By C.K. Gupta, N. Krishnamurthy
Gupta and Krishnamurthy survey the medical and engineering literature to supply an outline of present practices for extracting infrequent earths and getting ready their derivatives for particular purposes. They establish the positioning, caliber, and volume of the world's infrequent earth assets and current a close account of classical and smooth extraction tools. Chemical and electrochemical aid equipment also are coated, in addition to steel refining strategies. The authors are affiliated with the Bhabha Atomic examine heart in Mumbai, India.
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Additional resources for Extractive Metallurgy of Rare Earths
Most of the rare earth salts display colors that are characteristic of the tripositive ions. The striking colors persist in aqueous and nonaqueous solutions and are unaffected by alterations of anions present or the addition of complexing agents (Moeller 1971). 2. In the rare earths with electronic configurations 4f1 and 4f13 no f–f transition is possible. Thus, Ce3+ and Yb3+ do not absorb in the visible region. They do, however, absorb in the ultraviolet region due to transitions of the type 4fn–4fn−15d.
4 The Divalent State The divalent state of Sm, Eu, and Yb are well established both in solution and solid compounds. These species are obtained (Moeller 1967) by (i) thermal reduction of anhydrous halides or chalcogenides with metals or hydrogen. For example, solid oxide, chalcogenides, halides, carbonate, or phosphate of europium (II) may be obtained by reduction of the corresponding Eu(III) compound or from EuCl2 by metathesis, (ii) electrolytic reduction in aqueous solution or in halide melts, for example, Eu(II) and Yb(II), (iii) chemical reduction in solution: Eu(II) using Zn in aqueous solution, Sm(II) using Mg in ethanol, (iv) thermal decomposition of anhydrous triiodides, and (v) controlled oxidation of free metals or their amalgams.
The light rare earths (La to Nd) can form heptahydrates. On heating, the hydrated chlorides lose HCl more readily than H2O. The product is oxychloride. The bromides and iodides are quite similar to the chlorides. The iodides as well as the iodates and acetates are somewhat less soluble in water. The sulfates are sparingly soluble and their solubility decreases with increase in temperature. The rare earth oxides, sulfides, fluorides, carbonates, oxalates, and phosphates are insoluble in water. Among the halides only the fluorides are insoluble.
Extractive Metallurgy of Rare Earths by C.K. Gupta, N. Krishnamurthy