Removal of oil from ferrous grinding swarf of automobile industry by aqueous washing process.

This research focused on the recovery of valuable materials from ferrous grinding swarf. We received the sample from the automobile industry. The sample has consisted of approximately 20 wt% moisture and 80 wt% residue (oil and soild). The chemical composition of the oven-dried sample was approximately 87 wt% iron. In this study, aqueous washing process for oil removal from ferrous grinding swarf was investigated with two different commercial reagents, Micro-90 and Detergent 8. Three different amounts of solids (2, 3, and 4 g) were mixed with 20 mL of diluted reagents for the aqueous washing. In the Micro-90 solution, about 80% of the oil was removed after three washing cycles at a solids content less than 3 g/20 mL. On the other hand, when using Detergent 8, 100% oil was removed after three washing cycles at a solids content of less than 3 g/20 mL. Pulp density was an important factor in determining oil removal efficiency. For the scale-up experiment, different washing methods such as ultrasonication and overhead stirrer were examined. The preliminary reuse test of the Detergent 8 solution was also conducted for the feasibility of the aqueous washing process.