A method of making holes. Quickly.
This process was developed in France following the second world war, as a means to assist in the break up of gun emplacements, submarine pens, and other large concrete structures.
The principles of the operation are as follows, Oxygen is fed through a length of steel tube, usually ¼" bore, to a spot on the material which has been previously been heated, and the oxygen combines with the iron to form a slag rich in iron oxides. The slag produced is very fluid which enables cutting and boring to take place. The flow of slag is assisted by the velocity of the gas and vapours expelled within it.
The lance is ignited by applying heat to the end of the tube with oxygen-acetylene equipment. With the addition of a lance packed with mild steel rods the ratio of iron to oxygen is greater thus providing sufficient heat to melt ferrous and non-ferrous materials.
The heat generated from the iron/oxygen reaction is sufficient to melt concrete, the melting point of concrete varies between 1800-2500°C. The formation of iron silicate increases the fluidity of the slag produced, therefore the silicate content of the material has an appreciable effect on the speed of operation and the rate of consumption of packed lance and oxygen.