电石渣和氯化镁制备氢氧化镁过程中的动力学

摘要

常温下利用电石渣与氯化镁为原料沉淀氢氧化镁,对其反应过程进行了研究.结果表明:电石渣中杂质的存在对二次成核有一定的抑制作用,氢氧化镁得以生长从而粒度更大;成核过程为非均相成核,所需自由能低,成核过程极易发生;模拟了生长动力学,当体系中Mg2+浓度大于Ca2+浓度时,生长速率与反应物浓度无关,当Mg2+浓度小于Ca2+浓度时,随着Ca2+浓度的逐渐增加,生长速率逐渐增大,表明氯化钙浓度的增加对氢氧化镁的生长起到促进作用.%The reaction of using carbide slag and magnesium chloride as raw material to precipitate magnesium hydroxide in normal temperature was studied.The result showed that the impurity of carbide slag suppressed the secondary nucleation,resulting in the growth of magnesium hydroxide and bigger particle size.The nucleation of magnesium hydroxide was heterogeneous which was easy to take place due to the free energy of nucleation.The growth kinetics was modeled,and the results showed when the concentration of Mg2+ was higher than that of Ca2+,the growth rate was of no relevance to the concentration,while when the concentration of Mg2+ was lower than that of Ca2+,the growth rate increased with the increase of the concentration of Ca2+,indicating that the increase of the concentration of CaC12 could promote the growth of magnesium hydroxide.