Metal recycling plays an important role in manufacturing activities, providing environmental benefits in terms of energy saving, reduced greenhouse gas emissions and reduced waste volumes. Manufacturing activities attempt to reduce the related costs and shorten the recycled metal supply chain. In the case of titanium, recycling is even more important, because the current titanium extractive metallurgy process, leading to titanium sponge, is extremely labour-, energy- and capital-intensive. Moreover, subsequent crushing and repeated melting of the sponge is necessary to remove inclusions and reach the required level of uniformity. Therefore, the multiple steps of the primary metallurgical processes mean that titanium-embodied energy is relatively high compared to that of other commonly-occurring metals.
The LIFE for life's material project aims to develop and test two innovative technologies: cryogenic machining and spark plasma sintering (SPS). Either technique alone would not allow reprocessing or recovery of titanium chips on site, but used in conjunction they open the way for a completely new approach to machining and closed cycles with zero waste production. The project will thus combine the two technologies to develop a small demonstration line for complete and direct recycling of titanium chips, and the chip removal process (about 1 500 kg/year). The process entails lower temperature and low thermal conductivity, meaning longer useful life of cutting tools and higher machining speeds for greater energy efficiency. By using liquid nitrogen instead of lubricant oil, high-quality grade 5 titanium pieces will be produced, titanium chips will not be superficially polluted by oils, and the final product will be protected against oxidation.