Mercury mass flow in iron and steel production process and its implications for mercury emission control

The iron and steel production process is one of the predominant anthropogenic sources of atmospheric mercury emissions worldwide. In this study, field tests were conducted to study mercury emission characteristics and mass flows at two iron and steel plants in China. It was found that low-sulfur flue gas from sintering machines could contribute up to41% of the total atmospheric mercury emissions, and desulfurization devices could remarkably help reduce the emissions. Coal gas burning accounted for 17%–49% of the total mercury emissions, and therefore the mercury control of coal gas burning, specifically for the power plant burning coal gas to generate electricity, was significantly important. The emissions from limestone and dolomite production and electric furnaces can contribute29.3% and 4.2% of the total mercury emissions from iron and steel production. More attention should be paid to mercury emissions from these two processes. Blast furnace dust accounted for 27%–36% of the total mercury output for the whole iron and steel production process. The recycling of blast furnace dust could greatly increase the atmospheric mercury emissions and should not be conducted. The mercury emission factors for the coke oven,sintering machine and blast furnace were 0.039–0.047 g Hg/ton steel, and for the electric furnace it was 0.021 g Hg/ton steel. The predominant emission species was oxidized mercury, accounting for 59%–73% of total mercury emissions to air.     

我国煤中汞含量水平及洗选过程汞流向分析

介绍了我国煤中汞含量与分布特征、煤中汞的赋存形态,分析了汞释放对环境的影响以及汞的脱除与控制技术。结果表明:我国(华南)晚三叠世(T3)煤中汞含量最高,平均含量为0.26μg/g;贫煤和无烟煤中汞含量最高,平均含量都超过0.20μg/g。含汞较高的晚三叠世、晚二叠世煤田主要分布于华南各地;多数煤中汞含量在0.300μg/g以下,但华南的江西、广西、贵州等地煤中汞含量总体水平较高;汞的赋存形态可分为有机结合态和无机结合态,煤中汞的控制方法可分为利用前脱汞、利用(燃烧)后脱汞和过程中汞形态转化。提出了煤炭洗选过程汞分布、脱除率和汞平衡等计算公式,指出了煤炭洗选过程中汞迁移行为的主要影响因素。     

Variation on leaching behavior of caustic compounds in bauxite residue during dealkalization process

Bauxite residue,a byproduct of alumina manufacture,is a serious environmental pollutant due to its high leaching contents of metals and caustic compounds.Four typical anions of CO₃^2-,HCO₃^-,Al(OH)₄^- and OH-(represented caustic compounds) and metal ions(As,B,Mo and V) were selected to assess their leaching behavior under dealkalization process with different conditions including liquid/solid ratio(L/S ratio),temperature and leaching...     

Environmental analysis of mercury in China

1　Ｄｅｔｅｒｍｉｎａｔｉｏｎｏｆｔｏｔａｌｍｅｒｃｕｒｙａｎｄｓｐｅｃｉａｔｉｏｎｏｆｍｅｒｃｕｒｙｃｏｍｐｏｕｎｄｓｉｎａｔｍｏｓｐｈｅｒｅ1.1　ＤｅｔｅｒｍｉｎａｔｉｏｎｏｆｔｏｔａｌｍｅｒｃｕｒｙＡｓａｍｐｌｉｎｇｔｒａｉｎｃｏｎｓｉｓｔｉｎｇｏｆａｆｉｌｔｅｒｔｏｒｅｔａｉｎ ｐａｒｔｉｃｕｌａｔｅｐｈａｓｅｍｅｒｃｕｒｙｆｏｌｌｏｗｅｄｂｙａｎａｂｓｏｒｂｅｎｔｔｒａｐｗｈｉｃｈｒｅｔａｉｎｓｔｏｔａｌｇａｓｅｏｕｓｍｅｒｃｕｒｙｉｓｕｓｅｄｆｏｒｄｅｔｅｒｍｉｎａｔｉｏｎｏｆｔｏｔａ…     

电石法聚氯乙烯行业履约的成本效益分析

构建汞物质平衡模型以识别高汞触媒及低汞触媒电石法聚氯乙烯(CCPVC)企业中汞的产生、转化和排放过程.进一步针对典型企业开展成本效益分析,比较通过低汞触媒替代来履行《关于汞的水俣公约》要求的各种方案.结果表明,案例企业将在履约的情况下,使废气和废水汞排放量分别减少25%和85.7%~98.9%,净效益增加50.7%~55.4%.案例企业最有利的选择将是在厂内回收废触媒并改进汞减排设施,但含汞固体废物的环境风险不可忽视.原因是《关于汞的水俣公约》侧重于CCPVC行业的汞输入而非汞排放.此外,目前的汞环境税率低于最优税率,无法为CCPVC企业提供足够的激励以控制汞排放.因此,为了提高《关于汞的水俣公约》的政策效力,有必要推动我国CCPVC行业汞物质平衡的构建,加强对含汞固体废物堆存的监管力度,提高汞排放的环境税率,并将所含的环境风险物质量作为固体废物的计税依据.     

