Thermodynamic simulations of fluorine/chlorine-SiO2-CaO system show that halides have the potential to partially remove the components from the system or decrease melting points of the components. Fast heating experiments support thermodynamic simulations. These results provide a possible modification for thermal lance cutting of concrete. The possibilities of applying halides to thermal lance cutting technology are discussed. The experiment shows that a fluorine-modified lance substantially improved the efficiency of thermal penetration of concrete. This modification allows converting a substantial part of concrete to volatile products. Consequently, the amount of molten lava is substantially reduced and the cutting/piercing speed of the thermal lance is increased by a factor of two.