低钙石灰烧结法处理粉煤灰高效提取氧化铝研究

Extraction of Alumina from Desiliconized Fly Ash by Low-calcium Lime Sinter Process

为解决石灰烧结法配钙量高、渣量大和氧化铝回收率低等问题,提出了低钙石灰烧结法从脱硅粉煤灰提取氧化铝的新工艺,并研究了不同配钙比和碱铝比对熟料烧结行为、粉化性能和氧化铝浸出性能的影响。结果表明:低钙石灰烧结法处理粉煤灰烧结熟料主要物相组成为12CaO·7Al2O3和γ-2CaO·SiO2,并含有少量CaO·Al2O3、2Na2O·3CaO·5Al2O3、2CaO·Al2O3·SiO2和β-2CaO·SiO2;提高钙铝比有助于2CaO·Al2O3·SiO2向12CaO·7Al2O3和γ-2CaO·SiO2的转化,从而提高氧化铝浸出性能和熟料粉化性能;提高碱铝比促进2CaO·Al2 O3·SiO2向12CaO·7Al2O3和2Na2O·3CaO·5Al2 O3的转化,有利于提高氧化铝的浸出性能,但过高的碱铝比增加熟料中的β-2CaO·SiO2含量,从而降低熟料粉化性能;在1 350℃烧结1 h的条件下,当钙铝比为1.20、碱铝比为0.15时,脱硅粉煤灰烧结熟料氧化铝浸出率达到90%左右。

To address large amount of calcium addition and residue and low alumina recovery of lime sinter process,a new process to extract alumina from desiliconized fly ash by low-calcium lime sinter process was proposed Effects of different ratios of calcium oxide to alumina(C/A) and alkali to alumina(N/A) on sintering behavior,pulverization and alumina leaching performance of clinker were investigated The results show that main phases of fly ash clinkers by low-calcium lime sinter process are 12 CaO·7 Al2O3 and γ-2 CaO·SiO2,with some CaO·Al2 O3,2 Na2 O·3 CaO·5 Al2 O3,2 CaO·Al2 O3·Si2 and β-2 CaO·SiO2.Increasing C/A ratio is helpful for conversion of 2 CaO·Al2 O3·SiO2 to 12 CaO·7 Al2 O3 and γ-2 CaO·SiO2,which improves alumina leaching and pulverization performance of clinker.Increasing N/A ratio can promote conversion of 2 CaO·Al2 O3·SiO2 to 12 CaO·7 Al2 O3 and 2 Na2 O·3 CaO·5 Al2 O3,which improves leaching performance of alumina,but over N/A ratio rises β-2 CaO·SiO2 content in clinker and reduces pulverization performance of clinker.Alumina leaching efficiency of clinker sintered at 1 350℃ for1 h is 90% with C/A=1.20 and N/A=0.15,and clinker possesses a good pulverization.