用低品位菱镁矿制取高纯镁砂

来源期刊：中南大学学报(自然科学版)2006年第4期

论文作者：徐徽 蔡勇 陈白珍 苏元智

文章页码：698 - 702

关键词：低品位菱镁矿;轻烧粉;氯化铵;高纯镁砂

Key words：low-grade magnesite; light burning powder; ammonium chloride; high-purity magnesia

摘    要：研究一种以低品位菱镁矿为原料制取高纯镁砂的新方法。首先,用氯化铵溶液作浸出剂与菱镁矿轻烧粉反应分离硅、铁和铝等杂质,得到以氯化镁为主要成分的浸出液,将反应过程中产生的氨用纯水吸收;然后,将浸出液直接与回收氨进行沉镁反应制备氢氧化镁;最后,将氢氧化镁进行两步煅烧得到高纯镁砂。沉镁反应产生的氯化铵母液可循环使用。研究结果表明:在800℃将氢氧化镁轻烧2.5 h,得到的轻烧粉活性最高。在温度为110℃、液固比为9、时间为60 min时,一段浸出时镁浸出率可达80%,浸出液中Mg²⁺质量浓度为65.6 g/L。用氨法沉镁制备的Mg(OH)₂颗粒大、过滤性能好,滤饼含水率为12%;镁砂产品的氧化镁含量高达99.97%。

Abstract: A new technique for preparation of high-purity magnesia from low-grade magnesite was studied. Firstly, the low-grade magnesite was calcined to get the light burning powder of magnesite, which reacted with NH₄Cl to get the solution of MgCl₂and separated from the impurities Si,Fe, Al, etc. The gas NH3generated in the reaction was absorbed by pure water to make ammonia, which then reacted with the solution of MgCl₂to produce the precipitation of Mg(OH)₂with good filtering and washing performance and filtrate of NH₄Cl solution can be used circularly. Finally through two-step-calcination of Mg(OH)₂, the high-purity magnesia was obtained. The experimental results show that under the conditions of reacting at 800℃for 2.5 h, the activity of the light calcination powder is the best; when the leaching temperature is 110℃, the ratio of liquid to solid of the leaching reaction is 9 and the leaching time is 60 min, the extracting ratio of magnesium is about 80%, and the content of Mg²⁺in the leaching solution reaches 65.6 g/L.The particle size of Mg(OH)₂prepared is large and its water content is about 12% after filtration. The purity of the magnesia is as high as 99.97%.