关键词: 微细粒, 铁矿石, 高梯度强磁选, 阴离子反浮选

Abstract: The process flow of stage grinding， low intensity magnetic separation， high intensity magnetic separation and anion reverse flotation was originally adopted in a certain fine-grained iron ore concentrator in Shanxi. However， problems existed in the practical production， such as high iron grade of tailings from high intensity magnetic separation and unsatisfactory flotation indexes.Therefore， the technological process was optimized by optimizing the magnetic field intensity of the first stage of high intensity magnetic separation， replacing flocculation and desliming with low intensity magnetic separation and high intensity magnetic separation.The results showed that:① For the sample with the iron grade of 30.60%， under the condition of grinding fineness of -0.076 mm accounting for 85%， using the first stage of low intensity magnetic separation (143 kA/m) and high intensity magnetic separation (1 114 kA/m) process flow， the iron grade of tailings from high intensity magnetic separation can be reduced to 6.18%.At this time， the loss of iron recovery rate is only 4.82%.② The second-stage low intensity magnetic separation and high intensity magnetic separation process is used to replace the original flocculation desliming process. Under the condition of the second-stage grinding fineness of -0.038 mm accounting for 85%， the magnetic field intensity of the second-stage low intensity magnetic separation and high intensity magnetic separation are 143 kA/m and 637 kA/m， respectively， the particle size contents of the second-stage of high intensity magnetic separation concentrate which below 10 μm decreases from 27.22% to 22.19%. The particle size contents below 20 μm decreased from 48.79% to 44.21%， and the iron grade of flotation feeding increased from 39.90% to 48.36%.③ The closed-circuit flotation process of "one roughing， one cleaning and three scavging" was adopted for the second stage low intensity magnetic separation and high intensity magnetic separation combined concentrate . Under the condition of one roughing flotation concentration of 25% and the temperature of 30 ℃，NaOH dosage of 1 200 g/t， starch dosage of 1 000 g/t and CaO dosage of 500 g/t were successively added.The roughing and cleaning dosage of RA-915 were 900 g/t and 150 g/t， respectively. The flotation iron concentrate with iron grade of 66.13% and iron recovery rate of 88.44% was finally obtained， and the iron grade of flotation tailings was 15.83%.The optimized test process can reduce the iron grade of tailings from high intensity magnetic separation， improve the iron grade of flotation feeding ore， and reduce the difficulty of flotation quality improvement and impurity reduction. It has a reference significance for the development and utilization of the same type of iron ore.

Key words: fine particle size, iron ores, strong magnetic separation with high gradient, anion reverse flotation