Kinetics of the carbothermic reduction of zinc sulfide in the presence of calcium oxide

Rate equation of the carbothermic reduction of zinc sulfide in the presence of calcium oxide and lithium carbonate

“…The finding coincides with other catalyzed systems [1,2]. The following empirical rate expression of zinc yield has been regressed for the uncatalyzed carbothermic reduction [9] r Zn ¼ where d C is the initial size of carbon aggregate (m); h is the sample height (m); N c ; N CaO ; and N ZnO are the initial numbers of moles of C, CaO and ZnS, respectively (kmol); Q is the argon flow rate (m 3 /s); R is the universal gas constant (8.314 kJ/kmol K); r Zn is the rate of zinc yield (1/s), T is the reaction temperature (K); t is the reaction time (s), and q 0 is the initial bulk density (kg/m 3 ). The experimental data obtained in this work were also correlated using a nonlinear regression method of DRNLIN subroutine of IMSL [10] …”

“…The effect of argon flow rate, however, is not significant. The reasons for interpreting the results of the uncatalyzed carbothermic reduction [9] can also be applied to this system. The effect of initial molar ratio Li 2 CO 3 /ZnS, however, has not been reported before.…”

“…The effect of carbon aggregate size becomes less pronounced for the catalyzed system, shown in Table 2, which can be explained as follows. When the size of carbon aggregates becomes smaller, the contact area between reactants increases, which enhances the reaction in the uncatalyzed system [9]. In the case of the Li 2 CO 3 -catalyzed system, the molten layer of Li 2 CO 3 covering zinc containing grains, calcium-containing grains and carbon grains [9] reduces the effect of decreasing the sizes of carbon aggregate.…”

“…In continuation of the former study [8], the effects of the following factors on the rate of zinc yield are studied in this investigation: argon flow rate, sample height, reaction temperature, initial molar ratio of C/ZnS, initial molar ratio of CaO/ZnS, size of carbon aggregate, and initial bulk density. Furthermore, an empirical rate expression of zinc yield for Li 2 CO 3 -catalyzed reaction is determined and compared with that for the uncatalyzed reaction [9].…”

Carbothermic reduction of zinc sulfide in the presence of sodium carbonate

“…Several reports on the carbothermic reduction of zinc sulfide in the presence of calcium carbonate (or calcium oxide) are available (Abramowitz and Rao, 1978;Huang et al, 2005Huang et al, , 2007Skopov et al, 1976;Ueda et al, 1983;Wu, 2004;Wu et al, 2006Wu et al, , 2007aZhang et al, 1988aZhang et al, ,b, 1989. These reports focused on the strength of briquette for reduction (Zhang et al, 1988a,b), final reduction of zinc sulfide (Zhang et al, 1988a,b), activation energy (Abramowitz and Rao, 1978;Skopov et al, 1976), reaction mechanism (Abramowitz and Rao, 1978;Huang et al, 2005;Skopov et al, 1976;Ueda et al, 1983;Wu et al, 2006) and reaction rate (Abramowitz and Rao, 1978;Huang et al, 2007;Skopov et al, 1976;Ueda et al, 1983;Wu et al, 2006) and reaction rate (Abramowitz and Rao, 1978;Huang et al, 2007;Skopov et al, 1976;Ueda et al, 1983;Wu et al, 2006Wu et al, , 2007aZhang et al, 1988aZhang et al, ,b, 1989.…”