Improving of Balling Performance by High Pressure Roll Grinding
The experiments were conducted based on the study of one kind of ultra fine-sized magnetite concentrate with nearly 85% of the material being less than 0.044mm in size. The preliminary study has shown that this iron concentrate has middle ballabitity(K=0.61) because the iron concentrate characterized with flaky and spherical particle shapes. Such features are detrimental to the granulation of green pellets. Much more research work was carried out on how to improve balling performance by processing this magnetite concentrate with high pressure roll grinding (HPRG). The results indicated that newly-created cracks and edges would appear. Specific surface area of iron concentrate would increase from 2161.72 cm2.g-1 (base case) to 2703.51cm2.g-1 and fine particles percentage (-0.044mm) would increase to 94.69%. For the balling performance experiment, the results revealed that the ballability would increase to 1.59. Drop strength of green pellets would increase from 6.1 times/0.5m to 14.7 times/0.5m. Compression strength of green pellets would increase from 10.5N.P-1 to 12.61N.P-1. But break down temperature would decrease from more than 600°C to 480°C. The whole experiments revealed that HPRG could improve the balling performance of ultra fine-sized magnetite concentrate.
Y. P. Mo et al., "Improving of Balling Performance by High Pressure Roll Grinding", Key Engineering Materials, Vols. 480-481, pp. 533-538, 2011