镀镍漂洗水反渗透浓缩液的使用

利用反渗透技术将镀镍漂洗水浓缩分离,浓缩液补加到镀镍槽中,透过液在镀镍漂洗槽中循环使用。向镀镍槽中加入硫酸钾,提高镀液的导电性能,同时降低镀液中氯化镍的浓度,使镀镍过程中阳极溶解速度和阴极沉积速度相等。镀件在镀镍前和镀镍后都经过回收槽漂洗,使回收槽中镍离子的浓度保持不变。用过硫酸钠氧化和活性炭吸附浓缩液中的有机杂质,用氢氧化钾沉淀铁杂质,用电解法处理铜杂质,用电解法和锌抑制剂组合法处理锌杂质。采用这些措施后,可实现反渗透浓缩液的完全回收利用。     

镀镍液中铜杂质的去除

铜离子是光亮镀镍中较常见的杂质之一。镀液受Cu2+污染,会使镀件低电流密度区光亮度差,过多的Cu2+还会造成镀层脆性增大及结合力不良的弊病。在光亮镀镍液中,ρ(Cu2+)应?0.01g/L。去除镀液中的Cu2+有以下几种方法。1)电解法。即用低电流密度使镀液中的Cu2+沉积在处理阴极板上的方法。用于处理的阴极板     

用反渗透技术回收镀镍漂洗水

利用反渗透技术将镀镍漂洗水浓缩分离,浓缩液中ρ(Ni2+)达到20 g/L左右,浓缩液补加到镀镍槽中,透过液在镀镍漂洗槽中循环使用,实现了镀镍废水的零排放.向镀镍槽中加入硫酸钾,提高镀液的导电性能,同时降低镀液中氯化镍的质量浓度,使镀镍过程中阳极溶解速度和阴极沉积速度相接近.镀件在镀镍前和镀镍后都经过回收槽漂洗,使回收槽中镍离子的质量浓度保持不变.大约是镀镍槽中镍离子质量浓度的一半.采用这些措施后,可实现反渗透浓缩液的完全回收利用.     

高锰酸钾氧化法处理镀光亮镍电解液

定期处理电镀液，是去除溶液中不断积累的各种有害杂质的技术手段。镀光亮镍电解液因对Cu、Fe、Zn、Pb离子及有机杂质敏感性较强，做好定期大处理，尤为重要。     

硫化物沉淀法处理镀镍溶液中的铜杂质

研究了用硫化钾处理镀镍溶液中铜杂质的方法,搅拌镀液,向镀液中缓慢加入硫化钾(0.1-0.25)g/L,反应(40-50)min,硫化钾与铜杂质以及镍离子生成沉淀物,加活性炭吸附,过滤镀液。实践表明,向镀镍溶液中加硫化钾至0.25g/L,铜杂质的去除率为96.8%-99.5%。与传统的亚铁氰化钾沉淀法相比,本法处理成本较低。     

硫酸盐三价铬镀铬工艺中杂质的影响及去除

研究了硫酸盐三价铬镀铬工艺中铜、锌、铁、镍离子(含量均为50mg/kg)对镀层外观和厚度、镀液极化的影响,比较了不同除杂方法的除杂效果。结果发现,金属离子杂质对镀液的污染使镀层外观发生变化,使镀层厚度减少、镀液极化增大;金属离子的去除可以采用加入除杂剂和电解相结合的方法。指出六价铬、镀镍光亮剂等杂质对三价铬镀铬工艺影响较大,加入双氧水可以去除六价铬;往循环过滤泵中加入活性炭,可以去除镀镍光亮剂。     

锡杂质对镀镍溶液的影响

研究了锡杂质对镀镍溶液的不良影响。实验表明,当亚锡离子质量浓度≥30mg/L,霍尔槽试片低电流密度区发黑。一些络合剂能络合镀镍溶液中的亚锡离子,消除锡杂质对镀液的不良影响。向镀液中加4mL/L络合型镀镍除锌剂,能够掩蔽100mg/L的亚锡离子,用抗坏血酸掩蔽法也能够消除锡杂质的不良影响。     

由除锌剂引起的滚镀光亮镍故障分析及处理

对一次由除锌剂引起的滚镀光亮镍故障进行了分析,并总结了处理方法.生产实践表明,在滚镀光亮镍的过程中,过量使用除锌剂会导致锌杂质的电沉积速率变慢,造成镀液中锌杂质的积累.向镀镍槽中加过硫酸钠破坏除锌剂,并加1～2g/L活性炭吸附,最后用电解法去除镀镍溶液中的锌杂质,可消除除锌剂的不良影响.     

