Preparation of high-purity bismuth by sulphur deleadization in vacuum distillation

The feasibility of separation of impurities in refined bismuth and sulphur deleadization with vacuum distillation was studied theoretically. Experimental studies on sulphur deleadization were carried out under vacuum. The influences of amount of sulphur, distillation temperature, vacuum degree and distillation time on deleadization were investigated and an optimal technical condition was achieved. The content of lead in refined bismuth can be decreased from 30μg/g to 0.21 μg/g, which has reached the level of“5N” high-purity bismuth. Other impurities in refined bismuth can be also removed effectively under certain conditions.     

Experimental study on separation of valuable refractory aggregate from investment casting ceramic shell waste

In the present study, a processing technique for recycling investment casting ceramic shel waste was proposed to separate valuable refractory aggregate zircon sand. The microstructure and phase constituents of the shel waste and separation process were investigated. The results show that the characteristics of microstructure and phase constituents of the shel waste can meet the conditions for preferentialy separating zircon sand, and zircon sand can be separated by gravity separation on a shaking table. The separated zircon sand has good shape and high purity, and can be used for the production of castings and other applications.     

Hydrochloric acid recovery from rare earth chloride solutions by vacuum membrane distillation

The possibility of the recovery of hydrochloric acid from rare earth （RE） chloride solutions was first experimentally studied by batch vacuum membrane distillation （VMD）. The recovery by continuous VMD was also studied to devise methods that enabled the operation of VMD setup in a stable condition as well as to increase the membrane-operating life The results indicated that HCl separation with RE by VMD was possible, and the recovery ratio of 80% could be achieved by batch VMD. In continuous VMD, when the temperature of circular solutions, circular rate, and downstream pressure was 62-63℃, 5.4 cm/s, and 9.33 kPa, respectively, the HCl concentration in circular solutions and the processing capacity per membrane area were obtained. The mathematical results were in accordance with the experimental ones.     

Application of vacuum distillation in refining crude indium

Vacuum distillation is a technique suitable for low boiling and melting point materials,to remove the heavy and low vapor pressure impurities at low level.As indium has low melting point and high boiling point,it is suitable for refining by vacuum distillation.First,saturation vapor pressure for major elements in crude indium was calculated by the Clausius–Clay Prang equation,which could approximately predict the temperature and pressure during vacuum distillation process.Second,the activity coefficients for In–Cd,In–Zn,In–Pb,In–Tl at 1373 K,and In–Sn at 1573 K were acquired by means of molecular interaction on volume model.Vapor–liquid equilibrium composition diagrams of those above systems in crude indium were drawn based on activity coefficients.These diagrams could estimate the compositions of products in each process during the refinement of crude indium.Finally,1.2–1.6 ton crude indium was used per day when vacuum distillation experiments were carried out,and experimental results are in good agreement with the predicted values of the vapor–liquid equilibrium composition diagrams.     

Strontium ferrite powders prepared from oily cold rolling mill sludge by solid-state reaction method

Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study, using oily CRM sludge as sources of iron oxide, the strontium ferrite powders were synthesized in multiple steps including vacuum distillation, magnetic separation, oxidizing roasting, and solidstate reaction. The optimal technological conditions of vacuum distillation and oxidizing roasting were studied carefully. To consider the effects of Fe203/ SrCO3 tool ratio, calcination temperature, milling time and calcination time on magnetic properties of prepared strontium ferrite powders, the orthogonal experimental method was adopted. The maximum saturation magneti- zation （62.6 mA-m2.g-1） of the synthesized strontium ferrite powders was achieved at the Fe203/SrCO3 mol ratio of 6, 5 h milling time, 1250 ~C calcination temperature, and 1 h calcination time. Strontium ferrite powders syn- thesis method not only provides a cheap, high quality raw material for the production of strontium ferrite powders, but also effectively prevents the environmental pollution.     

Modeling of thermal conductivity of stainless-steelmaking dust pellets

The thermal conductivity of stainless-steelmaking dust pellets, an important parameter for the direct recycling of the dust, is naturally of interest to metallurgists. The measurement of central temperature and surface temperature was taken in a furnace. The physical model and calculation model for the heating process were set up to check the thermal conductivity of the dust pellets. The physical structure parameters δ and γ of the basic unit are 0.92 and 0.45 based on the calculation. The temperature in the pellet can be expressed in a linear equation α5 Tp =α1TN α2TM α4. This is convenient to determine the central temperature of a pellet in the direct recycling process.     

