Na_2WO_4与CaWO_4在电解制钨过程中的解离及离子运动形式分析

Dissociation and ion movement forms of Na_2WO_4 and CaWO_4 in tungsten preparing process by molten salt electrolysis method

对熔盐电解法在NaCl-KCl-Na2WO4和NaCl-KCl-CaWO4体系制取钨粉的过程中采用瞬时断电计量,对电极产物进行X-射线衍射分析,对比分析Na2WO4和CaWO4两种钨酸盐在熔盐中的解离运动形式,从而能够深层揭示体系的电解机理.研究结果表明:由于活性物质本身的结构、外部条件及电解质体系、电子传递过程和扩散过程的影响,Na2WO4和CaWO4在电解过程中的活性基团解离及离子运动形式有较大差别,Na2WO4以Na+和WO42-为活性离子基,而CaWO4可视为中性分子团,其中的活性基团可近似为CaO·WO3,电极的浓差极化仍是Na2WO4和CaWO4电解过程的控制步骤.

The dissociation and motion state of Na2WO4 and CaWO4 in the molten were analyzed qualitatively based on the characterization of molten salt electrolytic process and tungsten powder products in NaCl-KCl-Na2WO4 and NaCl-KCl-CaWO4 system. The results show that there was a big difference between the electrolytic dissociation and ion movement forms of Na 2WO4 and CaWO4 in the electrolysis process due to different structures of active material, external conditions, electrolyte system, electron transfer and diffusion process. Concentration polarization of electrode is still the domination step in the electrolysis process.