1673K下SiO_2-CaO-MgO-Al_2O_3熔渣中Ni^(2+)的电化学行为

ELECTROCHEMICAL BEHAVIOR OF Ni^(2+) IN SiO_2-CaO-MgO-Al_2O_3 MOLTEN SLAG AT 1673 K

利用Mg O部分稳定的Zr O2固体电解质管集成构建Pt,O2(air)|Zr O2作参比电极的可控氧流电解池,采用循环伏安、方波伏安、计时电位、恒电位电解等电化学测试技术研究了1673 K高温下Si O2-Ca O-Mg O-Al2O3熔渣中Ni2+的电化学行为.结果表明,O2-在熔渣中的扩散和在Zr O2固体电解质内的电迁移不是熔渣中电活性物质还原的限制性环节,在本实验条件下利用构建的可控氧流电解池研究熔渣中Ni2+的电化学行为是可行的.熔渣中Ni2+在Ir电极上还原到Ni是受扩散控制的一步还原的可逆过程,利用循环伏安和计时电位测试技术所得数据计算得出了含有3%Ni O的熔渣中Ni2+的扩散系数分别为(3.50±0.18)×10-6和(2.80±0.22)×10-6cm2/s,与相关文献结果基本吻合.

The modern iron and steel industry produces large emissions of CO2 annually. Electrolytic reduc- tion of molten slag containing iron oxide at high temperature using an inert oxygen evolving anode is an alternative process to reduce or eliminate the formation of CO2. In order to establish reasonable process parameters of electro- lytic method for steel containing Ni, it is necessary to master the electrochemical behavior of Ni^2＋ in molten slag. However, investigations on the electrochemical behavior of Ni^2＋ in molten slag at higher temperatures were very lim- ited, which can probably be attributed to the experimental difficulties associated with the operation of high-temper- ature electrochemical cells. An electrolytic cell with a controlled oxygen flow and Pt, O2（air）｜ZrO2 used as reference electrode was constructed integrally through a one-end-closed magnesia partially stabilized ZrO2 solid electrolyte tube. Electrochemical behavior of Ni^2＋ on Ir electrode was investigated in SiO2-CaO-MgO-AhO3 molten slag at 1673 K by means of electrochemical techniques such as cyclic voltammetry （CV）, square wave voltammetry （SWV）, chronopotentiometry （CP） and potentiostatic electrolysis. The results show that both diffusion in the molten slag and electromigration in the ZrO2 solid electrolyte for the O^2- are not rate-determining steps of electrochemical reduction reaction process of electroactive ions. It is feasible to study electrochemical behavior of Ni^2- in the molten slag with the aid of the electrolytic cell with a controlled oxygen flow under the present experimental condi- tions. The reduction of Ni^2＋ on the Ir electrode in the molten slag is found to be a reversible reaction with a single step, and the rate of the process is diffusion controlled. Two diffusion coefficients of Ni^2＋ in the molten slag containing 3%NiO derived respectively from CV and CP are （3.50±0.18）× 10^-6 and （2.80±0.22）× 10^-6 cm^2/s, which are consistent with records in the relevant literatures.