Recovery of Tantalum and Manganese from Epoxy-Coated Solid Electrolyte Tantalum Capacitors through Selective Leaching and Chlorination Processes

Electronic products are ever growing in popularity, and tantalum capacitors are heavily used in small electronic products. Spent epoxy-coated solid electrolyte tantalum capacitors, containing about 22 wt.% of tantalum and 8 wt.% of manganese, were treated with selective leaching by hydrochloric acid and chlorination after removing the epoxy resin, and the products converted, respectively, to Mn(OH)2 and TaCl5. The effects of acid type, acid concentration, liquid–solid ratio, and reaction time were investigated to dissolve the manganese. The optimal selective leaching conditions were determined as 3 mol/L of HCl, 40 mL/g at 25 °C for 32 min. Next, residues of selective leaching after washing and drying were heated with ferrous chloride to convert to pure TaCl5. Mixing 48 wt.% of chloride and 52 wt.% of residues for a total of 5 g was conducted to complete the chlorination process in the tube furnace at 450 °C for 3 h. A total of 2.35 g of Ta was collected and the recovery of Ta achieved 94%. Finally, Mn(OH)2 and TaCl5 were separated and purified as the products.

COMBINED TECHNOLOGIES FOR MANUFACTURING PARTS IN SOLID ELECTROLYTES

Рассмотрены вопросы изготовления открытых и полуоткрытых полостей в труднообрабатываемых деталях путем использования твердого электролита, наносимого на заготовку перед установкой удаляемой вставки. Показаны особенности протекания процесса анодного растворения припуска при статическом состоянии рабочей среды. Такие исследования выполнены впервые. Разработаны и проверены на практике изготовления типовых деталей режимы обработки для реализации процесса. Показано, что твердые электролиты имеют перспективы для дальнейшего использования при проектировании технологических процессов изготовления сложнопрофильных изделий из металлических труднообрабатываемых материалов, в том числе внедряемых на создаваемых образцах ракетно-космической техники. Они расширяют технологические возможности комбинированных методов, в которых одним из воздействующих факторов является электрическое и электромагнитное поле с высокой концентрацией мощности в импульсе. Впервые достигнута возможность разделять сборочные единицы путем образования зазора между сопрягаемыми деталями без доступа в зону обработки жидкой рабочей среды, определяющей возможность локального съема припуска в месте сопряжения и удаления слоя материала, достаточного для разборки узлов. Заложены основы использования для нанесения твердого электролита аддитивных технологий путем наращивания равномерных слоев перед сборкой изделия. Предлагаемая технология перспективна для изготовления сборных конструкций с ограниченным доступом инструмента в зону выполнения операции. Кроме того, новая технология может успешно применяться в процессе ремонта машин We considered the issues of manufacturing open and semi-open cavities in difficult-to-machine parts by using solid electrolyte applied to the workpiece before installing the removable insert. We show the features of the process of anodic dissolution of the allowance at a static state of the working medium. Such studies have been performed for the first time. We developed and tested in practice the processing modes for the implementation of the process for the manufacture of standard parts. We show that solid electrolytes have prospects for further use in the design of technological processes for the manufacture of complex-profile products from metal hard-to-machine materials, including those introduced on the created samples of rocket and space technology. They expand the technological capabilities of combined methods, in which one of the influencing factors is an electric and electromagnetic field with a high concentration of power in a pulse. For the first time, the ability to separate assembly units by forming a gap between mating parts without access to the processing zone of a liquid working medium has been achieved, which determines the possibility of local removal of the allowance at the mating point and removal of a layer of material sufficient for disassembling the units. We laid the foundations for the use of additive technologies for applying solid electrolyte by building up uniform layers before assembling the product. The proposed technology is promising for the manufacture of prefabricated structures with limited tool access to the operation area. In addition, the new technology can be successfully applied in the process of car repair

Enhanced Electrochemical Properties of Na0.67MnO2 Cathode for Na-Ion Batteries Prepared with Novel Tetrabutylammonium Alginate Binder

Both the binder and solid–electrolyte interface play an important role in improving the cycling stability of electrodes for Na-ion batteries. In this study, a novel tetrabutylammonium (TBA) alginate binder is used to prepare a Na0.67MnO2 electrode for sodium-ion batteries with improved electrochemical performance. The ageing of the electrodes is characterized. TBA alginate-based electrodes are compared to polyvinylidene fluoride- (PVDF) and Na alginate-based electrodes and show favorable electrochemical performance, with gravimetric capacity values of up to 164 mAh/g, which is 6% higher than measured for the electrode prepared with PVDF binder. TBA alginate-based electrodes also display good rate capability and improved cyclability. The solid–electrolyte interface of TBA alginate-based electrodes is similar to that of PVDF-based electrodes. As the only salt of alginic acid soluble in non-aqueous solvents, TBA alginate emerges as a good alternative to PVDF binder in battery applications where the water-based processing of electrode slurries is not feasible, such as the demonstrated case with Na0.67MnO2.