基于磷资源高效利用的含磷渣制备磷酸铁基础研究

The using of abundant reserves of high-phosphorus ores in smelting will inevitably bring about the problems of high phosphorous slag utilization problems. At the same time, with the development of new generation of steel processes and the demand of dephosphorization in converter, steel enterprise have no good treatment for large quantities stockpiling of phosphorus-bearing slag. A new thought utilizing phosphorus resources in slag during slag tapping is proposed in this project, which means that it is using the residual heat from steel slag to reductively dephosphorize the P-bearing slag to produce high value-added ferric phosphate (the main raw material for new energy batteries), and the slag and molten iron after processing are recycled. Then not only can the utilization problem of iron and phosphorus can be solved, remarkableeconomic benefit can also begained. However, the basic research on the utilization of phosphorus-containing slag resources is relatively lacking, especially lack of deeply systematic research on the efficient distribution and migration mechanism of phosphorus in slag, and the basic theory and technology of high-efficiency dephosphorization for preparation of ferric phosphate. Therefore, the relevant basic theoretical research is carried out in the project, the efficient distribution and migration mechanism of phosphorus in slag under reducing conditions is analyzed, the ultimate dephosphorization of phosphorus-bearing slag and the ultimate phosphorus-rich mechanism of ferrophosphorus are explored, efficient dephosphorization of P-bearing slag to produce ferrophosphorus is researched, and preparation of ferric phosphate with low-grade ferrophosphorus is studied, and suitable phosphorus resource utilization in slag and residual heat utilization of steel slag and the required thermal compensation process matching technology are discussed, the model and process route for utilization resources of P-bearing slag to produce ferric phosphate are established, which provides theoretical guidance for the high efficient use of high-phosphorus iron ore and P-bearing slag in china.

我国储量丰富高磷矿在冶炼中使用，必然带来高磷渣利用的难题；同时随着新一代钢铁流程发展及转炉脱磷需要，钢企对大量堆存含磷渣尚无好的处理办法。本项目提出了出渣时充分考虑渣中磷资源高效利用的新思路，即利用钢渣余热对钢渣还原脱磷制备高附加值磷酸铁（新能源电池主要原料），处理后炉渣和铁水进行冶炼回用，这样既解决渣中铁、磷等资源的利用问题，又带来显著经济效益。然而关于含磷渣资源利用的基础研究相对缺乏，尤其是渣中磷的高效分配及迁移机制、高效脱磷制备磷酸铁基础理论及工艺技术缺乏深入系统研究。因此本项目对此开展相关基础理论研究，分析还原条件下渣中磷的高效分配及迁移规律，探索含磷渣极限脱磷及磷铁极限富磷机制，研究含磷渣高效脱磷制备磷铁和低品位磷铁制备磷酸铁技术，探讨适合渣中磷资源利用和钢渣余热利用及所需热补偿工艺匹配技术，建立含磷渣资源利用制备磷酸铁模式及工艺路线，为我国含磷渣及高磷矿的高效利用提供理论指导。

我国储量丰富高磷矿在冶炼中使用，必然带来高磷渣利用的难题；同时随着新一代钢铁流程发展及转炉脱磷需要，钢企对大量堆存含磷渣尚无好的处理办法。因此本项目对此开展相关基础理论研究，分析还原条件下渣中磷的高效分配及迁移规律，探索含磷渣极限脱磷及磷铁极限富磷机制，研究含磷渣高效脱磷制备磷铁和低品位磷铁制备磷酸铁技术，建立含磷渣资源利用制备磷酸铁模式及工艺路线，主要研究结论如下：（1）综合热、动力学分析，脱磷钢渣碳热还原有利的条件和参数范围为炉渣碱度1.0~2.0，Fe2O3含量为20%左右，P2O5含量适中，还原温度在确保钢渣熔化下兼顾能耗小和回收率高等综合因素即可；（2）基于脱磷转炉钢渣磷、铁等有价元素含量较高和炉渣碱度较低的特点，提出了基于钢渣显热利用的脱磷钢渣“熔融改质+碳热还原”回收磷、铁等有价元素制备磷铁及钢渣资源化利用制备水泥等建材的工艺路线。采用碳热还原方法可使渣中磷回收率可达到80%以上，铁回收率可达到99%以上，实现脱磷钢渣中磷、铁等有价元素有效回收制备磷铁（磷含量10~15%）；并在还原过程中兼顾对碱度较高的脱磷钢渣调质（进行钢渣改质使炉渣碱度降低至1.0~1.5等）消除低活性、难磨相（RO相）和弱稳定性（f-CaO）相的影响，经碳热还原与调质处理后脱磷钢渣中含铁物相（Ca3Fe2Si3O12）物相得到有效的控制，调质还原后渣中全铁都降到3%以下，游离氧化钙都降到0.1%以下，满足了水泥等建筑材料国标的要求；（3）基于“熔融改质+碳热还原”工艺制备的低品位磷铁资源，建立了低品位磷铁资源制备磷酸铁的工艺路线，溶液体系的pH值>0.5，磷酸铁析出达到最优；高磷低铁不利于磷酸铁的析出，确定了制备磷酸铁合理的磷铁比。（4）集成建立含磷渣资源利用制备磷酸铁模式及工艺路线，为我国含磷渣的高效利用提供理论指导。