Y. Zhang et Rj. Fruehan, EFFECT OF CARBONACEOUS PARTICLES ON SLAG FOAMING, Metallurgical and materials transactions. B, Process metallurgy and materials processing science, 26(4), 1995, pp. 813-819
Citations number
13
Categorie Soggetti
Material Science","Metallurgy & Metallurigical Engineering
Use of carbonaceous particles such as coke or coal char in controlling
slag foaming is of great practical significance for bath-smelting and
other steelmaking processes. The foamability of the liquid slag in te
rms of the foam index has been determined with the presence of differe
nt amounts of coke and coal char particles. Different sized and shaped
particles were used in the experiments. It was found that the foam in
dex decreased significantly as the ratio of the total cross-sectional
area of the particles to the liquid slag surface area increased. When
the foam was generated by argon gas injection through an alumina nozzl
e (i.d. = 1.5 mm), a liquid slag, CaO-SiO2-CaF2-(Al2O3), depending on
the alumina content, could have an initial foam index of about 2 to 4
seconds at 1500 degrees C without any carbonaceous particles. When the
slag surface was covered only 15 similar to 20 pet with either coke o
r coal char particles, the foam was totally suppressed regardless of t
he initial foam index. In order to understand the mechanism of the ant
ifoam effect of the carbonaceous particles, interactions of a coke sph
ere, an iron ore pellet, an alumina tube, and a coal char particle wit
h the liquid slag foam were examined by X-ray observation. It was conc
luded that the antifoam effect of coke or coal char particles is prima
rily contributed by the nonwetting nature of the carbonaceous material
s with the liquid slag. Possible mechanisms of carbonaceous particles
rupturing a slag film could be (1) the rapid thinning of the liquid sl
ag film driven by a difference between the instantaneous contact angle
and the equilibrium contact angle or (2) the ''dewetting'' of the liq
uid slag from the interface when the film is ''bridged'' by the partic
le.