ANALYSIS OF TRACE-ELEMENTS IN COAL FLY-ASH AND THEIR LEACHATES - RESULTS OF THE ENEL-EDF ROUND-ROBIN TEST

The ENEL-EDF collaboration handling with the ashes and residues produc ed by fossil-fired power plants, began on early 1993, allowed to get e xtensive research on analytical field. The present study deals with as sessment and improvement of trace element analysis reliability in coal ash and coal ash leachates. Eight Italian Laboratories from ENEL and four French laboratories from EDF took pan in this test. Two samples w ere studied (a certified reference material NIST 1633a and a fly ash w ith unknown concentration coming from an Italian coal-fired power plan t) and eleven trace elements (As, Cd, Cr, Cu, Hg, Ni, Ph, Sb, Se, V an d Zn) were analysed. A ''standardised'' mineralization procedure for t he fly ash samples, which employs a microwave oven, has been validated by means of this Round Robin Test. For die analysis step, name atomic absorption spectrometry (FAAS), graphite furnace atomic absorption sp ectrometry (GFAAS) or inductively coupled plasma atomic emission spect rometry (ICP-AES) have been employed by die laboratories. Leaching tes t have been applied to the unknown ash sample, following the Italian s tandard test (IRSA, using acetic acid) and the French standard test (A FNOR, using demineralized water). In order to assess separately the co ntribution to the total error due to the sample preparation and that t o the analytical determination an aliquot of each solution has been fo rwarded to ENEL Central Laboratory of Piacenza for ICP-MS analyses. St atistical analysis is achieved following ISO 5725 Standard.