南方88镀镍除杂水的应用

镀镍槽液中由于阳极和化工材料不纯或工件跌落等原因使各种金属杂质离子必然进入镀液,加上由光亮剂分解的有机残存物等杂质离子逐渐积累,就会给镀液性能带来危害,影响镀层的外观,恶化镀层的质量,出现发黑、发雾、针孔毛刺、脆性增加、结合力下降等弊病.镀镍液中允许的金属杂质含量为:Cu~(2+)10毫克/升,Fe~(3+)30毫克/升,Zn~(2+)20毫克/升,Cr~(6+)10毫克/升,若超出此范围必须进行处理.对这些有害杂质金属离子的处理方法通常是化学沉淀—过滤法和电解法两大类.长期的     

采用铁氰化钾去除酸性镀锌液中的铁杂质

采用铁氰化钾处理酸性镀锌溶液中二价铁杂质的方法为:向镀液中加铁氰化钾,Fe2+离子与铁氰化钾反应生成亚铁氰化钾和三价铁,亚铁氰化钾与锌离子反应生成亚铁氰化锌沉淀,三价铁水解生成氢氧化铁,过量的铁氰化钾与锌离子生成铁氰化锌.实验表明,用这种方法处理酸性镀锌液中的铁杂质,铁氰化钾的利用率为65.9%～87.6%.     

Investigation of solution chemistry to enable efficient lithium recovery from low-concentration lithium-containing wastewater

In the production of lithium-ion batteries (LIBs) and recycling of spent LIBs, a large amount of low-concentration lithium-containing wastewater (LCW) is generated. The recovery of Li from this medium has attracted significant global attention from both the environmental and economic perspectives. To achieve effective Li recycling, the features of impurity removal and the interactions among different ions must be understood. However, it is generally difficult to ensure highly efficient removal of impurity ions while retaining Li in the solution for further recovery. In this study, the removal of typical impurity ions from LCW and the interactions between these species were systematically investigated from the thermodynamic and kinetics aspects. It was found that the main impurities (e.g., Fe³⁺, Al³⁺, Ca²⁺, and Mg²⁺) could be efficiently removed with high Li recovery by controlling the ionic strength of the solution. The mechanisms of Fe³⁺, Al³⁺, Ca²⁺, and Mg²⁺ removal were investigated to identify the controlling steps and reaction kinetics. It was found that the precipitates are formed by a zero-order reaction, and the activation energies tend to be low with a sequence of fast chemical reactions that reach equilibrium very quickly. Moreover, this study focused on Li loss during removal of the impurities, and the corresponding removal rates of Fe³⁺, Al³⁺, Ca²⁺, and Mg²⁺ were found to be 99.8%, 99.5%, 99%, and 99.7%, respectively. Consequently, high-purity Li₃PO₄ was obtained via one-step precipitation. Thus, this research demonstrates a potential route for the effective recovery of Li from low-concentration LCW and for the appropriate treatment of acidic LCW.     

CaCl2-HCl-H2O体系中铁、镁、铝对 二水硫酸钙转晶过程影响研究

以CaCl2-HCl-H2O电解质溶液为转晶介质,在70 ℃、3.5 mol/kg氯化钙、0.5 mol/kg 盐酸的实验条件下,研究金属杂质Mg2+、Al3+、Fe3+对二水硫酸钙转半水硫酸钙的转晶时间、晶体形态变化的影响。以结晶水含量变化确定转晶时间,以晶体图片表征晶体形态的变化。结果表明：在该体系中,杂质离子促进转晶过程的进行。当Mg2+、Al3+质量分数超过0.01%后,转晶时间分别缩短至1.5、1.0 h左右后趋于稳定;当Fe3+质量分数超过0.001%后,转晶时间缩短至1.0 h左右后趋于稳定;杂质离子含量较低时,不同金属杂质离子对转晶过程促进作用的大小顺序为Al3+＞Fe3+＞Mg2+;晶体逐渐由片状变为针状,且维持针状形态。     