Feasibility of rice straw as a raw material for the production of soda cellulose pulp

The main objective of this work is to evaluate the suitability of rice straw and soda–anthraquinone (soda–AQ) pulping process to produce pulp and paper. To reach this aim, it was used a central composite factorial design to study the influence of operational variables (temperature (155–185 °C), cooking time (30–90 min), soda concentration (10–20%), anthraquinone concentration (0–1%) and liquid/solid ratio (6–8)), in soda–anthraquinone cooking of rice straw on pulps and paper sheets properties obtained.Based on the yield values obtained, nearly one half of the raw material can be efficiently converted into cellulose pulp and paper sheets. Also, the Kappa number/viscosity ratio of the pulp facilitates its efficient bleaching. Finally, based on the values for above-described physical properties, the pulp can be used to obtain paper or board and recycled paper (as % virgin fibre).In Spain are produced annually 757,000 t of rice straw. If we considered an average yield process of 45%, it would be possible to obtain 340,000 tons of pulp. These tons would be absorbed by the market taking into account the necessities in cellulosic pulp consumption.     

Effect of process parameters on the performance of EDM process with ultrasonic assisted cryogenically cooled electrode

In this work the parametric study on EDM process using ultrasonic assisted cryogenically cooled copper electrode (UACEDM) during machining of M2 grade high speed steel has been performed. Electrode wear ratio (EWR), material removal rate (MRR) and surface roughness (SR) was the three parameters observed. Discharge current, pulse on time, duty cycle and gap voltage were the controllable process variables. The effect of process variables on EWR, MRR and SR has been analyzed. The MRR, EWR and SR obtained in EDM process with normal electrode, cryogenically cooled electrode and ultrasonic assisted cryogenically cooled electrode have been compared. EWR and SR were found to be lower in UACEDM process as compared to conventional EDM for the same set of process parameters, while MRR was at par with conventional EDM process. The surface integrity of work piece machined by UACEDM process has been found to be better as compared to conventional EDM process. The shape of the electrode has also been measured and it was found that the shape retention was better in UACEDM process as compared to conventional EDM process. Thus in the present work UACEDM process has been established to be better than conventional EDM process due to better tool life, tool shape retention ability and better surface integrity.     

基于数学模型的AAO系统阶跃响应特性分析

以厌氧/缺氧/好氧(AAO)工艺数学模型为基础,利用灵敏度分析和响应速度从幅度和动力学两方面进行了AAO工艺操作变量的阶跃响应特性分析.结果表明,在AAO系统中,进水流量(Qf)、剩余污泥排放量(WAS)、污泥回流量(RAS)和混合液回流量(MLR)对出水水质的灵敏度较高.其中,WAS的响应速度较慢,适用于系统的长期调整.好氧区溶解氧(DO)适合于出水氨氮的短期调整,RAS和MLR对于出水总氮均是灵敏、快速的变量,RAS会显著影响出水总磷,而MLR对出水总磷影响很小.AAO系统功能性菌群受Qf影响很大.除Qf外,WAS和RAS是对异养菌和自养菌浓度影响较大的变量,聚磷菌浓度对操作变量的灵敏度大小顺序为WAS>MLR>RAS>DO.     

烟气单质汞氧化去除过程络合反应机理

湿法氧化去除烟气Hg⁰过程中产物Hg²⁺易发生络合反应,络合产物可能改变氧化体系形成新反应机制,这一现象尚未被认识研究.为获得Hg²⁺络合物生成及其对烟气脱汞影响机理,研究了配体阳离子、配体浓度、反应pH值、反应温度和摩尔比等对Hg²⁺络合反应的影响和氧化去除烟气Hg⁰的络合反应机理.结果表明MgCl₂、KCl、NiCl₂和BaCl₂配体均能与HgCl₂形成络合物,而CuCl₂和SnCl₄则不能生成络合物.络合物生成量随配体浓度的增加先升高然后趋于平衡;络合反应在酸性环境下发生且不受pH值变化影响;碱性环境下络合反应不能进行;反应温度基本不影响络合反应效应;增加配体浓度可提高络合物产量,不同配体络合效应不同,但最大吸光度基本相同,为（4.20±0.03）A.配体对络合反应有响应区间,低于区间下限值时不能形成络合物,高于上限制值时络合物产量不随配体浓度而变化.HgCl₂络合反应累积稳定常数β₄=10^15.07;[HgCl₄]^2-可螯合Hg（aq）和O₂（aq）使其与ClO^-和Hg₂Cl₂反应,形成氧化-络合氧化反应新机理.     

