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

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.

IMPROVEMENT OF SAMPLE PREPARATION IN ICP-AES ANALYSIS OF FERROALLOYS

A set of ICP-AES techniques has been developed for determination of rated elements: Ti, Si, R Al, Cu, Mo, V, Sn, and Zr in ferrotitanium; Ni, Fe, Cu, Co, and As in ferronickel; Si, Cr, and P in ferrochrome silicon; Zr, Si, Al, R and Cu in zirconium ferrosilicon; Mn, Si, and P in manganese ferrosilicon. Combination of the multi-element ICP-AES method which allows precise determination of the elements in ferroalloys in a wide range of concentrations and microwave sample preparation in closed autoclaves which excludes the loss of the components to be determined provides the rapidity of the analysis procedure. The composition of solutions for opening samples of ferroalloys and temperature-time modes of microwave sample preparation in an autoclave are substantiated. Conditions for ICP-AES determination of the rated elements in ferroalloys are studied. Analytical lines of the elements to be determined free from significant spectral overlaps are chosen. The dilution rates of the solutions are determined. The method of internal standard was used to improve the reproducibility of the analytical signal for Ti determination in ferrotitanium, Si and Cr in ferrochrome silicon, as well as all rated elements in manganese ferrosilicon and ferronickel. The spectrometer was calibrated using model solutions and solutions of standard samples added with the certified solutions of the elements to be determined. To determine Ti, Si, FJ Al, Cu, У and Zr in ferrotitanium; Ni, Fe, Cu, and Co in ferronickel; Si, Cr, and P in ferrochrome silicon; Zr, Si, Al, P, and Cu in zirconium ferrosilicon; Si and P in manganese ferrosilicon a multidimensional graduation by two analytical lines was used. The correctness of the determination was evaluated in analysis of standard samples of ferroalloys and comparative analysis of the obtained results with the data of standard methods: comparison of the variances according to the Fisher criterion did not reveal any significant difference between them, whereas the use of the modified Student test showed the absence of the systematic error.

Analysis of Cadmium and Lead in honey: direct-determination by Graphite Furnace Atomic Absorption Spectrometry

<p>One of the emerging issues regarding the analysis of inorganic contaminants in food is the determination of Cadmium (Cd) and Lead (Pb) in honey. In fact, this kind of analysis is foreseen in most of the National Residue Control Plans (NRCPs) that European Union Member States (EU MSs) have to perform according to Directive 96/23.</p><p>With the aim to provide technical support to the EU National Reference Laboratories (NRLs), an easy-to-use method on direct determination (DD) of Cd and Pb in honey by graphite furnace atomic absorption spectrometry (GF-AAS) after dissolution in an aqueous mixture of 2.5 % HNO₃ (v/v) and 12.5 % H₂O₂ (v/v) was in-house validated and distributed to the NRLs network. Analyses were carried out on a batch prepared for the feasibility study of the EURL-CEFAO 19^th PT on honey. The validation levels (20 and 100 µg/kg for Cd and Pb, respectively) were chosen similar to those that would have been proposed for the PT.</p><p>The method proved its efficacy in terms of analytical performance; it appears to be low cost and time saving compared to a microwave sample preparation. In addition, it also decreases the environmental impact, being the amount of acid and reagents considerably reduced. </p>