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.
Use of laser scanning confocal microscopy for morphological taxonomy and the potential for digital type specimens (e-types)
The use of laser scanning confocal microscopy (LSCM) for creating taxonomic descriptions of copepods is investigated. A new technique is described, which employs a contour filter to process digital LSCM images, allowing taxonomic information to be quickly and accu- rately distilled into a simple illustration. LSCM allows the imaging of whole specimens, which can be rotated and viewed from any angle—a major benefit over light microscopy. Using this tech- nique, it is suggested that taxonomic descriptions can be rapidly produced in a fraction of the time required to produce similar descriptions using traditional light microscopy and hand drawing techniques. Good staining of specimens is, however, essential to produce accurate descriptions and more research is required in this area. The use of LSCM for morphological taxonomy shows great potential, not only for producing taxonomic descriptions, but also providing a comple - mentary adjunct to traditional type specimens in the form of 3D digital 'e-types' deposited in recognised international databases.