流化床脱水制无水氯化镁工艺研究

水氯镁石(六水氯化镁)脱水制无水氯化镁是盐湖镁资源利用的关键环节,复盐法是水氯镁石脱水的重要方法,由复盐合成、造粒及流态化热分解等步骤组成。采用热分析技术(TG-DTG)研究了复盐热解过程。结果显示,复盐热解主要分为两个阶段:第一个阶段脱去六个结晶水;第二个阶段脱去盐酸苯胺助剂,热重结果为后续实验提供理论依据。实验首先通过均匀液滴喷射技术(振动造粒)制备得到六水氯化镁-盐酸苯胺复盐颗粒。然后在流化床中进行复盐热分解脱水、脱助剂得到无水氯化镁。通过实验探索得到水氯镁石复盐流态化热分解的最佳工艺参数:脱水氮气流量1.6 m3/h～1.8 m3/h、脱盐酸苯胺氮气流量1.0 m3/h～1.2m3/h、脱水温度300℃、脱水时间0.5 h、脱盐酸苯胺温度350℃、脱盐酸苯胺时间1 h。

Study on the Hydrochloride Complex Salt and Production of Anhydrous Magnesium Chloride in Fluidized Bed

Preparation of anhydrous magnesium chloride by dehydration of bischofite(magnesium chloride hexahydrate) is the key point to the use of magnesium resources in salt lake.Double salt method is an important method for bischofite dehydration with promising application prospects.It is composed of double salt synthesis,granulation and fluidization thermal decomposition,Behavior of double salt thermal decomposition is studied by the TG-DTG technique.The results show that the thermal decomposition of double salt can be divided into two steps: six crystallized waters are eliminated at first;and then,aniline hydrochloric is removed.TGA results offer the theoretical foundation for the follow-up thermal decomposition in fluidized bed.In the experiment,bischofite-aniline hydrochloride double salt particles are obtained by uniform droplet spray technology(vibration granulation).And then,the crystal water and the additives are removed in fluidized bed.Finally,anhydrous magnesium chloride is obtained.Optimal process parameters of complex’s fluidized thermal decomposition can be obtained by experiment,which is as follows: nitrogen flow of dehydration and hydrochloride aniline taking off is 1.6 m3/h~1.8 m3/h and 1.0 m3/h~1.2 m3/h respectively,dehydration temperature is 300 ℃,for 0.5 h,temperature of hydrochloride aniline taking off is 350 ℃ for 1 h.