Indonesia is one of the countries with the largest number of artisanal gold miners in the world. An artisanal miner, also known as a small-scale miner, is an individual or group of individuals who operate informally with little mechanical assistance to produce gold or other commodities. In the West Nusa Tenggara province in Indonesia it is estimated that 22,000 people participate in artisanal small-scale gold mining and produce upwards of 400kg of gold per annum and contributes about $22 million US to the economic activity of Indonesia. The scope of artsinal mining in the WNT province and the impact it has on people and environment are the driving forces for an annual Artisinal Small-scale Gold Mining (ASGM) workshops.
This year the workshop was called “Planning for the sustainable future of ASGM in the West Nusa Tenggara Province.” It began with an introduction from the university President, Prof. Sunarpi, and a presentation from Dr. Dewi Krisnayanti who put the scale of ASGM in perspective and also touched on the detrimental health impacts that can be experienced with some of the processes the artisanal miners use. Using mercury to recover gold often results in mercury losses in the tailings, this mercury ends up in drinking water, rice, and fish and eventually into the miners themselves. There are 85,000 tonnes of tailings discharged on Lombok alone. This can lead to skin lesions, cancer, kidney disease, and overall poor health.
Dr. Marcello Veiga from UBC then gave a presentation on International trends in ASGM and how he has learned to teach and improve the ASGM practices. He touched on simple processes that can be used to recover gold using homemade devices and easily accessible reagents. Dr. Veiga also elaborated on the artisinal mining teaching facility he has worked on in Ecuador and the excellent impacts it has had on the artsinal miners from all parts of the world that choose to come and visit and learn at the center.
Day 2 was spent visiting different artisanal mines and processing facilities. The first mine produced about 120kg of ore per day at approximately 50 g/t gold. The ore was sold to a processing facility that would process the ore. The ore was treated with mercury in the ball mill (1kg or mercury per trommel) and then was treated with cyanide. A rough calculation indicates recoveries of no more than 15% gold. The second site did not include grinding, the miners were expected to bring ground ore to the facility where they would process it. The slurry was mixed with mercury and was put into one of the tanks for cyanidation. The tailings were stored in an area directly beside a channel that led to the ocean. The storate area was known to leak CN-Pb complexes directly into the channel. The last site visited was an old tailings area that was now being used as a farm for growing rice. The rice has the highest level of Pb in the world. This site was a research facility for phytomining, performed by Dr. Christopher Anderson. Phytomining uses the ability of plants to absorb metals into their leaves to remove metals from the tailings and recover them for sale. The research was being done using different kinds of plants on small patches of tailings. The research is still in its infancy.
Entrance to a underground working
Trommels using mercury to recovery gold.
Cyanide tailings dam
UBC Mining Grad Trip 2013 