Impact of Water Blending on Calcium Carbonate Equilibrium in Water Distribution Systems

A set of equations describing calcium carbonate equilibrium in water was applied to water mixtures found in an existing water supply system. A theoretical model was used to calculate the total alkalinity and pH resulting from the mixing of two waters of different origin. The accuracy of the results was tested experimentally. The experimental results confirmed the theoretical calculations with acceptable accuracy. Two different sources of possible errors in the Langelier saturation index computations were investigated and compared graphically. The first source resulted from possible inaccuracy of data, assumed to be equal to the standard errors of laboratory measurements. The second was caused by neglecting the inorganic complexes of calcium and magnesium in calculations.     

Effect of Nitrification and GAC Filtration on Copper and Lead Leaching in Home Plumbing Systems

Nitrification and granular activated carbon (GAC) filtration impact leaching of lead/copper to potable water under typical home plumbing configurations. GAC filters removed the disinfectant and caused rapid establishment of nitrification in chloraminated systems. The potential adverse consequences of whole house GAC filters deserve increased scrutiny in chloraminated systems. The lower pH values from nitrification and other microbes during overnight stagnation in pipes can markedly increase (up to 800%) lead and copper contamination of water.     

铅冶炼过程铅和汞的流向与分布

以我国传统工艺炼铅法(烧结焙烧—鼓风炉熔炼法)为研究对象,调研其主体冶炼过程中铅、汞的分布状况,构建烧结焙烧—鼓风炉熔炼工艺铅、汞走向分布图。     

稀土元素对Ca在细胞中分布影响机制的探讨

本文采用HPLC与ICP-AES联用及HPLC与ICP-MS联用的方法研究了细胞质膜上稀土元素与Ca的化学形态,同时还研究了土壤施加混合稀土对生物膜上Ca分布的影响.研究结果表明,稀土元素和Ca竞争膜磷脂上的结合位点,从而影响了膜上的Ca2+转运机制,导致了Ca在细胞中分布的改变.     

Effect of Slag Basicity on Phase Equilibria and Selenium and Tellurium Distribution in Magnesia-Saturated Calcium Iron Silicate Slags

New measurements have been made on the phase equilibria of magnesia-saturated CaO-FeO_x-SiO₂ slags at 1573 K (1300 °C) and an oxygen partial pressure of 10⁻⁹ atm. The thermodynamic behavior of selenium (Se) and tellurium (Te) in the slag and the stability of oxide mineral phases within the slag were examined as a function of slag composition. The measured equilibrium distribution of Se and Te between the slag and the copper showed nonlinear dependence on the slag basicity, reaching maxima at CaO/(CaO + SiO₂) ratios of about 0.2 and 1 and a minimum at a ratio of about 0.5. The solubility of the copper oxide in the bulk slag also passed through a minimum value at a ratio of about 0.5. Results from drop-quench experiments confirmed the stability of various oxide solid solution phases at 1573 K (1300 °C) that had virtually no solubility for Se and Te. The deduced capacity of the liquid slag for Se was found to be independent of basicity in relatively basic slags, and decreased sharply as SiO₂ replaced CaO in relatively acidic slags.     

铅冶炼企业重金属污染物粒径分布特征研究

对某铅冶炼企业的有组织源和无组织源进行监测研究,利用AERMOD空气质量模型模拟重金属污染物扩散,通过拟合废气中重金属污染物的预测值与监测值,研究铅冶炼企业废气中重金属粒径的分布特征。     

Valve Distribution and Impact Analysis in Water Distribution Systems

In water distribution systems, valves play a crucial role in system reliability and security by providing a shutoff function when it is necessary to isolate subsystems. In this paper failure of shutoff valves to close is considered. The failure impact is quantified in terms of the expanding subnetwork and the increased number of customers out of service. To evaluate a system-wide valve failure impact, three methods are suggested: segment–valve matrix, decision tree analysis, and simulation. The segment–valve matrix shows the propagation of failure through the network as valves fail to close. The decision tree enumerates all possible valve failure combinations and corresponding event probabilities. Because the complete enumeration can be unwieldy, simulation procedures are offered that approximate the enumeration results closely. The details of the methods are illustrated with the aid of an example.     

