Activity of SnS in copper-saturated matte
- PDF / 298,836 Bytes
- 4 Pages / 603.28 x 783.28 pts Page_size
- 82 Downloads / 215 Views
METALLURGICALTRANSACTIONS B
made by using 50 vol pet ethanol and 20 vol pct hydrochloric acid. The use of ethanol increased the sensitivity of tin analysis by Atomic Absorption Spectrophotometer. However, the results obtained with ethanol were substantially the same as those obtained by using 20 vol pct hydrochloric acid. Table I shows experimental results presented in terms of the distribution coefficient Ls,, the ratio of wt pct tin in copper and in matte phases. Results of runs 301 through 303 show that at 1400 K equilibrium is attained in Jess than five hours. The samples were equilibriated for 7.5 and 5.25 hours at 1400 and 1500 K, respectively. At a constant temperature and dilute solution of tin, Nernst's distribution law ~'z may be expressed by: [Sn]cu Ls, - - - constant [Sn]M,
[1]
The results of runs 302 through 306 in Table I, which are plotted in Figure 1, show that Eq. [1] is obeyed in the range of 0.0158 to 0.0297 wt pct tin in copper-saturated and iron-free matte. From the statistical analysis of the data shown in Figure 1, the following values of the slopes and thus the distribution coefficients Ls, at infinite dilution were obtained: L~, = 33.2 at 1400K
[2]
L~, = 36.5 at 1500K
[3]
Figure 2 shows the variation of Ls, with wt pet iron in matte at 1400 and 1500 K. An increase in wt pet iron in matte tends to increase Ls, slightly. Table I and Figures 1 and 2 represent first efforts to measure the distribution coefficient of tin between copper and matte as the function of temperature and matte composition. Figure 3 shows the distribution of iron between copper and matte with various elements in minor amounts. For cobalt, lead, and silver, results are taken from earlier work. ~,3 It is apparent from Figure 3 that minor amounts of cobalt, lead, tin, or silver have no effect on the distribution of iron. Several reliable thermodynamic data are essential for the calculation of activity coefficients of SnS in coppersaturated matte. A careful l i t e r a t u r e survey was carried out to obtain such data. Selected free energy data are presented in Table II. Table III presents the available data for the activity coefficient of Sn(l) at infinite dilution in Cu-Sn alloys. The results of Hager et al. 6 may be expressed by 8 log Y~./~ = - 1 3 0 0 / T - 0.45
[4]
Equation [4] is very close to those recommended by Sigworth and Elliott 7 (No. 2, Table III) and the experimental results of Alcock et al. 9 (No. 3, Table III), Equation [4] is used in the present work. The activity coefficient of SnS was calculated by considering Reaction [3], Table II, the equilibrium constant for which is given by:
g,= (acu)2asns ash " ac~2s = 0.0464 at 1400 K
[5]
VOLUME I5B, SEPTEMBER 1984--595
Table I.
Distribution of Tin between Metallic Copper and Copper-Saturated Matte
SI No.
Run No.
Temperature (K)
Equilibration Time (Hours)
Wt Pet Sn in Copper
Wt Pct Fe in Copper
Wt Pet Sn in Matte
Wt Pet Fe in Matte
Ls,
1 2 3 4 5 6 7 8 9 10 11 12 13 14
301 302 303 304 305 306 307 308 309 310 311 312 313 314
1400 1400 140
Data Loading...
