Abstract: The content of siderite in Yanqianshan Iron Mine is high,which is difficult to directly separate and utilize. In order to achieve reasonable utilization of Yanqianshan Iron Mine ores,chemical analysis,XRD and other methods were used to identify the mineral composition and iron phase of them. By grinding-magnetic separation and flotation experiment,the changes in concentrate indexes of two ores under different ore blending ratios were studied. The results showed that when the ore content in Yanqianshan is less than 45%,the siderite content in the mixed ore is less than 5. 41%,and the flotation process is basically not affected. The concentrate with a grade greater than 65% and a recovery rate higher than 60% could still be obtained with grinding fineness of -74 μm accounting for 90%. When the proportion of Yanqianshan iron ore is between 45% and 50%,and the content of siderite in mixed magnetic concentrate is between 5. 41% and 6. 05%,the flotation environment has been severely deteriorated by siderite. If the concentrate grade reaches 65%,the recovery rate will significantly decrease. When the ratio of Yanqianshan iron ore is higher than 50% and the siderite content is higher than 6. 05%,the concentrate and tailings cannot be separated. Further the mechanism of deteriorating flotation of siderite through laser particle size tests was analyzed,and the results showed that siderite is prone to mud formation during the grinding process,resulting in a large number of micro fine minerals or even fine mud. These fine partical can easily cover the surface of large particles,hindering the adsorption of flotation reagents,reducing the hydrophobicity difference between gangue minerals and iron minerals, and deteriorating the flotation effect.

Key words: siderite,flotation,ore blending,fine mud cover,hydrophobic difference