High-Temperature Cutting Mechanism

The efficacy of the thermal lance stems from its ability to generate extreme temperatures locally. While an oxy-acetylene flame reaches about 3,500 °C, the burning of iron in pure oxygen within the lance can push the reaction temperature towards 4,500 °C. This is due to the highly exothermic nature of iron oxidation. When this superheated jet of molten iron, iron oxide, and unreacted oxygen strikes a target, multiple processes occur simultaneously. On a steel target, the lance provides the activation energy and an oxygen-rich environment to ignite the target steel itself, which then undergoes the same exothermic oxidation as the lance. This creates a self-propagating cut. When used on concrete, the mechanism is different. The intense heat melts the silica (\(SiO_2\)) components of the aggregate and cement, which have melting points around 1,700 °C. The steel rebar within the concrete is oxidized and cut as described before. The high-pressure gas stream then expels the molten silicate slag and molten steel, clearing the kerf. The process is less of a ‘cut’ and more of a controlled, high-speed erosion via thermal and chemical attack. The addition of aluminum or magnesium wires to the lance’s core can further increase the reaction temperature, enhancing its effectiveness on materials with very high melting points or thermal conductivity.