Method of acid-alkali combined extraction of aluminum-based products and silicon-based products from fly ash

The invention discloses a method of acid-alkali combined extraction and preparation of aluminum-based products and silicon-based products from fly ash. In the method, on the basis of increasing extraction ratio of aluminum oxide, residue acid- and alkali-removal processes are optimized, so that low alkali washing water generated in the alkali-removal process can be used in the acid-removal process. The low alkali washing water generated in the alkali-removal process is used for performing secondary water-washing to a first aluminum extraction residue, so that not only is a secondary pollution problem in an acid-alkali combination method in the prior art overcome, but also the extraction ratio of silicon dioxide follow-up is greatly increased. The method achieves high-value application of the fly ash, reduces the influence on environment, and is possible to achieve large-scale treatment and recycling utilization of the fly ash.