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China is the first steel-producing country in the world, iron ore has been in short supply in our country for a long time, more than50%of the iron ore needs imported from abroad. With the continuous rising of international iron ore prices, developing domestic iron ore has become an inevitable trend. However, ours iron ore resources are with a large number but not rich, by the end of2008the total proven reserves of iron ore are more than60million tons, and the lean ore reserves are as much as47%, most of them are hard for separation with a complex type. Hematite resources we can make use of increasingly tend to be poor, complex and fine, because of its low content of useful components, complex components and fine dissemination size, using conventional mineral processing technology is difficult to obtain satisfactory results, magnetic roasting-magnetic separation is still the most effective method in iron ore upgrade.In this paper, we made use of circulating fluidized bed(CFB)’s advantages of strong material backmixing and efficient mass and heat transfer, developed a new and efficient technology of flash magnetic roasting of iron ore, It is effective to overcome the defect of traditional mineral processing technology on complex processes, high energy consumption, low efficiency and so on.This paper does an in-depth study on the problems of upgrading China’s oolitic hematite hard to be extracted and selected using this new process "magnetic roasting of CFB-high intensity magnetic separation".In power generation process of CFB boiler, low-NOx combustion technology is often used to suppress NOx formation, staged-air combustion is one of commonly used low-NOx combustion technology in China, if we can make full use of local reducing atmosphere in rich fuel area to achieve magnetic roasting of iron ore, it will be a cost-effective iron ore enrichment technology.Using iron ore instead of part material of CFB boiler, at the same time of coal-fired power generation reductive roasting the hematite into magnetite, not only can achieve effective magnetic roasting of iron ore, but also get significant savings of operating costs without affecting the normal operation of the boiler, thus, create a new type of multi-generation technology.In this paper, we creatively developed a dynamical CFB experiment device, and completed the optimal design and selection of experimental conditions for magnetic roasting of hematite. By burning Datong lump coal with staged-air combustion technology to create local reducing atmosphere, do magnetic roasting-low intensity magnetic separation experiment on Hubei oolitic hematite with iron grade47.45%, and the results show that in the optimized roasting conditions after water quenching, sorting, grinding and low intensity magnetic separation of the roasted ore, the beneficiation index of iron concentrate with iron grade more than55%and recovery rate more than70%can be obtained, and removed phosphorus nearly60%of the total mineral content.Experiments show that the new technology "CFB magnetic roasting-low intensity magnetic separation" has such advantages as strong system stability, easy to be operated, fast response, low power consumption. Calculated, the daily capacity of a circulating fluidized bed boiler with capacity100MW magnetic roasting such iron ore is up to165ton.The new technology "CFB magnetic roasting-low intensity magnetic separation" provides a new way for efficient separation of poor hematite, at the same time,If we can use the technology to extract iron of fly ash from coal combustion, extract useful heavy metals from the ash, it will bring huge economic and social benefits.
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