Experience of the manufacture and operation of blowing plugs (lances) produced by OOO Keralit

Abstract

One way of improving metal quality is bottom blowing with inert gas in a steel-pouring ladle through a blowing plug with treatment in a furnace-ladle unit and in an evacuator. Information is provided about experience of producing and operating OOO Keralit blowing plugs (lances).Development of contemporary steel smelting production requires improvement of methods for smelting and extra-furnace steel treatment technology in order to prepare high quality steels. Extra-furnace steel treatment is an important link in the production chain for preparing steel in the section between the steel smelting unit and steel pouring. Currently ladle metallurgy makes it possible:-to increase the productivity of a steel smelting unit as a result of increasing the rate of chemical processes during extra-furnace steel treatment;-to accomplish fine steel finishing with respect to chemical composition; -to improve steel cleanliness with respect to non-metallic inclusions;-to accomplish metal degassing; -to prepare a melt for subsequent pouring by regulation of the casting temperature and casting properties;-to coordinate with respect to time the work of steel smelting units and the pouring section.Most widespread is the process of blowing metal in a ladle with inert gas with correction of steel composition and its temperature. The requirement for this process from the time of its appearance in the 1950 -60s is explained mainly by the fact that the continuous steel casting method developed at that time required clear regulation of metal temperature in the ladle and uniformity of its chemical composition [1].An inert gas, passing in stirred metal, may be introduced into the metal through a plug installed in the bottom of the ladle, or introduced into the metal from above [2]. According to representatives of one metallurgical plant, as a result of using bottom blowing plugs assimilation of manganese by the metal increased compared with the technology without bottom blowing by 19%, silicon by 12%, and aluminum by 9.5%. In order to achieve 95% metal homogenization 6 -8 min of bottom blowing is sufficient. In melts with upper blowing this time varies from 12 to 14 min [3].Thus, the most effective technology for resolving the task of ladle metallurgy is bottom blowing of the metal with an inert gas through blowing plugs, that operate under severe conditions of abrasive action of heated molten metal, chemical erosion of slag of variable composition, and thermal shock that arises during metal pouring [4]. In order to provide high stability during operation blowing plugs should exhibit low open porosity, high mechanical strength and thermal shock resistance, be stable towards the chemical action of molten metal and slag. Plug construction should provide constant gas flow rate at a prescribed pressure, controlled plug wear during operation, and the possibility of normal service and as necessary its replacement.Since 2005 OOO Keralit has been concerned with developing the construction of blowing plugs, and production technology of refractory mater...