Monitoring of slag composition changes by density measurements

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I.

INTRODUCTION

IT is sometimes necessary to determine whether or not the chemical composition of a given batch of mold powder of the type used in continuous casting conforms with the manufacturer's specifications. This can be done by a full chemical analysis, but such analyses take time and are usually outside the control of the casting department. Since slag density is very much a function of slag composition, a simpler approach would be to determine the density of slag made from the mold powder and compare this to either the density of a standard sample or a calculated density based on slag composition. In the glass industry, where density measurement has traditionally been used, it has been found possible to measure composition changes as small as 0.1 wt pct. The objective of this project was therefore to investigate the use of slag density measurements as a means of monitoring changes in mold powder composition. Such a technique could be used to identify quickly and simply batches of mold powder which do not conform to specifications and which should be quarantined for full analysis. II.

A 10 g sample of the mixed mold powder was placed in a platinum crucible which, in turn, was placed into a preheated (1400 ~ molybdenum-wound furnace for 30 minutes to ensure homogeneity of the slag. The crucible was then removed from the furnace and the slag poured into a preheated (250 ~ brass mold. The mold was preheated to prevent cracking of the sample. To prevent devitrification, low viscosity (