ZeroWaste PCBs project D5.1: Report on Task 5.1

The main objective of this workpackage is to develop sustainable technologies for the recovery/re-use of the Metal Fractions (MF) and Non-Metal Fractions (NMF) contained in the powders obtained in output by mechanical pre-treatments of PCBs. For MF the specific objective of this WP has been to assess the state of ICPMS, and SIMS methodologies for the detection and quantitative analysis of precious metals and lanthanides both in solid and liquid phases. Mass spectrometry techniques are good tools to evaluate where the elements of interest are present and in which amount. The results of this WP are very important to evaluate the leachability of the different wastes processed in the other WPs. In fact, the combined use of these techniques (SIMS for surface analysis and ICPMS, LA ICP-MS for bulk analysis) gave useful information about the composition of waste during the various steps of waste processing. Literature mineralization techniques employ many kind of acid attacks using HNO3, HCl, HF and H3BO3 [1-3]. HF is usually used because the lanthanide elements are present as trace elements in silica matrix (geological samples). Some lanthanides, as example La and Ce, produce insoluble fluoride [4]. A second step by adding stoichiometric excess of H3BO3 re-dissolved the fluoride precipitates. Unfortunately, H3BO3 is not a high purity acid, with many impurities that could cause some errors in ICP-MS quantification [4]. In our case, the lanthanides are present as free elements, not in a silica matrix. For this reason is possible to develop a analytical procedure avoiding the HF use. The development of the free HF mineralization is very attractive with a view to an industrial application of this method, because HF is a very dangerous acid for health and for the glass part of the instrument. Only few work are present in literature regarding mineralization methods for lanthanides in non geological (silica) matrix [3, 5]. For this reason a deep study of the digestion processes was carried out, taking into account the different matrix that we had to mineralize.