India dives deep on way to mining gold from sea
Published on Wed, 31 May 2017
Times Of India reported that India has begun its first-ever deep sea exploration for precious minerals and metals including gold, silver and platinum in a location close to an active underwater volcanic region of the southern Indian Ocean.
Experts said that the development has not only inducted India into the elite group of countries that are exploring seabeds across the world including the mid-Atlantic, Pacific and the Indian oceans, but also points to India’s technological advancement in the sea. The Union cabinet while approving the project contract with the International Seabed Authority (ISA) in 2016 had said that the exploration will enhance India’s presence in the Indian Ocean where other players like China, Korea and Germany are active.
In 2013-2014, National Centre for Antarctic and Ocean Research, Goa in collaboration with National Institute of Ocean Technology conducted an extensive survey in the Central Indian and South West Indian Ridges to map area for exploration for polymetallic sulphide. In September 2016, India signed a 15 year contract with ISA to get exclusive rights to conduct exploration in a 10,000sqkm location near Rodrigues Triple Junction a junction in the Southern Indian Ocean near Mauritius where three tectonic plates meet.
The exploration for polymetallic sulphides began in April this year and is being conducted by a team of 25 scientists from NCAOR.
Polymetallic sulphides are mineral deposits with three or more metals, including gold, silver and platinum. Experts say the exploration for these minerals, mostly found in ocean ridges, will be of immense strategic and commercial value for India, though it will take a few decades to mine these deep sea resources. The exploration will be done in parts of Central and South West Indian Ridges of the junction over the course of the next 15 years.
The team of scientists is currently looking for active and inactive hydrothermal vents in RTJ. Hydrothermal vents are fissures on the ocean crust commonly found near active volcanic areas associated with tectonic structures. These vents are a source of minerals and metals like copper, zinc, lead, manganese, iron, silver and gold. At RTJ, there are venting black smokers, which are chimneys formed from deposits of iron sulphide. They emit jets of particle-laden fluids. The particles are predominantly very finegrained sulphide minerals formed when the hot hydrothermal fluids mix with near-freezing sea water. These minerals eventually solidify as they cool, forming chimney-like structures.
NCAOR scientist John Kurien said that “These black smokers have plumes. They emit fluids along with minerals which would be at 360ºC or 370ºC. Once emitted, the minerals attain buoyancy at 500m above the vent and settle in nearby places." So far, the team has identified three locations where they are likely to find these vents at a depth of about 4000m.
Kurien says a Conductivity Temperature and Depth probe with auxiliary sensors has been deployed to measure several parameters including the change in water temperature, depth, conductivity and turbidity. If the data collected shows an anomaly, scientists say it is a sign that there could be hydrothermal plumes underneath indicating the presence of minerals.
Mr Kurien said that “We have got good inference from the preliminary analysis of the water samples we collected from those three locations. They show geological, chemical and physical signatures. The water is also metalliferous (contains metal)."
The next step is to send an autonomous underwater vehicle fitted with cameras and identify the exact location of the active vents and search for inactive vents in nearby areas, where minerals can be seen.
Scientists said that the ultimate goal of their exploration is to find inactive vents after identifying the locations of active vents. An NCAOR scientist said that “We are looking for inactive vents that were active a few thousand years ago and now have minerals and metals settled around them. Active vents keep shifting over several thousand years. Once we find them, we expect there will be inactive vent field a few kilometres around them."
The team would also study marine organisms that survive around the vents without light. These organisms including metal tolerant bacteria, shrimps and gastropod snails depend upon chemical processes that result from the interaction of seawater and hot magma associated with underwater volcanoes.
Source : Times Of India