烧成镁-铝-铁系耐火砖中铁的存在形式

水泥窑烧成带用镁铬砖残砖产生的铬污染已经引起人们的重视,本文主要研究一种可替代镁铬砖在水泥窑上使用的新型耐火材料Mg O-Al2O3-Fe2O3(Fe O)系耐火材料。利用XRD和SEM分别研究了以高纯镁砂与电熔铝铁尖晶石制备的镁-铁铝尖晶石砖和烧结镁铁砂与电熔铝镁尖晶石制备的镁铁砖烧成后铁的存在状态。结果发现:铁铝尖晶石在高温下分解出Fe2+与Al3+,与Mg O相互扩散,Fe2+与Mg O反应生成(Fe,Mg)Oss固溶体,Al3+与Mg O反应,形成Mg Al2O4,试样中Fe2+的扩散速度大于Al3+;在高温状态下,烧结镁铁砂中Mg Fe2O4的Fe3+不稳定转变为Fe2+,Fe2+扩散到镁铝尖晶石表面,取代了部分Mg2+的位置,形成镁铁铝固溶体。

Iron form in magnesium-aluminum-iron refractory bricks after buring

The chromium pollution generated by cement kiln calcining zone with magnesite chrome brick has been paid more attention,a new style MgO-Al2O3-Fe2O3(FeO) refractory material instead of magnesia-chrome brick used in cement kiln is researched. XRD and SEM,the existance status of magnesium-hercynite brick prepared by high purity magnesia and fused hercynite. By using,and the magnesia-iron brick prepared by sintered magnesium iron ore and fused spinel after firing iron are also researched.The results show that:the hercynite decomposes Fe2+and Al3+at high temperature,which is mutual diffusion with MgO,Fe2+reacts with MgO and(Fe,Mg)Oss slid solution is generated,Al3+reacts with MgO and MgAl2O4 is formed,the diffusion velocity of Fe2+is greater than Al3+in the samples;Under high temperature condition,Fe3+in MgFe2O4 in the sintering magnesium-iron oxide is transformed to Fe2+,which is diffused to the surface of spinel and replaces the positions of the parts of Mg2+,and(Fe,Mg)Oss slid solution is generated.