In the global effort to reduce greenhouse gas emissions and combat climate change, the demand for critical minerals is rapidly increasing. Essential elements like lithium, cobalt, and graphite are vital for the production of electric vehicle batteries, wind turbines, solar panels, and other low-carbon technologies that are transforming the world's energy systems.
While terrestrial mining of these materials is already in progress, the soaring demand is prompting interest in the vast metal ore deposits found on the ocean floor, spanning millions of square kilometers.
What is Deep-Sea Mining and How is it Conducted?
Deep-sea mining targets valuable mineral deposits located on the ocean floor, often hundreds or even thousands of meters below the surface. These depths, home to a diverse array of marine life, also harbor significant reserves of copper, cobalt, nickel, zinc, silver, gold, and rare earth elements. These materials are essential for building zero-carbon energy components and other advanced technologies but are challenging to source.
In the deep sea, these minerals are found in slow-forming, potato-sized polymetallic nodules, as well as in polymetallic sulphides (large deposits composed of sulfur compounds and other metals that form around hydrothermal vents) and metal-rich crusts on underwater mountains (seamounts). While commercial interest in these minerals has existed for decades, recent technological advancements have enabled the deployment of specialized vehicles to harvest these deposits from the seafloor.
Polymetallic nodules
Polymetallic nodules cover vast areas of the ocean floor. They are more abundant in areas off the west coast of Mexico in the Pacific (known as the Clarion-Clipperton Fracture Zone), the Central Indian Ocean Basin, and the Peru basin. They primarily consist of precipitated iron oxyhydroxides and manganese oxides, onto which metals such as nickel, cobalt, copper, titanium and rare earth elements sorb. The enormous tonnage of nodules on the seabed, and the immense quantities of critical metals that they contain, have made them a target for future mining operations.
For polymetallic nodules, which are currently the primary focus of deep-sea mining, specialized mining vehicles would collect mineral deposits from the seabed surface, akin to a tractor plowing a field. These vehicles would gather both the nodules and the top layers of sediment. The collected materials would then be transported via a pipeline to a surface vessel for processing. Any waste, including sediments and organic materials, would be returned to the water column.
Unlike land-based ores, nodules do not contain toxic levels of heavy elements. Producing metals from nodules allows us to utilize nearly 100% of the nodule mass and design a metallurgical process that generates no tailings and leaves almost no solid waste.
Using nodules to create EV batteries is expected to reduce CO2 equivalent emissions by an average of 90% compared to using ores from land-based mines. Additionally, nodule exploitation avoids disrupting Indigenous communities, prevents deforestation, and eliminates child labor during the mining phase.
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