关键词: 微晶菱镁矿;除钙;氯化镁;高纯氧化镁

Abstract: Magnesium hydroxide (MH) emulsion was prepared using microcrystalline magnesite as raw material by lightly calcination and digestion.It is found that Ca impurities can be effectively removed by adding MgCl2 .In this paper, the Ca-removing effects of MgCl 2 content, reaction time, reaction temperature, calcination temperature and sintering time during the whole process of impurity removal was investigated .The experimental results showed that the Ca-removing effect on light burned magnesium was obviously improved by mixing MgCl2 .The preparation of high-purity MH precursor which contained 99.45％ of magnesium oxide and 0.20％ of calcium oxide includes the following steps :(1)calcining the microcrystalline magnesite at 920 ℃ for 2 h; (2)hydrating the light burned magnesium to be slurry ; (3)adding 8％ of MgCl2 into the slurry and reacting for 1.5 h.It is also proved that the Ca removal could be finished in a wide temperature range, and achieved a better and stable result in indoor environment .

Key words: microcrystalline magnesite;Ca removal;magnesium chloride;high-purity magnesium oxide