Peter the Great St. Petersburg Polytechnic University, Saint Petersburg, Russia:

E. N. Bespalov, Postgraduate Student
A. V. Kalmykov, Researcher, e-mail: alexkalmyk@mail.ru
I. A. Matveev, Associate Professor

This paper describes a technique for preparing the precision alloy grinding swarf for pyrometallurgical processing through compacting with the application of calcium oxide binders. The specific properties of swarf – mainly strong mechanical bonds between microswarf and abrasive grains – and its relatively high price make this process cost-effective as there is no need to mechanically separate the abrasive from the metal. The processes involved are environmentally friendly, no chemical reagents are used so there is no need for waste neutralization. The process involves a cleaning stage (when the residual lubricoolant is removed) and the actual compacting followed by drying. There are no special transportation or storage requirements for the resultant semi-finished product. The material has acceptable mechanical strength and moisture retention properties which make it easy to store and utilise in metallurgy as it contains approximately 40% of metal. Due to the low density (~1.2 g/cm³), there is no risk that the attached moisture will interact with the metal when the material is heated in an induction furnace. By adding fluorspar, the authors managed to obtain fluid slag of the triple system Al₂O₃ – CaF₂ – CaO. Fluorspar was added after soaking to ensure there was no residual attached moisture in the material. A series of experiments was conducted with the metal mark YuN14DK24 (Fe-based alloy, consist Al, Ni, Cu and Co, till 24 mas. %) grinding swarf in an induction furnace with a graphite crucible. To prove the efficiency of metallurgical processing for waste treatment, the authors did a balance heat with fine chemicals. No residual metal was found in the resultant slag indicating a high recovery ratio. Composition-wise, this slag appeared to be similar to the slags used in electroslag remelting process, which suggests that metallurgical processing of grinding swarf can be an almost waste-free process.

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