摘要
以废旧镍基高温合金作为原料合成制备高纯铼酸铵,考察废旧高温合金的最优电解条件、稀散金属铼在电解过程中的分布情况和存在形态以及高纯铼酸铵制备工艺。通过电化学溶解的方法,将镍基高温合金的活泼金属转至溶液内、较惰性的金属以固态阳极泥形式与活泼金属元素分离,阳极泥中的铼通过高温氧化、高纯氨水吸收、结晶直接制备高纯铼酸铵。研究结果表明:以废镍基高温合金作阳极、金属铜板作阴极,以1.2 mol·L^(-1)镍离子(氯化镍)和0.5 mol·L^(-1)氢离子(盐酸)的水溶液作为电解液电化学溶解合金,控制电流密度:200 A·m^(-2)、电解液温度:60℃、循环量:12 ml·min^(-1)是废旧镍基高温合金电化学的最优电解条件;稀散金属铼有90%以氧化态形式存在于阳极泥中,其他则以高铼酸根形式进入溶液;阳极泥中的铼在600℃、氧气氛围下转变为易升华的七氧化二铼、经高纯氨水吸收、结晶后直接获得高纯铼酸铵产品。经检测,铼酸铵产品纯度大于99.999%,铼回收率近85%。
Rhenium presents interesting physicochemical properties including high melting points(3180 ℃)and several stable valence states. There were some difficulties to the transform from the mineral state into the pure rhenium metal and the productions were not adequate to meet supply. In this consideration,more and more researchers had paid more and more attention to recover rhenium from the waste materials. The recycle of the rhenium from waste nickel-based superalloys and preparation of the high purity ammonium perrhenate were systematically studied. Electrochemical dissolution was selected to recycle these materials rather than pressurized oxidation acid leaching,roasting alkali-acid leaching and chlorine leach,due to it could comprehensively and economically recover the main metal elements into the solutions. The optimal electrolysis conditions,the distribution and formation of rhenium and the scheme of preparing high purity ammonium perrhenate were investigated. The active metals and the inert metals were separated by electrochemistry method through the former dissolving into the solution and the latter transferring into the anode mud. The rhenium in anode mud could be transferred into high purity ammonium perrhenate by oxidation and sublimation under the high temperature,dissolution into high purity ammonia water and crystallization. The concentrations of metal elements were immediately measured by inductively coupled plasma-atomic emission spectroscopy(ICP-AES)and the states of rhenium in mud were meticulously studied by the X-ray photoelectron spectrometer(XPS),X-ray diffraction spectrometer(XRD)and X-ray fluorescence spectrometer(XFS)respectively. The results showed that the optimal conditions of electrolysis of the waste nickel-based superalloys through the variable current efficiency or voltage changed along with the single factor conditional experiments were as following:the superalloys and metal copper worked as anode and cathode;the concentrations of nickel ion(nickel chloride)and hydrogen ion(hydrochloric acid)were 1.2 and 0.5 mol·L^(-1);the electric current density was 200 A·m^(-2),temperature was 60 ℃ and the circulation amount was 12 ml·min^(-1). It was necessary to indicate that these current efficiencies sometimes larger than 100% because of the total dissolution steps included the electrochemical and chemical dissolved. The introduced Ni2+into the electrolyte could obviously enhance the current efficiency and the dissolved rate of nickel in anode. XRD pattern of anode mud demonstrated that the mud was composed by Cr3Ni3,WO_(3)·0.33H_(2)O and TaCl4·7H_(2)O and so on. XFS of mud and ICP-AES experiments showed that the 90% rhenium metal in nickel-based superalloys were transferred into metal oxide and presented in the anode mud,and the others were dissolved into solution. XPS indicated that the valences of rhenium in anode mud were +4,+6 and +7 respectively. The curiously exist of +7 state in mud may because that they were coexisted with the lower valence state and immediately protected by the surrounded undissolved solid. According to dissolution mechanism of rhenium,they were derived into the highest oxide state and dissolved into water as the anion state ReO4-. According to our knowledge,the highly purity of ammonium perrhenate could be obtained by resin extraction,and the route and operation were complicated and time-consuming.In addition,the resin extraction method required a large financial investment with the lower adsorption capacity. Different from the method,the oxide sublimation-absorption-recrystallization coupling technique were proved that it was a viable method to direct prepared ammonium perrhenate from the anode mud. The rhenium in the anode mud could be converted into the sublimation Re2O7 under the 600 ℃ and oxygen atmosphere. Re2O7 could be easily absorbed by the water and ammonia water and formed the perrhenate acid and ammonium perrhenate respectively. They directly dissolved into ammonia water could reduce the probability of the introducing of impurities into the system. The high quality of ammonium perrhenate solution could be prepared through the high purity ammonia water absorption. The crystal of them were obtained by slowly evaporating the water from the solution when the concentration of them were supersaturated. The purity of ammonium perrhenate was as high as 99.999%,and the total recovery rate of rhenium was closed to 85%.
作者
卢晓锋
朱纪念
卢苏君
李亦婧
赵淑琴
郭勇
Lu Xiaofeng;Zhu Jinian;Lu Sujun;Li Yijing;Zhao Shuqin;Guo Yong(Key Laboratory of Chemistry of Northwestern Plant Resources,CAS/Key Laboratory for Natural Medicines of Gansu Province,Lanzhou Institute of Chemical Physics,Lanzhou 730000,China;State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilization,Jinchuan Group Co.,Ltd.,J inchang 737100,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2021年第8期972-979,共8页
Chinese Journal of Rare Metals
基金
镍钴资源综合利用国家重点实验室开放基金(2019620001000141)资助。
关键词
废旧高温合金
铼
高铼酸铵
电化学法
氧化升华
waste superalloys
rhenium
ammonium perrhenate
electrochemistry method
oxidation sublimation
