Chemical purification method for preparing ultralow ash content coal from clean coal

The invention belongs to the technical field of clean coal carbon preparation, and particularly relates to a chemical purification method for preparing ultralow ash coal from clean coal, which comprises the following steps: S1, oxygen-isolated activated roasting: roasting clean coal in an oxygen-free environment to obtain an oxygen-isolated activated roasting product; s2, low-temperature alkali dissolution and silicon separation: adding the oxygen isolation activated roasting product obtained in S1 into a caustic alkali solution, dissolving out active silicon at low temperature, and filtering to obtain aluminum-containing coal and silicon-containing filtrate; and S3, high-temperature alkali dissolution and aluminum separation: adding the aluminum-containing coal obtained in S2 into a sodium aluminate solution, dissolving out aluminum at a high temperature, and filtering and washing to obtain ultralow-ash coal and the sodium aluminate solution. The method provided by the invention can realize deep purification