Novel approach to recycling of steel swarf using hydrometallurgy

Steel swarf is a hazardous waste which is challenging to recycle due to its high content of heavy metals and cutting fluids and is today commonly landfilled. The swarf can contain up to 80% iron and represents a potential secondary raw material for production of reagents like ferric chloride, which can be utilized in wastewater treatment. This work presents a novel hydrometallurgical approach for recycling steel swarf and production of ferric chloride by selective separation of iron from heavy metals. Swarf containing 69% iron was leached with hydrochloric acid. A leachate containing 24.600 mg/L Fe with 150 mg/L Mn, 12 mg/L Ni and <1 mg/L Cr and Mo was obtained. The oil-based cutting fluids largely remained in the solid residue with only 1% dissolution in the aqueous phase. These findings showed that ferric chloride solutions of 99% purity can be produced from steel swarf in a single leaching step.