Experimental methods of flowsheet development for hard drive recycling by preferential degradation and physical separation

Abstract

Neodymium-iron-boride magnet recycling by applying mineral processing practices of liberation and separation to hard disk drives is designed, discussed, and evaluated. Magnetic material, observed to be brittle, is liberated from the hard drive constructed mostly of malleable metals by preferential degradation of the magnet material. The process developed is shown to recover greater than ninety-five percent of the neodymium-iron-boride magnet material in the feed with a product grade of up to over 80 percent magnet material by mass. The process is designed to co-produce stainless steel, aluminum, nickel alloy, carbon steel, and printed circuit board concentrates as contributors to the recycle value of hard drives. The value of materials enclosed in hard drives is explored and discussed. Economic evaluation of this process, including estimation of capital and operating expenditures coupled with revenue based on demonstrated recovery of valuable materials, shows a positive net present value at various depreciation rates up to thirty percent.