Environmental beneficiation of machining wastes - Part III. Effects of metal working fluids on the spontaneous heating of machining swarf

Machining swarf is a finely divided metal powder that is prone to spontaneo us heating and, in some cases, spontaneous combustion. The fine particle si ze, large amount of particle surface area, and the presence of moisture all promote rapid oxidation. This hazard dramatically increases disposal costs for swarf and interferes with recycling efforts. A potential method for mi nimizing spontaneous heating and facilitating recycling of the swarf is to spray a fluid on the material that coats the particles and creates a barrie r between the metal and oxygen. Surface coatings could be tested for their effects on the spontaneous heating potential of swarf by treating a sample of swarf with a fluid that would coat the particles, then monitoring its he ating behavior. This paper describes the results of applying corrosion inhi bitors and machining fluids to the swarf, and monitoring the spontaneous he ating behavior using a testing method developed specifically for this purpo se. The effects of different types of surfactants and the effects of surfac tant concentration on the spontaneous heating of swarf are discussed.