铅钙合金浇铸生产线设备的研制

铅钙合金浇铸生产线是为国内某大型冶炼企业研制的生产设备 ,介绍该设备组成、工作原理及特点。铅钙合金浇铸生产线自动化程度高 ,减轻了工人的劳动强度 ,改善的工作环境 ,具有良好的社会效益和经济效益。     

亚硫酸钙脱硫法在铅烧结烟气脱硫中的应用

冶炼厂铅烧结烟气中 SO2 浓度高 ,波动大 ,用亚硫酸钙脱硫法和 XP型板式吸收塔脱硫 ,其平均脱硫率达 95 %左右 ,每吨 SO2 脱硫成本 371元。以电石渣作脱硫剂副产石膏销往水泥厂 ,有一定经济效益。该工艺较好地解决了设备结垢的问题。     

关于铅锌原矿Pb、Zn品位分布状况的研究

铅锌矿所采出原矿的Pb、Zn品位在出矿随机取样分析时所得到的检测结果的统计分布状况同时也反映了矿产资源在一定的地质条件下所生成的地质原矿金属品位的分布.根据统计资料对原矿的Pb、Zn品位分布状况进行研究,目的就是找出其分布规律,以建立其分布的概率密度函数,结合探矿时矿体的资料科学地计算出原矿Pb、Zn品位分布区间的概率.以便更准确地推断矿产资料储有量.     

铅氧化物熔体碳热还原过程中银的分配研究

模拟基夫赛特炼铅工艺搭配处理浸锌渣过程的碳热还原阶段,主要研究了不同温度下银在粗铅及炉渣之间的分配。结果表明,在1 200℃还原熔炼温度下,银在铅与炉渣中的分配比值最大为30.13;1 300℃时最大分配比值为19.17。金属银能很好地在粗铅中富集,为使更多的银进入粗铅相,提高银回收率,铅氧化物熔体的碳热还原温度不宜太高。     

铅冶炼过程汞流向分布及产排情况分析

铅冶炼过程汞污染来源于铅精矿伴生,目前冶炼过程产生的汞污染物并没有得到有效回收利用。分析了铅冶炼行业汞污染来源和流向分布,并构建了铅冶炼行业废气中汞产排污系数体系,为我国铅冶炼行业汞污染防治提供技术支撑。     

Modeling Discoloration in Potable Water Distribution Systems

Discoloration of potable water supplied to customer taps is one of the biggest causes of water quality related customer complaints. At present, understanding of the fundamental processes that cause discoloration is limited and the modeling of events unfeasible. This paper describes the development, verification, and validation of a novel cohesive transport modeling approach to simulate discoloration within distribution systems. The model is based on the principal that strength characteristics of fine particulate material accumulated at the pipe walls are conditioned by the shear stress of the usual daily hydraulics. Discoloration occurs when the flow through the systems changes, exceeding the peak daily value. Fieldwork results from two sites are presented in detail: Site 1 demonstrates model application including sensitivity and parameter dependence, while data from Site 2 is used to investigate the hypothesis that daily hydraulic forces condition the material layers within the pipes. Model simulations are also presented for a selection of other field sites to demonstrate the wider applicability of the model.     

