Torpedo ladle cars are used to transfer molten iron from the iron-making section of the plant to the steel-making section. Under normal conditions, the residence time of the molten iron in the ladle is two to four hours, and the distance traveled is usually less than one-half mile. In addition to transporting molten iron, the torpedo ladle can also be used as a refining vessel. For example, during desulfurization, powdered reagents are injected into the molten iron by means of a lance. The reagents react with the sulfur in the molten iron and separate from the iron in the form of slag. This process is detrimental to the refractory lining due to the turbulence created.
HarbisonWalker International recommends zoning the refractory lining in the slag line to minimize any refractory damage that might occur during this operation. HWI also offers two different lining designs for torpedo ladle cars: a maintenance-free lining for which periodic shotcreting maintenance is not intended and a conventional high-alumina lining that is intended to be maintained with shotcrete.
HWI’s maintenance-free lining is designed to run the entire torpedo ladle campaign on the original refractory lining, with no shotcrete maintenance required. Thus the brick workmanship for the initial refractory installation is critical—all joint sizes must have minimal thickness. Ladles with this refractory design are capable of campaigns of 400,000 net tons of hot metal (NTHM) without any maintenance. The keys to HWI’s maintenance-free lining design are the IRONMASTER® and NARCARB® BSC products.
The conventional torpedo ladle refractory design consists of high-alumina brick (KRUZITE®-70) with an alumina/silicon carbide/carbon (NARCARB® BSC) impact pad. These linings are designed to be maintained with shotcrete (SHOTKAST® HMC) and/or gunning material at intervals of 50,000 to 60,000 NTHM.