利用熔渣电解对钢液进行脱氧和合金化

The present study is aimed at completing the deoxidation and alloying operations of Si and Mn of liquid steel by the way of electrochemical method. In the traditional steelmaking process, the ferroalloy is first prepared by smelting the oxide ores, and then added into the liquid steel for deoxidation and alloying. The deoxidation and alloying operations in this study will be completed directly by the electrolysis of molten slag in which process the alloy elements are produced in the slag-steel interface when the electric voltage is applied to the electrodes which are placed in the steel and slag respectively. So, the preparation of ferroalloy can be avoided which is beneficial to the energy conservation and reduction of pollutant emissions. The deoxidation operation will be achieved by electrolyzing CaO-Al2O3-SiO2-FeO slag, while the alloying operations of Si and Mn will be achieved by electrolyzing CaO-Al2O3-SiO2-MnO slag. In order to deoxidize the dissolved oxygen and precisely control the contents of Si and Mn in the steel, the influences of composition of molten slag and temperature as well as the anode material (carbon and ceramet) on the electrolysis of molten slag at the conditions of potentiostatic and galvanostatic will be studied. The electrical conductivity of CaO-Al2O3-SiO2-FeO and CaO-Al2O3-SiO2-MnO systems, as well as the influences of composition, temperature and electrochemical parameters on the precipitation orders of metal ions are two important tasks of the present study.

本课题拟通过电化学的方法实现钢液的脱氧和Si、Mn的合金化操作。在传统的炼钢过程中，需要首先将氧化物矿冶炼成铁合金，然后将铁合金加入到钢液中进行脱氧和合金化。本研究通过在熔渣和钢液中放置电极并施加直流电场，使熔渣发生电解，在渣钢界面析出合金元素并直接进入钢液完成钢液的脱氧和合金化操作，可避免铁合金的生产，有利于节能减排。本课题将通过对CaO-Al2O3-SiO2-FeO渣系的电解完成钢液的脱氧操作；通过对CaO-Al2O3-SiO2-MnO渣系的电解完成钢液的Si和Mn的合金化操作。将在恒电位以及恒电流两种模式下研究渣成分、温度以及阳极材料(石墨和金属陶瓷)的影响，旨在实现对钢液溶解氧的脱除和Si、Mn含量的精确控制。CaO-Al2O3-SiO2-FeO和CaO-Al2O3-SiO2-MnO体系的电导率以及成分、温度和电化学参数对熔渣中不同金属离子的析出顺序的影响是本课题重点要研究的内容。

在传统的炼钢过程中，需要首先将氧化物矿冶炼成铁合金，然后将铁合金加入到钢液中进行脱氧和合金化。本课题通过在熔渣和钢液中放置电极并施加直流电场实现钢液的脱氧和合金化操作。由于该工艺避免了铁合金的生产，有利于节能减排。主要的研究内容及结果如下：研究了含铁氧化物熔渣中铁离子的价态，建立了铁离子价态随熔渣成分、温度和氧分压的理论方程，发现三价铁离子的比例随着氧分压的增加，碱度的增加，温度的降低而增加；通过实验测量研究了成分、温度和氧分压对含铁氧化物熔渣、锰氧化物熔渣的电导率，阐明了其离子电导率和电子电导率随不同因素的变化规律；考虑到在利用熔渣电解对钢液进行脱氧或合金化时渣的电化学行为的重要性，单独研究了含铁氧化物熔渣在直流电场下的电解行为，研究了电流、渣系成分和温度对电流效率及电解速率的影响规律，发现大电流，高温度和高碱度有利于电流效率和电解速率的增加；研究了利用熔渣电解对钢液的脱氧，推导了熔渣电化学脱氧的动力学方程，并发现随着施加电压的增加，脱氧速率急剧增加，脱氧也更彻底；研究了利用熔渣电解对钢液进行硅的合金化操作，发现随着电极两端施加电流的增加，钢液中的Si含量和Si的合金化速率都在增加，同时钢液中Ca和Al的含量变化很小。本课题得到的结论有望对电化学脱氧和合金化的工业生产提供基础支持。