颗粒级配对溜井放矿矿石混合特性的影响

Influence of Grain-Size Composition on Mixing Characteristics of Ores Through Ore Pass

将放出混合矿样的中值粒径(d50)与放矿前初始中值粒径(d50′)的差值与d50′的百分比定义为中值粒径偏析量(MDS),并将其作为矿石混合特性的定量评价指标。以湖北金山店铁矿主溜井放矿过程为背景,借助相似试验与数值模拟,采用TFe品位在24.75%~59.21%的7种铁矿石,以及粉矿含量为11%~19%对应的5种颗粒级配,组成35种不同品位的矿石级配方案,研究主溜井放矿过程中矿石的混合特性。结果表明:相似试验与数值模拟所得结果吻合性较高;同一级配方案下,不同品位矿石放矿计算得到中值粒径偏析量的变化趋势基本一致,随着入井矿石品位升高,MDS均不断减小,矿石混合均匀性越高;同一品位、不同级配下,级配中粉矿含量占比不断增大,MDS表现为先减小后增大,矿石混合情况首先变好逐渐变差;粉矿含量为13%对应级配方案下,MDS最小,矿石混合情况最优;MDS能对溜井放矿过程中矿石的混合特性进行有效评价。

The percentage difference between the median diameter of mixed ore samples(d50)and the initial median diameter before ore drawing(d50′)is defined as the median diameter particles segregation(MDS)for drawn ore and taken as the quantitative evaluation index for ore mixing characteristics.With the ore-drawing process of the main ore pass in Jinshandian Iron Mine as an example,seven kinds of iron ores grading(TFe)within 24.75%~59.21%,using five different grain-size compositions corresponding to powdered ore content within 11%~19%,were taken to prepare 35 kinds of ore proportioning schemes for studying the mixing characteristics of the ores through the main ore pass.It is shown that results obtained from the similarity test and numerical simulation are almost identical to each other.With the same size-composition scheme,the calculated MDS for drawn ore with different iron grade is almost same in variation.Increasing the ore grade can lead to a gradual decrease in MDS and higher uniformity in the mixed ore.As for the ores with the same grade and different size compositions,an increase in the content of powdered ore therein can lead to an increase after an initial decrease in the MDS,as well as the deterioration of the mixing characteristics of the ores.The corresponding grain size composition scheme for the ores with the powdered ore content at 13%results in the minimum MDS and best ore mixing characteristics.It is concluded that MDS can be used to effectively evaluate the ore mixing characteristics for ore drawing.