NaCl-KCl-MgCl2熔盐Mg2+在钨电极上的 电化学还原机理

采用三电极在NaCl-KCl熔盐电解质体系,以MgCl₂为原料应用AUTOLAB电化学工作站分别通过循环伏安法、计时电流法、计时电位法研究了1 073 K时NaCl-KCl-MgCl₂熔盐体系中Mg2+在钨电极上的电化学还原过程.循环伏安测试结果表明:1 073 K时NaCl-KCl-MgCl₂熔盐体系中Mg2+在钨电极上的电化学还原是1步反应转移2个电子过程,电极反应受扩散控制,扩散系数为3.81×10-6 cm2/s,电极反应为Mg2++2e-→Mg.计时电位测试结果验证了循环伏安测试结果的正确性.计时电流测试数据拟合结果表明:1 073 K时NaCl-KCl-MgCl₂熔盐中Mg2+在钨电极上的电结晶是瞬时成核方式.      

KCl-NaCl-NaF-SiO_2熔盐体系中硅离子的还原机理研究

在KCl-NaCl-NaF-SiO2熔盐体系中,以铂丝为参比电极、研究电极,高纯石墨坩埚为辅助电极,采用循环伏安法和计时电位法对硅离子的还原机理进行了研究,结果表明此电化学反应为扩散控制的不可逆电极过程;求得硅离子在熔盐中的扩散系数D=1.33×10-3cm2/s(CSi4+=1.21×10-4mol/cm3,T=1 073 K)。     

LiCl-KCl熔盐La^3+在钨电极上的电化学还原机理

以LiCl-KCl为电解质体系,LaCl3为原料,利用循环伏安法、计时电位法和计时电流法研究773K时镧离子在钨电极上的电化学还原过程。结果表明,在773K、50%KCl-50%LiCl-2%LaCl3的熔盐体系中,镧离子在钨电极上还原是一步转移3个电子反应(La^3++3e→La),相对于Ag/AgCl电极析出电位为-2.05V;镧在钨电极析出过程中出现成核极化现象,且通过循环伏安和计时电流法可判断镧离子在钨电极上的析出还原过程为受扩散控制的准可逆反应,扩散系数D=6.36×10^-5 cm^2/s。     

KCl-NaCl-NaF-SiO2熔盐体系中硅离子的结晶机理研究

在KCl-NaCl-NaF-SiO2熔盐体系中,以铂丝为参比电极、研究电极,高纯石墨坩埚为辅助电极,采用循环伏安法和计时电流法对硅离子的结晶机理进行了研究。结果表明:该体系中硅的电结晶过程符合扩散步骤控制的半球形三维晶核连续长大成核机理;增大过电位可使晶核密度增加,有利于获得较好的沉积硅层。     

LiF-CaF2-BaF2-ZrO2熔盐中Zr4+在钨电极上的电化学还原机理

以LiF-CaF₂-BaF₂为熔盐体系, ZrO₂为原料, 1 373 K条件温度下利用循环伏安法, 计时电位法, 计时电流法, 研究锆离子在钨电极上的电化学过程,对不同ZrO₂含量0.5 %,0.7 %,0.9 %的熔盐体系进行电化学分析,研究结果表明:Zr4+在钨电极上还原是通过两步得电子反应, 即Zr4++2e→Zr2+,Zr2++2e→Zr,相对参比电极铂还原峰分别为0.9 V和1.2 V,析出过程是受扩散控制的准可逆反应. 1 373 K时Zr4+在LiF-CaF₂-BaF₂-ZrO₂熔盐中的扩散系数D为6.7×10-6 cm2/s.      

LiF-SrF2-SrO熔盐体系中Sr2+电化学行为的研究

在电化学工作站AUTOLAB 上采用三电极体系以循环伏安法、计时电流法和计时电位法研究了LiF-SrF2-SrO熔盐体系于1253 K温度下锶在钨电极上的电化学还原过程及其控制步骤.研究结果表明：Sr2+在钨电极上的还原过程是一步得两个电子的准可逆反应,析出电位在-1.0 V 附近.阴极过程受离子的扩散步骤控制,计算得出扩散系数为6.07×10-5 cm2/s.     

熔盐电沉积硅的基础研究

在FLINAK-Na2SiF6熔盐体系中,以Pt为参比电极、硅钢片为工作电极、石墨为辅助电极,在750℃下,用循环伏安法和计时电位法对Si4+的电化学反应机理和扩散系数进行了研究。结果表明:该熔盐体系进行电沉积硅是可行的,该体系中硅离子的还原为扩散控制的可逆电极过程,且产物不可溶;整个还原过程为Si4++4e→Si0;该熔盐体系中阴极电位不应负于-2V,否则会有Na沉积出来,从而影响沉积层质量;Si4+的扩散系数为:D=5 42×10-11m2/s(C=2 58×103mol/m3)。     

NaCl-KCl-Na_2WO_4共融体系的计时电流与计时电位曲线分析

采用铂丝(RE)-钨丝(WE)-钨棒(AE)组成三电极系统,通过计时电流法与计时电位法相结合,系统分析在一定温度及配比条件下NaCl-KCl-Na_2WO_4共融体系的电化学特性,重点考察和分析钨(Ⅵ)离子的电子转移步骤、电化学还原过程的可逆性、活性钨(Ⅵ)离子的扩散系数、钨金属单质的成核过程,结果表明:计时电流曲线得出钨(Ⅵ)离子在阴极区的电极过程是由扩散控制,扩散系数为1.645×10~(-10)cm~2·s~(-1),金属钨在阴极上析出为三维瞬时形核过程,不存在成核极化现象;由计时电位法得出钨(Ⅵ)离子的电极还原过程亦为扩散控制,扩散系数为2.349×10~(-11)cm~2·s~(-1),钨(Ⅵ)离子在电子转移过程分两步,第一步为钨(Ⅵ)离子→钨(Ⅳ)离子的2电子转移,其为准可逆反应,第二步为钨(Ⅳ)离子→钨(0)的4电子转移过程,此过程为高度不可逆反应。同时,采用不同的电化学方法得到的活性钨(Ⅵ)离子的扩散系数差异表明实验过程中存在时效性和偶然性因素影响,对扩散系数等动力学参数的计算有待优化。     

