DIRECT DETERMINATION OF LANTHANIDES, YTTRIUM AND SCANDIUM IN BAUXITESAND RED MUD FROM ALUMINA PRODUCTION

An analytical procedure for the rapid, accurate and reproducible deter mination of lanthanides, yttrium and scandium in iron-aluminium rich m atrices as bauxites and red mud from alumina production was developed. After a suitable dissolution, the samples were directly analysed for these elements by inductively coupled plasma atomic emission spectrosc opy (ICP-AES), without using any separation or preconcentration step. Some of the investigated elements were also directly determined in the solid samples by x-ray fluorescence analysis (XRF). The optimum condi tions and analytical wavelengths were selected by both methods for eac h investigated element, after detailed studying of the spectral interf erences from the major elements from the matrix and the interlanthanid e-interferences. In the unique reference bauxitic material BX-N, for w hich only some proposed values exist, the concentration of nearly all lanthanides, yttrium and scandium Sc could be determined. The precisio n and accuracy of the described ICP-AES and XRF methods for these elem ents were tested on the geological standard materials SY-2, SY-3 (Cana dian syenites) and the proposed values of BX-N. In this study the enri chment factor of the above mentioned elements in red mud were also det ermined in comparison to the feed bauxites and the constancy of the co ncentration level in productions samples, followed up over three years . The obtained results for the lanthanides were evaluated on the basis of chondrite normalized distribution patterns.