The metal manganese is ubiquitous. It is found in spinach, rice, eggs and oil. It is a trace element that is important in the body, it contributes, among other things, to bone formation and vitamin absorption. An adult has about 12 milligrams of manganese in the body.
At the same time, manganese is a toxic substance. Too much causes hallucinations, forgetfulness and Parkinson-like complaints. Egg and spinach lovers need not fear, welders, on the other hand, should be careful, manganese poisoning is usually caused by inhalation of manganese dust when welding.
It is not surprising that welders are particularly at risk: the largest application of manganese is in steel. Steel consists mainly of iron, with some carbon. To influence the mechanical properties of the steel, alloying elements are added, of which the steel can consist of 1.5 to more than 12 percent. Manganese is added to the alloy to make the iron less brittle, it increases the yield strength and tensile strength.
Steel and batteries
The battery industry also likes to use manganese in the cathode of the battery. Manganese can absorb and release electrons well, which is necessary when charging and discharging a battery. Cathodes come in many compositions. The best known at the moment is the nickel-manganese-cobalt cathode, which is used in many electric cars. A car with a battery weighing 185 kilos contains about 10 kilos of manganese.
The availability of steel and batteries is crucial for the success of the energy transition. The demand for batteries will grow strongly in the coming years. The need for steel is growing less rapidly, but it has been widely used for decades, around 1.8 billion tons in 2020, and the expected demand for 2030 is 2 billion tons. There are therefore serious concerns about material scarcity.
One of the solutions to this scarcity is being sought on the seabed. There are ‘polymetallic nodules’, which are usually called manganese nodules. The fact that manganese is so prominent in that name is because they mainly consist of manganese oxides, enriched with iron, cobalt, nickel and copper – almost the entire shopping list of metals for the energy transition. The tubers grow slowly: millimeters to tens of millimeters per million years. They are found in places where little sediment deposits.
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Collecting manganese nodules from the seabed is a highly controversial activity that is not yet permitted. In practice, ‘collecting’ is sucking up, which is done by vehicles with caterpillar tracks, after which the tubers (and any grit and soil life that come along with them) are taken via an enormous tube to a ship on the surface. It is not known to what extent ecosystems on the seabed will be disturbed by this, but nature organizations do not expect much good. The seabed authority will soon have to decide on the manganese nodules.
Thus, the metal, whose existence was first suspected by Heinrich Pott in 1740, and which was first isolated by Johan Gahn in 1774, has become an element that shines at the center of many highly topical discussions that touch on the future habitability of the planet.
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