Synthesis And Application Of Zinc Alumina Spinel

With the vigorous development of Chinese economy,the amount of waste produced has increased by years,and the problem of urban waste has entered the public eye and has become an urgent problem to be solved.The original garbage disposal method has great environmental pollution,cement kiln co-processing of municipal waste has good application prospects,the composition of municipal waste is complex,which puts forward new requirements for refractory materials used in the burning zone of cement kilns,and there is an urgent need for a new type of refractory material to appear.Zinc-aluminum spinel has a high melting point and strong corrosion resistance,which can be used in cement kiln co-processing.This paper mainly studies the reaction mechanism of Al（OH）₃,active Al₂O₃,calcined Al₂O₃ and ZnO,and the effect of B₂O₃,Y₂O₃ and TiO₂ additives on the synthesis of zinc alumina spinel,analysis of reaction mechanism of MgO-ZnO-Al₂O₃system,to preparation periclase-zinc-alumina spinel bricks.Study the mineral composition and microstructure of the sample by XRD and SEM,The result shows:The sample of aluminum hydroxide source started to react with ZnO to produce zinc aluminum spinel at 800°C.The other two aluminum sources did not react,activated alumina source and calcined alumina source samples start to react with ZnO at 1000°C to produce zinc alumina spinel,at the 1550℃,grain size of calcine Al₂O₃ source sample>grain size of active Al₂O₃ source sample>grain size of Al（OH）₃ source sample.The three additives B₂O₃,Y₂O₃ and TiO₂ all have a sintering effect on the zinc alumina spinel,the sample with TiO₂ is the most obvious,B₂O₃ generates a liquid phase at low temperature to promote the sintering of the sample,when the content of TiO₂ is less than 1.5%,it will form a solid solution with Al₂O₃,after more than 1.5%of titanate is formed,Y₂O₃ reacts with Al₂O₃ to form Y₃Al₅O₁₂,which is located between the crystals,and the sample with TiO₂ has the best resistance to KCl erosion.In the MgO-ZnO-Al₂O₃ ternary system,ZnO first reacts with Al₂O₃ to produce zinc alumina spinel,as the temperature rises,MgO diffuses to produce magnesia-zinc-alumina composite spinel,the phase composition is Mg_2.84Zn_5.18Al_15.98O₃₂,when the temperature reaches 1550℃,as the MgO content increases,the amount of solid solution of MgO into the zinc alumina spinel increases,when it exceeds 15%,MgO has surplus;With the increase of MgO content,the grain size of the composite spinel increases,and the replaced ZnO surrounds the grains to fill the pores and increase the density.The periclase-zinc-alumina spinel brick was prepared from pre-synthesized zinc-alumina spinel and sintered magnesia,the normal temperature flexural strength of over 14MPa,bulk density of 3.01g/cm³,and the refractoriness under load of over1700℃,all of which are excellent for periclase-iron-alumina composite spinel bricks;In terms of alkali corrosion resistance,it is also better than other samples.