Browsing by Author "Lamb, A. E."

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    The Extraction Of Gold From Plants And Its Application To Phytomining
    (Massey University., 2001-09-01) Lamb, A. E.; Anderson, C. W. N.; Haverkamp, Richard G.
    Phytomining is the use of hyperaccumulating plants to extract a metal from soil with recovery of the metal from the biomass to return an economic profit. This work looks at the possible methods for recovering gold from plant material, including chemical reduction with and without solvent extraction, thermal reduction and copper electrodeposition. Some progress was made with ascorbic acid as the chemical reductant. A solid phase was produced at the liquid-liquid interface after solvent extraction. The deposition reaction reduced the gold concentration in methyl isobutyl ketone (MIBK) to less than 2 ppm, equating to 85% recovery, in 3.5 hours. Copper electrodeposition also gave some promising results. However, both require much more work before they are viable for scale-up.
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    The Induced Accumulation Of Gold In The Plants Brassica juncea, Berkheya coddii and Chicory
    (Massey University., 2001-09-01) Lamb, A. E.; Anderson, C. W. N.; Haverkamp, R. G.
    In this study the growth stubstrate of the plants Brassica juncea, Berkheya coddii and chicory were amended with thiocyanate and cyanide solutions to induce uptake and the gold concentrations in the different organs determined. Both species showed maximum uptake with cyanide amendment although thiocyanate also induced hyperaccumulation. Gold concentrations ranged from negligible in the leaves of B. coddii amended with thiocyanate, to 326 mg Au/kg dried biomass in the leaves of B. juncea amended with cyanide. The chemical additives KI, KBr, NaS2O3 were also used with the B. juncea and chicory. The results showed varying degrees of hyperaccumulation with all chemical treatments. Cyanide again gave the best results with 164 mg Au/kg dried biomass measured in the chicory plant. NaS2O3, KI and NaSCN gave maximum results of 51, 41 and 31 mg Au/kg dried biomass respectively. This technology has potential application in the economic recovery of metals.