Rare earths (La, Ce, Nd) and rare metals (Sn, Nb, W) as by-products of kaolin production – Part 3: Processing of fines using gravity and flotation

[Display omitted] •A fine −53μm kaolin residue was treated by flotation/gravity for LREE recovery.•Effect of dispersant addition during the desliming operation have been tested.•Flotation efficiency with oleate increases with dispersant removing clay coating.•Falcon UF saturation tests shows an incr...

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Bibliographic Details
Published in:Minerals engineering 2016-09, Vol.95, p.96-106
Main Authors: Filippov, L.O., Dehaine, Q., Filippova, I.V.
Format: Article
Language:English
Subjects:
Antimony
Byproducts
Clay coating
Falcon concentrator
Flotation
Gravitation
Light rare-earths
Low grade ore
Rare earth metals
Recovery
Residues
Sodium
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Summary:[Display omitted] •A fine −53μm kaolin residue was treated by flotation/gravity for LREE recovery.•Effect of dispersant addition during the desliming operation have been tested.•Flotation efficiency with oleate increases with dispersant removing clay coating.•Falcon UF saturation tests shows an increased separation performance with desliming.•Benefit of screening is shown as well as the superiority of flotation for the fines. This is the last in a series of papers addressing the by-product potential of Light Rare-Earth Elements (LREE, La, Ce, Nd) and rare-metals (Sn, Nb, W) within the St Austell kaolin deposits (UK). Previous results have shown that heavy minerals are pre-concentrated in the micaceous residue which displays relatively high LREE content (around 170ppm) hosted by monazite. A combined gravity/flotation concentration flowsheet, starting with classification of the residue into 3 size fractions (+150μm, 150–53μm and −53μm) was developed. This study presents the results of the clay-rich −53μm size fraction beneficiation by flotation using sodium oleate and hydroxamate as collectors and compares them to results obtained with a Falcon Ultra-Fine (UF) concentrator. The effect of dispersant addition during de-sliming operations on flotation efficiency was also investigated. The LREE grade in the floated product obtained with sodium oleate increased from 3370ppm to 5350ppm and recovery from 30% to 80% with dispersant which is attributed to clay coating. Saturation tests performed on the Falcon UF show a positive effect of desliming on separation performance which produces higher LREE grades and recoveries. Comparison of flotation performance and Falcon UF concentration of monazite to previous results obtained with the Falcon Semi-Batch (SB) gravity concentrator on the un-screened raw residue clearly shows that flotation of the fine residue is more efficient than the Falcon UF and Falcon SB. Indeed the Falcon UF produced high recoveries (87–95%) but with almost no enrichment (1.3–1.4 ratios) whereas the Falcon SB concentration of un-screened residue produced higher grades (up to 0.6% LREE) but with low recoveries (17–22%). This study has shown that LREE can be recovered with simple two-stage operations, suggesting that the micaceous residue stream (and the associated tailings dams) could be considered as a potential resource for these metals.
ISSN:0892-6875
1872-9444
DOI:10.1016/j.mineng.2016.06.004