The fineness of the high sulfur gold concentrate leached from a certain gold smelting company is -37 μm,accounting for 93 %.After leaching,the cyanide residue gold level is around 1.30 g/t.In order to further reduce the gold grade of cyanide residue,ALC-3900L ALC mill was installed on the production site to regrind the high sulfur gold concentrate based on the successful pilot test of ALC mill in the early stage.The industrial application results show that after the ALC mill is applied to the regrinding of high sulfur gold concentrate,the fineness of -37 μm increases from 92.42 % to 98.80 %,and the fineness of -20 μm increases from 70.56 % to 89.29 %;After leaching high sulfur gold concentrate,the cyanide residue gold level decreased from 1.30 g/t to 1.08 g/t,indicating significant economic benefits.