The effect of mechanical grinding on the reduction of iron steel wastes with carbonized almond shells

In this thesis, the effect of advanced milling process on reduction of mill scale which is one of iron and steel wastes and obtained from KARDEMİR, with carbonized almond shells, was investigated. The studies consist of carbonization of almond shells, grinding of the mixture of scales and carbonized almond shells in a high energy mill, pelletizing the ground powders, and treating these pellets at different temperatures and times. The carbon content of the almond shells which were processed at 800 °C for 1440 minutes was 97.97% and the sulphur content was 0.014%. The thermal value of this sample was found to be 8647.6 cal / g. In the second stage of the studies, the mixture consisted of the mill scale and carbonized product, was prepared with mixture/ ball ratio of 1/10, FeO/C ratio of 80/20, 70/30 and 60/40 and milled in a high energy mill for periods ranging from 30 to 120 min. After grinding, active powders were pelleted with the help of a binder (CMC) and these pellets were subjected to reduction process in a furnace at different temperatures and times. In the preliminary experiments of the reduction studies, FeO / C ratio was prepared as 60/40, 70/30 and 80/20 and subjected to advanced grinding process in the spex mill for 30, 60, 90, 120 minutes, and it was found that the most appropriate ratio for FeO /C was 70/30. After the reduction process at 1100 ℃ for 120 minutes, both in the macro image and at the XRD analysis of the sample which was prepared as FeO/C=70/30 and subjected to the grinding process for 120 minutes, were observed that the metallic Fe was obtained. In the A2-1 coded sample which was processed at 1200 oC for 30 minutes, reduction was completed, melting was observed in A2-2 and A2-3 coded samples, melting was completed and re-oxidation started in A2-4 coded sample. A high metallic Fe phase was observed in the sample (A3-1) which was reduced for 30 minutes at 1300 oC. However, as the residence time at 1300 oC increased, a phase with iron oxide and iron carbide was formed (A3-2 coded sample). In the longer residence time at a temperature of 1300 oC, it was observed that completely formed phases of iron and iron carbide. It was observed that a metallic and wavy phase was formed on the surfaces of the samples obtained as a result of the experiments carried out at 1400 oC. The structures seen at this temperature were not seen in the studies carried out at 1100,1200 and 1300 oC. As a result of the studies, the most suitable results in terms of total iron content were observed in A1-3, A2-2, A2-3, A3-1 and A3-2 coded samples. In the analysis of these samples with metal spectrometer, it was seen that the highest metallic iron was obtained as 94.6% in the sample which was processed at 1200 oC for 120 minutes (A2-3 coded sample).