Mineralogy and Microstructure of Skull Versions in AO EVRAZ NTMK Blast Furnace No. 6
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Vol. 61, No. 4, November, 2020
REFRACTORIES IN HEATING UNITS MINERALOGY AND MICROSTRUCTURE OF SKULL VERSIONS IN AO EVRAZ NTMK BLAST FURNACE No. 6 V. A. Perepelitsyn,1 K. G. Zemlyanoi,1,3 K. V. Mironov,2 A. A. Forshev,2 F. P. Nikolaev,2 and D. V. Sushnikov2 Translated from Novye Ogneupory, No. 7, pp. 11 – 20, July, 2020.
Original article submitted June 1, 2020. Results of a comprehensive study of the material composition and microstructure of 20 skull samples taken after blowing out AO EVRAZ NTMK blast furnace No. 6 are provided. More than 30 mineral and metal phases of different chemical classes are diagnosed in skull samples. Unlike the skull of blast furnaces of other metallurgical plants (NLMK, ZSMK), NTMK blast furnace skull has an abnormally high content of titanium, zinc, and vanadium compounds, as well as heavy non-ferrous metals and sulfur. On the basis of detailed petrographic analysis, five structural and genetic types (versions of composition and origin) of the skull are identified. Skull versions contain a large amount of grenal, which is dominated by refractory compounds of titanium and vanadium carbonitrides of the general formula (Ti, V)(C, N). Keywords: skull, EVRAZ NTMK blast furnace, structural genetic analysis, grenal, titanium and vanadium carbonitride (TVCN), graphite, cementite, zincite, slag silicates.
from the hearth bottom. The points for skull sample collection over the height of blast furnace No. 6 are shown in Fig. 1. More detailed information is provided below of the points for sample collection and the number of skull of test specimens is from G1 to G13.
RESEARCH OBJECTS The EVRAZ NTMK blast furnace No. 6 with a useful volume of 2200 m3 (hearth diameter 970 mm, two cast iron tapholes, 22 air tuyeres) was blown in after reconstruction in 2004 and blown down for subsequent repair in 2018. During this period 27,950 thousand tons of finished vanadium-containing cast iron was smelted. The average cast iron chemical composition, w.t%: Fe 94.1, Ti 0.14, V 0.496, Mn 0.38, C 4.6, Si 0.08, S 0.024, P 0.05. After blowing down the furnace and cooling with air and the water lining the skull was broken down by means of machines for breaking a lining with a hydraulic hammer and removed from the furnace. In this case samples were collected from the hearth, tuyere zone, and shoulders. Altogether a study was made of representative 17 skull specimens (13 pieces) and the lining (4 pieces) predominantly from the hearth and partly from the level of the shoulders and bosh extension. A sample of “malleable” cast (G13) was selected 1 2 3
RESEARCH METHODS FOR SUBSTANCE COMPOSITION AND MICROSTRUCTURE Five main fundamental research methods were used in the work for the composition and microstructure of inorganic materials: mineral petrological, chemical, x-ray phase (XPA), differential thermal, and x-ray microanalyses. Comprehensive mineral and petrographic analysis was performed using an Olympus (Japan, 1000-fold magnification) metallographic microscope in reflected light. In order to prepare sections diamo
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