| With the rapid development of exploration of iron resources, it is imperative to utilize lean fine hematite. At present, separation technology of weak magnetic-high intensity magnetic-anionic reverse flotation has matured for hematite, but with the depletion and increasingly fine particles of hematite, anionic reverse flotation technology gradually exposes the problems including low separation efficiency, long process flow and high separation cost, etc. Consequently, it is rather important to develop the efficient separation methods, equipment and technology based on the whole technology framework.Firstly, studies of process mineralogy and floatability of lean fine hematite were conducted; the mineralogical properties were analyzed; significant influences of"lean and fine"on separation process of hematite were revealed; and the floatability process characteristics of lean fine hematite were studied. Features of various separation methods and processes, especially FCSMC, were systematically analyzed, and the idea that enhancement of separation efficiency of lean fine hematite and intensification of separation technology could be achieved by using high turbulence mineralization of pipe section in FCSMC and multiple-flow-pattern gradient intensifying process of integrated roughing and cleaning was proposed.Study of high turbulence mineralization in pipe section based on jet started from bubble characteristics. The change in single bubble diameter in motion was analyzed; meanwhile, bubble size distribution in pipe section was studied for the first time with application of photo-image method. Pressure difference method was used to study the variation and distribution of gas holdup in pipe section based on jet. Effects of cycle pressure, gas flow rate, back pressure and frother dosage on total gas holdup of pipe section were investigated; and distribution of local gas holdup of pipe section was disclosed.The velocity distribution characteristics of single phase flow field in pipe section based on jet were mastered by study of corresponding 2-D velocity distribution using Laser Dopper Velocity (LDV). FLUENT software was used to conduct single-phase and gas-liquid two-phase fluid dynamic numerical simulation of pipe section based on jet. The results show that generally velocity distribution of single phase numerical simulation shares the similar tendency with that of LDV, indicating that it is reasonable to study flow field of pipe section with numerical simulation technology. Moreover, the gas-liquid two-phase numerical simulation was used to analyze the distributions of velocity, pressure, turbulent kinetic energy and gas holdup, and basic flow field characteristics were mastered. Besides, the influences of diameter of pipe section, back pressure and bubble size on flow field of pipe section were revealed.Expressions of flotation rate constant, average residence time and recovery for pipe section were derived from flotation kinetics research of highly turbulent mineralization in pipe section based on cycle middling.The separation research of lean fine hematite was carried out lastly. Lab separation system and column-shortened-process research system (industrial divergent stream test system) were built, through which separation process of high efficient column roughing equipment was studied. And"roughing- scavenging"two-segment column shortened process was developed, which was a simplified process with a dramatic increase of 8.25% in recovery in the case of similar concentrate grade comparing to flotation machine technology. It strengthened the recovery of micro-fine minerals. This research fills in the blank of iron ore processing technology in China.On the bases of technology development and industrial application of column separation technology for magnetite, modification of adaptation of column separation equipment was conducted and one roughing - two scavengings - middling sequential returning process was designed.
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