Gold and Copper Phytoextraction by Composite plants

Phytomining has suggested as a low cost and environmentally friendly technology that uses plants to extract valuable metals from a given substance. To evaluate the potential for application of gold phytomining, and the corresponding uptake of copper that is induced at the same time, greenhouse scale experiments were arranged as a factorial experiment based on randomized complete design, consisting of four chemical amendments (sodium cyanide, ammonium thiocyanate, ammonium thiosulphate and Potassium cyanide) on factor A and 2 rates (1 and 2 mg kg-1) of these chemicals on factor B with three replications. Plants were harvested and concentrations of gold and copper were analyzed in samples of plant organs after harvest using the Atomic Absorption Spectrophotometer. The results show that Alyssum minus and Broga officinalis had a high concentration ( 80mgkg-1) of gold in the dry matter of aerial tissues with 2 mg kg-1 potassium cyanide, but Alyssum had low growth rate and poor biomass and is not suitable for successful gold phytomining. Translocation factor of gold and copper were between 0.7- 0.9 and 3.7-11.7 respectively. Our results confirmed that phytomining with Borage can be used to recover gold, and that at the current market price for gold, this recovery can be economic.