Abstract: Aiming at the practical problems of iron grade decrease and aluminum content increase caused by deep mining in Chengchao Iron Mine，taking the -535/-552 level raw ore and on-site iron con⁃ centrate of Ⅵ orebody as the object，the process mineralogy analysis，grinding-magnetic separation test and elutriation aluminum reduction test were carried out. The results show that the grade of TFe is 24.42%，the content of Al2O3 is 7.43%，and the content of SiO2 is 31.64%. The on-site iron concentrate has a TFe grade of 64.74%，an Al2O3 content of 1.71%，and a SiO2 content of 3.81%. The results of pro⁃ cess mineralogy analysis show that aluminum mainly occurs in magnetite，chlorite and mica，with the dis⁃ tribution rates of 38.64%，23.39% and 15.46%，respectively. The close dissemination of magnetite and aluminum-bearing gangue is the fundamental reason for the difficulty in removing aluminum. The grinding�magnetic separation test shows that when the raw ore is milled to 17 min，the magnetic separation concen⁃ trate index is consistent with the actual production. When the grinding time is 21 min，the TFe grade of the concentrate increases to 66.54%，the Al2O3 content decreases to 1.56%，the SiO2 content decreases to 2.85%，and the iron recovery rate is 76.29%. The on-site iron concentrate was reground for 11 min and then magnetically separated. The concentrate TFe grade reached 67.35%，Al2O3 content decreased to 1.44%，SiO2 content decreased to 2.65%，and the iron recovery rate was 98.73%. The aluminum reduction effect of the elutriation test is limited，which can only reduce Al2O3 by about 0.1 percentage points，and ac⁃ companied by obvious iron loss，which is not suitable as the aluminum reduction process of the mine.

Key words: iron upgrading and aluminum reduction, grinding fineness, process mineralogy, magnetic separation, elutriation