Differences in Early Rejection of Gangue for Low-Grade Iron Ores with Different Textures from HPGR

Abstract

ABSTRACT The ore texture determines the proportion of the early rejection of gangue of the low-grade iron ores. However, a detailed study of the early rejection of gangue for low-grade iron ores with different textures is still highly desirable. In this study, three types of low-grade iron ores with different grain sizes were crushed to −3 mm by a high-pressure grinding roller (HPGR). Mineral Liberation Analyzer (MLA) and dry magnetic separation tests were performed on the resulting products. The MLA test results showed that the gangue in fine-grained iron ores was more difficult to liberate than in coarse-grained iron ores. The dry magnetic separation tests indicated that only 15.23% of gangue could be rejected for fine-grained iron ores, which was much lower than that of coarse-grained iron ores. Liberation analysis revealed that a large proportion of the gangue contained only a small amount of valuable iron oxide minerals. By returning the middling from dry magnetic separation to HPGR for crushing again, the gangue rejection percentage for fine-grained iron ore increased to 33.56%. These results demonstrate that liberation studies can help improve the efficiency of early rejection of gangue.