Optical and Chemical Methods of Metal Ash Analysis and Tin Recovery

‘Metal ash’ presents a waste disposal problem in most of the developing countries as the industries employ obsolete technologies. In this paper we describe analysis of tin ash, zinc ash and aluminium ash by means of optical methods, such as X-ray diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS), electron probe micro analysis (EPMA), scanning electron microscopy (SEM) and chemical methods. The results of tin ash obtained by XRD method matched well with the cassiterite, a naturally occurring mineral of tin. ICP-MS studies reveal the presence of a large number of tracer metals, which may cause pollution by tertiary dispersion and this aspect is discussed. Conversely, the data generated by chemical methods are limited. However, the methods are simple and cost-effective. Then, they can easily be adopted by low-budget industries. Simple and cost-effective process to recover tin from tin ash is described. It is based on heating tin ash with sodium cyanide to about 900°C to separate tin component from the metal ash. The process recovers good quality tin and offers a very high yield. The process can be scaled up to small pilot plant.     

国家实施污染预防的政策建议

文章对我国污染预防现状进行了评估,并对如何进一步实施污染预提出初步建议,形成污染预防框架行动计划,试图人们从行为和观念转向污染预防提供方向。框架行计划着重从政策和法律,组织和人力资源,研究和开发,污染预防活动和实践到评估、推广等方面进行了建议。     

NOx分解还原催化研究进展

介绍和评价了ＮＯ_ｘ分解还原的３类催化剂：贵金属催化剂、氧化物催化剂、金属离子置换的分子筛。在ＮＯ_ｘ的碳氢化合物选择性催化还原反应（ＨＣ－ＳＣＲ反应）中,同样有３类催化剂,即金属氧化物、贵金属和分子筛。由于Ｃｕ－ＺＳＭ－５是目前最有希望投入实际使用的一种,故本文重点介绍了它对ＮＯ_ｘ的ＨＣ－ＳＣＲ反应的催化机理,以及温度、Ｏ_２含量、Ｃｕ~（２＋）的置换度、不同种类ＨＣ及ＨＣ含量等各种因素对Ｃｕ－ＺＳＭ－５的影响,并对其工作台试验进行了评价,指出了其存在的问题及当前的研究热点。     

植物根圈污染生态研究进展

阐述了植物根圈的概念 ,根圈三大结构主成份是 (1)植物根系 ,(2 )微生物 ,(3)土壤或水等 ,并从它们的相互关系出发讨论了国内外有关根圈污染生态的研究情况 ,同时提出了根圈污染生态的研究前景和意义。     

化肥氮素在水稻田中迁移与淋失的模拟研究

为了研究氮化肥施入农田对地表水和地下水的影响 ,在一种特殊的大型人工模拟土层和地下水装置中进行试验。研究结果表明 :即使尿素和生物矿质复混肥以中、低施肥量施入水田 ,也会造成地表淹水、耕层土壤和不同深度土层溶液有较高含量的有机 N和 N H3- N,并对地下水补给状况极差的地下水有明显的污染 ;水田中 N O- 3 - N很难长期存在 ,其污染程度可忽略不计     

长江中游地区防洪与农业现代化

１９９８年长江大洪水后开始实施的“平垸行洪,退田还尖”的土地利用调整方案,从长远来说应录求农业安且且收入逐渐提高条件下的土地利用,长江中游地区应积极推进农业现代化,提高农业劳动生产率,转移,减水分蓄洪区的人口,移民建镇,对区内的土地要促进其规模经或,由优秀的有文化的农民经营,平时只有少量的直接从事农业生产的经营管理人员,农忙时则大量地作用委节性合同工或实现机械化;大洪水时退田还湖,减轻长江干流大洪     

生物过滤技术在大气污染控制中的应用

生物过滤是控制大气污染的经济有效技术,具有较好的发展前景。本文介绍了生物过滤技术处理废气的研究,应用历史,现状,和生物过滤理论,分析了工艺的使用范围,设计及运行控制要点,列举了应用的范例。     

亚铵法制浆黑液作肥料对水环境影响的研究

通过亚铵法制浆蒸煮黑液直接作农肥施于水稻田的研究,给出了不同施肥方式连续数天田间水和渗滤水中黑液污染物变化情况,定量描述了黑液作肥料直接施于水稻田对水环境的影响。     

Effect of field exposure to 38-year-old residual petroleum hydrocarbons on growth, condition index, and filtration rate of the ribbed mussel, Geukensia demissa

In September 1969, the Florida barge spilled 700,000 L of No. 2 fuel oil into the salt marsh sediments of Wild Harbor, MA. Today a substantial amount, approximately 100 kg, of moderately degraded petroleum remains within the sediment and along eroding creek banks. The ribbed mussels, Geukensia demissa, which inhabit the salt marsh creek bank, are exposed to the spilled oil. Examination of short-term exposure was done with transplantation of G. demissa from a control site, Great Sippewissett marsh, into Wild Harbor. We also examined the effects of long-term exposure with transplantation of mussels from Wild Harbor into Great Sippewissett. Both the short- and long-term exposure transplants exhibited slower growth rates, shorter mean shell lengths, lower condition indices, and decreased filtration rates. The results add new knowledge about long-term consequences of spilled oil, a dimension that should be included when assessing oil-impacted areas and developing management plans designed to restore, rehabilitate, or replace impacted areas.     

Anthropogenic lead distribution in soils under arable land and permanent grassland estimated by Pb isotopic compositions

The role of land use on fate of metals in soils is poorly understood. In this work, we studied the incorporation of lead in two neighboring soils with comparable pedogenesis but under long-term different agricultural management. Distributions of anthropogenic Pb were assessed from concentrations and isotopic compositions determined on bulk horizon samples, systematical 5-10 cm increment samples, and on 24-h EDTA extracts. Minor amounts of anthropogenic lead were detected until 1-m depth under permanent grassland, linked to high earthworm activity. In arable land, exogenous Pb predominantly accumulated at depths <60 cm. Although the proximity between the two sites ensured comparable exposition regarding atmospheric Pb deposition, the isotopic compositions clearly showed the influence of an unidentified component for the cultivated soil. This work highlights the need for exhaustive information on historical human activities in such anthropized agrosystems when fate of metal pollution is considered.