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.
Reaction Behavior during Heating Waste Plastic Materials and Iron Oxide Composites
Effective utilization of waste plastic materials is one of key technologies for environmental protection. In this work, we conducted fundamental researches on production techniques of reduced iron and H2 and CO gases from waste plastic materials (polyethylene and Refuse Derived Fuel) and iron oxide mixtures. The mixtures were heated up at the temperatures of 1000–1300°C in Ar gas stream. Concentrations of generated gases from samples were continuously measured by a quad-pole mass spectrometer.Conversion ratios into H2 from waste plastic materials reached 60–70% at 1300°C both in thermal decomposition of the waste plastic materials and reduction of the mixture samples. In the reduction of the mixture samples, conversion ratios into CO reached 70–80% at 1300°C. Final fractional reductions of samples containing RDF at 1200°C and 1300°C were 100%. When waste plastic materials are used as a reducing agent, plastics which contain large amount of fixed carbon are suitable to obtain a high fractional reduction.
Bevel RIE application to reduce defectivity in copper BEOL processing
Bevel etch used during wafer fabrication for semiconductor devices is discussed. In this case, the bevel etch process was utilized in middle of the line processing (MOL) to reduce back end of line (BEOL) defectivity. Tungsten and titanium nitride films, from the formation of contacts to the transistors, extend into the bevel region of the wafer and have been shown to initiate arcing. This can spread foreign material defects on the front side of the wafer in various BEOL post processing steps including subsequent reactive ion etching, SEM metrology and film depositions. The bevel etch tool confines a plasma etch to the outer edge of the front side of the wafer (which can be individually adjusted) and can remove dielectric, organic and Ti/TiN/W films using a fluorine based chemistry.