Recycling oil and steel from grinding swarf

The aqueous washing process using nonionic surfactants and detergent builders was investigated for recovering cutting oil and alloy steel from swarf generated during high-speed grinding operations. Bivariate regression and the response surface methodology were applied to find the optimal concentrations of surfactant and detergent builders. Experimental results showed that 95% of oil removal could be achieved. Nonylphenol decaethoxylate (NPE-10), Tergitol 15-S-7 and 15-S-9 with low oil/water interfacial tension were most efficient in oil removal. Washed samples containing less than 3% of oil and 0.03% of phosphorous were acceptable for recycling in a smelter. A hypothetical 40-t per month processing unit installed at the manufacturer's site would break even, if 24.7 and 58.6% of the recoverable oils were recycled as cutting oils for the base and the alternative cases, respectively. Higher profit would be obtained if more recoverable oil could be recycled as cutting oil.