Effect of silica concentration on degree of sintering of chromite-silica ladle well filler sand based on South African raw materials

Abstract

During steelmaking, one important factor for production efficiency is the free opening of the ladle nozzle during continuous casting. Free opening occurs when the well filler sand and the steel flow freely when the slide gate is opened. Well filler sands are used for the slide gate of a ladle to separate the slide gate refractory and the molten steel. The well filler sand is partially sintered by the heat of the molten metal, which can result in the ladle nozzle failing to open if the sand is not sintered to an appropriate extent. It is therefore of great importance that the sintering behaviour of well filler sand is understood. We studied the effect of the well filler sand chemistry on its sintering properties. Samples of well filler sand with various chemical compositions were sintered in a high-temperature chamber furnace. Quantitative X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), and wavelength dispersive spectrometry (WDS) by electron microprobe analysis (EMPA) were used to analyse the various well filler sand mixes. Points of analysis were indicated on backscattered electron (BSE) micrographs. Quantitative element mapping was undertaken by energy dispersive spectrometry (EDS). Thermodynamic calculations in FactSage predicted the percentage liquid phase present for the various well filler sand compositions at equilibrium conditions. The results of this work show that the degree of sintering of chromite-silica well filler sand depends strongly on the silica content. The amount of liquid phase formed increases with increasing silica content.

Effect of Cr2O3 Addition on Sintering Behavior of Novel Chromite‐Based Ladle Filler Sand

“…The effect of Al in steel has also been confirmed in the case of chromite filler sand, [ 13–15 ] and it has been observed that the liquid phase can react with dissolved Al in liquid steel, leading to an increase in Al 2 O 3 content. Previous research [ 33 ] has indicated that the Al 2 O 3 crucible does not significantly impact the experimental results. In the current study, all steels contain 2 mass% Al, but the liquid phase has an entirely different content of Al 2 O 3 , as shown in Table 5.…”

The Influence of Filler Sand Composition in a Free Opening Rate of Steel Ladle

“…A mixture of refractory raw materials, called "filler sand", is used to protect ladle slide gate from the liquid steel during refining process (Figure 1) [1]. The top layer of the filler sand needs to be sintered in an appropriate degree so that when the slide gate nozzle is opened, the sintered layer needs to break due to the pressure of the liquid metal, allowing the liquid steel to flow out [2]. This is called "ladle free opening".…”