Gold phytomining. A review of the relevance of this technology to mineral extraction in the 21st century.

The precious metal gold can be found at high concentration in tailings dumps and waste rock piles at many mining locations around the world. Conventional technology is generally unable to economically recover this residual gold, and, as a result, the potential resource is wasted, presenting environmental risk to the wider ecosystem through particulate and dissolved metal leaching and erosion. For the past 14 years, the idea of gold phytomining to recover this gold resource has been researched by various scientific groups worldwide. A number of plant species have been tested under laboratory, greenhouse, and field conditions to determine their potential for use in the phytoextraction of gold. This paper presents a review of reported gold phytomining trials developed in the laboratory, the greenhouse under soil and hydroponic conditions, as well as in the field, between 1998 and 2011. A summary economic assessment for gold phytomining in Mexico is also presented. Mexico is an example of a developing country with a long history of gold mining that has a large resource of sites that might be suitable to gold phytomining. The technology remains limited by certain environmental and plant physiology factors. However, the increase in the market price for gold during the first decade of the 21st century and into 2011, and advances recorded for the gold concentration and biomass yield of a range of plant species, suggest that gold phytomining might be an economically viable technology.