失效汽车催化剂精炼渣中铂族金属的碱焙烧富集

针对难溶解的失效汽车尾气净化催化剂精炼渣,采用碱焙烧-水浸工艺去除渣中的硅和铝,使铂钯铑得到富集。考察了碱用量、焙烧温度、焙烧时间、料层厚度和水浸温度等因素对精炼渣溶解率的影响。结果表明,当碱料比1:1、焙烧温度650℃、焙烧时间3 h、料层厚度4 cm、水浸温度70℃时,精炼渣溶解达到90%以上,富集渣中铂族金属品位提高10倍。     

硝酸氧化浸出难冶炼高砷钴矿

在100g钴矿加入39mL浓硫酸、浸出温度80℃、浸出时间2h、液固比2:1时,采用常规的硫酸浸出,钴浸出率仅为16.86%;当100g钴矿中加入42.5mL浓硫酸、在焙烧温度630℃、焙烧时间1.5h的焙烧条件下,采用硫酸化焙烧后硫酸浸出,钴浸出率达到67.48%;在100g钴矿中加入39mL浓硫酸和56mL浓硝酸、浸出温度60℃、浸出时间4h、液固比为3:1时,采用硝酸氧化下硫酸浸出,钴浸出率为96.35%。     

高碳石煤流态化氧化焙烧提高钒的浸出率

采用流态化氧化焙烧方式预处理广西某难浸高碳石煤以提高钒的浸出率,对氧化焙烧过程的热力学和钒的氧化动力学进行了分析,并考察了流态化焙烧对钒浸出率的影响。结果表明:石煤在氧化焙烧过程中,碳、黄铁矿的氧化反应在热力学上比V(Ⅲ)氧化反应更易进行,它们的存在对钒氧化具有抑制作用。钒的氧化反应受扩散动力学控制,其表观活化能为347.00 kJ/mol。钒浸出率随焙烧温度的增加先增加后减小,当焙烧温度为700℃和750℃时,钒浸出率随焙烧时间的延长而增加;当焙烧温度为800℃,焙烧时间0.5 h时,钒浸出率最高,达97.51%,延长焙烧时间反而不利于钒浸出。与传统的钠化氧化焙烧法相比,浸出率高,环境污染少。     

再生铝过程铝灰渣提取冶金级氧化铝研究

本文以再生铝冶炼过程产生的二次铝灰渣为原料,经加碱焙烧、水解浸出、液固分离等工艺,综合回收利用铝灰渣。通过单因素试验考察了碱量、焙烧温度、焙烧时间、液固比、浸出温度等因素对铝灰渣中铝浸出率的影响。结果表明,铝灰渣与碳酸钠质量比为1∶1.4,焙烧温度1000℃,焙烧时间2 h,焙烧熟料在液固比为4∶1,浸出温度60℃,浸出时间60 min条件下,铝灰渣中铝的浸出率达到85.54%,加碱焙烧后铝灰渣产出的浸出渣为第Ⅱ类一般固体废弃物,实现了铝灰渣的资源化和无害化利用。     

低品位含铝矿物焙烧转型浸出铝试验研究

提出了从低品位含铝矿物中提取铝的新思路。采用微生物浸出技术,考察了低品位含铝矿物高温转型浸出铝的动力学,结果表明矿石在525℃下焙烧4h后铝的浸出效果最好,而铁的浸出率大幅度下降。系统研究了焙烧温度、浸出温度、浸出时间、更换浸出剂等因素对浸铝效果的影响。高温转型后的低品位含铝矿物浸出铝的条件为:配矿液固比100:10,浸出温度90℃,浸出时间10h,每2h更换一次浸出剂。结果铝的浸出率可达到90.99%。     

铜镍氧硫混合矿焙烧-浸出过程铜、镍、铁的转化

随着硫化镍矿资源的日趋枯竭,铜镍氧硫混合矿的利用将会愈发受到关注。通过对原矿进行差热-热重、XRD以及热力学分析,揭示焙烧过程矿石矿相的转变历程,研究铜镍氧硫混合矿焙烧过程中矿物粒度、焙烧温度和焙烧时间对铜、镍、铁转化的影响,探索浸出过程中溶剂、液固比、浸出温度及浸出时间对铜、镍、铁浸出的影响。结果表明:矿物粒度为74~80μm、焙烧温度为600℃、焙烧时间为2 h、选择水作为浸出溶剂、浸出温度为60℃、液固比为6:1、浸出时间2 h时,镍和铜的浸出率达到最高分别为46.25%和96.27%,铁的浸出率低于1%。     

