硅热法炼镁用白云石球团制备及煅烧工艺研究

Two-Stage Calcination of Dolomite Pellets for Mg-Extraction by Silicothermic Reduction in Vacuum

为改变硅热法炼镁工艺存在资源利用率低、能耗高等缺陷,本文提出了造球→煅烧→还原硅热法炼镁新工艺,并对其造球关键步骤进行研究。考察了煅烧温度、制度等对煅烧效果的影响规律,结果表明:白云石球团煅烧过程是分步进行的,首先是低温阶段MgCO3的煅烧分解过程,然后是高温阶段CaCO3的煅烧分解过程。分阶段煅烧可有效缩短煅烧分解过程,低温煅烧分解过程球团烧损率为18.43%,高温煅烧分解过程球团烧损率为21.06%,总烧损率为39.49%。

A novel technique was developed to extract Mg from calcinated dolomite pellets by silicothermic reduction in vacuum,for the purpose of effective decrease of both the burning loss rate of dolomite and energy consumption.In the newly-developed technique,the dolomite pellets were calcinated in two stages： the decomposition of MgCO3 at1073 K for 30 min,followed by the decomposition of CaCO3 at 1273 K for another 30 min. The dolomite phases in the two calcination stages were characterized with X-ray diffraction. The results show that the two-stage calcination significantly reduced the burning loss rate of dolomite. For example,in addition to reduction of calcination time and energy consumption,the total burning loss rate of the fairly compact dolomite pellets was estimated to be 39. 49%,including18. 43% in low temperature decomposition of MgCO3 and 21. 06% in high temperature decomposition of CaCO3.