Separation of Emulsified Metalworking Fluid by Destabilization and Flotation

Metalworking fluids (MWFs) is one among the emulsions widely applied in various industries in machining process. Generally, MWFs consist of oil, emulsifiers, and addi -tives, are used either in the forms of diluted and undiluted fluids. The spent metalwork - ing fluids usually become a very stable emulsion, it requires an appropriate handling procedure. Two typical approaches for dealing with rejected MWFs are recovery and disposal, in which largely involve separation as the first essential step. This chapter pres ents the topics related to metalworking fluids, ranging from their types, composition, usages, lifecycle, and handling. Afterwards, processes for separating MWFs emulsion are presented, including chemical coagulation, flotation, and electrocoagulation-flotation for their background and results from experiments. Performance in separation, condi tion, and mechanisms of these three processes dealing with oily emulsion are shown. The understanding in the separation of MWFs by physico-chemical processes can benefit the selection of proper technology for handling of oil emulsion, either generated from machining industries or other activities such as household or petrochemical process.