Life cycle assessment as a tool for cleaner production: Application to aluminium trifluoride

Life Cycle Assessment (LCA) is a powerful tool in order to identify sustainable alternatives in process engineering. In this work, the LCA of two fluoride effluent treatment processes in the aluminium trifluoride (AlF3) manufacture has been carried out. Two scenarios have been considered: (i) chemical precipitation for fluoride removal, leading to a water-rich sludge, which has poor dewatering properties and therefore, must be managed in inert waste landfills, and (ii) the recovery of fluoride by crystallization as synthetic fluorite to be reused in the hydrogen fluoride (HF) manufacture. The LCA software SimaPro 7 (PRe Consultants BV) makes it possible to compare in terms of different methodologies like Eco-Indicator 99 and CML 2 Baseline 2000. Environmental metrics developed by IChemE were included in the software. The crystallization process in a Fluidized Bed Reactor allows reductions in the range of 20-40% for most metrics because of the recycled synthetic fluorite to the HF manufacture.