返滴定法测定氯化钾无氰镀镉溶液中氯化镉

制定了氯化钾无氰镀镉溶液中氯化镉的返滴定分析方法,在强酸性和加热条件下用过硫酸铵氧化镀液中的配位剂,使镉离子从配合物中释放出来。用氟化钠掩蔽Al³⁺和Sn⁴⁺杂质,用三乙醇胺掩蔽Fe³⁺杂质。加入过量的EDTA标准溶液配位Cd²⁺,在pH≈9.3的条件下,以铬黑T作指示剂,用硫酸锌标准溶液返滴定EDTA,用差减法计算镀液中氯化镉的质量浓度。结果表明,测定结果的相对平均偏差为0.19%,回收率为98.03%。     

含锂脱附液制备碳酸锂

对锰系离子筛吸附法提锂所得脱附液除杂制备碳酸锂粉体,考察了浓缩级数对NaOH沉淀法除杂效果、碱耗、沉淀粒度及锂损失率的影响,并采用Na2CO3沉淀法用高压反渗透5倍浓缩除杂后的脱附液制备Li2CO3,研究了Na2CO3加入量对脱附液中Li+回收率、产品纯度和产品形貌的影响. 结果表明,浓缩倍数对脱附液除杂效果、沉淀粒度及Li+回收率有重要影响. 优化的除杂工艺为：采用高压反渗透将脱附液浓缩5倍,脱附液反应终点pH=12,加料速率72 mL/min,搅拌速率300 r/min. 该条件下可保证Mg2+和Mn2+完全除尽,Mg(OH)2和MnO2×H2O混合沉淀的平均粒径最大(28.05 mm),碱耗[NaOH/(Mn2++Mg2+)摩尔比]为3.48. 用Na2CO3直接沉淀脱附液中的Li+所制Li2CO3粉体纯度为99.51%,符合GB/T 11075-2013(工业级)一级标准,Li+回收率为71.26%,平均粒径为16.38 mm.     

甲缩醛合成用催化剂的中毒及再生

本文研究了工业甲醛原料中所含Fe³⁺ 、Cr³⁺ 、N i²⁺ 和Mn²⁺ 四种微量金属离子对离子交换树脂型固体酸催化剂的中毒效应及其再生方法。结果表明, 这些金属离子在催化剂上的吸附量随接触时间的延长而增加, 而其吸附速率各不相同。催化剂对四种金属离子的吸附强度依次为Fe³⁺ >Cr³⁺ > Ni ²⁺ > Mn²⁺ , 其中Ni ²⁺ 和Mn²⁺ 的吸附对催化活性的影响甚微, 而Fe³⁺ 在催化剂上以较快速度吸附, 其对催化活性的影响也最为明显。对因吸附金属离子而中毒的催化剂, 研究了一种液相再生法, 可使中毒催化剂恢复至新鲜催化剂的活性水平。     

不锈钢老化着色液预还原草酸沉淀除杂过程研究

为实现不锈钢老化着色液杂质离子的分离与回收,采用预还原-草酸沉淀法对老化液中铁、镍、锰沉淀除杂过程进行研究。通过溶液化学计算及条件优化实验,考察铁、镍、锰离子沉淀效率,并使用X射线衍射仪、扫描电子显微镜、X射线光电子能谱仪对草酸沉淀物进行物相及形貌结构的表征。结果表明,通过控制溶液pH及草酸用量可有效实现溶液中铁离子、锰离子、镍离子与草酸根络合,形成草酸盐沉淀,实现杂质离子与溶液铬离子分离,杂质离子沉淀顺序依次为锰离子、镍离子、铁离子。老化液预还原后,在草酸过量系数为1.2、溶液pH为2、反应温度为25℃的条件下沉淀反应2 h,铁、锰、镍离子沉淀率分别可达98.12%、99.35%、87.26%,沉淀物主要为二水草酸亚铁及少量草酸镍、草酸锰。     

