STUDY OF COMPOSITION AND STRUCTURE OF NLMK BF No. 6 HEARTH SCULL. Report 2

Abstract

Resistance of hearth walls lining and their joint with hearth plug considerably governs a blast furnace (BF) campaign duration. Development of hearth design of modern BFs provides a high effective heat sink by copper cooling plates and application for the lining carbonaceous blocks having high heat conductivity, which causes stable scull formation. Study of the composition and the structure of the scull is an important and actual task to provide the highest technical and economical indices of blast furnace production, increasing of the furnaces campaign duration. It was shown that the scull in the hearth zone has a laminated structure. It was established that content of titanium compounds (oxide, carbides and nitrides) in the scull is low. Zinc buildups were not found on the carbonaceous refractories of the hearth walls lower the tap hole. Considerable content of zinc compounds was revealed in the scull of brickwork of the hearth top, in the area of tap holes and hole channels, on the hearth refractories. It was found that basic components of the scull were represented by carbon in the form of graphite, metal (mainly in the form of α-Fe) and slag, amount of which was nincreasing from the lower part of the hearth to the upper one while the content of metal and graphite in it was decreasing.