白云石制备高纯氧化镁工艺研究

Technology of preparing high-purity magnesia with dolomite

以白云石为原料,经煅烧、消化、碳化、热解、烘干制备出CaO质量分数小于0.1%的碱式碳酸镁,煅烧后制备出MgO质量分数高于99%的高纯氧化镁。研究了白云石煅烧温度、消化条件、碳化终点pH、碳化时(NH4)2C2O4的加入及加入时的pH对消化效率、碳化效率以及产品纯度的影响。确定了最佳工艺条件:白云石最佳煅烧温度为910～950℃,煅烧时间为30～60min;在50～70℃下按液固比40～50∶1消化;碳化至pH=9.0～8.0时加入精镁乳液质量的0.02%～0.05%的(NH4)2C2O4,继续碳化至pH=6.5;碱式碳酸镁最佳煅烧温度为700～800℃。

Through calcination, assimilation, carbonation, py rolyzation and drying, basic magnesium carbonate with the content of CaO less than 0. 1% was prepared from dolomite. And then high-purity magnesia with the content of MgO more than 99% was gained by calcining the basic magnesium obtained a- bove. The influences of calcination temperature of the dolomite and the assimilation conditions on assimilation efficiency, that of the final pH of carbonation on carbonation efficiency, and that of the addition of （NH4）2C2O4 and the choice of the corresponding pH on the purity of products were completely investigated. Thepaper has eventually ascertained the optimal conditions as fol lows： the best calcination temperature of dolomite was 910-950 ℃, and calcination time ranged from 30 min to 60 min, and assimilation was carried out under 50 - 70 ℃ according to liquidsolid ratio 40- 50 ： 1. When the pH of carbonation reached 9.0 -8, 0, （NH4）2 C2 O4 was added into the solution with carbonating constantly until the final pH reached 6. 5. The calcination temperature of basic magnesium carbonate was 700-800 ℃.