Study of scull and lining in the hearth of blast furnace No. 2 of JSC EVRAZ ZSMK (Report 1)

Abstract

Results of study of lining and scull of the hearth of blast furnace No. 2 of JSC EVEAZ ZSMK presented, done after BF stop for major overhaul. It was determined, that the scull has a zonal structure, due to different conditions of the forming of it during the furnace running and blowing-down. The scull consists of isolations of graphite, metal and slag inclusions having distinctly lamellar structure. Number of slag inclusions in the scull of the hearth walls lower the hot metal tap hole is not big and sharply arises in samples at levels above the tap hole. In metal structure within the scull ferrite (a-Fe) prevails, also there are some lamellar graphite isolations and perlite. Quantity and thickness of metal isolations in the samples increases from the scull periphery to the center of blast furnace (from 20–30% and tens of microns to 70–90% (mass) and 30–50 microns correspondently) and decreases from the lower part of the hearth wall to the upper one. Titanium nitride (osbornite) TiN and titanium oxide (rutile) TiO2, sulfides of calcium, iron, manganese, silicon carbide SiC present in the scull in a small quantity (less 2%). In samples taken higher the hot metal tap hole, in the scull slag isolations there are a considerable amount of alkali metals oxides and sulfides, and phosphide and iron sulfides were exhibited in the metal phase. It speaks about considerable evaporation/sublimation of compositions of potassium, sodium, Sulphur and phosphorus in the blast furnace hearth following by their condensation/crystallization at the cooled lining of hearth walls.