Abstract: The ore properties of different ore bodies in the open pit of Sijiaying iron mine are quite different,and the same ore body has more changes along strike and vertical direction.Number IV ore body is located between N14 and N18 lines,with ore reserves accounting for about 12% of the total ore reserves in the open pit.The ore has the worst beneficiability,which will affect the technical and economic indicators of beneficiation when the ore distribution ratio is large.In order to better guide the ore supply,distribution and beneficiation production,systematically studied the occurrence,chemical composition,mineral composition,imbedding characteristics and grindability of ore body IV.The results show that: the average geological grade of ore body IV is 25.97%,and the average ferrous iron content is 3.53%.At the south end of the ore body,there are some magnetic ores distributed,and the magnetic rate of the ore increases gradually from shallow to deep.The distribution of the ore inlaid particle size is uneven,especially the oxidation degree of the shallow part is deep and the weathering is serious.The ore is easy to be muddy in the grinding process,and the grindability and washability is poor.From the shallow part to the deep part,the grindability and washability of the iron ore is obviously improved.

Key words: Sijiaying Iron Mine,Process mineralogy,Grindability and washability