Reduction of iron-oxide by ball-milling with hydrogen gas flow

A new method for reducing iron-ore without greenhouse effect gas exhaust was developed to prevent the global warming. The reduction of α-Fe₂O₃ (hematite) by ball-milling with hydrogen gas flow was studied by XRD, SEM, TEM and Moessbauer spectroscopy. Iron oxide (α-Fe₂O₃) powder was charged into a container for ball-milling with stainless steel balls. The container was designed to flow gas during ball-milling process. It has two holes, one of which is for inducing hydrogen gas into container, other one is for exhausting a producing gas out of the container. Milling was interrupted to take samples for estimating the deoxidization process. Charging and removal of the samples were done in a high purity argon atmosphere. A vibrating ball-mill machine was used. The results of X-ray diffraction measurement show that the reduction of iron-oxide starts at 18.0 ks of ball-milling. The intensity of Bragg peaks corresponding to the Fe₂O₃ decreased with milling time. Conversely to this, the intensity of Bragg peaks of α-Fe increased. At 216.0 ks of milling, almost the Bragg peaks of Fe₂O₃ disappeared and the only Bragg peaks of α-Fe remained. During this reducing process, Fe₃O₄ and FeO appeared as intermediate states between α-Fe₂O₃ and α-Fe. Nano-crystalline Fe was obtained by the reduction of iron-oxide by ball-milling with hydrogen gas flow.