Carbonate Decomposition Was Prepared Sheet Of Alumina

The flaky powder was prepared by the precursor Al(OH)3 which was obtained from carbonation, using sodium aluminate with low concentration and carbon dioxide as raw material via dispersants control the process. Base on the reaction mechanism and the crystalloid grows behavior, this text have studied the factors of effecting of the flaky powder preparation.It is found that:the aK and NK of sodium aluminate have the important influence to the precursor preparation. Along with NK increase, efficiency of the carbonation will reduce, reduces the NK, will affect the conversion rate of boehmite to gibbsite, and aK and NK are restrict mutually, controling the dynamic force of carbonation.The productor of traditional carbonation was agglomerated. SEM show that add stearinic acid, TiCl4 and pyrophosphate as annexing agents will make the precursor have hexagonal shape and reduce agglomerate. The XRD indicated that the precursor can not complete transformation to a-Al2O3.Add AlF3 during calcination will solve the problem and reduce the calcine temperature.In summary, the proper carbonation conditions are:sodium aluminate concentration is 2.0mol/L(whichαK=1.7, NK=100g/L)and reaction gas mixture carbon dioxide concentration is 250L/h(which N2:CO2=1:1)as raw material, carbonation is under 45℃water bath and the reaction end point is pH=12 with of 10%(mass fraction,the same below)stearinic acid,5%AlF3,3%TiCl4 and 3%pyrophosphate as annexing agents, dry-out the precursor using 10% 2-methyl-1-propanol as dispersant agent, and a temperature of 1200℃calcined for 5 hours. The best production of hexagonal plate a-Al2O3 has smooth surface, good dispersion property, average particle size of 30.13μm. Experimental results also show that the powder has good acid and alkali resistance.Using two methods to measure the aspect ratio of production, the result respectively was 39.12 and 42.09.