污泥中汞的存在形态及其在干化过程中的动态变化

在测定市政污泥、印染污泥和造纸污泥中汞含量及其存在形态分布特征的基础上,通过模拟实验,系统研究了不同类型污泥中汞存在形态在干化过程中的动态变化,同时分析了污泥中汞含量和各存在形态发生变化的原因.结果表明,市政污泥的汞含量依次大于印染污泥和造纸污泥;污泥中无酸溶态汞和可还原态汞,只存在可氧化态汞和残渣态汞;被试污泥在25~100℃干化时,含水率降低不会导致汞的析出;在100~200℃干化时,污泥中汞含量随温度的升高呈现出缓慢降低的趋势;当干化温度200~300℃时,随污泥中有机质和硫化物的分解,可氧化态汞消失;当干化温度达到400℃时,污泥中汞不复存在.     

扩散管在大气汞分析中的应用

本文叙述一种分离大气中气态汞和颗粒态汞的扩散管采样方法 ,将它与传统的滤膜过滤法测得的结果进行比较。当使用 6 0 0 mm长的扩散管 ,采样流速为 1L· m in-1时 ,它对气态汞的采样效率可达 99%以上     

絮凝天然碱碱泥的絮凝剂产生菌的筛选及最佳产絮条件研究

从生活污水中分离得到一株在强碱性条件下能絮凝天然碱碱泥的高效絮凝剂产生菌EWY1,并通过稳定性试验证明了其具有较好的稳定性,经鉴定为肠球菌属(Enterococcus)中的盲肠肠球菌(E.cecorum).通过单因素试验和正交试验确定了该菌产絮凝剂的最佳培养基为:麦芽糖15 g·L-1,KNO3 1.2 g·L-1,KH2PO4 0.5 g·L-1,MgSO4·7H2O 0.4 g·L-1,NaCl0.6 g·L-1,FeSO4·7H2O 0.008 g·L-1;该菌产絮凝剂的最佳培养条件为pH 7.0、温度30℃、摇床转速170 r·min-1.絮凝实验结果表明,用该菌产生的絮凝剂处理天然碱碱泥效果较好,絮凝率达到了89%.     

新疆生物质能资源的经济效益分析与评价

生物质能资源具有可再生和环境友好的双重属性,现已成为新疆能源发展的重要组成部分。对新疆生物质能资源进行总量估算,分析其地区分布特点,运用替代价值法分别计算秸秆、牲畜粪便及能源植物三大类生物质能资源的经济效益,并从结果中分析得出,新疆生物质能资源在区域分布上具有资源分布不均、＂西高东低＂以及效益高低与自然条件关联性大等特征。因此,新疆在发展生物质能源产业时应当因地制宜,才能最大限度将区域资源优势转化为经济优势。     

Eco engineering for wastes treatment in process of alcohol production

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青岛霾天气下大气汞的污染特征分析

2013年1月14~17日青岛市经历了一次大范围的霾污染过程,采集并测定大气气态汞和颗粒态汞,研究汞的污染特征.结果表明,气态汞(TGM)的平均浓度为(2.8±0.9)ng/m3,颗粒汞(PHg)的平均浓度为(245±174)pg/m3.在霾发生的14、15日PHg/TSP的比值明显高于16、17日,且TGM与PHg浓度呈负相关关系,霾日气象条件有利于TGM向PHg转化.大气汞浓度与温度、相对湿度正相关,与风速负相关.TGM与SO2、NO2显著正相关,化石燃料的燃烧是大气汞的主要来源.对大气气团的后向轨迹进行聚类分析,将其分为5类,霾日大气中的汞主要来自近距离传输,受山东本地污染影响,气态汞含量最高.     

