Abstract

In this paper the devolvement progress of a monolithic permanent lining concept based on sintered magnesia for the application in the EAF, BOF and the steel ladle will be presented. The usage of such a mix will reduce the lining duration, increase safety during relining and reduce the cost. Currently for a permanent lining in the different fields of application either basic fired bricks, shotcrete  mixes or dry mixes based on non-basic raw materials are used. All these applications show some disadvantages such as higher costs, higher water intake and low stability against steel or slag penetration. The approach of the new mixes is to focus on a water free, ready for use application or at least significantly reduce the water content to minimize the potential for hydratisation and to speed up the relining practice.

Based on the individual requirements of each aggregate individual mixes for the EAF, BOF and steel ladle were developed. Each aggregate requires individual properties such as binding strengths at room temperature, smoke and dust release during preheating/application, binding strength development with temperature etc. To investigate the best binding concept for each aggregate, various laboratory tests at different temperatures such as cold crushing strength (CCS), shrinking behaviour, cracking behaviour, thermo-gravimetrical analysis and refractoriness under load were determined. Based on these tests, the most usable binding agents and binder amount were selected and tested in detail. To verify the lining procedure and the developed strength at room temperature and application temperature a special laboratory lining test was carried out. .  

For the permanent lining of the EAF and BOF either a ready for use water free mix or a dry mix with a chemical binder (setting with small water addition) have shown the best results. For the steel ladle, where no strength at room temperature is required, a dry lining similar to a dry setting tundish mixes showed the most promising results.

Furthermore the slag resistance for different binder concepts in comparison with a standard basic permanent lining brick were investigated during a induction furnace test using a typical ladle slag. All mixes show a reasonable good slag resistance which ensures certain emergency running properties in case of a brick breakout. 

Based on the successful laboratory trials, field trials at various customers for EAF, BOF and steel ladle are currently carried out, first results will be expected in Q1/2017.