水镁石制取高纯氧化镁的研究

Study on Preparation of High-purity Magnesia from Brucite

采用氯化铵溶液直接与水镁石进行复分解浸出反应先得到氯化镁浸出液,同时用水吸收反应产生的氨;然后将氯化镁浸出液与回收的氨进行沉镁反应得到中间体氢氧化镁,最后将氢氧化镁在900℃高温下煅烧制取高纯氧化镁,沉镁反应过程中生成的氯化铵可循环使用.研究了水镁石浸出过程中各因素对镁浸出率的影响,当浸出温度为110℃,液固比8∶1,浸出时间为60 min时,镁浸出率达90%以上.通过控制氯化镁溶液与氨反应的温度及pH值等条件,可得到过滤、洗涤性能好的Mg(OH)2中间体,滤饼含水率仅12%,经高温煅烧得到的氧化镁纯度达99.92%.

The preparation of high-purity magnesia from brucite was introduced in this paper. First, the solution of NH4Cl has to be used to react with brucite to get MgCl2, and the gas NH3 produced in the reaction is absorbed by water; then the MgCl2 is used to react with NH3 to get the Mg（OH）2 intermediate, at the same time the mother solution of NH4Cl produced in the reaction could be used circularly; Finally in order to get the high-purity magnesia the Mg（OH）2 is calcined at 900 ℃. When the leaching temperature is 110 ℃, the liquid/solid ratio 8： 1, the leaching time 60 min, the leaching ratio of Mg from brueite was more than 90 %. Through controlling the conditions such as temperature and pH of the reaction of MgCl2 with NH3, the Mg（OH）2 intermediate produced has the good properties of filtration and washing and its water content is below 12%. After being calcined the purity of magnesia is up to 99.92%.