| 摘要 |
<p>Process for mfg. aq. solns. contg. 220-320 g/l MgCl2 and 4-6 wt. % CaCl2 w.r.t. the wt. of MgCl2, for the prodn. of MgO by thermal decompsn., esp. by spray calcining. An aq. soln. contg. 220-320 g/l MgCl2 and over 6 wt. % CaCl2 w.r.t. to the wt. of MgCl2, is treated with CO2 and MgO in the form of caustic magnesia or Mg(OH)2, and the pptd. CaCO3 is removed. The initial material is pref. a soln. obtd. by (a) treating an aq. suspension of crude magnesite and/or magnesite wastes with HCl gas, or (b) treating HCl contg. CaCl2 with crude magnesite. The CO2 requires is pref. obtd. by the soln. of crude magnesite in HCl or by using exhaust gases from combustion. High purity MgO is easily obtd. in the desired coarse grain and the loss of chloride from the system is reduced to a minimum.</p> |
