Chlorination of magnesium carbonate in a stirred tank reactor

A study was conducted on the reaction of solid MgO formed from magnesite (MgCO$ sb3),$ with Cl$ sb2$ and CO gas, in a stirred tank reactor containing a liquid bath of MgCl$ sb2.$ The reaction rate was found to be controlled by CO mass transfer from the gas to the liquid phase and was zero order with respect to the concentration of MgO. At temperatures from 743 to $824 sp circ$C, the reaction rate exhibited an activation energy of 80 kJ/mol, which is typical of a diffusion controlled reaction.The chlorinaton rate was effected by both temperature and CO/Cl$ sb2$ ratio and estimates of the optimum conditions were obtained: temperature $(856.6 sp circ$C) and ratio of CO/Cl$ sb2$ (1.24). The addition of an inert gas (N$ sb2)$ to the reagent mixture was found to decrease the reaction rate. Iron was found to have a negligible effect on reaction rate at the levels tested (up to 560 P.P.M.).For those experiments conducted at $ rm 820 sp circ C pm 5 sp circ C,$ an overall correlation was obtained which related the MgO reaction rate, with impeller power (kW/m$ sp3),$ superficial gas velocity (cm/s) and the partial pressure of CO (atm.): rm Rate = 0.609 (P sb{g}/V sb1) sp{0.35} (v sb{s}) sp{0.64} (P sb{CO}) sp{1.14}, (kgmol/m sp3/h) eqno lbrack 55 rbrack. ixing and gas dispersion characteristics were defined for the specific impeller/tank geometry used in these experiments.Using the results presented here, it would be possible to estimate the size and number of commercial stirred tank chlorination reactors, which would be required to produce any specified quantity of magnesium, starting from magnesite, with an accuracy of $ pm$44%, with 95% confidence