Manganese nodule

Ferromanganese nodules are mineral concretions composed of silicates and insoluble iron and manganese oxides that form on the ocean seafloor and terrestrial soils.

[2] The high relative abundance of nickel, copper, manganese, and other rare metals in nodules has increased interest in their use as a mining resource.

The total amount of polymetallic nodules on the sea floor was estimated at 500 billion tons by Alan A. Archer of the London Geological Museum in 1981.

In both marine and terrestrial environments, ferromanganese nodules are composed primarily of iron and manganese oxide concretions supported by an aluminosilicate matrix and surrounding a nucleus.

[17] The sorption of divalent cations such as Mn2+, Fe2+, Co2+, Ni2+, and Cu2+ at the surface of Mn- and Fe-oxyhydroxides, known to be strong sorbents, also plays a main role in the accumulation of these transition metals in the manganese nodules.

[3] Total nodule composition varies based on the formation mechanism, broadly broken down into two major categories: hydrogenetic and diagenetic.

[3] The majority of observed nodules are a mixture of hydrogenetic and diagenetic regions of growth, preserving the changes in formation mechanisms over time.

[3] Terrestrial ferromanganese nodules form in a variety of soil types, including but not limited to ultisols, vertisols, inceptisols, alfisols, and mollisols.

In manganese-dominated nodules, enriched elements include barium, strontium, nickel, cobalt, copper, cadmium, lead, and zinc.

[2] Marine ferromanganese nodules form from the precipitation of primarily iron, manganese, nickel, copper, cobalt, and zinc around the nucleus.

[3][4] Nodule growth occurs more readily in oxygenated environments with relatively low sedimentation rates that provide adequate levels of labile organic matter to fuel precipitation.

Assessment of the changing paleoclimate conditions during soil evolution can be explored by analyzing the nodule's concretion structure when combined with dating techniques.

Almost half a billion dollars was invested in identifying potential deposits and in research and development of technology for mining and processing nodules.

[citation needed] In the late 1970s, two of the international joint ventures collected several hundred-ton quantities of manganese nodules from the abyssal plains (18,000 feet (5.5 km) + depth) of the eastern equatorial Pacific Ocean.

[15] Significant quantities of nickel (the primary target) as well as copper and cobalt were subsequently extracted from this "ore" using both pyrometallurgical and hydrometallurgical methods.

In the course of these projects, a number of ancillary developments evolved, including the use of near-bottom towed side-scan sonar array to assay the nodule population density on the abyssal silt while simultaneously performing a sub-bottom profile with a derived, vertically oriented, low-frequency acoustic beam.

There is also improved technology that could be used in mining including pumps, tracked and screw drive rovers, rigid and flexible drilling risers, and ultra-high-molecular-weight polyethylene rope.

[27] The International Seabed Authority has granted new exploration contracts and is progressing development of a mining code for the area, with most interest being in the Clarion–Clipperton zone.

Environmentalists have criticized this move on the grounds that too little is known about seabed ecosystems to understand the potential impacts of deep-sea mining, and some of the major tech companies, including Samsung and BMW, have committed to avoid using metals derived from nodules.

[32] The high natural abundance of nickel, copper, cobalt, zinc, iron, and manganese in ferromanganese nodules has promoted research into their use as a rare metal resource.

[3][4] As the grade of ores from terrestrial mines has decreased over time, ferromanganese nodules may offer a way to meet the growing global demand for rare metals.

[3] Technologies like electric car batteries, wind turbines and solar panels require rare types of resources that can be found in the seabed.

Manganese Nodules are therefore needed for batteries, laptops, and smartphones, in e-bikes and e-cars, solar and wind turbines as well as for the storage of green electricity.

[2] Microbes in the soil can utilize the nutrient enrichment on the surface of nodules coupled with their redox potential to fuel their metabolic pathways and release the once immobile phosphorus.

[2] Along with nutrients, ferromanganese nodules can sequester toxic heavy metals (lead, copper, zinc, cobalt, nickel, and cadmium) from the soil, improving its quality.

[50] Due to the complexity and remoteness of the deep-sea, environmental scientists work in a knowledge poor situation with many gaps and high uncertainty.

These could include: The dump-truck-sized collection vehicles that scour the seafloor for nodule-bearing sediment, do necessarily destroy the top of the seabed – at a depth of often more than three kilometers below the surface.

[34] Recent growth estimates suggest that "microbially mediated biogeochemical functions"[53] need over 50 years to return to their undisturbed initial state.

The extreme background noise caused by the mining machines can interfere with the communication between animals and limit their ability to detect prey.

Mining activities could impair the feeding and reproduction of deep-sea species through the creation of intense noise and light pollution in a naturally dark and silent environment.