Mould flux plays an important role in continuous steel casting, providing high quality of steel surface and trouble-free caster operation. Mould flux broadly used in steelmaking contains fluoride which ensures good lubrication properties and appropriate heat transfer. However, high volatility of fluorine leads to environment pollution, equipment corrosion, and health and safety hazards. The aim of this project is to establish scientific ground for development of fluoride-free boracic mould flux and feasibility of the use of this flux in industrial steel casting. A comprehensive study of the flux properties will lead to development of environmentally friendly steel casting technology for Baosteel.