Detection of Iron Wear in Mechanochemistry Using Magnetometry

M. Baláža, M. Rajňákb, c, Zh. Shalabayevd, A. Zubrika aInstitute of Geotechnics, Slovak Academy of Sciences, Watsonova 45, 04001 Košice, Slovakia bInstitute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04001 Košice, Slovakia cFaculty of Electrical Engineering and Informatics, Technical University of Košice, Letná 9, 04200 Košice, Slovakia dAl-Farabi Kazakh National University, al-Farabi ave. 71, 050040 Almaty, Kazakhstan

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Mechanochemistry is already established in various research fields. However, the production of unfavorable wear from milling media can adversely affect quality of obtained products. In the present study, the possibility to detect iron wear in trace amounts using magnetometry is shown. As a model, the novel mechanochemical synthesis of covellite/sulphur (CuS/S) composite from elemental precursors was realized. After 12.5 min of treatment, the peaks of Cu could no longer be identified in the X-ray diffraction pattern, whereas those of CuS and S were quite intensive. The kinetics of the process was evaluated by determining the amount of free sulphur. As both reactants and products are diamagnetic, possible magnetic response can be registered only due to wear from stainless steel milling chamber and balls. Magnetization increased with milling time, always showing the diamagnetic slope until 15 min of milling. After termination of the CuS formation, the wear production seems to be boosted. After 30 min, the saturation magnetization of 0.166 A m2/kg corresponding to 0.76‰ of iron in the reaction mixture was detected. In general, magnetometry could be used for possible identification of trace amounts of wear in reactions performed using stainless steel media, which are most commonly used in mechanochemistry.

DOI:10.12693/APhysPolA.137.684 topics: magnetometry, wear, iron, copper sulfide, composite, sulphur