0191-9067/82/020121-11$03.00/0 Copyright ® 1982 SUNSAT Energy Council LUNAR RESOURCE BENEFICIATION BY MAGNETIC SEPARATION DAVID R. KELLAND Francis Bitter National Magnet Laboratory Massachusetts Institute of Technology Cambridge, Massachusetts 02139, USA The use of lunar material for construction on the Moon and in space has been proposed for such projects as solar power satellites. Glasses and metals would be produced with the advantage of a great reduction in cost over shipping terrestial resources for construction of support structures. As with terrestrial materials, the collection, transportation, and beneficiation of lunar raw materials will be required to make suitable feed stocks available for refining and manufacturing. One beneficiation method which may have distinct advantages in a space environment and has been the subject of recent extensive technological improvement is magnetic separation. Its features and the possibilities for application in solar power satellite construction were outlined at the Glass and Ceramics Workshop at the Lunar and Planetary Institute in 1979. Recent research has enhanced the applicability of magnetic separation to lunar resources. MAGNETIC SEPARATION The retention or separation of solid particulates through the use of magnetic separators has been a well-established art for most of this century. Until the late 1960's, most of the commercial applications were confined to the removal of ferromagnetic materials with fairly large particle sizes. The equations for the forces on magnetic dipoles were formulated during the previous century but until this time there had not been any major theoretical consideration of the overall magnetic separation process. A breakthrough in this field occurred when high gradient magnetic separation (HGMS) was introduced about ten years ago. Reviews of the more recent developments can be found in the IEEE Transactions on Magnetics since 1973. The theoretical basis for HGMS can be found in a paper on electrostatic separation by Zebel (1). In electrostatic separation and in HGMS, high gradients (and hence, large forces) are obtained by placing small dielectric or ferromagnetic fibers in a uniform electric or magnetic field. In most practical HGMS devices, a matrix of ferromagnetic steel wool with a packing fraction of the order of 5% is placed in a magnetic field produced by an iron-clad electromagnet or by a superconducting coil. The substances to be separated are passed through the matrix in a gaseous or, more commonly, a liquid carrier. It is possible to remove weakly paramagnetic (magnetic Supported by the National Science Foundation.
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