Background Steelmaking plants generate various kinds of residues, including oily mill sludge and scales. They are generated at the rolling mill plant during the cooling and rolling processes of hot steel. Generally, lowly polluted sludge and scales are recycled internally while highly polluted residues are landfilled. Both solutions lead to environmental issues: air pollution through dust and gas emissions and soil pollution by polycyclic aromatic hydrocarbons (PAH). The European steel industry generates an estimated 500 000 tonnes/yr of oily sludge and mill scales. More than 30% of this total is not valorised. Managing these residues will help combat soil, water and air pollution. Objectives The PLD project aimed to ‘de-oil’ the sludge and mill scales from metal industries through the application of the Paul Wurth Lhoist De-oiling (PLD) process. The heart of this recycling-process is a Multiple Hearth Furnace (MHF). The process consists of injecting air into the MHF, which induces an auto-thermal catalytic oxidation of the organic compounds. The feasibility of this process has been proved through laboratory tests and short-term semi-industrial pilot tests, but the project aimed to demonstrate it for the first time on an industrial scale. The project therefore aimed to demonstrate the feasibility, efficiency and cost-effectiveness of the PLD process, and to show that it lowers environmental impacts compared to current de-oiling technologies (e.g. lower CO2 and NOX emissions, lower energy consumption, a positive effect on air pollution, reduced landfilling of sludge). Results The PLD project aimed to demonstrate at full-scale, for the first time, the Paul Wurth Lhoist De-oiling (PLD) process for treating and recovering metallurgical residues. This technology would help industrial plants meet environmental legislation and cope with potential shortfalls in raw material supply. The project confirmed the efficiency of the process for treating oily sludges and mill scales from metal-working industries in laboratory tests, but the LIFE project was terminated early and the large-scale pilot plant was not completed. In the preparatory phase, the beneficiaries sought industrial partners willing to host the PLD pilot plant, with Carsid joined the partnership. However, at the Carsid site, an abandoned industrial area in Charleroi (Belgium), there were no guarantees that the local authority would grant a permit for the development of recycling activities, so work on a plant at this site was discontinued. The beneficiaries conducted a market analysis, focussing on the larger Charleroi region (North of France, Wallonia, Luxemburg, and the Ruhr region), to assess if enough oily sludge and mill scales would be available. It was concluded that the available amount per year is not sufficient to successfully run the pilot plant in a sustainable manner during and after the LIFE project. Although the project did not succeed in demonstrating the feasibility or cost-effectiveness of the PLD process on a large-scale, the beneficiaries confirmed the efficiency of the PLD technology in laboratory tests conducted with oily sludge and mill scales from five different steelmakers. The results were reported in a feasibility study (laboratory tests). The PLD process is thus capable of treating a wide range of different raw materials coming from various steelmaking plants. The feasibility on a larger scale, however, still needs to be demonstrated.