【作者】 陈燕；

【导师】 杜军；

【作者基本信息】 重庆大学 ， 化学， 2012， 硕士

【摘要】 金属锰是生产不锈钢、高强度合金钢及锰合金的重要原料，同时在医药、化工等领域也有广泛应用。目前，工业上普遍采用直流电沉积法生产金属锰。然而，直流电沉积金属锰时，一方面阴极上发生析出氢和沉积锰两种竞争反应，析氢反应的发生降低了电沉积锰的电流效率；另一方面，锰电沉积过程中会形成一些自阴极表面向溶液中“突出生长”的枝晶，这也是导致电流效率降低和产量减小、引起电极间短路和生产不稳定的主要因素之一。因此，探索新型的锰电沉积方法，对于金属锰生产的节能减排具有重要意义。本文采用脉冲电流电沉积制备金属锰，主要研究内容如下：①通过线性电位扫描法考察了电解液成分对电沉积锰的影响，结合生产实际，确定脉冲电沉积制备金属锰的电解液组成为：30g·L^-1Mn²⁺、120g·L^-1（NH₄）₂SO₄、0.03g·L^-1SeO₂。②采用计时电流法研究脉冲电流对阴极电位的影响。脉冲电沉积锰阴极电位随着脉冲电流的周期性变化呈现出周期性波动，在同一电流密度下，脉冲电沉积时的阴极过电位比直流电沉积过电位大90～110mV。③采用光学显微镜和扫描电镜观察了脉冲电沉积锰的表面形貌和颗粒尺寸，得出：在电沉积过程中有少量的氢气在阴极吸附，电沉积初期锰表面有半径约10μm的球状颗粒生成，随着占空比的降低，球状颗粒有所减少；与直流相比，脉冲电沉积物的颗粒尺寸较小，当占空比为20%时的颗粒尺寸约为直流时的1/3。④通过自制隔膜电解槽进行脉冲电解实验，考察脉冲参数（占空比、频率、电流密度）对电解锰电流效率、产品质量的影响，得出最佳脉冲参数为：脉冲频率1000Hz、占空比50%、平均电流密度350A/m²，在此条件下脉冲电沉积8小时的电流效率达到82.6%，产品中硒含量为0.042%。⑤在电解锰工厂进行现场放大试验，考察脉冲电沉积技术运用到实际电解锰生产的效果。根据试验结果，采用脉冲电沉积技术制备金属锰时，电流效率比传统直流电沉积法高6%。更多还原

【Abstract】 Pure metallic manganese is a good alloy element, which is used in certain types ofsteel, particularly high-strength steels, and in nonferrous alloys. Similarly, it has beenextensively used in medicine, chemistry, and so on. At present, electrolysis is the mainway to refine manganese. However, because of the very negative potential of theMn²⁺/Mn couple in aqueous solution, reduction to Mn²⁺to Mn is always accompaniedby hydrogen evolution, which reduces the current efficiencies. On the other hand, manybranchses grow on the surface of cathode in metallic manganese deposition, which maybring down the current efficiencies and output of manganese, make the short circuitbetween anode and cathode, result in exceptional manufacture. So, a new technology ofenergy saving and emission reduction for electrolytic manganese metal is a hot researchtopic.This paper studied the preparation of manganese from a sulfate bath by pulsecurrent. The main content of the dissertation are as follows:①Linear sweep voltammetry （LSV） technique was used to investigate influenceof the electrolyte component to the manganese electrodeposition. Combine the industrypractice, the ideal compose of the electrolyte was30g·L^-1Mn²⁺、120g·L^-1（NH₄）₂SO₄、0.03g·L^-1SeO₂.②Chronopotentiometry was carried out to investigate the influence of pulsecurrent to cathode voltage. The results showed that, with the periodic variation ofcurrent, the cathode potential waved periodicity. At the same current density, aprogressive enhancement of the cathode polarization was observed, and theoverpotential of pulse electrodeposition was bigger than traditional directelectrodeposition for90～110mV.③The grain size and surface morphology of manganese deposits were studied byoptical microscope and scanning electron microscopy. At the initial stage ofelectrodeposition, there were many spherical grain （the radius was about10μm）growing on the surface because of a small quantity of hydrogen adsorbed on the cathode,when decreasing the pulse duty cycle, the spherical grain gradually reduced. At constantpulse current density and frequency, the grain size increased asymptotically withincreasing duty cycle. And at appropriate electrodeposition parameters, pulseelectrodeposition of manganese deposits resulted in ca. threefold reduction in the grain size in comparison with direct current electrodeposited samples.④Pulse electrodeposition of manganese by simulating the industry process inorganic glass electrobathes, investigated the influence of pulse parameters, i.e. currentdensity, frequency and duty cycle on the current efficiency, product quality and surfacemorphology in manganese electrodeposited. The results show that the ideal pulseparameters were frequency1000Hz, duty cycle50%and current density350A/m², andthe current efficiency achieved82.6%from the electrolysis experiment of8h.⑤In order to fit realistic industry produce, the pulse electrodeposition techniquewas put into industry process. The results show that the new method has betterperformance in current efficiency than the traditional electrodeposition technique for6%.更多还原