Development Of Andalusite Based Refractory & Study Of Corrosion Mechanism Of Carbon Monoxide

The andalusite based refractory(hereinafter shorten toABR)with excellent properties is a kind of high-temperature material which needs developing father in China. Aiming at the production of high-quality ABR , this thesis has probed the use amount ranges of andalusite concentrates and other applied alumina raw materials. In addition, in this thesis, the influences of some technological factors, such as sintering temperature and soaking time at this temperature , and two additives, zircon and silica carbide, on the properties of ABR are studied.The mineral compositions and microstructares of some typical samples are analysed by means of XRD and SEM, and, the influences of them on the properties of ABR have been discussed. Besides, the corrosion mechanism of carbon monoxide on ABR, and the effect of iron oxide on this corrosion course have also been studied in this thesis. The results show that: (1) The use amount of andalusite concentrates should be 80%~90%, the use amount of alumina powder should be 10% to 16%. (2)The properties of ABR depend on mullitization extend of andalusiiite concentrates and its sintering extend, Whereas sintering temperature and soaking time at this temperature have remarkable influences on them. (3)Adding appropreciate amount of fine zircon power or fine silica carbide power can not only play a promotive part in sintering of ABR, but can improve its thermal shock resistance.As concerns the corrosion mechanism of carbon monoxide on ABR, it could be summed as follows: (1) At lower temperature (<700 ),the bounduard reaction (2CO-C+CO2) occurs firstly, which results in carbon deposition inside ABR and on its surface. Then mullite in the material is reduced into A12O3, SiO and CO2 by Carbon. (2) When temperature is at 1300 steadily, as far as the high-purity ABR is concerned, the corrosion reaction occurred in the material is chiefly that SiO2 in mullite and glass is reduced into SiO; as far as the ABR with high iron content is concerned, in addition to the reactions dissertated above, the corrosion reactions occurred in the material include that Fe2O3 is reduced into FeO and Fe3O4, that FeO reacts with Al2O3 to form FeAl2O4 and Fe3O4 is reduced into metallic iron subsequently. (3) The corrosion reactions discussed above will cause remarkable changes in chemicalcomposition, mineral composition and microstructure of ABR. (4) In addition, when ABR is oxidized and reduced over and again, the effects of iron oxide on the corrosion course include that it will result in the disruption of structure of ABR, the formation of macroscopic cracks, and the descent of strength of ABR.