Understanding the electrode reaction process of dechlorination of 2,4-dichlorophenol over Ni/Fe nanoparticles: Effect of pH and 2,4-dichlorophenol concentration

Herein,with the exploitation of iron and nickel electrodes,the 2,4-dichlorophenol(2,4-DCP)dechlorinating processes at the anode and cathode,respectively,were separately studied via various electrochemical techniques(e.g.,Tafel polarization,linear polarization,electrochemical impedance spectroscopy).With this in mind,Ni/Fe nanoparticles were prepared by chemical solution deposition,and utilized to test the dechlorination activities of 2,4-DCP over a bimetallic system.For the iron anode,the results showed that higher 2,4-DCP concentration and solution acidity aggravated the corrosion within the electrode.The charge transfer resistance(R_(ct))values of the iron electrode were 703,473,444,and 437Ω·cm~2 for the initial 2,4-DCP concentrations of0,20,50,and 80 mg/L,respectively.When the bulk pH of the 2,4-DCP solution varied from 3.0,5.0to 7.0,the corresponding R_(ct) values were 315,376,and 444Ω·cm~2,respectively.For the nickel cathode,the reduction current densities on the electrode at-0.75 V(vs.saturated calomel electrode)were 80,106,and 111μA/cm~2,for initial 2,4-DCP concentrations of 40,80,and125 mg/L.The dechlorination experiments demonstrated that when the initial pH of the solution was 7.0,5.0,and 3.0,the dechlorination percentage of 2,4-DCP by Ni/Fe nanoparticles was 62%,69%,and 74%,respectively,which was in line with the electrochemical experiments.10 wt.%Ni loading into Ni/Fe bimetal was affordable and gave a good dechlorination efficiency of 2,4-DCP,and fortunately the Ni/Fe nanoparticles remained comparatively stable in the dechlorination processes at pH 3.0.     

Effect of process integration on the exergy balance of a two-stage process for fermentative hydrogen production

In this paper, a process for the fermentative production of hydrogen is analysed with respect to its exergy efficiency. Parametric studies show the influence of used feedstock, applied process parameters as well as process and heat integration measures on exergy efficiency. It is shown that heat integration and recirculation of fermentor effluents reduce process irreversibilites and the amount of exergy leaving the process in waste streams. Nevertheless, depending on the used feedstock, a large amount of exergy leaves the process via by-products. Internal use of by-products and waste materials for providing process heat could increase chemical exergy efficiency up to 74%.     

Design sensitivity of reactive absorption units for improved dynamic performance and cleaner production: the NOx removal process

The dynamic characteristics of reactive absorption processes are of great importance for the smooth operation of the unit and the overall performance of the implemented control system under the influence of process disturbances and the presence of tight environmental and safety constraints. In the present study, the effect of the major design parameters and column configurations on the dynamic behaviour of the environmentally sensitive NO_x removal processes, through the use of rigorous rate-based dynamic models, is investigated. Static and dynamic disturbance rejection properties are evaluated for the screening and assessment of alternative design decisions.     

北京城区夏季O3化学生成过程

选取2007年7月1日—8月31日中的21个晴空日,利用观测资料和光化学箱模式计算了北京城区测点的O₃生成速率G(O₃)和O₃生成效率OPE.结果表明,21个晴空日中G(O₃)日最高小时值分布在(18~82)×10^-9h^-1之间;在O₃污染和非污染日G(O₃)最高值的平均水平无显著差异,且与O_x浓度之间不存在一致的对应关系,表明O₃化学生成过程不能全面解释地面O₃浓度的累积,物理传输过程对测点O₃实测浓度有显著作用;各个化学过程对G(O₃)的贡献率对比结果显示,HO₂ 在 NO向NO₂的转化中贡献最大;OPE值分布在2.8~5.8之间,总体水平为4.1±0.1;OPE值与NO_x浓度之间为非线性关系,OPE值随NO_x浓度的增加而减少,表明消减测点附近VOCs排放能有效降低O₃浓度.     

基于 分析的余热发电对水泥熟料生产能源利用率影响评价

本文研究水泥熟料生产过程中各个生产系统的效率,并对余热发电前后每个系统的效率进行分析对比,从而得出各个系统的资源能源利用程度以及余热发电工程对每个系统能量利用率的影响,诊断水泥熟料生产过程的损失发生位置并发现系统的节能和余热回收利用的潜力,为管理者实施节能降耗的方案提供技术支持.研究表明,实施余热发电工程前,水泥熟料生产的原料制备系统、煤粉制备系统、回转窑系统的效率分别为4.5%、1.4%和33.7%;实施余热发电工程后,效率分别为7.8%、2.8%和38.1%.余热发电工程可回收回转窑系统总投入的3.7%,同时使原料制备系统、煤粉制备系统、回转窑系统的效率分别提高3.3%、1.4%和4.3%.