溶媒抽出による鉄の高純度精製

抄録

A purification process of iron by solvent extraction in a medium of hydrochloric acid solution has been developed. Utilizing the difference between extractable ferric chloride and non-extractable ferrous chloride into metyl isobutyl ketone (MIBK, 4-metyl-2-pentanone) in the range of 5 to 6 kmol/m³ hydrochloric acid solution even at a high iron concentration of 30 kg/m³, the purification by solvent extraction with MIBK consists of two steps; 1st step is the extraction of ferrous chloride in which extractable impurities can be separated from Fe(II), and 2nd step is the extraction of ferric chloride in which non-extractable impurities can be separated from Fe(III). Iron was produced from the purified and oxidized ferric chloride solution by evaporation to dryness, heating in air and hydrogen reduction. The produced iron sponge was then melted in H₂-Ar plasma arc. The purity of iron was evaluated by residual resistivity ratio (RRR_H) and glow discharge mass spectrometry (GDMS) analysis. Iron obtained by this purification process for iron with 99.9% in purity and nearly 100 in RRR_H as a starting material showed RRR_H of 1300 and its purity increased to about 99.999%.