Recycling thin film transistor liquid crystal display (TFT-LCD) waste glass produced as glass–ceramics

The waste electrical and electronic equipment (WEEE) directives are designed to deal with the rapidly increasing waste stream comprised of electrical and electronic equipment. Recycling electrical and electronic equipment reduces the quantity of waste going to final disposal. The demand for thin film transistor liquid crystal display (TFT-LCD) panels, commonly used in everyday electronic products, is increasing. Conventionally adopted treatments of TFT-LCD waste glass cannot meet WEEE directives. This study adopts the following operating conditions in fabricating glass–ceramics: sintering temperature of 800–950 °C; sintering time of 6 h; and, temperature increase rate of 5 °C/min. The glass–ceramic samples then underwent a series of tests, including the Vickers hardness, water absorption and porosity tests, to determine product quality. The Vickers hardness was 12.1 GPa when fired at 900 °C for 6 h, and density was 2.4 g/cm³ and water absorption was 0%. Thus, TFT-LCD waste glass can be regarded as a good glass–ceramic material.     

Transboundary hazardous waste management. Part I: Waste management policy of importing countries.

Mixed metal-containing waste, polychlorinated biphenyls (PCB) containing capacitors, printed circuit boards, steel mill dust and metal sludge were among the most common wastes exported from Taiwan. Before the implementation of the self-monitoring model programme of the Basel Convention (secretariat of the Basel Convention 2001) in the Asia region, Taiwan conducted a comprehensive 4-year follow-up project involving government authorities and the waste disposal facilities of the importing countries. A total of five countries and nine plants were visited in 2001-2002. The following outcomes can be drawn from these investigations. The Chinese government adopts the strategies of 'on-site processing' and 'relative centralization' on the waste management by tightening permitting and increasing site inspection. A three-level reviewing system is adopted for the import application. The United States have not signed the Basel Convention yet; the procedures of hazardous waste import rely on bilateral agreements. Importers are not required to provide official notification from the waste exporting countries. The operation, administration, monitoring and licensing of waste treatment plants are governed by the state environmental bureau. Finland, France and Belgium are members of the European Union. The procedures and policies of waste import are similar. All of the documents associated with transboundary movement require the approval of each government involved. Practically, the notification forms and tracking forms effectively manage the waste movement.     

Hydrometallurgical processing of Nd–Fe–B magnets for Nd purification

An evaluation of various metal purification processes subsequent to the leaching processing of the neodymium (Nd) product from neodymium–iron–boron (Nd–Fe–B) magnets has been conducted. These post-leaching purification processes included precipitation; replacement and electrolysis were studied in order to check the purity of the recovered neodymium. A hydrometallurgical investigation was adopted to digest the metal content of the scrap Nd–Fe–B magnets for the recovery of valuable Nd metal and other metals such as Fe, B, Co and Ni. The effect of leaching conditions such as solid-to-liquid ratio and temperature were optimized and 100 % Nd, 100 % Fe, 100 % B and 85.87 % Co leaching efficiencies were achieved under these conditions. The coating material of the magnet, Ni, achieved 50 % impregnation after increasing the reaction temperature to 70 °C. The metals present in the optimal leaching solution were recovered 99 % by pH adjustment. However, the replacement had the highest separation efficiency for the recovery of Nd metal. Further, the optimal leaching Nd–Fe–B solution was subjected to the electrolysis processes in order to verify the recovery efficiency for all metals.     

Report: transboundary hazardous waste management. part II: performance auditing of treatment facilities in importing countries.

Before implementing the self-monitoring model programme of the Basel Convention in the Asia, Taiwan has conducted a comprehensive 4-year follow-up project to visit the governmental authorities and waste-disposal facilities in the countries that import waste from Taiwan. A total of nine treatment facilities, six of which are reported in this paper, and the five countries where the plants are located were visited in 2001-2002. France, Belgium and Finland primarily handled polychlorinated biphenyl capacitors, steel mill dust and metal waste. The United States accepted metal sludge, mainly electroplating sludge, from Taiwan. Waste printed circuit boards, waste wires and cables, and a mixture of waste metals and electronics were the major items exported to China. Relatively speaking, most treatment plants for hazardous waste paid close attention to environmental management, such as pollution control and monitoring, site zoning, system management regarding occupational safety and hygiene, data management, permits application, and image promotion. Under the tight restrictions formulated by the central environment agency, waste treatment plants in China managed the environmental issues seriously. For example, one of the treatment plants had ISO 14001 certification. It is believed that with continuous implementation of regulations, more improvement is foreseeable. Meanwhile, Taiwan and China should also continuously enhance their collaboration regarding the transboundary management of hazardous waste.     

Integrated process development for the recovery of Europium and Yttrium from waste fluorescent powder

Journal of Material Cycles and Waste Management - Fluorescent powder plays an important role in the modern electronic lighting products. During the production of electronic lighting products, a...