India is actively exploring methods to boost its gold output by focusing on extracting gold from mine tailings. This initiative has gained traction as gold prices have surged in global markets, even crossing 100,000 rupees per 10 grams in India. Scaling up this extraction process requires increased mechanization.
The Union Ministry of Mines has initiated the auction of nine tailing dumps at Karnataka's Kolar Gold Fields (KGF) to extract residual gold and other platinum group elements from leftover ore. Mill tailings, which are byproducts of mining, have accumulated into hillocks over time and contain residual gold. The mines ministry has appointed SBI Caps as a transactional advisor to finalize the auction modalities. However, the entire auctioning process is expected to take between one-and-a-half to two years to complete.
KGF possesses approximately 33 million tonnes of mill tailings, occupying over 15% of the area, with an estimated mineral worth of Rs 25,000 crore to Rs 30,000 crore. A 2021 survey by the Non-Ferrous Materials Technology Development Centre (NFTDC) revealed that these tailing dumps contain not only enhanced residual gold content but also platinum group elements (PGEs) like rhodium and palladium, as well as traces of tungsten. PGEs are used in various industrial applications, including catalytic converters for reducing emissions in automobile exhaust. Previous studies have only found traces of residual gold in the tailing dumps. The mines ministry estimates that approximately 1 gram of residual gold could be extracted from each tonne of tailings.
KGF, which was started by John Taylor and Sons in 1880 and nationalized in 1956, was once a prominent gold mining site. Bharat Gold Mines Limited (BGML) took over KGF in 1972 and continued mining and production until the mines were shut down in February 2001 due to profitability issues. In its prime, KGF's peak gold output was around 47 grams per tonne of ore. However, by 2001, production had declined to less than 3 grams per tonne. From its inception until closure, KGF produced over 800 tonnes of gold from 51 million tonnes of ore.
The Kolar Gold Fields have a history of environmental issues, including land and water contamination. The closure of the mine in 2001 resulted in environmental waste being left near the BGML site. Over the years, the mines generated approximately 35 million tonnes of residue from ore processing, which were dumped in mounds containing cyanide and silica. There are 13 major dumps on the surface, covering about 15 percent of the total land area, with some cyanide dumps reaching a height of 40 meters. This toxic residue contaminates the land, air, and water, posing health risks to the local population.
Studies have explored the potential of phytomining, using plants to extract gold from tailings at KGF. Additionally, research has focused on assessing the impacts of mill tailings on agricultural lands and identifying suitable plant species for reclamation. These studies have shown that tailings can affect soil properties and nutrient availability, with varying effects on plant growth.
India's current gold mining production is low compared to its potential. In 2020, gold mine production was just 1.6 tonnes. Legacy processes and unwieldy regulations have discouraged investment in the sector. However, the government has taken steps to address this through regulatory changes like the 2019 National Mineral Policy and amendments to the Mines and Minerals Act. While the effects of these measures may take time to materialize, there is potential for the industry to grow with the right investment and regulatory progress.
The Karnataka cabinet has approved a proposal to continue mining activities on 13 tailing dumps in Kolar district, under the Mines and Minerals (Regulation and Development) Amendment) Act. This move is expected to generate jobs and contribute to the establishment of an industrial township in the area.