A new dynamic method for measuring hydrogen partial pressure in molten aluminum alloy

Hydrogen partial pressure is an important parameter to calculate hydrogen concentration levels in molten aluminum alloy. A new dynamic method for measuring hydrogen partial pressure in molten aluminum alloy is studied. Dynamic and rapid measurement is realized through changing the volume of the vacuum chamber and calculating the pressure difference ΔP between the theoretical and measured pressures in the vacuum chamber. Positive ΔP indicates hydrogen transmits from melt to vacuum chamber and negative ΔP means the reverse. When ΔP is equal to zero, hydrogen transmitted from both sides reached a state of dynamical equilibrium and the pressure in the vacuum chamber is equal to the hydrogen partial pressure in the molten aluminum alloy. Compared with other existing measuring methods, the new method can significantly shorten the testing time and reduce measuring cost.     

Hot spray technology of TA7 titanium alloy coated by molybdenum and its bonding strength

A kind of surface modification test was introduced, by which plasma spray in argon atmosphere with CNC4500 system was applied for TA7 titanium alloy to be coated with molybdenum, and technology to produce metallurgical bonding at interface of coating and base meal was tested by heating in vacuum condition for diffusion after hot spray. With the help of scan electron microscope analysis （SEM）, the effect of argon inlet pressure and heating temperature on coating structure as well as product of diffusion layer were studied. The glued tensile test method was used to measure bonding strength of base metal to coating. The result has shown that both argon inlet pressure and heating temperature exert some effect on coating structure and the width of diffusion layer. A bonding strength of base metal to coating which is greater than molybdenum coating itself may be attained and can be controlled in more than 50 MPa level with tested hot spray technology.     

A study on twin-tungsten TIG welding method

A new twin-tungsten TIG （T-TIG） welding method was studied. This method differs from the conventional TIG method, it places two electrodes insulated from each other in the same welding torch, and a coupling arc is generated from the two electrodes. The coupling arc pressure was measured and preliminary welding experiment was made. The results show that the coupling arc can keep arc pressure at a low level compared with conventional TIG arc, and welding can be achieved under higher current and high travel speed with sound appearance of weld. Therefore, this new method can applied widely in high effwiency welding.     

Constitutive relationship of IN690 superalloy by using uniaxial compression tests

The hot deformation behavior of IN690 superalloy was characterized in a temperature range of 1273-1473 K and a strain rate range of 0.01-10 s-1 using uniaxial compression tests on process annealed material.The constitutive relations between flow stress and effective strain,effective strain rate as well as deformation temperature were studied.It can be concluded that the flow stress significantly reduces with the deformation temperature of IN690 superalloy increasing.Whereas,there is a significant increase of flow stress when the strain rate increases from 0.1 s-1 to 10 s-1.Based on the hyperbolic-sine Arrhenius-type equation,a constitutive equation considering compensation of strain was developed.The activation energy and the material constants(Q,n and ln A) decrease as the deformation strain increases.The strain dependent term is successfully incorporated in the constitutive equation through a quartic equation.A good agreement between the experimental data and the predicted results has been achieved,indicating that the proposed constitutive equation and the methods of determing the material constants are suitable to model the high temperature deformation behavior of IN690 superalloy.     

Recovery of cadmium by high-temperature vaccum evaporation from Ni-Cd batteries

1　INTRODUCTIONPortableelectricityhasbecomeapartofdailyliving .Batteriesempowermanykindsof portableelectricandelectronicdevicestobeused ,butonthecontraryattheirend of lifetheycanharmtous .Ev eryyear 4 0 0millionpiecesofspentNi CdbatteriesproducedinChina[1,2 ] .Ifthespentbatteriesaredis cardeddirectlyintotheenvironment,soilandwaterare potentially polluted .Atthesametime ,largequantitiesofusefulsubstancesaredisposedwithoutrecycling .Therefore ,therecoveryandtreatmenttechnologiesofNi Cdba…     

劣质高危废镁真空蒸馏回收

劣质高危废镁(简称高危废镁)回收可消除为企业带来的潜在安全隐患,同时节约企业成本,提高企业竞争力.文中通过对镁金属三相平衡相图,固态金属饱和蒸汽压与温度之间的关系,金属蒸发速率与温度之间的关系进行理论分析,确定了高危废镁回收的可行性.回收设备主要由控制柜、真空系统、回收炉组成,按照装料、除油、蒸馏、出镁的工艺进行回收,结果证明高危废镁真空蒸馏回收是一项低成本、高效益、无污染的回收技术.     

