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To reduce environmental pollution caused by fluoride from conventional electroslag remelting (ESR)-type slag and meet the requirements of vacuum ESR, it is strongly needed to develop low-fluoride and fluoridefree slag. The crystallization behaviors and evaporation of CaF 2 -CaO-Al 2 O 3 -MgO-Li 2 O slag as a candidate for low-fluoride ESR-type slag were studied. The sequence of crystal precipitation in CaF 2 -CaO-Al 2 O 3 -MgO-Li 2 O slag during cooling process was 11CaO·7Al 2 O 3 ·CaF 2 to CaO, followed by CaF 2 . The dominant crystalline phase in the slag was 11CaO·7Al 2 O 3 ·CaF 2 . The liquidus temperature and crystallization temperature of slag decreased significantly with increasing Li 2 O content from 1.59 mass% to 4.46 mass%. Increasing Li 2 O contents suppressed the crystallization behaviors of ESR-type CaF 2 -CaO-Al 2 O 3 -MgO-Li 2 O slag. The weight loss of the slag melts increased with increasing Li 2 O content in the slag from 1.59 mass% to 4.46 mass%. The gaseous species evaporated from the slag melts were mainly LiF and contained a few amounts of CaF 2 . A proper amount of Li 2 O could be considered as an effective component for the design of low-fluoride ESR-type slag. Serious fluoride evaporation of LiF from CaF 2 -CaO-Al 2 O 3 -MgO-Li 2 O slag melts takes place when Li 2 O content exceeds a critical value.

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