低钙烧结法从高铝粉煤灰脱硅产物中提取氧化铝

Extraction of alumina from high- alumina fly ash desilicated residue by Low- lime sintering process

本文采用低钙烧结法,对从高铝粉煤灰脱硅滤饼中提取氧化铝过程进行了研究。首先采用NaOH溶液在95℃条件下对高铝粉煤灰进行预脱硅,然后将Na2CO3、CaCO3按比例加入到脱硅滤饼中在不同温度下进行煅烧。根据热力学计算得到体系完全反应的最低温度,同时分析烧结温度对氧化铝标准溶出率的影响。实验结果表明:经过碱液预脱硅,脱硅滤饼中的Al2O3/SiO2质量比由原试样中的1.27提高至2.08;烧结熟料中的Al2O3在高于1050℃条件下可完全转化为NaAlO2,与热力学计算结果相一致。按照工业标准溶出条件,脱硅滤饼在1050℃下煅烧120 min后所得熟料的Al2O3溶出率达93.4%。

Low - lime sintering process was used to extract alumina from the high - alumina fly ash desilicated residue in this study. The first step obtained a relatively high A1203/SiO2 ratio by taking a desilication treatment for fly ash with sodium hydroxide solution at 95℃. The desilicatod filter cakes were mixed with Na2CO3 and CaCO3 in different proportions and then calcined at different temperatures. According to the thermodynamic calculations, the low- est temperature of system completely reactions were obtained, and the influence of sintering temperature on the alumina standard leaching yield was investi- gated. The experimental results indicated that the weight ratio of A1203/SiO2 in fiher cake of fly ash could be improved from raw sample 1.27 to 2.08 after desilication process, and the A1203 in sinter could be completely translated into NaAIO2 above 1050℃ which coordinated with the results of thermody- namic calculations. On the basis of standard industrial dissolution condition, the optima alumina leaching yield could be up to 93.4% under conditions of desilicated cake sintering at 1050℃ for 120rain.