Metalworking fluids (MWFs) is one among the emulsions widely applied in various industries in machining process. Generally, MWFs consist of oil, emulsifiers, and additives, are used either in the forms of diluted and undiluted fluids. The spent metalworking 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 presents 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, condition, 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.
Part of the book: Science and Technology Behind Nanoemulsions