Farming For Minerals

Agromining may provide new opportunities to extract remaining value from mined land

With a significant portion of large mineral deposits having been discovered worldwide, and, in many cases, reaching the end of viable economic recovery, phytomining is one option that could be chosen to extract the remaining value from this mined ground, Florida International University geosciences research professor Stephen Haggerty tells Mining Weekly.

Phytomining is the exploitation of ‘hyperaccumulator’ plants to obtain valuable elements from degraded or already mined land. These unusual plants can accumulate exceptionally high concentrations of certain elements in their living biomass.

Agromining refers to the full agronomic chain in using hyperaccumulator plants as ‘metal crops’ and is considered a variant of phytomining technology.

The process involves farming such crops on subeconomic deposits or industrial or mineral wastes to obtain valuable elements from their harvested biomass through the production of a ‘bio-ore’ (which is incinerated biomass rich in metals). This bio-ore can then be processed through hydrometallurgical or pyrometallurgical processes to obtain high value products.

In agromining, the plants are grown, harvested for biomass, dried, incinerated, or ‘ashed’, and processed to recover the target metals.

Australian Research Council postdoctoral research fellow at the University of Queensland, in Australia, and the Université de Lorraine, in France, Dr Antony van der Ent agrees, reiterating that the increasing demand for critical elements challenges conventional methods of resource extraction.

Van der Ent’s work focuses on biogeochemistry, with a specialisation in hyperaccumulator plants. He is part of a team developing agromining in the Asia-Pacific region.