Acid dissolution of neodymium magnet Nd-Fe-B in different conditions

The separation of rare-earth elements (REE) from a neodymium magnet has been widely studied last year. During the research it was identified that the waste of computer hard disk contains 25.41 % neodymium, 64.09 % iron, and <<1 % boron. To further isolate rare-earth metals, the magnet was acidically dissolved in open and closed systems. In both methods of dissolution, concentrated nitric acid was used. The difference between these methods is the conditions of dissolution of magnet. The magnet was dissolved in a microwave sample preparation system at different temperatures and pressures in a closed system. In the open system, the acid dissolution of the magnet is conducted at room temperature. 0.2 g of the neodymium magnet sample was taken under two conditions, and the dissolution process in the closed system lasted 1 hour, and in the open system 30-40 minutes. The open system is a non-laborious, simple, and cheap method of dissolving the magnet by comparing both systems. Therefore, an open sample preparation system is used for further work. To remove the iron in the magnet, oxalic acid was used and REEs are precipitated as oxalates under both conditions. According to the result of the Inductively coupled plasma mass spectrometry (ICP-MS) method, it was identified that the neodymium and iron contents in the precipitate are 24.66 % and 0.06 %, respectively. This shows that the iron has almost completely passed to the filtrate

High-Temperature Fluidized Bed Processing of Waste Electrical and Electronic Equipment (WEEE) as a Way to Recover Raw Materials

This paper explores the effectiveness of metal recovery and values of gaseous emissions during thermal e-waste processing followed by magnetic separation. The thermal process of conversion of this kind of waste is difficult due to the uncertainty of the operation when compared to the processing of homogeneous materials. This is due to their complex and heterogeneous structure. The adoption of the fluidized bed reactor makes the process feasible, stabilizing it significantly and limiting emissions of harmful gases. Mobile cellphones were used as the raw input material of 450 g total mass. During the thermal transformation, the exhaust gases such as: CO, CO2, NOx, SO2, HCI, HBr, HCN, NH3, phenol, hydrocarbons, HF and COCI2 were analysed. The thermal treatment resulted in 333.6 g of solids in the fluidized bed. They were fragmented into grains smaller than 1 mm and 0.5 mm. The process of magnetic enrichment was used next on grains greater than 1 mm and smaller than 0.5 mm. The process was carried out using a neodymium magnet for particles >1 mm and a plate electromagnetic separator (powered by a three-phase current) together with a 1-disc tape-type separator, which was used for particles <1 mm. Such an approach resulted in the recovery of 81.9% of cobalt, 96.6% of iron and 99.2% of neodymium. The most efficient method of magnetic enriching (MS) proved to be the use of the electromagnetic plate separator.

Acid Dissolution of Neodymium Magnet Nd-Fe-B in Different Conditions

The separation of rare earth metals (REM) from a neodymium magnet has been widely studied in the last year. We have shown that the waste of computer hard disk contains 25.41 % neodymium, 64.09 % iron, and &amp;lt;&amp;lt;1 % boron. To further isolate rare-earth metals, the magnet was acidically dissolved in open and closed systems. In both methods of dissolution was used concentrated nitric acid. The difference between these methods are the conditions of dissolution of magnet. The magnet was dissolved in a microwave sample preparation system at different temperatures and pressures in a closed system. In the open system, the acid dissolution of the magnet conducted at room temperature. 0.2 g of the neodymium magnet sample was taken under two conditions, and the dissolution process in the closed system lasted 1 hour, and in the open system-30-40 minutes. The open system is a non-laborious, simple and cheap method of dissolving the magnet by comparing both systems. Therefore, an open sample preparation system is used for further work. To remove the iron in the magnet, oxalic acid was used and precipitated as oxalates under both conditions. According to the result of the ICP-MS method, it is shown that the neodymium and iron contents in the precipitate are 24.66 % and 0.06 %, respectively. This shows that the iron has almost completely passed to the filtrate. Thus, it is possible to remove the iron from the sample.

The magnetic field about a three-dimensional block neodymium magnet

Neodymium magnets were independently discovered in 1984 by General Motors and Sumitomo. Today, they are the strongest type of permanent magnets commercially available. They are the most widely used industrial magnets with many applications, including in hard disk drives, cordless tools and magnetic fasteners. We use a vector potential approach, rather than the more usual magnetic potential approach, to derive the three-dimensional (3D) magnetic field for a neodymium magnet, assuming an idealized block geometry and uniform magnetization. For each field or observation point, the 3D solution involves 24 nondimensional quantities, arising from the eight vertex positions of the magnet and the three components of the magnetic field. The only unknown in the model is the value of magnetization, with all other model quantities defined in terms of field position and magnet location. The longitudinal magnetic field component in the direction of magnetization is bounded everywhere, but discontinuous across the magnet faces parallel to the magnetization direction. The transverse magnetic fields are logarithmically unbounded on approaching a vertex of the magnet. doi:10.1017/S1446181120000097

Dynamic Reversible Evolution of Wrinkles on Floating Polymer Films under Magnetic Control

In this paper, we present a simple and versatile method to dynamically and reversibly tailor surface wrinkles on a floating polymer film by combining a magnetic droplet and neodymium magnet. The magnetic force from the attraction of the neodymium magnet to the magnetic droplet is the main reason for surface instabilities of floating polymer films, which can induce radial stress in the radial direction, and further, compressive stress in the circumferential direction. This compressive stress can trigger not only floating film wrinkling but also a wrinkle-fold transition. Surface morphologies on the floating polymer film have been systematically studied, by varying the distance between the magnetic droplet and neodymium magnet, polymer film thickness, and magnetic droplet volume. With the decrease in the distance between a magnetic droplet and a neodymium magnet, the decrease in polymer film thickness, and the increase in the magnetic droplet volume, the wrinkle numbers increase and even a wrinkle-fold transition happens. Additionally, the coupling effect of multiple magnetic droplets on the floating film has also been used to achieve novel surface wrinkle patterns, which greatly widens the applications of surface wrinkling.