Recovery of rare earth metal neodymium (Nd) as value added product from scrap hard disc of personal computer (PC).

Abstract

This research work explores the leaching followed by selective precipitation study of neodymium from magnet of obsolete hard disk of personal computer. The experiments were carried out to study influence of several parameters on neodymium dissolution, including the concentration of acid, pulp density and time. Leaching with diluted sulfuric acid at a pulp density of 50-150 g/L resulted in the recovery of 99.8% neodymium. In optimized condition with sulfuric acid 99% Fe, 60% Ni and 7.5% B is also leached. Leaching kinetics of neodymium in sulfuric acid fitted well to the Film diffusion control dense constant size small particle - all geometries model i.e. X=Kct. Neodymium could subsequently be separated selectively from the leach liquor by selective precipitation process to produce double salts using sodium hydroxide solution. These neodymium-sodium precipitate is further treated with HF solution to convert neodymium-sodium salt to pure NdF3. The results obtained in this paper establish that the sulfuric acid dissolution system has potential practical application in the recycling of neodymium from magnets of discarded hard disk.