Magnetic separation of nickel-plating waste liquid using a high temperature superconducting bulk magnet

Tetsuo Oka, K. Sudo, J. L. Dadiel, N. Sakai, H. Seki, M. Miryala, Masato Murakami, T. Nakano, M. Ooizumi, K. Yokoyama, M. Tsujimura

Research output: Contribution to journalArticlepeer-review


Ni is one of the important metal resources. Because Ni-containing waste liquid is drained after several plating turns in the factories, an effective recycling technique should be developed. A unique magnetic separation technique using high temperature superconducting bulk magnet has succeeded in collecting Ni-sulfate crystals, which were fabricated from the Ni-plating waste liquid. Pulsed-field magnetizing method was employed to activate the bulk magnet up to 2.80 T, which produced a field space of 1.40 T on the surface of the waste channel. Green coarse crystals were attracted from the flowing stream of Ni-saturated liquid containing weakly-magnetic particles of Ni-compounds. The magnetically-collected particles were identified as paramagnetic NiSO4/6H2O crystals, and slight differences in Ni concentration and grain size were observed between the particles attracted and not-attracted to the 1.8 T magnetic pole. In both cases, the large grains were found to consist of a single phase. The compound can be used as a raw material in the Ni-recycle process. This preferential extraction suggests a novel recycling method of Ni resource.

Original languageEnglish
Article number094006
JournalSuperconductor Science and Technology
Issue number9
Publication statusPublished - 2022 Sept


  • bulk magnet
  • magnetic separation
  • nickel plating
  • pulsed field magnetization

ASJC Scopus subject areas

  • Ceramics and Composites
  • Condensed Matter Physics
  • Metals and Alloys
  • Materials Chemistry
  • Electrical and Electronic Engineering


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