NaCl-KCl-Na2WO4熔融体系的电导率研究

针对NaCl-KCl-Na_2WO_4熔融体系,采用交流电极法对熔盐体系的电导率进行研究。结果表明:在1 173～1 203 K之间,NaCl-KCl-Na_2WO_4熔盐体系的电导率随着Na_2WO_4含量先逐渐减小再逐渐增大,在10%Na_2WO_4时电导率最小。在1 218～1 233 K之间,NaCl-KCl-Na_2WO_4熔盐体系的电导率随着钨酸钠含量的增加而逐渐增大。NaCl-KCl-Na_2WO_4(0%～15%)熔盐体系的电导率与温度之间呈线性关系。NaCl-KCl-10%Na_2WO_4熔盐体系受到温度的影响最大。     

铜在LiCl-KCl熔盐中的电化学行为研究

采用循环伏安、方波伏安、计时电位及线性扫描伏安法研究了500℃时Cu(Ⅰ)在LiCl-KCl熔盐体系中石墨电极和钼电极上的电化学行为,并且研究了不同CuCl浓度下铜的沉积电位。结果显示,铜离子在熔盐中的还原过程分两步进行,分别在-1.05 V和-1.55 V处依次还原,即Cu(Ⅱ)→Cu(Ⅰ)和Cu(Ⅰ)→Cu(0)。通过循环伏安及计时电位测试,均得出Cu(Ⅰ)在LiCl-KCl熔盐中的阴极还原过程为受扩散控制的准可逆过程,扩散系数分别为1.79×10-5 cm2/s和1.26×10-5 cm2/s。     

China's Major Non-ferrous Metals Imports & Exports

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Zinc Production by Province in 2014

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80% of Chinese Firms Purchasing Overseas Mines Ended up in the Red

<正>Minmetals Resources acquired the world’s largest copper mine under construction for USD5.85 billion.One after another,listed companies Jien Nickle,China Molybdenum and Chihong Zinc and Germanium raised money to get involved in overseas mining projects…SOEs and private enterprises are engaged in a frenzy of overseas mine purchasing.A reporter with Economic     

Copper Processing Profit Dropped Sharply,Copper Consumption Will Face Impact in the Second Half of the Year

正Judging from China’s copper consumption field,the biggest consumption unit is electric power,which accounts for 47%of total consumption;it is followed by light industry sector,including household electrical appliance,machinery,durable goods and hardware etc,which accounts for 22%of total consumption;followed by transportation field,     

Central Geological Prospecting Fund Newly Added 16.47 Million Tonnes of Bauxite in 2013

正In 2013,the Central Geological Prospecting Fund(CGPF)Project newly discovered 15 ore fields,including 3 large above ore fields,and 5medium sized ore fields.The reporter learned from the recently published"Annual Report of Central Geological Prospecting Fund Project(2013)"that,from 2006 to 2013 the CGPF     

Manufacturers of Copper Tube for Central Air Conditioner Use Face Mounting Pressure in the Final Quarter of the Year

正This year,the investment growth rate of real estate industry continued to slow down,sold area of commercial housing also dropped significantly,which brought huge pressure to the domestic air conditioning manufactures.In the first half of the year,by relying on high growth in national financial expenditure,along with investment in public infrastructure     

Xinjiang Ranks No.1 in Production of Primary Aluminum in China

正Kang Yi,Honorary Chairman of China Nonferrous Metals Industry Association,said recently at the Forum on Development of the Non-ferrous Metals Industry in Central and Western China held in Zhengzhou that,as more and more electrolytic aluminum factories in Xinjiang came into operation,the electrolytic aluminum output of Xinjiang had reached2,275,000 tons in the first 7 months this year,     

Shenhuo Coal Industry and Electricity Power Completed800,000 t/a Aluminum Project in Xinjiang

正"Xinjiang project has been completed according to schedule,but total completion and total start of production are two different concepts,after completion it still needs a gradual process of reaching production target."On the morning of November 3,Shenhuo Coal Industry and Electricity Power told investors the above statement on the investor interaction platform.     

Guangdong Metal Transaction Center has Become the Second Largest Precious Metal Transaction Platform Nationwide

正The reporter learned from Guangdong Province Precious Metal Transaction Center that in 2013the Center maintained healthy development momentum,and had become the second largest precious metal transaction platform in China in terms of market size;currently Guangdong is quickening steps of financial innovation for the Center,aiming to build a transaction center with international core competitiveness.     

Seven Rare Earth Projects Involving Close to 3 Billion Yuan Investment Landed In the HighTech Zone

正On May 22,Baotou Rare Earth Industry Cooperation Consultation MeetingProject Agreement-signing Ceremony was held in Ningbo,nearly 40 enterprises from Ningbo,Guangdong,Hunan,and Shanxi participated in project consultation.After multi-lateral communication,agreements were signed for a total of 7 rare earth projects successfully.