Process Of Low Grade Iron Ore By Circulating Fluidized Bed Roasting For Iron Upgrade And Dephosphorization

With the development of metallurgical industry, more better quality of iron ore concentrate is required. Compared with imported iron ore, the quality of iron ore in China is still in significant gap. The quality tendency of iron ore resources available in China is poor, tiny and complex, and the price of imported iron ore is dramatically rising. We need to develop a new technology to improve the iron grade and reduce the phosphorus content of oolitic hematite, especially in Hubei Ningxiang type of oolitic hematite with the storage of more than 3 billion tons. Because of its tiny disseminated grain size, complex composition and high phosphorus content, traditional concentrating methods are difficult to reach the smelting requirements.The paper used a new "circulating fluidized bed (CFB) roasting & weak magnetic separation" technology on China's oolitic hematite enrichment. In circulating fluidized bed (CFB), gas-solid materials mix rapidly, heat and mass transfer in a high speed, the whole zone in CFB reactor is in the isothermal state. Weakly magnetic oolitic hematite could be converted into strongly magnetic materials in the reductive atmosphere. In circulating fluidized bed boiler combustion power generation process, staged-air technology is often used to create reductive atmosphere to suppress NOx production. It will be a good technology to increase the iron content of low taste of iron ore by combining roasting technology with coal power generation technology. Reduce hematite in the power generation progress by substituting iron ore for some bed materials.Circulating fluidized bed boiler combustion power generation process, in order to suppress NOx production, often through Staged-Air to create a localized reducing atmosphere, allowing for the reduction roasting of iron ore and pulverized coal fluidized bed combustion technology are combined in a fluidized bed within a reasonable organization of the boiler combustion atmosphere and the combustion temperature, while the effective reduction of magnetite, hematite, will be a very effective means to upgrade low-grade iron ore grade and technology. Replaced by the mineral part of the bed material, the effective reduction in power generation, while hematite and greatly reduce operating costs.In this paper, CO and N2 mixed gas is used to simulate the coal-fired reduction roasting atmosphere. In the suitable calcination condition, the calcined product obtained through the stages of grinding-a rough and fine weakly magnetic separation, concentrate grade is 56.60% and iron ore recovery rate is 77.79%. Use hydrochloric acid to pickle concentrate, so that the goal of protecting iron and removing phosphorus could be reached. The pickling condition is that:the volume percentage content is 5% and reaction time is 0.5h. Through the test, phosphorus removal rate is 81.24% and iron loss rate is 2.84%.On the experiment data and other consideration, a reasonable procedure is clear. With the technology of "Circulating fluidized bed (CFB) magnetizing roasting-weakly magnetic separation-hydrochloric acid pickling" to solve oolitic hematite, we can get the target of concentrate contain iron 57.38%, phosphorus 0.15% and recycle ratio is 75.58%.