ON THE BASIC OPEN HEARTH SLAG.

THE SIMPLE DECIDINC METHOD OF SLAG COMPOSITION AND FEW EFFECTS UPON THE MOLTEN BATH.

Abstract

(1) Author propose the new method to decide the basic open hearth slag composition which can be adopted simply and rapidly before hearth. The process is as follows: taken sample is powdered in mortar made of cast iron and sifted through 100 mesh sieve. FeO% and CaO/SiO₂ are decided from the colour of powdered sample. The fortes are as follows: the process is very simple and rapid, the results are quantitative, the vessel need not special one.
(2) The connection between the powdered colours of slag and the values of FeO% and CaO/SiO₂gained from the actual melts are shown in fig I. According to the slag composition, colour changes white, grey, black, pitch-black, yellowish-brown, brown, dark-brown, reddish-brown, and russet.
(3) Slag composition is statistically investigated. The melt-down slags are in the field ABEF (fig 2) and its center line is M-M'. Slags befor-tap are in GHCD (fig 3), its center line is T-T'. When the basicity is the same, the FeO value of the former is larger than the latter.
(4) The effects of slags upon molten bath are studied. The larger FeO% and basicity, the smaller of C% at melt-down and P% of mgot. The limit line of C 100% is C-C' line (fig 2) and of P.03% of ingot is P-P' line (fig 3).