Through direct monitoring of the melt composition, the metallurgical smelting process can be controlled in a targeted manner, thus achieving the required melt quality precisely and efficiently. However, direct monitoring of melt composition can only be achieved at very high effort and expense with the currently available measuring and analysis techniques. Essential advantages of direct continuous online melt analysis are:

• to reduce the treatment time of melt
• to reduce of alloy consumption
• to improve of quality monitoring and documentation

The development of a measuring system for continuous optical determination of the composition of steel melts by means of optical-fibre-based infrared spectroscopy promises to deliver a costeffective alternative. An optical fibre immersed in the melt is connected to a spectrometer. The continuously recorded infrared spectra of the melt bath contain weak signatures of the trace elements within the steel, which can be evaluated quantitatively with the help of a special multivariate spectral analysis. Expensive external excitation of the melt (e.g. by means of lasers) is not required. The new measuring system for determination of carbon and phosphorus is currently being developed and tested. The measurement of further accompanying elements, such as silicon, manganese, sulphur, nickel and aluminium, is planned.