Papers by Author: Ambavalavanar Tharumarajah

Abstract: The aluminium industry is reducing its carbon dioxide emissions and environmental footprint. In order to identify and prioritise areas in the cast house where greenhouse gas emissions can be reduced it is necessary to quantify CO2e (CO2 equivalent tonnes) emissions for the various cast house operations. In this study two typical cast house layouts are examined. In one case, 22kg 99.85% aluminium remelt ingots are produced using chain conveyor ingot casting machines. In the second case, wrought alloy extrusion and rolling slab direct chill cast products are made. Both plants are sized at 500ktpa. The various process inputs in terms of energy and materials were identified and typical usage rates assigned. The results show that general electricity consumption, dross generation and furnace energy consumption are the three biggest areas of CO2e and should be targeted for improvement. Magnesium consumption also has a large effect in the case of the

Abstract: In spite of die castings being amongst the highest volume items manufactured by the metalworking industry, the influence of high pressure die casting (HPDC) process parameters on greenhouse gas (GHG) emissions remains largely unreported. In this article, the authors discuss the effect of some HPDC process parameters on GHG emissions using cradle-to-gate life cycle assessment (LCA) for both aluminium and magnesium alloys. Although the impacts reduced with increasing yields in both cases, it was determined that the GHG impact of magnesium alloy HPDC was more sensitive to HPDC yield irrespective of the ratio of primary/secondary alloys in the melt charge. The reasons for this include a greater dependence of magnesium alloy HPDC on high-emitting primary processing and the use of the highly potent GHG SF6 for melting. For magnesium alloy HPDC, a decrease in quality assurance (QA) rejects and cycle times also reduced GHG emissions, although their influences were found to be an order lower than that of yield.

Abstract: Light weighting of cars has the definite advantage of reducing fuel consumption and tail pipe emissions. In this respect, substitution of heavier steel components with magnesium ones can save on weight of the replaced component due to its weight advantage resulting in lowering green house gases (GHG). There are additional benefits when magnesium is applied to complex structures and assemblies such as an Instrument Panel (IP). The possibility of casting single piece magnesium cross-car beams of IP can reduce the number of components to be assembled as wells as ease the disassembly and recovery at the end of life. This study, considering these advantages of using magnesium for IPs, examines and compares the environmental life cycle impact of magnesium and traditional steel and plastic IPs. However, the results indicate that magnesium IPs can have higher GHG impact than equivalent IPs made from others. The technological avenues for reducing the impact of magnesium IPs are examined in an extended study, including impact of primary metal (assumed from China), improvements in casting manufacture and use of secondary metal. These improvements show substantial reduction of GHG in the manufacture of magnesium IPs and improvement in comparative GHG performance with other materials.