Report – ENVR206B – Phytomining

Phytotechnology
Over the last 10years the science behind using organic matter to extract natural resources have been developed and tested all over the planet. This technology can be used for extracting metals from the soil for economic profit – phytomining, for ecological/biological profit – phytoremediation or both. Heavy metals, i.e. chromium, arsenic, cadmium, lead, mercury, and manganese are big problems in the environment, but these metals are also expensive. If a way to extract the contaminants, even in small amounts, from the soil at a low cost, one could ‘swat two flies in one go’ by first, and primarily, remediate the heavy metals and later extract the metals from the plants and re-use them.
Studies in the US have shown that it is possible phyto-mine lead from contaminated soil using EDTA Studies in New Zealand showed, and backed by other field tests in Brasil etc, phytomining for gold to be quite successful. The issue I personally see is that the metals, in this case gold, must be made soluble before the plants can accumulate the metal. This is done by using cyanide and/or thiocyanate (very nasty chemicals). This way they would be able to get a yield of about 1kg of gold per hectare. 1oz of gold today cost about US$1100 and it goes approximately 35.2oz / kg which would equal a profit
of just short US$39.000/ha. Perhaps this will lead to a way of making remediation a profit instead of just a cost as it is in most places today?
REFERENCES:
Christopher Andersona, b, , , Fabio Morenoa and John Meechc
A field demonstration of gold phytoextraction technology (2004) aInstitute of Natural Resources, Massey University, Palmerston North, New Zealand
b Tiaki Resources Ltd., Palmerston North, New Zealand
c The Centre for Environmental Research in Minerals, Metals and Materials (CERM3), The University of British Columbia, Vancouver, BC, Canada
http://www.mining.ubc.ca/cerm3/growing%20metals.html

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