This Master’s Thesis concerns scaffold formation, its problems, and ways to detect the accretions. In order to do this, thermocouples has been installed in a pilot blast furnace. The pilot blast furnace is used by LKAB to develop better iron pellets, thus no planned experiments has been possible with aspect to this project. An attempt to detect scaffold formation by analyzing the data received from the thermocouples was done. Probably there has been some kind of accretions in the furnace, however little, since it has been working too well! There has most likely been some refractory penetration since samples collected at the end of the campaign show high contents of K2O-Al2O-SiO2 compounds. The two latter are the major compounds found in the pilot blast furnace refractory. The computer program SIMCA has been used in an attempt to: • Describe thermocouples as a function of other process parameters • Find low frequencies by using a wavelet function. Research has to continue, and other methods should be implemented in order to fully describe and detect scaffold formation.