Study on sulphidization roasting and flotation of cervantite

A new technology, sulphidization roasting of antimony mineral cervantite with elemental sulfur followed by froth flotation is reported in this paper. The effects of roasting temperature and time, sulfur to antimony molar ratio on the properties of treated product and its flotation behavior were studied. Optimum roasting conditions are: roasting temperature 723 K; roasting time 30 min; and sulfur to antimony molar ratio of 1.5. Under these conditions, the mineral phase changed from cervantite to stibnite as expected. The flotation recovery of the sulphidized cervantite is over 90%. A flotation concentrate grading 21.04% Sb with a recovery of 77.15% is achieved by sulphidization roasting and flotation from a feed grading 1.11% Sb in which cervantite is the main antimony mineral.     

30 m超高加筋土挡墙在宁化行洛坑钨矿的应用

论述了超高加筋土挡墙的设计过程与建造及挡墙的变形特征。较大墙高宜采用加筋土挡墙，其对地基的适应性强，占地少，建造周期短。行洛坑钨矿原矿运输铁路跨越深沟谷，与栈桥相比较后，采用了加筋土挡墙方案，设计建造了二级30 m超高加筋土挡墙作为路基，1 a累计最大水平位移16～83 mm，最大沉降24～115 mm，建成5 a来运行正常。     

Fire hazard assessment for a green railway station

A green railway station adopting natural ventilation was built in Hong Kong to promote sustainable architectural design. Similar to many other green or sustainable projects, such design failed to comply with the local fire safety codes. There are potential fire hazards due to the adopted green features. Better ventilation provision would supply more air to burn the combustibles in case of fire. Performance‐based design was applied using the timeline analysis to determine the fire safety provisions. In this paper, fire simulations were carried out to predict the available safe egress time (ASET) under low design fires with smoke toxicity including only the carbon monoxide concentration. Evacuation simulations were conducted to predict the required safe egress time (RSET) under low passenger loadings. Studies on human behaviour under big fires and heavy passenger loadings were not included. Problems to be encountered in this green railway station using the timeline analysis will be pointed out in this paper. ASET was estimated by computational fluid dynamics with bigger fires resulted from the green features. RSET was estimated by evacuation software under local passenger loadings. The results indicated that ASET are less than RSET under big fires with heavy passenger loadings. Copyright © 2013 John Wiley & Sons, Ltd.     

滚动压印装置研制与压印填充模拟

紫外滚动压印因其可以在室温下、普通大气环境中高效大面积地进行微结构制作而备受瞩目.利用自行研制的紫外滚动压印装置,实现了微结构的快速复制.实验中发现当压印速度达到某一特定值时,会不可避免地产生气泡缺陷.采用流体软件Fluent对滚动压印充填过程进行分析,来研究气泡缺陷的产生机理.结果表明,压印速度过高导致空气被堵在图形空腔内,最终形成气泡缺陷.同时,低黏度的胶液和小的接触角更利于模型填充.此研究对于获得优化的滚动压印工艺具有一定的意义.     

Mass Transfer in Molybdenum Extraction from Aqueous Solutions Using Nanoporous Membranes

Modeling of non‐disperse solvent extraction of molybdenum(VI) with PC‐88A as extractant and a nanoporous hollow‐fiber membrane contactor as extractor was performed. Computational fluid dynamics was applied for modeling and simulation of molybdenum extraction. Concentration, pressure, and velocity distributions for molybdenum were determined. The extraction of Mo⁶⁺ was greatly influenced by the flow rate of feed solution. The extraction efficiency was reduced with higher feed flow rate and increased with the molybdenum content in the feed. The pressure drop along the shell side of the membrane extractor was found to be not significant, being one of the advantages of membrane extractors which assist in reducing the operational costs. The proposed simulation method is capable to prognosticate the performance of solvent extraction of molybdenum in membrane extractors.     

含锌冶金尘泥特性分析及锌铁分离

为实现含锌冶金尘泥节能、环保、低碳的资源化利用，对原料进行水分、粒度、化学成分、物相组成、SEM-EDS等物理化学特性分析。结果表明：含锌冶金尘泥的水分为3.43%、水分容易脱除，颗粒大小不一、细小颗粒会聚集成团和黏附于大颗粒表面，具有回收利用价值的成分主要为锌和铁，含量分别为5.06%和29.24%,其中锌主要以ZnFe₂O₄的形式存在于细小颗粒中、铁主要以Fe₂O₃的形式存在。含锌冶金尘泥的锌铁分离试验研究表明：直接磁选和常规焙烧—磁选的锌铁分离效果均不理想，微波焙烧—磁选可以达到较好的锌铁富集分离效果；在微波焙烧温度700℃、焙烧时间10 min的条件下，磁选精矿产率为61.67%、铁含量为54.39%、锌含量为2.62%,磁选尾矿锌含量为12.15%、铁含量为9.74%,磁选精矿和磁选尾矿均能实现较好的资源化回收利用。     

Performance analysis of a steady flamelet model for the use in small-scale biomass combustion under extreme air-staged conditions

Small-scale biomass boiler development is often based on empirical methods resulting in high efforts for experimental test runs using several prototypes. CFD simulations are able to reduce both, development time and efforts for tests and prototypes, supposing that the models reliability is high and its computational effort is low. Extreme air-staging with an initial gasification stage and a subsequent fuel gas burnout in a downstream gas-burner is a promising new method to reduce NO_X and PM emissions in small-scale biomass boilers. Gasification conditions in the first combustion stage lead to high accumulation of gaseous tars in the fuel gas contributing challenges for combustion simulation because common CFD models use 2 or 3-step global methane reaction schemes to describe combustion chemistry. In this work, the performance of a computationally inexpensive steady flamelet model (SFM) together with a detailed reaction mechanism (18 species, 42 reactions) was scrutinized. In order to evaluate the performance of the SFM, two furnace designs were examined, running under different load shifts and various excess air ratio. Comparative numerical simulations were performed with classical species transport models. The numerical simulations and the experiments for validation were carried out on a wood-chip boiler with a heat output of 40 kW. Results show that flue gas temperature, flame shape, main flue gas concentrations and NO_X can be quantitatively predicted. The SFM shows also reasonable good predictions for CO variation trends. With the present approach, calculation time can be reduced by 90% compared to commonly used models (EDC). The SFM provides sufficiently accurate results within 24 h using a standard processor consisting of six cores (mesh size 1.5 million elements). Thus, the presented model is a perfectly suitable method for applied science and industrial research.