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.
Production of Iron Nuggets from the Akpafu-Todzi Iron Ore and Artisanal Ferrous Slag using Post Consumer Thermosets (Waste Electrical Sockets) as Reductants
AbstractPost-consumer thermosets are difficult to recycle because, unlike thermoplastics, they cannot be remoulded to create other items as a result of the extensive cross-linkages in their structure. The increased production of thermoset blends and composites in recent years has greatly increased the amount of waste materials. However, higher levels of carbon and hydrogen present in thermosets make them a potential reductant in the iron extractive industries. In this research work, postconsumer thermoset was transformed into carbon resource through a charring process. The resulting carbonaceous material from the thermoset was used as reductant in the production of metallic iron from the Akpafu-Todzi iron ore and artisanal slag using the microwave technology through the composite pellet approach at varying firing times. Analyses by XRF, XRD and SEM/EDS showed that the Akpafu Todzi iron ore is comprised of the iron oxides hematite (Fe2O3) and wustite (Fe0.942O), while the artisanal slag was predominantly fayalite (Fe2SiO4). Complete reduction of the ore was attained after 120 min reduction but the maximum extent of reduction was 78.84% for the slag, demonstrating the potential of postconsumer thermosets to function effectively as a reductant in the iron extractive industry. Keywords: Reduction; Akpafu-Todzi Iron Ore; Post Consumer Thermosets; Waste Electrical Sockets
The breakdown of dense iron layers on wustite in CO/CO2 and H2/H2O systems
Examination of wustite single crystals reduced in CO/CO2 and H2/H2O gas mixtures has shown that in all cases a dense iron layer is formed initially on the oxide surface and that the porous growth of iron which is obtained under certain experimental conditions occurs as a direct result of the breakdown of this initial dense iron layer. Possible mechanisms of the iron layer breakdown are examined and compared with the experimental observations. A qualitative model of the breakdown process involving the nucleation of gas bubbles and the expansion of these bubbles in the iron layer is presented.