About 650.000 t of BOF slag are generated each year during steel production process by Austrian steel plants of voestalpine. Austrian legislative authorities restrict its use as a recycled construction material in road building to the bituminous binder course with lifetime responsibility of the producer. This responsibility also applies to possible future contaminants, that are currently not considered. Process alternatives for the recycling of BOF - slag are therefore addressed in a project of K1-MET. In this work within project 1.2 (Utilization of Metallurgical Slags) selective leaching with citric acid is investigated to recover the iron bearing oxides contained in the slag (magnesio wuestite, Ca and Mg ferrites) with the least possible amount of phosphorus, which is contained in dicalcium silicate only. Based on the well-known testing method for bioavailable phosphorus, citric acid was tested for its potential as an industrial leaching agent. In the literature part the origin of BOF slag, on average produced annual quantities, problems involved with individual ingredients in case of recycling and selective leaching were discussed. The production of citric acid and the extraction of phosphorus from the eluate were also considered. In the experimental part, systematic tests for optimum leaching conditions concerning volume of eluate, leaching time, leaching temperature and pH value were performed on industrial BOF slag from voestalpine Stahl GmbH. Combination with carbonic acid and combined milling and leaching were also tested. As the acid consumption is comparatively high, special effort was spent on the regeneration of citric acid. Results are presented based on mass balances with special regard on Fe and P content yield in the residue. The dissolution of Fe could be avoided almost entirely, while complete removal of P from the residue could not be achieved. The possibility of citric acid regeneration has been proven.