Study On Arch Design And Material Of Light Fired Magnesia Vertical Kiln

Oxide-the oxide is an important way to improve the performance of high temperature refractory materials,for the light burned magnesia shaft kiln kiln arch in the high temperature performance and adoption of refractory castable fabrication,this article in corundum castable,silicon powder is added to the via in situ synthesis of oxide reduction method combined with nitride phase and improve its performance.In this thesis,the movement process of magnesite materials in the kiln,the stress size and distribution of kiln arch and the wear and deformation of kiln arch refractory are simulated by numerical simulation method.The performance requirements of corundum and Mullite castable for kiln arch are put forward.Then using industrial alumina and clay as the main raw materials,the effects of adding amount of silica powder and sintering temperature on the structure and properties of corundum based castable matrix were studied,and the optimal adding amount of silica powder and sintering temperature were determined.Finally,four groups of corundum mullite castables were prepared,and the effect of whisker on the structure and properties of castables was studied.The main conclusions are as follows:(1)When the ore particles collide with the kiln arch in the early falling process,the pressure on the kiln arch is the maximum,which is up to 161 MPa.Under the stable state,the stress on the contact between the tip ridge of the kiln arch and the working layer of the kiln body is the maximum,which is up to 8.41 MPa.The central part of the kiln arch is the most prone to deformation.The shear stress distribution of kiln arch is concentrated in the contact with the working layer inside the kiln,and the maximum is 1.13 MPa.The stress distribution of the kiln arch under the transient state is basically similar to that under the stable state,but the maximum stress of the kiln arch under the transient state is 18.51 MPa.In addition to the middle of the kiln arch,the kiln arch is also prone to deformation at the tip ridge of both ends inserted into the working layer,and the maximum shear stress on the kiln arch is 2.71 MPa.(2)When the temperature is the same,with the increase of silica powder addition,the sample shrinks after firing,the change rate of permanent line gradually increases,the volume density increases first and then decreases,and the flexural strength at room temperature gradually increases.The optimum amount of metallic silica powder in corundum castable matrix is 6%,and the sintering temperature is 1450 ℃.(3)With the increase of silicon powder addition,the normal temperature flexural strength of the samples sintered at 1400 ℃,1450 ℃ and 1500 ℃×3 h increased by68.1%,110.1% and 80.5%,respectively.When the sintering temperature is 1450 ℃and the silicon powder addition amount is 6%,the improvement of the normal temperature flexural strength of the samples is the greatest.(4)According to the comparison between the normal temperature pressure resistance and high temperature bending strength of the sample of corundum-mullite castable and the simulation results,the normal temperature pressure resistance and high temperature bending strength of the sample M2 and M3,which were sintered into Sialon or Si3N4 whisk by adding 6% silicon metal powder in nitrogen atmosphere at high temperature,are 166 and 174 MPa and 4.57 and 4.44 MPa,respectively.The maximum pressure is 161 MPa and the maximum shear stress is2.71 MPa,indicating that the samples M2 and M3 meet the simulation results.