基于转底炉直接还原的高磷铁矿铁磷分离新工艺基础研究

High phosphorus oolitic hematite is of huge amount and is difficult to be concentrated at home and abroad. It is of strategic significance to develop the dephosphorization technology of high phosphorus iron ore for guaranteeing the safe iron ore resources supply and promoting the sustainable development of iron and steel industry of China.The key factor in the comprehensive utilization of the high phosphorus oolitic hematite is to realize the separation between iron and phosphorus in the iron ore economically and effectively and obtain high grade raw material for iron making or low phosphorus pig iron.This project presents a new flow sheet for the separation between iron and phosphorus in the high phosphorus hematite based on the rotary hearth furnace(RHF) reduction and melting technology. The core content of the new flow sheet includes coal-based selective pre-reduction and fast melting separation between molten iron and slag of the reduced pellet.In order to understand the fundamental theories of the key technical problem of the new flow sheet, the main researching program is focused as follows: carbothermic reduction mechanism of the iron oxide and phosphorus containing mineral in the phosphorus oolitic hematite/carbon composite pellet,the evolution mechanism of the pellet phase structure during the pre-reduction process,the separation mechanism between iron and phosphorus during the fast melting separation of the molten iron and slag,research on the strengthening mechanism of the selective pre-reduction and slag and iron melting separation and so on. The research result to be obtained can provide scientific foundation for the developing of the new comprehensive utilization flow sheet for the phosphorus oolitic hematite.

高磷鲕状铁矿储量巨大，是国内外公认的难选铁矿石。开发高磷铁矿脱磷技术对于保障我国铁矿石资源的安全供给、促进我国钢铁工业的可持续发展具有重要战略意义。高磷铁矿综合利用的关键是如何经济有效地实现矿石中铁和磷的分离，从而获得优质的炼铁原料或低磷生铁。本项目构建了以转底炉直接还原工艺为基础，以高磷铁矿煤基选择性预还原和预还原矿快速熔分为核心的高磷铁矿铁、磷分离新工艺，针对该工艺关键技术环节的基础理论问题，重点开展如下研究：高磷铁矿含碳球团中铁氧化物与含磷矿物的碳热还原机理，还原过程中矿相结构演变规律，预还原矿快速熔分铁磷分离过程机理，选择性预还原和渣铁熔分强化调控等方面的基础研究，以期为新工艺的开发提供科学依据。

高磷鲕状铁矿储量巨大，是国内外公认的难选铁矿石。开发高磷铁矿脱磷技术对于保障我国铁矿石资源的安全供给、促进我国钢铁工业的可持续发展具有重要战略意义。高磷铁矿综合利用的关键是如何经济有效地实现矿石中铁和磷的分离，从而获得优质的炼铁原料或低磷生铁。本项目构建了以转底炉直接还原工艺为基础，以高磷铁矿煤基选择性预还原和预还原矿快速熔分为核心的高磷铁矿铁、磷分离新工艺，针对该工艺关键技术环节的基础理论问题，主要获得了如下结果。.首先，针对高磷铁矿矿物组成特点，对氟磷灰石与高磷铁矿中脉石相的反应进行了研究，揭示了高磷铁矿中含磷矿物在1200℃的碳热还原机理。研究发现：在配加石墨的情况下，氟磷灰石发生不同程度的还原，其中SiO2脱磷能力最强。当SiO2、Al2O3和Fe2O3同时加入氟磷灰石配碳反应后，氟磷灰石反应速率加快。.其次，针对鲕状特点进行了初步研究，通过原矿埋炭实验，对鲕状结构变化及矿物反应进行原位观察，进一步验证了矿物反应过程。鲕状结构变化与矿物反应过程相联系，原矿研究不仅证明了纯物质研究的正确性，还发现氟磷灰石在还原的同时，以晶体形式扩散进入铁氧化物中，嵌布紧密，很难通过机械方法进行分离。.最后，在高磷铁矿含碳球团中，加入CaCO3以调节碱度，加入Na2CO3与CaF2为添加剂，研究碱度、添加剂与反应时间对珠铁工艺还原熔分脱磷的影响。试验结果表明：提高碱度，加入Na2CO3及CaF2，缩短反应时间均有利于降低珠铁中磷含量。优化的工艺参数为：R=1.4，4%Na2CO3，4%CaF2，反应时间12min。此时珠铁中磷含量为0.22%，脱磷率为90%。