ISO 22444-2:2020 希土類—用語, 語彙—パート2：金属とその合金 | ページ 9

6.1

metallothermic reduction

method for preparing a metal or alloy by reducing the metal from its compound with another chemically active metal

Note 1 to entry: Commonly used reducing agents include Li, Na, Ca, Mg and Al. This method is used to prepare individual rare earth metals (4.2) , mixed rare earth metals (4.4) and rare earth master alloys (5.2) .

6.2

silicothermic reduction

ferrosilicon reduction process

method for producing rare earth ferrosilicon alloys (5.4) or other rare earth master alloys (5.2) from rare earth oxides, rare earth enriched slag or rare earth concentrate by reduction with silicon or ferrosilicon

6.3

carbothermic reduction

method for producing rare earth ferrosilicon alloys (5.4) from rare earth oxides, rare earth enriched slag or rare earth concentrate slag by reduction with coke

6.4

reduction-distillation method

method for producing higher vapour pressure rare earth metals (4.1) (e.g. Sm) using a metal with a lower vapour pressure (such as La) to reduce the oxides of target metals, the metal product evaporating into the gas phase, and then transferring and being collected at the condensing zone

Note 1 to entry: This method is used to prepare individual rare earth metals (4.2) of Sm, Eu, etc.

6.5

intermediate alloy method

method for producing individual rare earth metals (4.2) by the vacuum distillation (6.11) of a low melting point intermediate alloy, which is prepared using high-melting-point rare earth fluoride reduced by calcium thermal reduction, with other low melting-point and high-vapour-pressure metal(s) (such as Mg and Zn) at a low temperature

Note 1 to entry: This method is used to prepare individual rare earth metals of Gd, Tb, etc.

6.6

molten salt electrolysis

process involving the passage of an electric current through a molten-salt electrolyte with the subsequent migration of positively and negatively charged ions to the negative and positive electrodes, respectively

Note 1 to entry: Rare earth ions gain electrons to become neutral atoms, with the newly formed rare earth atoms depositing onto the cathode.

Note 2 to entry: This method is used to prepare La, Ce, Pr-Nd metal (4.6) , Dy-Fe alloy, etc.

6.7

reduction-diffusion method

R-D method

method for preparing rare earth alloys (5.1) by thermal diffusion between a rare earth metal (4.1) and the added cobalt, iron or other transition metals, in which the rare earth metal is reduced from its oxide (mainly used with Sm, Nd and Pr oxides) by calcium metal

Note 1 to entry: The rare earth alloys include Sm-Co (5.19) , Sm-Fe and Nd-Fe-B (5.16) alloys.

6.8

co-reduction method

method for preparing rare earth alloys (5.1) through the simultaneous reduction of a mixture of oxides of the alloying element(s) and rare earth oxide by Ca metal

Note 1 to entry: This method is mainly used to prepare Sm-Co (5.19) alloys.

6.9

mixed smelting

method for producing rare earth alloys (5.1) through smelting and uniform mixing of one or more rare earth elements and other alloying element(s) simultaneously, with specific proportions

6.10

vacuum refining

method for purifying rare earth metals (4.1) by volatilizing the volatile impurities at a temperature above the melting point of the rare earth metal under vacuum or negative pressure conditions

Note 1 to entry: It is used as the preliminary purification method for crude metal prepared by Ca thermal reduction or molten salt electrolysis (6.6) , and is typically, but not exclusively, applied to La and Y.

6.11

vacuum distillation

sublimation

purification method for separating rare earth metals (4.1) from impurities by heating rare earth metals under a vacuum, based on significant differences between the vapour pressure of the rare earth metal and the impurities

Note 1 to entry: This method is typically, but not exclusively, used to purify Sm, Dy and Tm.

6.12

electrorefining

method for purifying rare earth metals (4.1) through the exploitation of differences in anodic dissolution and cathodic precipitation for different elements, in which rare earth metal is used as a soluble anode and dissolved, then the high-purity rare earth metal of the same element is deposited at the cathode with direct electric current passing by

6.13

solid state electrotransport

method for purifying rare earth metals (4.1) by the ordered migration of impurity atoms to the two ends of an associated metal rod under the effect of direct electric field

Note 1 to entry: This method is typically, but not exclusively, used to purify La and Y.

6.14

zone refining

method for purifying rare earth metals (4.1) in which a narrow molten zone is moved slowly along the complete length of the specimen, to bring about impurity segregation, and which is based on compositional differences of the liquid and solid in equilibrium

Note 1 to entry: This method is typically, but not exclusively, used to purify La and Y.

6.15

electron beam melting purification

method for purifying rare earth metals (4.1) by an electron beam under vacuum conditions, in a water-cooled Cu crucible

Note 1 to entry: This method is typically, but not exclusively, used to purify La and Y.

6.16

levitation melting

method for melting and purifying metals without being in contact with a supporting substrate, by using the Lorentz forces induced current provided by a high-frequency magnetic field that surrounds the vessel to suspend the melt

Note 1 to entry: This method is typically, but not exclusively, used to purify La and Y.

6.17

fused-salt extraction method

method for purifying metals by separating impurities from the valuable elements based on the partition coefficient differences of different elements in the molten metal and the slag