The yield of humic acid of the coal residues increased with the increasing of the photooxidation time, coal residues increased.The order of the yield of humic acid of coal residues is D2>D3>D4.

• 各煤组分的腐殖酸产率随着光氧化时间的增加而增大，腐殖酸产率依次为D2>D3>D4。