用废旧电路板热解油制备酚醛树脂

在碳酸钙存在下,采用热解技术将废旧电路板中的树脂转化为富含酚的热解油,然后直接加入甲醛溶液反应制备热解油型酚醛树脂,实现了废旧电路板中树脂的再生,酚醛树脂的性能结构类似于氨催化的酚醛树脂。实验结果表明：在n（甲醛）：n（热解油）为1．8～2．1的条件下,无需外加催化剂,在60,80,90℃下分别反应30min制备的热解油型酚醛树脂的性能最佳,且可满足GB／T14732—93《木材工业胶黏剂用脲醛、酚醛、三氧氰胺甲醛树脂》中层压材料用酚醛树脂产品的相关标准。     

火场中纸面石膏板显微结构的SEM分析

运用SEM(扫描电子显微镜),对经历不同火场温度的纸面石膏板试块的显微结构进行观察和分析.结果表明:纸面石膏板在受热时,其组成、结构将发生改变.当受热温度达到300℃时,护面纸与石膏芯材的结合松动,护面纸发生热分解、炭化,以及石膏芯材网状晶体骨架结构疏松、断裂、破碎,完整性遭到破坏,强度基本丧失;受热温度越高,纸面石膏板显微结构的破坏越严重.     

Dust explosion incidents and regulations in the United States

The U.S. Chemical Safety and Hazard Investigation Board (CSB) investigated three fatal dust explosions that all occurred in 2003. These explosions caused the deaths of 14 people and injured hundreds more. Two of the facilities were damaged beyond repair, and several hundred employees lost their jobs.

CSB's investigations revealed that the explosions had common causes, despite their geographic and industrial diversity. Consequently, CSB commissioned a study of combustible dust fire and explosion hazards. This paper presents a summary of CSB's findings and recommendations developed during that study.     

The Wild Kangaroo Industry: Developing the Potential for Sustainability

Wildlife resources the world over have long been subject to harvest and management. As wildlife uses have grown, so too have the need and desire to ensure their sustainability. This new context of sustainability presents opportunities to merge ecological, economic and social elements to foster development. This paper presents the management and harvesting of wild kangaroos as an example of the potentially sustainable use of a natural resource. Some comparisons are drawn between the use of other wild living resources, deer in Europe and crayfish in Western Australia. However, sustainability of kangaroo species and the industry is not just a matter of market economics and ecology, it must also be socially sustainable. The public policy instrument of a statutory advisory board with a marketing function is proposed in order to integrate the cultural and social aspects of kangaroo management with the economic and ecological aspects. Through such integration, full sustainability of a wild resource then might be achieved.     

世界废弃印刷电路板的机械处理技术现状

电子废弃物中废印刷电路板的处置 ,一直是相当复杂的问题。根据废电路板中各种组分的结合方式 ,采用机械方法进行材料的分离 ,是经济适用并与环境相协调的处理手段。本文介绍了废电路板再利用技术中采用的各种机械设备 ,并总结了国外机械处置方法的实践进展。     

Converting waste polystyrene into a polymer flocculant for wastewater treatment

We have succeeded in converting waste polystyrene from electrical appliances into a polymer flocculant for treating some kinds of wastewater after chemical modification. Waste polystyrene, such as polystyrene foam and additive-containing TV cabinets, was converted into a water-soluble polymer, polystyrene sulfate (PSS), and PSS of various degrees of aqueous viscosity was obtained by introducing sulfone bridges during sulfonation. We examined the relationship between the degree of flocculation of wastewater and the aqueous viscosity of the PSS, and found that PSS with medium viscosity is most suitable for flocculating inorganic wastewater from a factory, and PSS with high viscosity is most suitable for dewatering organic domestic wastewater. We report how PSS containing sulfone bridges works as a polymer flocculant for treating wastewater. Received: July 19, 2000 / Accepted: September 21, 2000     

线路板生产丝印区有机废气的净化

针对电子线路板厂洁净房丝印区有机废气污染的问题,选择间歇式固定床活性炭吸附法净化有机废气的工艺流程,通过制冷能力和吸附量的估算,设计空塔气速为0 . 6m s,吸附剂为果壳活性炭,装填高度为1m ,分双层多个抽屉式填装,运行后,实际监测净化效果明显,苯、甲苯、二甲苯的净化效率分别为81 .5 9% ,83. 5 0 % ,85 . 4 3% ,换下的废活性炭经再生解吸后可循环使用。回收的有机溶剂掺在柴油中作为发电机的燃料。     

废印刷电路板的静电分选实验研究

金属与非金属材料的分离是回收利用废印刷电路板的关键环节。对废印刷电路板物料的静电分选进行了实验研究。实验以电压、辊筒转速、电晕电极与辊筒之间的距离、静电极位置、电晕电极位置、电晕电极数量等为考察因素,研究各因素对电选效果的影响规律。结果表明,影响金属与非金属材料分离的主要因素是电压、辊筒转速和电晕电极与辊筒之间的距离,对于-0.9 0.45mm的破碎物料,当电压为24kV,辊筒转速为15Hz(54.6r/min),电晕电极与辊筒之间的距离为5.2cm时,得到最大静电分选综合效率67.37%。     

斜板沉淀池在高炉煤气洗涤中的应用研究

对斜板沉淀池在新钢公司高炉煤气洗涤中的应用研究进行了报道,同时与原系统平流沉淀池从工艺参数和经济性等方面进行了比较。运行结果表明,采用斜板沉淀池节省了投资,使循环水利用率从55%提高92%,出水水质得到显著提高,减少了环境污染。     

An advanced study on the hydrometallurgical processing of waste computer printed circuit boards to extract their valuable content of metals

This study refers to two chemical leaching systems for the base and precious metals extraction from waste printed circuit boards (WPCBs); sulfuric acid with hydrogen peroxide have been used for the first group of metals, meantime thiourea with the ferric ion in sulfuric acid medium were employed for the second one. The cementation process with zinc, copper and iron metal powders was attempted for solutions purification. The effects of hydrogen peroxide volume in rapport with sulfuric acid concentration and temperature were evaluated for oxidative leaching process. 2 M H₂SO₄ (98% w/v), 5% H₂O_2, 25 °C, 1/10 S/L ratio and 200 rpm were founded as optimal conditions for Cu extraction. Thiourea acid leaching process, performed on the solid filtrate obtained after three oxidative leaching steps, was carried out with 20 g/L of CS(NH₂)₂, 6 g/L of Fe³⁺, 0.5 M H₂SO₄, The cross-leaching method was applied by reusing of thiourea liquid suspension and immersing 5 g/L of this reagent for each other experiment material of leaching. This procedure has lead to the doubling and, respectively, tripling, of gold and silver concentrations into solution. These results reveal a very efficient, promising and environmental friendly method for WPCBs processing.