In April 2016 the CoG3 team travelled to Brazil to carry out fieldwork at the Piauí deposit. Researcher Dr Paul Schofield describes their trip:
Cobalt is a technology-enabling metal with numerous applications that are particularly essential to the ‘green agenda’. Despite cobalt being such a critical material, there is a very high risk associated with its supply.
Our project, CoG3: Geology, Geochemistry and Geomicrobiology of cobalt, aims to increase the security of the cobalt supply chain by:
- identifying new, currently unused cobalt resources
- developing new biotechnologies for effective extraction and processing of cobalt
One resource with the potential for bioprocessing is limonitic laterite deposits, one of which is the Piauí nickel-cobalt laterite deposit in Brazil.
At the Piauí deposit, Brazilian Nickel Plc are opening a demonstration plant to explore the possibility of establishing environmentally benign, atmospheric heap-leach technology for the extraction of both nickel and cobalt from the laterite ore.
As major contributors to our project they invited us to obtain fresh samples from their test pit, from which 10,000 tonnes of laterite ore had just been excavated.
In April Richard Herrington and myself (Natural History Museum), Laura Newsome (University of Manchester) and Jens Kruger (University of Southampton) set out to the Piauí deposit to collect these samples.
Working in the warmth
Our days began at sunrise in the hope of getting as much work as possible done in the open pit before the temperatures approached 38-40ºC.
It was a 27km drive from the camp to the deposit, along dirt roads recently repaired from the February flooding, passing isolated farmsteads, cacti and euphorbia vegetation and herds of wild donkeys and goats.
We started by examining the vast core shed, containing about 67,000m of drill core from the exploration phase of the Piauí project. After this, Mike Oxley gave us a tour of the test pit and processing plant, with a full description of the heap-leach technology that Brazilian Nickel Plc is installing.
On our first day at the pit we mapped out the different soil, rock and mineralogical units that would allow us to establish a comprehensive sampling strategy. Then, over the next three days, Richard and Paul collected samples of the rocks, Laura collected samples to study the biogeochemistry of the deposit, and Jens began sampling the subsurface water.
Sampling in the pit whilst wearing the requisite protective equipment in unbroken, direct sunshine and temperatures close to 40ºC was thirsty work indeed. Back at the camp by sunset, around 6 o’clock, the cold beer was very much appreciated.
Our homeward journey unfortunately required an overnight stay in Recife and an unavoidable swim off the extensive Recife beach.
Following our return, the samples are now being studied and characterised to establish the mineralogy, geochemistry and microbiology of cobalt at Piauí. Bulk samples representative of the average ore that will be leached at Piauí were isolated and will be distributed among our project partners for bioleaching and bioprocessing tests.
Our hosts and the staff of Brazilian Nickel Plc were very friendly and hospitable, and we are very grateful for the help and support that they have provided for our work.