Extraction of Uranium from Synthetic Nuclear Conversion Plant Waste

ABSTRACT

The nuclear conversion plant operated at Necsa in the past resulted in the formation of a large amount of waste material containing ~ 50% U, which has reuse potential if the recovery thereof can be achieved. The waste material contains various impurities of which F, Ca, and Fe have been identified as the main contributing impurities after dissolution. These impurities are present in the waste material in varying concentrations and could interfere with the U recovery. During this investigation, the possibility of varying impurities being present during purification was addressed by simulating the waste material using synthetic solutions to investigate the effect of different concentrations of the main impurities, as well as nitric acid and TBP concentrations on the extraction of U. The results from this simulated approach will serve as motivation for obtaining more of the real waste samples for further investigation and confirmation of results. This was done using a statistical design of experiments approach, giving a predictive model which can be used to predict U recovery for a given waste sample composition. It was found that nitric acid had the most significant influence on U extraction, where an optimum amount (97%) was achieved in 5 M nitric acid at, or above 30% TBP. At low nitric acid concentrations, it was found that the U extraction increased with increasing TBP and decreasing F concentrations. An unexpected interaction between F and Fe was observed, which led to an increase in U extraction as the Fe concentrations were increased due to complex formation with F, which limits the amount of F available which would have decreased U extraction due to competition. Furthermore, a mathematical model was derived which describes the U extraction as a function of varying impurity, nitric acid and TBP concentrations. Optimum extraction conditions were confirmed using a feed solution containing additional impurities (Al, Na, K and Si) which are present in the waste material in concentrations above 0.5 wt %. While confirming the optimum extraction conditions, the validity of the statistical model was also confirmed from these experiments, indicating its suitability for U extraction predictions as a function of impurity concentrations.     

Origin of Grain-Boundary Diffusion in MgO

Preferential diffusion of Ni²⁺ and Co²⁺ along grain boundaries was observed in certain bicrystals of MgO. This enhancement is attributed to impurity segregation at the boundary. The identified impurities responsible for the effect are the principal impurities in the single-crystal MgO: Ca, Si, and Fe. No enhancement was observed in any bicrystal prepared above 1300°C, a temperature similar to that at which studies of the mechanical properties of MgO have implied a reabsorption of impurity precipitates into solid solution. It is concluded that enhanced grain-boundary diffusion of cations in MgO is an extrinsic, rather than an intrinsic, property of the boundary.     

活化稻壳纯化废液及再利用去除石英砂中的铁杂质

采用活化稻壳作为吸附剂纯化废液,再利用其去除石英砂中铁杂质。吸附剂的制备是在110℃下,质量分数1%的KOH溶液活化稻壳1 h,然后于600℃热处理2 h。研究了KOH的浓度、吸附剂的量、吸附时间、吸附液初始浓度和温度参数对去除废液中铁和铝的影响。结果表明,在最优试验条件下,铁和铝的去除率分别为97.2%和94.2%。研究发现纯化的废液对石英砂中铁的去除率远高于未纯化废液;在额外添加3.6%的磷酸时,纯化废液对铁的去除率达到77.1%,这项技术不仅可以节省大量的水(966 kg/m3)和磷酸(57.8 kg/m3)还可以避免环境污染。     

Separation of tungstates from aqueous mixtures containing impurities (arsenate,phosphate and silicate anions) using ion flotation

Ion flotation, using dodecylamine as surfactant and magnesium ions as depressant agents, was found to be an effective method for the selective separation and recovery of tungstate from arsenate anions in dilute aqueous solutions. Arsenates represent the main impurity in tungsten-containing waste waters or leaching solutions of hydrometallurgical origin; magnesium chloride is a relatively common precipitant, used in tungsten hydrometallurgy. The main parameters affecting this process were investigated, namely concentrations of reagents (Mg²⁺ ions, dodecylamine, arsenate and tungstate), solution pH, co-existence and effective separation from other impurities, such as phosphate and/or silicate anions, and the effectiveness of the separation process in solutions of high ionic strength (using NaCl and Na₂SO₄ salts). It was found that at pH range between 2 and 5, tungstate anions can be quantitatively recovered from aqueous mixtures containing arsenates, phosphates and silicates, while the co-removal of the impurities was below 20%.