| 摘要 |
1486333 Magnesium oxide METALLGESELLSCHAFT AG 13 Dec 1974 [21 Feb 1974] 54034/74 Heading C1A Magnesium oxide is produced from a magnesium-containing carbonate ore by, (a) leaching the ore with H 2 SO 4 to form magnesium sulphate, (b) subsequently neutralizing any surplus H 2 SO 4 with magnesium oxide, (c) separating the undissolved impurities from the solution, (d) crystallizing the magnesium sulphate under superatmospheric pressure and at a temperature above 150‹ C (e) separating the resulting crystals under such conditions that subsequent cooling results in a magnesium sulphate of composition MgSO 4 . 1À5-4 H 2 O (f) bringing the magnesium sulphate to such a particle size that it is suitable for decomposition in a fluidized bed, (g) heating the magnesium sulphate in a suspension-type-heat-exchanger, optionally to effect dewatering, (h) decomposing the magnesium sulphate in a fluidized-bed reactor to form magnesium oxide and sulphur dioxide, and feeding the exhaust gases from the fluidized bed reactor to the suspension-typeheat-exchanger, (i) feeding the reaction product from the fluidized-bed reactor to a multi-stage fluidized-bed cooler, which is operated with air as a fluidizing gas, (j) feeding the hot fluidizing air leaving the fluidized-bed cooler to the fluidized-bed reactor, (k) generating the extra heat required for the reaction by an approximately stoichiometric complete combustion of fuel (to CO 2 and H 2 O), which has been changed into the fluidized-bed reactor. (1) recovering H 2 SO 4 from the SO 2 produced in the decomposition step, and (m) recycling the H 2 SO 4 to the leaching stage. |
