以白云石为原料,通过氨法制备出高纯度（99.30%）圆片状的阻燃型微纳米级氢氧化镁。探究了反应温度、通氨速率、氨镁物质的量比对氢氧化镁分散性和形貌的影响,确定最佳工艺条件：反应温度为80 ℃、通氨速率为150 mL/min、氨镁物质的量比为23∶1。用扫描电镜、透射电子显微镜、X射线衍射仪、激光粒度分析仪、热重分析仪和白度仪表征产品的形貌、结构、粒度及稳定性。结果表明制得的圆片状微纳米级氢氧化镁的分散性好、晶型完整、粒度均匀,D₅₀为2.493 μm、D₉₀为6.132 μm、直径约为5.7 μm、厚度约为0.7 μm、长厚比约为8∶1。稳定性好、灼烧失量为31.03%、白度为97.4,高于工业氢氧化镁行业标准。

Micro-nano-sized high-purity（99.30%） round flake magnesium hydroxide as the flame retardant was prepared from dolomite by ammonia method.The effect of reaction temperature,ammonia-passing rate,ammonia-magnesium molar ratio on the dispersion and morphology of magnesium hydroxide were investigated.The optimal process conditions were determined：reaction temperature was 80 ℃,ammonia-passing rate was 150 mL/min,and ammonia-magnesium molar ratio was 23∶1.The morphologies,structures,size distributions and stability of products were characterized through scanning electron microscope,transmission electron microscope,X-ray diffractometer,laser particle analyzer,thermogravimetric analyzer and whiteness meter.The results showed that the prepared round flake micro-nano-sized magnesium hydroxide flame retardant had high dispersibility,complete crystal shape,uniform particle size with D₅₀ of 2.493 μm,D₉₀ of 6.132 μm,diameter of about 5.7 μm,thickness of about 0.7 μm and length thickness ratio of about 8∶1.The stability was good,the ignition loss was 31.03%,and the whiteness was 97.4,which was higher than industrial magnesium hydroxide industry standard.