水热活化法提取粉煤灰中的氧化铝

采用高压水热活化法对预先烧制的粉煤灰进行碱溶实验,探讨钙硅摩尔比、碱液浓度、液固比、苛性比、反应温度、反应时间等影响因素对于氧化铝溶出率的影响。考虑到氧化铝溶出率及反应成本等各方面因素,得出氧化铝溶出的适宜条件。结果表明:碱溶条件下,钙硅摩尔比为1.0,溶液碱浓度为350 g/L,液固比为10∶1,苛性比为14,反应温度280℃,活化时间为2 h。通过氧化铝溶出工艺条件的优化,可使氧化铝提取率达到95%以上。

Extracting alumina from fly ash by hydrothermal activation method

The pre- fired fly ash was dissolved with sodium hydroxide by the high- pressure hydrothermal acti- vation method． The influence factors on the dissolution rate of alumina were discussed，including the mole ratio of calcium to silicon，alkali concentration，the ratio of solid to liquid，caustic ratio，reaction temperature，reaction time，etc． Considering the dissolution rate of alumina，reaction cost and others，the optimum conditions of alumina dissolution were recognized． The results show that under condition of alkali- soluble the best experimental parameters include the ratio of calcium silicon molar as 1. 0，the alkali concentration as 350 g/L，the ratio of solid to liquid as 10∶ 1，the caustic ratio 14，the reaction temperature as 280℃，and with the activation time of 2 h． Through optimizing the conditions of alumina dissolution process，the alumina extraction could reach more than 95% in ratio．