高密度烧结镁砂的研究

以菱镁石为原料,先在850℃下煅烧2 h获得轻烧氧化镁,然后水化成氢氧化镁,干燥后在不同温度下轻烧,得到不同活性的轻烧氧化镁.将轻烧氧化镁按细磨—成形—烧结的工艺流程制备出烧结镁砂.考察了细磨程度、成形压力及轻烧温度对烧结镁砂密度的影响.实验结果表明:将细磨的氢氧化镁轻烧得到的氧化镁进行二道细磨工序,对提高烧结镁砂的密度有显著的影响;成形压力对烧结镁砂的密度影响较小;轻烧温度为600℃时的氧化镁经过轻烧前后两道细磨工序,在200 MPa成形,1 600℃烧结3 h可以制得w(MgO)为97.5%,w(CaO)∶w(SiO2)>2,体积密度为3.47 g/cm3的高密度烧结镁砂.

Investigation on Process Flow of High-Density Magnesia

Magnesia was used as starting material to prepare MgO specimens the way it was lightly roasted at 850°C for 2 hr to form MgO which was then hydrated, ground, filtered, extracted and dried to become Mg(OH)2 from which the powdered MgO with different activities were obtained at different temperature and, finally, the φ20 mm × 10 mm cylindrical MgO or magnesia specimens were provided through briquetting and sintering. How the fineness of powdered magnesia due to grinding, briquetting pressure and light roasting temperature affect the bulk density of sintered magnesia were investigated through tests. The results showed that both the grinding operations before and after the light roasting at 600°C of Mg(OH)2 to become powdered magnesia affect significantly the bulk density of sintered magnesia, while the briquetting pressure affects it not much. So, high-density magnesia can be obtained under the conditions that there are two grinding operations mentioned above, the briquetting pressure to form specimens is 200 MPa and sintering at 1 600°C for 3 hr. Such a magnesia shows TO (MgO) = 97.5%, w(CaO):w(SiO2)>2 and bulk density = 3.47g/cm³.