Levels of tin in core sediments along the Alexandria Coast, Egypt

Tin concentrations were determined in surface and core sediments from three hot spots along the Alexandria coast, namely: Abu-Qir Bay, Eastern Harbour, and Western Harbour. The mean concentrations in surface sediment were 2.434, 3.212, and 5.572 μg/g dry weight for Abu-Qir Bay, Eastern Harbour, and Western Harbour, respectively. A sharp decrease in tin level in core sediments with depth was observed in almost all locations except for core 4 in Abu-Qir Bay and core 17 in the Eastern Harbour, where the sub-sample at the 5 cm level recorded the highest tin concentrations.     

氢化物发生-原子荧光法测定环境水样中痕量锡

以醋酸 醋酸钠缓冲溶液为反应酸介质 ,应用氢化物发生 原子荧光法 (HG AFS)测定环境水样中痕量 Sn。该方法同 HCl为反应酸测 Sn方法相比 ,不仅扩大了酸浓度测定范围 ,某些阳离子干扰也降至最小或消除。其相对标准偏差(RSD)小于 3% ;回收率在 94 4 %～ 1 0 0 %之间 ;检测限为 0 76 μg L。     

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.     

碘酸钾氧化甲基绿褪色光度法测定痕量锡

研究了稀磷酸介质中痕量锡催化碘酸钾氧气甲基绿的褪色反应及动力学条件，建立了高灵敏度测定痕量锡的新催化光度法．方法的灵敏度为２．４×１０－１２ｇ／ｍＬ，线性范围为０～０．１２μｇ／Ｌ．用于人发、水样及矿石中痕量锡的测定，结果满意．     

粤东一个类型独特的锡矿床

作者对西岭凤地山锡矿床的成矿地质条件,特别是火山构造、岩浆演化与成矿的关系进行了研究,认为:西岭锡矿是一个与火山侵出相碎斑熔岩时、空、成因关系密切的次火山热液脉状锡矿床。根据西岭锡矿的地质环境和成矿物理化学条件、矿质、水介质来源建立了理想的成矿模式。进而指出粤东斑岩锡矿的远景。西岭锡矿类型的确定,对粤东和赣南火山岩地区锡矿普查具有重要意义。     

Uncovering the evolution of tin use in the United States and its implications

• US tin use decreases as the GDP value added by manufacturing sector increases. • Global and China’s tin use increases as the GDP added by manufacturing increases. • A sigmoid curve can fit the US tin use data well. • US tin use patterns is not due to the finite tin reserves or resources. • Policies, substitutions, etc. play key roles in the changing tin use patterns. Tin is of key importance to daily life and national security; it is considered an essential industrial metal. The United States (US) is the world’s largest economy and consumer of natural resources. Therefore, the analysis of historical tin use in the US is helpful for understanding future tin use trends in the world as a whole and in developing countries. Time series analysis, regression analysis with GDP or GDP/capita, and historical data fitted with logistic and Gompertz models are employed in this study. Historical tin use in the US shows three stages—increase-constant-decrease, as GDP per capita has increased. Tin use in the US is negatively correlated with the GDP value added by the manufacturing sector, while the use of tin worldwide and in China continues to increase along with the GDP value added by the manufacturing sector. Although a sigmoid curve can fit the US tin use data well, that use is not directly related to the limited tin reserves or resources. Rather, policies, economic restructuring, substitutions, new end-use markets, etc. have played key roles in the changing tin use patterns. This work contributes to understanding future tin use at both the global and national levels: tin use will continue to increase with GDP at the global level, but use patterns of tin at the national level can be changed through human intervention.     

Utilizing transparent and conductive SnO2 as electron mediator to enhance the photocatalytic performance of Z-scheme Si-SnO2-TiOx

• A novel Z-scheme Si-SnO₂-TiO_x with SnO₂ as electron mediator is first constructed. • Transparent and conductive SnO₂ can pass light through and promote charge transport. • V_O from SnO₂ and TiO_x improve photoelectrochemical performances. • Efficient photocatalytic degradations originate from the Z scheme construction. Z-scheme photocatalysts, with strong redox ability, have a great potential for pollutants degradation. However, it is challenging to construct efficient Z-scheme photocatalysts because of their poor interfacial charge separation. Herein, by employing transparent and conductive SnO₂ as electron mediator to pass light through and promote interfacial charge transportation, a novel Z-scheme photocatalyst Si-SnO₂-TiO_{x (1<x<2)} was constructed. The Z-scheme photocatalyst displayed an order of magnitude higher photocurrent density and a 4-fold increase in open-circuit potential compared to those of Si. Moreover, the onset potential shifted negatively for approximately 2.2 V. Benefiting from these advantages, this Z-scheme Si-SnO₂-TiO_x exhibited efficient photocatalytic performance toward phenol degradation and mineralization. 75% of the phenol was degraded without bias potential and 70% of the TOC was removed during phenol degradation. Other typical pollutants such as bisphenol A and atrazine could also be degraded without bias potential. Introducing a transparent and conductive electron mediator to construct Z-scheme photocatalyst gives a new sight to the improvement of photocatalytic performance in Z scheme.     

流动注射氯化亚锡还原光度法测定水中总磷

建立了流动注射氯化亚锡还原光度法测定水中总磷的方法.改进了氯化亚锡的配制方法,优化了试验条件,方法检出限为0.02 mg/L,精密度与准确度均符合要求.应用该方法测定天然水样,分析速度加快,结果令人满意.     

试论火山-斑岩型锡矿床中的氟异常分布及其成因机理- -以岩背锡矿为例

本文以岩背锡矿为例，对火山—斑岩型锡矿床中的氟地球化学异常分布特征作了扼要总结；指出在锡矿床中Sn与F的地球化学异常有“形影关系”，并对其形成的地球化学原因作了分析，揭示了氟异常与锡矿化的内在联系。论证了氟的地球化学异常在火山—斑岩型锡矿床普查过程中具有良好的指示意义。     

长埔——西岭锡矿资源定量评价模型

本文以长埔——西岭锡矿带的76个矿床为基础从中选取17个已知成型矿床,分别用矢量长度法和最优分割法进行地质变量的优化选择与储量等级规模的划分;采用特征分析与逻辑信息法建立锡矿资源半定量和定量评价广义模型;并对该区59个矿化点进行含矿性及可能矿床规模的定量预测评价,筛选出6个找矿靶区。