Exploring new methods for recycling lithium iron phosphate black mass is essential. Phosphorus, a critical raw material for the European Union, is often overlooked in battery recycling research. The standard practice involves selective leaching of lithium from lithium iron phosphate black mass, suggesting that the leaching residues can be reused directly for the synthesis of new lithium iron phosphate. Unfortunately, this aspect is disregarded by battery manufacturing companies because of the purity of the iron phosphate obtained through recycling. To address this, methodologies for the joint recovery of lithium and phosphorus are explored. Through pyrometallurgical and mechanical processes the active materials are separated from end-of-life battery cells. The obtained fraction is then leached in dilute sulfuric acid and sodium sulfide for selective leaching of lithium and phosphorus. Finally, the lithium and phosphorus are reprecipitated through pH control and heating. The overall process is simulated in the HSC Sim software for calculation of process mass and heat balance and benchmarking. All simulations are scaled with reference to a pilot plant to be constructed in Greece in cooperation with the Sunlight Group in the frame of the project “ReLiFe: Recycling of Lithium Ferrophosphate in the RIS Region.”