钙处理对齿轮钢中硫化物形貌的影响

采用金相、扫描电镜、能谱仪等分析手段,研究了钙处理DIN18CrNiMo7-6齿轮钢铸态组织中硫化物夹杂物的形貌、成分和特征参数,并讨论了成分对硫化物形态和分布的影响。结果表明,钙抑制Ⅱ类硫化物的形成,铝和硫的作用反之。随wCa/wAlsol.比值的增加,氧化物向低熔点方向转化。     

The Effect of Calcium Fluoride on Slag Viscosity

The effect of CaF₂ on the viscosity of high-basicity Al₂O₃-CaO-MgO-SiO₂ (-CaF₂) slags for secondary steelmaking was studied using a Brookfield digital viscometer. The addition of approximately 3 mass pct CaF₂ could decrease the liquidus temperature substantially in the case of high CaO containing slags, leading to good flowability of the slag at the temperature of the ladle treatment. The addition of CaF₂ had the strongest effect on the viscosity of liquid slag with high SiO₂ content.     

富氧底吹炼铅氧化熔炼元素分配热力学模拟

基于最小吉布斯自由能原理,模拟计算了铅精矿富氧底吹炼铅工艺氧化熔炼段的元素分配行为,并与半工业试验数据进行对比。在典型工业富氧底吹炼铅工艺参数条件下,重点考察了氧料比对Pb、Cu、As、Sb、Bi等元素分配行为的影响。计算结果表明,Pb、Cu、As、Sb和Bi在渣相中的分配率随氧料比的提高而增加。当氧料比为175kg/t时,Pb、Cu、Sb和Bi在金属相、渣相和气相中的分配比例基本符合半工业试验统计数据,但As计算结果与半工业数据存在一定偏差,原因可能是由于缺乏精确的活度系数。     

钙处理工艺对X70管线钢夹杂物的影响

 利用ASPEX扫描电镜(SEM+EDS)对某厂两种钙处理工艺(工艺A：LF→钙处理→RH,工艺B：LF→RH→钙处理)生产X70管线钢冶炼和浇铸过程中的夹杂物进行系统的研究。结果表明：工艺A生产的X70管线钢板中夹杂物是CA6和CA2(C代表CaO,A代表Al2O3)为主的高熔点的钙铝酸盐。产生此类夹杂物的主要原因是RH真空精炼中钙的严重损失以及中间包的二次氧化。CA6和CA2等夹杂物极易聚集成大尺寸夹杂物,经过轧制后严重影响钢板性能,甚至导致钢板探伤不合格。工艺B生产的X70管线钢中夹杂物为CaO-Al2O3(少量)-CaS系夹杂物,这种夹杂物尺寸小,弥散分布,对轧板性能危害小。     

钙处理对无取向硅钢中非金属夹杂物的影响

采用电解法和扫描电镜研究了300 t转炉-RH精炼钙处理对无取向硅钢板(%: ≤0.005C、1.2～2.2Si、0.2～0.6Mn、≤0.20P、≤0.005S、0.2～0.6Al、0～0.01Ca)中夹杂物的影响。结果表明,钢中Al含量为0.25%和0.35%时,钢中溶解氧均小于1×10^-4%,钙处理后都会产生CaS夹杂物,尤其是含0.35%Al的钢水;钙处理可以有效减少钢中的夹杂物数量,尤其是0.5μm以下的微细夹杂物数量;钙处理后夹杂物的种类以AlN、CaS为主,同时还含有少量的氧化物夹杂物以及AlN-CaS复合夹杂物,尺寸主要为1.5～5.0μm。     

Aging Effect on Lanthanum Doped Ferroelectric Lead Titanate Ceramics

Ferroelectric devices are widely applied in many fields, such as energy conversion and communication. The aging effect in ferroelectric materials plays a central role in the reliability of the related equipments. But it is very difficult to understand the origin of aging effect in ferroelectrics because these materials possess different defects and exhibit various aging behavior. The reverse transition temperature in lead titanate doped with lanthanum increases during aging at ferroelectric phase was reported. It is well known that lattice defects, such as vacancies and solute atoms, are ubiquitous in crystalline solids. These point defects affect physical properties in ferroelectrics significantly. The abnormal increase of the reverse transition temperature was discussed in terms of diffusion of point defects during aging. Dielectric performance in the material after aging was measured and discussed as well.