Green Conversion of Coal Fly Ash into Soil Conditioner: Technological Principle and Process Development
Green Conversion of Coal Fly Ash into Soil Conditioner: Technological Principle and Process Development
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DOI：
10.3390/min12030276
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发表时间：
2022-03-01
期刊：
影响因子：
2.5
通讯作者：
Jiang, Xiaolin
中科院分区：
文献类型：
--
作者：
Liu, Huidong;Xiao, Yongfeng;Jiang, Xiaolin
白色泥是粉煤灰提铝过程中酸法排放的废渣，对环境有一定的危害。如何实现白色泥的环保和有价值的利用是制约酸法粉煤灰氧化铝提取技术商业化应用的关键因素。对白色泥浆的分析表明：（1）它高度富集SiO2（70-80%），而酸溶性元素（如Na、Al和Fe）以及一些有害重金属（包括Pb和Cr）的浓度明显低于原粉煤灰;（2）由于前述的Al提取处理，约80%的SiO2具有相对较高的反应活性。通过巧妙的绿色化学工艺，在非常温和的反应条件（约100摄氏度和大气压）下实现了白色泥完全转化为硅钙肥料（SCF）。废液全部回收，无二次固体废物产生。SCF具有35%的有效硅含量（ASC），显著高于商业标准（20%）。将其转化为具有最低能耗和二次污染的土壤改良剂或生态修复材料可能是未来铝硅酸盐工业固体废物处置的最有前途的途径。
White mud is residue discharged during the acid method in the aluminum extraction process from coal fly ash, and this material is harmful to the environment. The implementation of an environmentally friendly and valuable way to use white mud is a key factor restricting the commercial application of the acid method in the fly ash alumina extraction technology. An analysis of white mud revealed the following: (1) it was highly enriched in SiO2 (70-80%) while concentrations of acid-soluble elements, such as Na, Al, and Fe, and some hazardous heavy metals, including Pb and Cr, were significantly lower than raw fly ash; (2) approximately 80% of SiO2 had relatively high reaction activity because of the foregoing Al-extraction treatment. Through an ingenious green chemical process, the complete conversion of white mud into silicon-calcium fertilizer (SCF) was achieved under very mild reaction conditions (approximately 100 degrees C and atmospheric pressure). Waste liquor was totally recycled, and no secondary solid waste was generated. The SCF had an available silicon content (ASC) of 35%, significantly higher than the commercial standard (20%). Converting them into soil conditioners or ecological remediation materials with the lowest possible energy consumption and secondary pollution may be the most promising approach for the future disposal of aluminosilicate industrial solid wastes.