Thermodynamics of removing impurities from crude lead by vacuum distillation refining

A novel technique was developed to remove impurities from crude lead by vacuum distillation. The thermodynamics on vacuum distillation refining process of crude lead was studied by means of saturated vapor pressure of main components of crude lead, separation coefficients and vapor-liquid equilibrium composition of Pb-i (i stands for an impurity) system at different temperatures. The behaviors of impurities in the vacuum distillation refining process were investigated. The results show that the vacuum distillation should be taken to obtain lead from crude lead, in which Zn, As and partial Sb are volatilized at lower temperature of 923-1023 K. Lead is distilled from the residue containing Cu, Sn, Ag and Bi at higher temperature of 1323-1423 K, but the impurity Bi is also volatilized along with lead and cannot be separated from lead.     

RECOVERY OF CADMIUM AND NICKEL FROM SCRAP Ni-Cd BATTERIES

1. Introduction Portable electricity has become a part of daily living. Batteries literally empower many kinds of portable electric and electronic devices, such as telephones, computers, radios, compact disks, tape recorders, cordless tools, and even electric cars. But at end-of-life they can come back to haunt us. Now, how to handle the niillion-tons of scrap Ni-Cd batteries is a big problem to all the countries[111]. 2. Ni-Cd Battery Applications and Effects on the Environment Profess…     

分子相互作用体积模型在真空蒸馏分离铅-锡-锑三元合金中的应用

基于分子相互作用体积模型(MIVM),计算Pb?Sn?Sb三元合金体系的活度,并使用活度系数计算真空蒸馏过程中Pb?Sn?Sb三元合金体系的气液相平衡。结果表明：随着蒸馏温度和液相中锡含量的增加,气相中锡含量也不断增加;然而,在1100°C液相中锡含量为97%(质量分数)时,气相中锡含量仅为0.45%,分离效果较好。在真空(10 Pa)条件下,在1100~1300°C蒸馏温度范围内进行真空蒸馏分离Pb?Sn?Sb三元合金实验。结果表明：在1100°C时,当液相中锡含量为97%时,气相中锡含量为0.54%。最后对比分析了实验结果和预测值,分析表明实验结果和预测值吻合较好。     

废弃PCB板电子元件高效无损绿色自动分离技术研究

为了实现废弃PCB板的规模化和产业化回收,研发了一种废弃PCB板电子元件的高效无损绿色自动分离设备。该设备包括送料装置、加热装置、分离装置和出料装置4个部分。重点设计了分离装置的机械结构,分析了分离装置的工作原理,设计了分离装置的控制系统,并对PCB板电子元件高温分离过程所产生的有毒、有害气体进行了有效的收集和综合治理,以实现拆解尾气的绿色安全排放。企业实践表明,该设备适应PCB板范围宽,分离电子元件效率高,元件损坏率低,焊料回收纯度高,设备自动化程度高,经济效益、社会效益和环境效益好,具有一定的推广应用价值。     

金银合金真空分离的理论研究（英文）

为准确预测金银合金真空蒸馏过程中产品成分与温度和压力的关系,并为工业生产参数的设计提供便捷和有效的指导,根据分子相互作用体积模型(MIVM),计算不同温度下金银合金的分离系数(β)和气-液平衡成分。结合气液相平衡(VLE)理论,绘制金银合金真空蒸馏的温度-成分、压力-成分相图。同时,对金、银三相点和金、银蒸气冷凝温度进行计算。理论研究结果表明：随着蒸馏温度的升高,分离系数减小,金在气相中的含量增加;低温对分离金银具有积极效果;在压强1～10 Pa范围内,金、银冷凝温度相差约450 K。