into the oxide material, stirring, and filtering to obtain the waste lithium iron phosphate battery. Then, adding the leaching residues into a ferric iron salt solution, and carrying out reaction and filtration, so as to obtain carbon black; and alkaline substances are added into the leachate to adjust the pH value so as to carry out fractional precipitation, so that ferric phosphate, aluminum salt and lithium carbonate are precipitated in sequence. And the aim of completely recycling the lithium element, the iron element and the phosphorus element is fulfilled. According to the method, the waste lithium iron phosphate is oxidized an