Environmental beneficiation of machining wastes - Part II: Measurement of the effects of moisture on the spontaneous heating of machining swarf

Machining swarf consists of finely divided iron powder generated from machi ning of metal components. This material spontaneously heats due to rapid ox idation of the metal, which can lead to fires. While it is known that spont aneous heating of metal powders requires water as a reactant, there has bee n no quantitative information regarding how much moisture must be present f or the material to spontaneously heat. The purpose of this paper is to dete rmine the general heating characteristics of swarf and measure the effects moisture has on spontaneous heating. The moisture content and the effects o f repeated water additions were studied. These experiments were conducted u sing a newly developed spontaneous heating test specifically designed for t his purpose, as no suitable standard methods were useful. It was determined that spontaneous heating was most severe from 10 to 25% moisture by weight for the swarf sample studied.