Ladle filler sand evaluation

CAMERUCCI, MARÍA A.; TOMBA MARTINEZ, ANALÍA G.; CAVALIERI, ANA L.; MARTORELLO, LEANDRO F.; GALLIANO, PABLO G.

Orlando, Florida, USA

Congreso; 9th Biennial Worldwide Congress on Refractories (UNITECR'05); 2005

The American Ceramic Society

High free opening rates of ladles are required in steelmaking to improve steel quality. The use of an oxygen lance for the artificial opening results in product downgrading by steel oxidation. Free opening rate is mainly determined by the performance of the ladle filler sand. Different types of sands are incorporated into the inner nozzle and well block after ladle preheating in order to act as a filler material. Chromite-based sands are one of the most widely used. Several operative variables and materials characteristics affect their inservice performance. In this work a set of chromite ladle filler sands of different compositions is analyzed by different laboratory characterisation techniques. The work is focused on the understanding of the sintering behaviour of the sands inder operative conditions. With this aim, samples were shaped and sintered by different thermal treatments for further microstructural and mechanical evaluations. Thermal evolution was also evaluated through dynamic thermal analysis tests. Results from laboratory tests showed two sintering patterns of the sands at liquid steel temperatures. The predominance of each of them mainly depend on the quartz content of the sand. Quartz-containing sands show higher densification during sintering and high percentages of liquid phase formation.On the contrary, quartz-free sands show lower volume changes on sintering, but sintered samples present higher mechanical strengths.