The article originates from geological miscellaneous notes
Rare metals are generally classified into the following five categories technically based on the physical and chemical properties, occurrence states, production processes, and other characteristics of various elements:
① Rare light metals include lithium, rubidium, cesium, and beryllium. Small specific gravity and strong chemical activity.
② Rare and refractory metals include titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, and tungsten. The melting point is higher, and the compounds generated with carbon, nitrogen, silicon, boron, etc. also have a higher melting point.
③ Rare dispersed metals, abbreviated as rare dispersed metals, include gallium, indium, thallium, germanium, rhenium, as well as selenium and tellurium. Most occur in minerals of other elements.
④ Rare earth metals, abbreviated as rare earth metals, include scandium, yttrium, and lanthanide elements. They have very similar chemical properties and are associated with each other in minerals.
⑤ Rare radioactive metals include naturally occurring francium, radium, polonium, and actinide metals such as actinium, thorium, protactinium, and uranium, as well as artificially produced technetium, promethium, actinide and other elements, as well as elements 104 to 107.
The above classification is not very strict. Some rare metals can be included in both this category and another category. For example, rhenium can be listed as a rare and refractory metal.
Rare metals: Due to their relatively low or dispersed content in the Earth's crust, they are also known as "rare metals". Such as niobium, tantalum, zirconium, lutetium, gold, radium, hafnium, uranium, etc
Rare earth metals:
1、 Rare earth elements are a general term for the rare earth element group in the lanthanide series, including scandium Sc, yttrium Y, and lanthanide La, cerium Ce, praseodymium Pr, neodymium Nd, promethium Pm, samarium Sm, europium Eu, gadolinium Gd, terbium Tb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, ytterbium Yb, and lutetium Lu in the lanthanide series, totaling 17 elements.
The term "rare earth" is a name that has been used since the 18th century because the minerals used to extract this type of element were relatively rare at that time, and the obtained oxides were difficult to melt, dissolve in water, and separate. Its appearance resembled "soil", and it is called rare earth. Rare earth elements are divided into "light rare earth elements" and "heavy rare earth elements":
Light rare earth elements "refer to scandium Sc, yttrium Y, and lanthanum La, cerium Ce, praseodymium Pr, neodymium Nd, promethium Pm, samarium Sm, and europium Eu with smaller atomic numbers.
Gadolinium Gd, terbium Tb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, ytterbium Yb, lutetium Lu with relatively large atomic numbers of "heavy rare earth elements".
2、 Rare Earth Resources and Reserve Status
Due to the active nature of rare earth elements, they have become lithophile elements. No natural metal anhydrous or sulfide has been found in the crust. The most common forms are complex oxides, hydrated or anhydrous silicates, hydrated or anhydrous phosphates, phosphorus silicates, fluorocarbonates, and fluorides. Due to the similarity in ion radius, oxidation state, and all other elements of rare earth elements
They often coexist with other elements in minerals.
China's rare earth resources account for 80% of the world's rare earth resources, with 36 million tons of oxides (REO), and the actual prospective reserves are 100 million