A new method for separating rare earth elements is translated from: scientific preface: Rare earth elements and their compounds occupy an important position in modern technology, but the separation of their single elements is a complicated process.
In 2000, Science, the most authoritative academic journal in the world, published a paper (289 volumes, 2326-2329 pages) by Japanese scientist Uta et al., which provided a brand-new method, greatly simplified the steps of rare earth separation and provided an exciting opportunity for reducing the high price of rare earth.
They separated rare earth elements by controlling the different oxidation states of rare earth and using the volatility difference between dihalides and trihalides. This is not only an interesting scientific phenomenon, but also will have a great impact on the production of rare earths and the manufacture of materials and devices based on rare earths.
Professor Fray of Cambridge University in England made an authoritative comment on this paper, which was published on pages 2326-2329 in the same period, and is now translated as follows. The term "rare earth elements" originated from the early view that these elements can only be separated from very rare materials.
However, the geological survey results show that these elements are quite abundant in the crust. For example, the reserves of cerium are higher than that of cobalt, yttrium is higher than that of lead, and lutetium and thulium are equivalent to antimony, mercury and silver. However, due to their close physical and chemical properties, rare earth elements usually gather in the earth's crust, which makes their separation very difficult. Because of this, it took nearly 70 years to separate and identify all the rare earth elements from 1839 to 1907.
Rare earth elements occupy an important position in modern science and technology, but compared with other metals, rare earth elements are very expensive. The price of rare earth oxides ranges from $20/kg to $7,000/kg according to their rarity and extraction methods, and rare earth metals are about $80/kg more expensive than their oxides.
This situation is entirely due to the difficulty in separating rare earth elements. Traditional rare earth separation is based on solvent extraction and ion exchange. These methods are very complicated. In recent years, there are only some minor improvements and no substantial changes. In the traditional process, the ore rich in rare earth elements must be dissolved with concentrated acid or concentrated alkali, which is the simplest step, and then the further separation of rare earth elements is a huge difficulty in inorganic chemistry.