Abstract

Study on the Properties and Performance of Basic Refractory Mixes for EBT Taphole Sleeve: Effect of Sintering Aids

 Smita Satpathy, Dr. A. K. Samanta, Kido Naofumi, E. Arimitsu, P. B. Panda

TRL Krosaki Refractories Limited, Belpahar-768218, Odisha (India)

Repair of a furnace taphole is usually done on hot condition free from molten metal. Typically, refractory sleeves are placed in the taphole. With increased number of tapping the thickness of the sleeve reduces invariably and therefore it is essential to repair the sleeve on regular basis. Repairing around the sleeves is preferred simply because to replace the entire taphole block after it is worn out would require shutting down the entire furnace which usually requires at least 8 to 10 hours of down time. In order to achieve the original taphole diameter, the space inside the sleeve is filled with a basic repairing mix. Therefore, for reasons of economics, the industry has developed an inconvenient procedure of frequent repairing of taphole sleeves. It has been found that a repairing mix which works well for emergency repairs to the taphole sleeve is preferred. The usual time required for emergency repairs of a taphole sleeve is about 30 minutes. The need clearly exists for a longer lasting maintenance material which requires less frequent repair.  These materials should have easy installation, high bulk density, fast sintering, excellent resistance against molten metal penetration, and superior erosion/corrosion resistance.

The present study is based on the effect of different sintering aids on the properties of basic repairing material and its performance during application. The hot setting behavior of the dry mass depends on the sintering aids, binder content and curing temperature. Grain sizes and material chemistry are carefully controlled to allow for proper density and sintering. Trials were done with chromate, sulphate and phosphate bonded additives and sintering study was carried out both in rammed as well as site conditions at temperatures ranging from 600°C to 1400°C. The Bulk Density, Porosity, Strength and other high temperature properties of samples were evaluated for all the trials and it was found that at intermediate temperatures the sintering aids plays a vital role during application. The developed material has been tested at different integrated steel plants and the performance is satisfactory.