利用菱镁矿尾矿制备纳米级片状氢氧化镁

The preparation of plate-shape nano-Mg(OH)_2 powder from magnesite tailing

为了对菱镁矿尾矿进行综合回收利用，文中对利用菱镁矿尾矿制备纳米级片状氢氧化镁工艺进行了研究。通过对菱镁矿尾矿的煅烧、与硫酸反应制备硫酸镁以及纳米氢氧化镁的制备工艺和性能表征，成功制备了原始粒径为纳米级、颗粒呈片状的氢氧化镁粉体。利用轻烧镁粉制备硫酸镁溶液的工艺是将轻烧镁粉与水配制成浆料，然后与酸进行反应。反应后控制体系的pH值在5～6，然后进行过滤。制备氢氧化镁的工艺条件为：Mg^2＋初始浓度为22．75g／L，反应温度为50℃，反应时间为5min，原位表面改性剂为钛酸酯偶联剂YB-502，用量为氢氧化镁质量的1．5％。制得的氢氧化钱结晶情况良好，为片状纳米粉体，其片径100nm左右，片厚10nm左右。氢氧化镁的二次颗粒粒径为d50=0．95μm，d97=3．53μm。

For comprehensive utilization of the magnesite tailing as a new kind of resource, research is done on the magnesite tailing used as raw material in the preparation of plate-shape nano-Mg（OH）2 powder. The powder can be obtained through the calcinations of magnesite tailing, the preparation of magnesia sulphate solution by the reaction of the sulfuric acid and MgO, and the preparation of plate-shape nano-Mg（OH）2 powder. The process of magnesia sulphate solution preparation is to mix the MgO powder with water, and then react the so- lution with acid. It is important to control the pH value between 5-6. Then, the slurry should be filtrated. The process parameters for the preparation of plate-shape nano-Mg（OH）2 powder are： initial concentration of Mg^2＋ at 22.75 g/L, reaction temperature at 50 ℃, 5 rain of reaction time, and organotitanate YB-502 used as reagent of in-situ surface modification with a dosage of 1.50/00 of the mass of nano-Mg（OH）2 powder. This study shows good crystallization of Mg（OH）2 powder with the particle in plate-shape with a diameter of about 100 nm and nanometer grade with a thickness of 10 nrn. There is obvious agglomeration of the powder and the size of the agglomerated particle is d50=0.95μm, d97=3. 53μm.