Collection of Ni-bearing material from electroless plating waste by magnetic separation with HTS bulk magnet

T. Oka, H. Fukazawa, S. Fukui, J. Ogawa, T. Sato, M. Ooizumi, M. Tsujimura, K. Yokoyama

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


The magnetic separation experiment to collect the Ni compounds from the waste liquid of electroless plating processes was conducted in the open-gradient magnetic separation process with the high temperature superconducting bulk magnet system. The magnetic pole containing Gd-based bulk superconductors was activated to 3.45 T at 35 K in the static magnetic field of 5 T with use of a superconducting solenoid magnet. The coarse Ni-sulfate crystals were formed by adding the concentrated sulfuric acid to the Ni-phosphite precipitates which yielded from the plating waste liquid by controlling the temperature and the pH value. The open-gradient magnetic separation technique was employed to separate the Ni-sulfate crystals from the mixture of the Ni-sulfate and Ni-phosphite compounds by the difference between their magnetic properties. And we succeeded in collecting Ni-sulfate crystals preferentially to the Ni-phosphite by attracting them to the magnetic pole soon after the Ni-sulfate crystals began to grow.

Original languageEnglish
Pages (from-to)58-62
Number of pages5
JournalPhysica C: Superconductivity and its applications
Issue numberC
Publication statusPublished - 2014 Jan 15
Externally publishedYes


  • Bulk superconductor
  • Electroless plating
  • Magnetic separation
  • Nickel compound
  • Waste liquid

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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