Recycling Waste Bakelite As A Carbon Resource In Ironmaking
Bakelite is a 3-dimensional cross-linked network structured thermosetting polymer which is difficult to recycle after use. However, it contains high levels of carbon and CaCO3 that can be recovered for use as reductant and fluxing agent in ironmaking. In this work we report the use of postconsumer bakelite as reductant for the production of metallic iron from iron oxide in a horizontal tube furnace through the composite pellet approach.Gas emission studies were conducted by pyrolysing raw bakelite at different temperatures within the temperature range 1200-1600 °C in a horizontal tube furnace. Following this,composite pellets were then formed from mixtures of iron oxide and post-consumer bakelite.The iron oxide-bakelite composites were heated from room temperature to 1200 °C and then between 1200-1600 °C in a continuous stream of pure argon and the off gas was analysed continuously using an infrared (IR) gas analyser. Elemental analyses of samples of the reduced metal were performed chemically for its oxygen content using a LECO oxygen/nitrogen analyser. The extent of reduction after ten minutes was determined from the oxygen content. Gas emission studies revealed the emission of large volumes of the reductant gases CO and CH4along with CO2.It is further demonstrated that post-consumer bakelite is effective at reducing iron oxide to produce metallic iron.
A Laboratory Study of the Reduction of Iron Oxides by Hydrogen
To reduce the emission of greenhouse gases by the steel industry, particularly for ironmaking, the production of DRI (Direct Reduced Iron) using hydrogen as the reducing gas instead of carbon monoxide is being considered. In this context, the reduction of pure hematite by hydrogen was studied at the laboratory scale, varying the experimental conditions and observing the rate and the course of the reaction. All the reduction experiments were performed in a thermobalance and supplementary characterization methods were used like scanning and transmission electron microscopy, X-ray diffraction, and Mossbauer spectrometry. The influence of rising temperature in the range 550-900°C is to accelerate the reaction; no slowing down was observed, contrary to some literature conclusions. A series of experiments consisted in interrupting the runs before complete conversion, thus enabling the characterization of partially reduced samples. Interpretation confirms the occurrence of three successive and rather separate reduction steps, through magnetite and wustite to iron, and illustrates a clear structural evolution of the samples. Finally, the influence of the sample type was revealed comparing a regular powder, a nanopowder and a sintered sample. The regular powder proved to be the most reactive despite its larger grain size, due to a more porous final structure.
Utilization of Waste Wood for Production of Iron, Carbon Monoxide and Hydrogen without generating Carbon Dioxide
National legislation within Japan has increased the need for the development of new process technologies that will utilise waste wood materials. The present study is aimed at generating some fundamental data with respect to the reduction of iron oxide by waste wood. By using a high frequency induction furnace, mixtures of wood + Fe2O3 were heated very rapidly to temperatures between 1673 and 2073K in a stream of argon. Gas chromatographic technique applied on exhaust gases escaping from the furnace revealed that the gaseous reaction products consisted mainly of carbon monoxide and hydrogen. On the other hand, conventional chemical analysis and X‐ray diffraction technique made on condensed‐phase reaction products detected the presence of Fe‐C alloys, solid carbon (char) and ferrous oxide, depending upon the atomic ratio of C/O within wood + Fe2O3 mixture. Thus, the reaction products consisted of metallic iron, ferrous oxide, char, CO, CO2, H2O, H2 and CH4, depending upon C/O atomic ratio within the mixture and the experimental temperature. The results were in good agreement with values calculated from thermodynamic equilibrium.