2/20/2023 0 Comments Earth magnetSimilar to what happens when you quickly stir a cup of tea, the rapid rotation of the Earth once per day makes the fluid in the outer core spin too. This means the metal is constantly moving and flowing, like the oceans. The outer core flows as easily as water on the surface of the Earth does. The metal is still extremely hot (>3,000☌) but despite the high pressure, the outer core is actually very runny, as the heat overcomes the effects of the pressure. Figure 1a, ’s_magnetic_field_pole.svgįurther away from the very center of the Earth is the liquid outer core, which is about the size of Mars. On the right is an artist’s view of the Swarm magnetic satellite, which senses the compass direction changing as it flies through the Earth’s magnetic field in its orbit (gray line). The magnetic field (blue lines) is created in the outer core. The outer core is shown in orange, with the inner core shown by the darker sphere at the center. The rocky mantle and crust are transparent in this picture. (b) The Earth’s core is visible at the center of the planet. Like the Earth, the southern pole (labeled “S”) is actually in the northern hemisphere.Figure 1 - (a) An illustration of the magnetic field lines from a simple bar magnet, similar to the Earth’s magnetic field.It is very hot (>5,000☌) and is solid due to the extremely high pressure from the weight of the material above it. The inner core is about the size of the moon. It is made up of around nine-tenths iron and nickel. The core of the Earth is around 6,800 km wide and starts about halfway to the center of the planet ( Figure 1b). Planet Earth can be divided into four layers: the solid inner core at the center, the liquid outer core, the rocky mantle and the crust at the surface, which we live on. Maps of the declination angle are very complicated and because of the flow of the outer core, the position of magnetic North moves over time. The angle between true North and magnetic North at any particular position on the Earth is called the declination angle. A compass needle generally does not point to true North (the axis of rotation of the Earth), but to the magnetic North pole. The magnetic field formed by the Earth’s core is expected to align with the axis of rotation, but it deviates a bit for reasons that are not well-understood. The electrical current creates a magnetic field that reaches out from the core to the surface of the Earth and beyond. The metal carries an electrical current that is powered by the movement of the liquid. In fact, the alloy used to make magnets is called PrNd because these two elements are chemically so similar that not only are they too similar to easily separate, but they are also so similar that it would make only a small difference in the quality of the magnet.The Earth has a solid inner core and a liquid outer core, both made of iron and nickel. įor example, it’s not well known, but about 20-30% of the Neodymium in Neodymium magnets is really Praseodymium. This is one of the cost factors because the refinement methods require the use of expensive chemicals and time –consuming processes. Extraction of rare earths is difficult because many of them have very similar properties, making refinement a challenge. Rare Earth Elements are often found with other valuable metals, such as precious metals and even significant quantities of base metals like copper and nickel, so multiple steps are taken to separate them. This means it is heated up to very high temperatures (~1500☌) so the valuable metals can be separated from unusable materials in the ore. The concentrate (refined ore) is then smelted. Rare earth metals can be refined and extracted electrochemically, or by distillation, ion exchange or other techniques. Depending on the source of the ore, the concentrate may also undergo electrolytic refining. Then the ore goes through a flotation process where it is mixed with water and special reagents to separate the rare earth elements from the tailings. Next, the Rare Earth Ore is crushed and milled.
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