Analysis of Magnesia Carbothermic Reduction Process in Vacuum

Pressure dependent kinetics of magnesium oxide carbothermal reduction

“…A further assumption can be made that at low system pressure, the surface concentration of CO on C and MgO is low, therefore the reaction rate expressions given in equation (14) and (15) reduce to first order. Given this, the analytical solutions to the equilibrium partial pressures of product gases are greatly simplified and the overall reduction rate can be calculated by equation (25), 1 -137 --* Parameters taken from literature [19,40,41] Model parameters in Table 1 are computed by non-linear least squares minimization of the difference in experimental and predicted conversion curves shown in Figures 11 and 12. The system of differential equations was solved using ode15s in MatLab.…”

On the prevailing reaction pathways during magnesium production via carbothermic reduction of magnesium oxide under low pressures

“…In spite of the limited experimental evidence supporting the contribution of the reaction pathway comprising reaction steps 4 and 5, 14,17 the current literature 12,14,[17][18][19][20] neither conclusively proves its prevalence in the overall reaction nor justifies ruling out the contribution of the alternative pathway comprising reactions (2) and (3). The objective of this work is to reconcile previously reported findings and conclusively discriminate prevailing reaction pathways that dominate the Mg (g) production.…”

“…In eqns (18) and (19), N i    represents the total molar amount of species i entrained with the product gas up to the point of time  calculated as N n t t…”

“…  standardized with a flow definer (MesaLabs, Bios DryCal Definer 220) at p N = 101.3 kPa and T N = 0°C for a given output to the mass-flow controller MFC 2. The only remaining variables needed to calculate the temporal amounts of carbon via eqns (18) and (19) are the extents of Boudouard reaction (5)  5…”

“…3.5.2 Selecting the initial amounts of C and partial pressures of CO in the sweep for the reference CTR experiments. As already discussed in section 2.2, the initial amounts of C for the reference CTR experiments performed in phase 3 of the experimental program were selected according to eqns (18) and (19). It should be noted that eqns (18) and (19) account for the consumption of C not only from the reactant blend but also from both the extra layer of C and the graphite felt, thereby making the effective C/MgO ratios in the reference CTR experiments lower than their counterparts in the comparison runs of experimental phases 1 and 2.…”