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ANCED CONSTRUCTION MATERIALS

High Temperature Superconducting Magnetic System for High Gradient Magnetic Separator1 D. N. Dieva, V. M. Lepehina, M. N. Makarenkoa, A. V. Polyakova, M. I. Surina, D. I. Shutovaa,*, and V. I. Shcherbakova aNational

Research Centre Kurchatov Institute, Moscow, 123182 Russia *e-mail: [email protected]

Received November 9, 2018; revised November 9, 2018; accepted December 9, 2018

Abstract—High gradient magnetic separation is an effective method for ores enrichment and industrial wastes recycling (including radioactive wastes). The possibilities of separators based on resistive and permanent magnets are limited due to relatively low value of magnetic induction and rather high energy consumption. LTS magnetic systems require liquid helium and complicated cryogenics which can be costly and not always optimal for use at industrial facilities. High-temperature superconductors operated in liquid, sub-cooled and solid nitrogen and equipped with cryocoolers are promising materials that can help expanding industrial application of superconducting devices. In this study, we discuss the design of an HTS rotary separator prototype with the horizontally oriented rotor axis together with the magnetic fields and forces calculations that define prototype working parameters; overall design of HTS-2G coils and preliminary test results of the said coils at different operating temperatures. Keywords: high-temperature second generation superconductors, HTSC tapes, REBCO tapes, high-gradient magnetic separator, superconductivity, superconducting magnetic systems DOI: 10.1134/S1063778818120037

1. INTRODUCTION The magnetic separation is an environmentfriendly technique enabling to separate particles basing on the difference of their magnetic properties. The method can be potentially used for cleaning of the heat carrier on nuclear power plants as well as soil and water in contaminated areas. Efficiency of separation process depends on multiple factors: the magnetic field induction, the particles average size, the particles concentration etc. In order to trap fine magnetic particles or feebly magnetic substances a high magnetic force Fm is required. It can be expressed as follows (1):

Fm = α(χ p − χs )VB grad B,

(1)

where B is the magnetic flux density, χ p,s is the volumetric magnetic susceptibility for the magnetic particles and for the solvent, V is the particle volume, α is the particle’s form factor. Open Gradient Magnetic Separation (OGMS) uses the magnetic field generated by a magnet itself (without any filters). On the one hand, a continuous process can be easily organized for OGMS. On the other hand, the OGMS is suitable for ferromagnetic 1 The article is published in the original.

ores enrichment only because of the low level of magnetic forces. In High Gradient Magnetic Separation (HGMS) special magnetic filters consisted of thin ferromagnetic wires in external magnetic field increase the magnetic gradient. It allows to achieve much stronger extraction forces in comparison with the OGMS process.