New cooling panels for reduction of heat losses in EAF steelmaking

At the EAF, current water-cooled panel technology shows several drawbacks. First, heat losses to these panels are high: they account for 10 to 20% of the total energy consumption in modem furnaces (50 to 100 kWh/t steel in standard operation). Moreover, in critical areas ("hot spots"), the water-cooled panels do not stand properly the excessive heat load and must be frequently repaired for leaks, thus causing hazardous situations (explosion risk), maintenance work and some production downtime. The objective of the research project was to develop new water-cooled panels that allow reducing heat losses (and thus the overall energy consumption in EAF steelmaking) and increasing panels service life. One of the ideas that were suggested for improvement at the start of the project consists in hanging relatively small refractory parts on the water-cooled panels. These refractory parts would first act as slag holders with improved retaining capacity. Moreover, the refractory parts would stand heat and protect steel panels in case of slag removal. Such refractory parts should thus greatly lower thermal losses, thermal stress in the panels and maintenance work. Because developing new EAF water-cooled panels for the roof and the upper side wall most probably requires different technological solutions, the work has been shared out among project partners as follows. CRM and ProfilARBED have concentrated their work on the roof (industrial trials performed at the EAF plant of Differdange, Luxembourg), while CSM and DALMINE have worked on the upper side wall (industrial experimentation conducted at the EAF plant of TenarisDalmine, Italy). For the "roof" group, a test stand able to simulate the thermal shocks that refractory parts have to withstand inside the Differdange furnace has been designed and built at CRM. This stand has been used for testing various qualities of refractory materials with a first simple design of refractory part and fixing. Although all tested materials have comparable thermal shock resistance according to supplier data sheets, two qualities of refractory materials were found to be more resistant in our test: a fired bauxite and a silicon carbide (SiAlON-bonded). These results were discussed with experts from ProfilARBED in order to prepare the first industrial tests in Differdange.