Growth of metallic iron particles during reductive roasting of boron-bearing magnetite concentrate

The growing characteristics of metallic iron particles during reductive roasting of boron-bearing magnetite concentrate under different conditions were investigated. The size of the metallic iron particles was quantitatively measured via optical image analysis with consideration of size calibration and weighted ratio of image numbers in the core, middle and periphery zones of cross-section of pellets. In order to guarantee the measurement accuracy 54 images were captured in total for each specimen, with a weighted ratio of 1:7:19 with respect to the core, middle and periphery section of the cross-section of pellets. Increasing reduction temperature and time is favorable to the growth of metallic iron particles. Based on the modification of particle size measurement, in terms of time (t) and temperature (T) a predicting model of metallic iron particle size(D), was established as:D=125-0.112t-0.2352T-5.355x10(-4)t(2)+2.032x 10(-4)tT+1.134x10-T-4(2).