A new method for obtaining nickel metal from the hyperaccumulator plant Alyssum murale
Résumé
Soils based serpentines have high levels of Ni difficult to value economically by current mining technologies. The Ni-hyperaccumulating plant Alyssum murale, naturally present in soil-based serpentines, can extract and store Ni from these soils by phytoextraction. Some parts of plants can accumulate up to 16.9 g Ni/kg dry matter. Leaching in 0.5 M H2SO4 solution at 90 C with a 15% solids concentration during 120 min of a crushed mixture of flowers and seeds of A. murale can produce leachate concentrated in Ni. This work has proposed to process A. murale leachate for Ni recovery. Processing techniques like selective precipitation or electroplating has not allowed a selective recovery of Ni from A. murale leachate. Flocculation of dissolved organic matter in A. murale leachate has revealed that both Ni and organic acids like malate, citrate or histidine were bonded into complexes. Selective recovery of Ni from A. murale leachate was processed by solvent extraction with bis(2,4,4-trimethylpentyl) phosphonic acid (Cyanex 272). There results has showed that 72.4 ± 6.4% of the total Ni content from the A. murale leachate was recovered. Nickel was recovered as nickel cathode.