Collecting Ni-Sulfate Compound from Electroless Plating Waste by Magnetic Separation Technique with Use of HTS Bulk Magnets

Tetsuo Oka, S. Sasaki, H. Sasaki, S. Fukui, J. Ogawa, T. Sato, T. Nakano, M. Ooizumi, M. Tsujimura, K. Yokoyama

Research output: Contribution to journalConference article


The authors have developed a useful technique for extracting the Ni-sulfate compound from the "processed waste/fluid" of the electroless Ni-plating processes. After forming the fine NiHPO3 precipitate from the waste, the coarse NiSO4 crystals were synthesized through the reaction with the concentrated sulfuric acid. In the experiment, the open-gradient magnetic separation was employed to collect the NiSO4 crystals from the muddy mixture composed of these compounds. The experiments were practically conducted with use of the Gd123-based HTS bulk magnets generating up to 3.99 T, which were activated by the field cooling magnetizing method operated at 35 K. Intense magnetic field emitted from the bulk magnet attracted the paramagnetic fluid and coarse NiSO4 crystals on the bottom of the water channel, forming a giant drop of NiSO4-saturated clear fluid and the slurry of nickel sulfate hexahydrate. This preferential collection suggests a feasible recycling process of Ni resource as a raw material in the plating processes.

Original languageEnglish
Article number012047
JournalJournal of Physics: Conference Series
Issue number1
Publication statusPublished - 2018 Jul 26
Externally publishedYes
Event30th International Symposium on Superconductivity, ISS 2017 - Tokyo, Japan
Duration: 2017 Dec 132017 Dec 15


ASJC Scopus subject areas

  • Physics and Astronomy(all)

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