从镍钼矿中提取镍钼的工艺

针对现行镍钼矿处理工艺存在的钼镍需要分别提取的缺陷,提出镍钼矿加钙氧化焙烧-低温硫酸化焙烧-水浸提取镍钼的新工艺。以贵州遵义镍钼矿为原料,对CaO加入量、氧化焙烧温度、氧化焙烧时间、硫酸加入量、硫酸化焙烧温度、硫酸化焙烧时间以及焙砂水浸工艺参数对镍钼浸出率的影响进行研究。结果表明:在最佳工艺条件下,钼的浸出率为97.33%,镍的浸出率为93.16%,且最佳工艺参数为100 g镍钼矿加入35 g CaO,700℃氧化焙烧2 h,得到的焙砂加入70 mL浓硫酸,再经250℃硫酸化焙烧2 h;硫酸化焙烧得到的焙砂按液固比2:1加水搅拌,经98℃浸出2 h。加入CaO不仅能有效减少镍钼矿氧化焙烧烟气对环境造成的污染,而且能显著提高镍的浸出率。     

高铁锌焙砂选择性还原焙烧-两段浸出锌

采用还原焙烧将高铁锌焙砂中的铁酸锌选择性地分解为氧化锌和磁铁矿,再通过两段浸出工艺回收锌,以实现锌铁分离和获得以磁铁矿为主的浸出渣。主要考察了还原焙烧、中性浸出及低酸浸出条件对锌焙砂中锌、铁浸出率的影响。结果表明:通过还原焙烧可以显著地提高锌焙砂的锌浸出率;中性浸出的最佳条件为浸出温度60℃、液固比10:1、初始酸度45 g/L和浸出时间2 h;低酸浸出的最佳条件为浸出温度70℃、液固比10:1、初始酸度60 g/L、搅拌速度300 r/min和浸出时间2 h。在最佳条件下,两段浸出的总锌浸出率约为90%,总铁浸出率约为5%。经XRD和SEM/EDS分析,浸出渣以磁铁矿为主,其次是闪锌矿和铁酸锌;铁酸锌存在的主要原因是在还原焙烧过程中被氧化锌等矿物包裹,使其分解不充分。     

铀钼矿硫酸焙烧提取铀钼

采用硫酸焙烧-水浸法强化过程高效提取铀钼矿中的铀钼,运用单因素试验考察焙烧过程参数对铀钼浸出率的影响。结果表明:硫酸焙烧过程推荐参数为酸矿质量比0.5:1、硫酸浓度82%、焙烧温度270℃、焙烧时间120 min。优化条件下验证实验所得焙烧熟料水浸后铀钼浸出率可达92%～93%和81%～84%,较现有低温直接酸浸过程铀浸出率(85%～90%)有一定提高,钼浸出率(45%～50%)有大幅提高。对原矿、焙烧熟料、浸出渣物相进行XRD分析后发现,铀钼矿经过硫酸焙烧和水浸后主要组分已由原矿中铝硅酸盐和SiO_2转变为浸出渣中SiO_2。     

微波碱溶法对粉煤灰中镓浸出效果的影响研究

采用微波碱溶法浸取焙烧处理的粉煤灰,研究了烧结温度、烧结时间、添加剂比例、微波反应温度、钙硅比、碱液浓度、液固比、微波反应时间等因素对镓溶出效果的影响。综合镓的溶出率以及反应成本等因素,确立了浸取镓的优化条件。试验结果表明:微波碱溶的最优条件应为烧结温度850℃、烧结时间2h、添加剂比例1∶1、反应温度为90℃、钙硅比为1∶1、碱液浓度为200 g/L、液固比为14∶1、反应时间为40 min。在优化条件下,粉煤灰中镓的浸出率可达82.28%。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。