The sulfide capacities of CaO-SiO 2 melts containing MgO, FeO, TiO 2 , and Al 2 O 3
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IN a recent publication, ~the background and experimental procedures of the current investigation and data for CaO-SiO2-CaF 2 and CaO-SiO2-B203 melts were presented. Additional data on the influences of FeO,* MgO, TiO2,* and A1203 on the sulfide capacities of * Total iron content expressed as equivalent FeO and total titanium content expressed as equivalent TiO 2.
CaO-SiO 2 melts are presented here.
of the reference melts are based on the work of Abraham and Richardson? RESULTS Flux additions were made as substitutions for either CaO or SiO 2 to maintain a constant molar base to acid ratio (R u). For basic flux additions (CaF v MgO, or FeO), the ratio is given by Eq. [2]. R M = Xc~~ +XFlux
EXPERIMENTAL Slag samples contained in platinum cups were placed within a quartz capsule wherein equilibrium with a sulfurizing gas atmosphere, (Ps/Po) ~/2, at 1503 ~ (1776 K) was established. Each capsule contained several slag samples for which sulfide capacities, (pct S) x (Po2/Ps2) tn, are known from previous experiments. When Q represents the sulfide capacity for a particular reference sample, then (Ps/Po) ~/2for the system is given by pct S~ where pct S~ is the equilibrium sulfur content of the reference slag. The sulfide capacities of all samples may be calculated by direct comparison with a reference slag as shown in Eq. [1]. pct S Cs = C~ pct S~
[1]
Particular details of the quartz capsule system have been given previously? The CaO-SiO 2 binary melts used in the previous investigation were also used in the current study as shown in Table I. The sulfide capacities ARTURO BRONSON is Assistant Professor, Department of Metallurgical Engineering, The University of Arizona, Tucson, AZ 85721 and GEORGE R. ST. PIERRE is Professor, Department of Metallurgical Engineering, Ohio State University, Columbus, OH 43210. Manuscript submitted November 17, 1980.
[2]
Xsio~
For acidic flux additions (B20 3, A120 3, or TiO2), the molar basicity ratio is defined by Eq. [3] Ru =
Xc~o
[3]
X sio2 + XFlux
The results are summarized in Figs. 1 and 2. The capacities of CaO-SiO2-CaF2 and CaO-SiO2-B20 s melts reported previously ~are included in Figs. 1 and 2 for comparison with the new data. All of the melts presented in Figs. 1 and 2 are entirely liquid at 1776 K. DISCUSSION The transfer of sulfur between gas and slag may be described by the following reaction: 1
1
~S2(g) + O2-(slag) = 2492(g) + S2-(slag)
[4]
The sulfide capacity defined by Fincham and Richardson 3 is obtained by rearrangement of terms contained within the equilibrium constant of Eq. [4] as shown in Eq. [51. ($2-)
9 (Po/Ps)
m -ao~= Cs = K4 fs2-
[5]
($2-), ao~-, and fs2 represent the sulfide ion concen-
ISSN 0360-2141/81/1211-0729500.75/0 METALLURGICAL TRANSACTIONS B
9 1981 AMERICAN SOCIETY FOR METALS AND THE METALLURGICAL SOCIETY OF AIME
VOLUME 12B, DECEMBER 1981--729
Table I. CaO-Sl02 Binary Reference Melts Used In Equilibration Capsules Capsule Number*
Wt Pct CoO Wt Pet SiO2
Number of Reference Slag Samples
Average Pct S
Standard Deviation
- logl0 Cs
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