Refractory linings in various metallurgical units undergo considerable fluctuations in temperatures for long periods, which cause changes in mechanical stresses in the lining and affect the life of the same considerably.The existing conventional methods for the investigation of refractories do not reflect actual operational conditions in metallurgical units. Forecasting of refractory lining life can be carried out by investigating refractories fatigue. With this aim in view, a procedure was developed for conducting fatigue investigations of refractories at a pulsating compressive cycle. Trials were conducted under a wide range of temperatures, i.e. from room temperature up to 1500°C. Fatigue tests of refractories made it possible to establish conditions of their durability and methods of improvement in metallurgical units.
The roof of electric arc furnaces for steel smelting (EAF) are exposed to very demanding operational conditions and its service life is shorter than that of the other parts of the lining. The durability of the roof can be improved by modifying its design.Compared with the sector-arch type of roof currently used on most electric arc furnaces, the advantages of a roof of annular masonry are as follows: more uniform distribution of the stresses in the crown, significantly lower labor intensity and time consumption in the laying of the masonry, more scope for efficient intermediate cold patching, and the need for fewer different types of brick.The types of brick produced to the correct dimensions for the annular masonry of roof of the 100-ton EAFs of the Chelyabinsk Metallurgical Plant were the magnesite --chromite (periclase-spinel) types MKhS (PShS)-40, MKhS (PShS)-41, and MKhS (PShS)-42, and the magnesite --chromite types MKhS-41, MKhS-42, and MKhS-43 ( Fig. 1 and TaMe 1).Bricks Nos. 40 and 41 (see Fig. 1A) were intended for the construction of the annular masonry by laying them on their edges (relative to the roof ring), bricks No. 42 for the construction of the annular masonry by laying them on their fiats (see Fig. 1B), and on their edges in conjunction with bricks No. 41 (see Fig. 1C), and bricks No. 43 (see Fig. 1D and E) for the construction of the circular electrode openingsand the annular center part of the roof.In 1973-1974 the Magnezit Combine produced three experimental batches of these bricks. The first batch was produced in magnesia brick Section No. 2 (MBS-2) by the technology for periclase --spinel roof brick. The batch consisted of PShS-40 and PShS-42 types. The second and third batches were produced in MBS-1 by the technology for magnesite--chromite roof brick. The second batch consisted of MKhS-41, MKhS-42, and MKhS-43 types, and the third batch of MKhS-41 and MKhS-43 types.
During the operation of large-tonnage steel-smelting furnaces, stresses arise in the refractory lining of the crown; these are caused by the weight of the crown and the variable temperatures of the subcrown space [i]. The cyclic nature of the change in stress is responsible for the fatigue-type fracture of the components of the crown, which, in addition to the physicochemical processes of wear in the refractories, is a factor determining the durability (resistance) of the crown lining [2].In order to improve the durability of the refractory linings a design of crown has been developed for an arc furnace which ensures that the stresses in the lining are reduced as a result of the partial off-loading of the load on the crown due to its weight and the localization of the stresses arising in the peripheral and central regions of the lining [3].The suspended design of crown includes making the linings of the peripheral and central region from shaped, periclase--chromite crown refractories, grades PKhSE-3 and PKhSE-5 (Tech. Spec. (TU) 14-8-271-7:8).The peripheral region is made up of round tiers of items on their "edge,"and the central region by using a sector-arc method in a water-cooled central ring. The ring lining of the peripheral section is suspended from suspension beams by means of pins and metal plates. The load is off-loaded from the crown lining using the adjusting equipment.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.