钙化合物对碱焙烧氧化锌矿的影响

为了检验钙化合物的存在对氧化锌矿碱熔融焙烧过程的影响,选择了纯物质ZnCO3、SiO2、PbO2分别与NaOH反应,分析了焙烧熟料的物相结构。结合氧化锌矿碱熔融焙烧熟料和熟料溶出渣的物相结构分析,得到了钙化合物在碱熔融焙烧反应中的产物物相,难溶的Ca2SiO4和Ca2PbO4降低了硅和铅的提取率,而Na2ZnSiO4的存在降低了锌和硅的提取率。最后讨论了碱焙烧过程中ZnCO3、SiO2、PbO2和钙化合物发生的化学反应。      

氯化焙烧粉煤灰脱除Pb、Cd的机理及其应用

这是一篇冶金工程领域的论文。采用氯化钙作为氯化剂,对粉煤灰中重金属进行了脱除实验。考查了焙烧温度、焙烧时间和CaCl₂添加量对重金属去除率的影响。将实验结果与热力学计算结果相结合,阐明了粉煤灰氯化焙烧脱除重金属的机理,并对焙烧过程的动力学模型进行了讨论。此外,以粉煤灰为原料制备土壤调理剂,通过盆栽实验研究其肥效。研究发现,添加16%氯化钙和高温锻烧40 min后,混合物中 Pb和 Cd的含量分别下降了89.26%和76.88%,而余量仅为10.22 g/t和0.54 g/t。粉煤灰中含有的石英、莫来石、氧化铝、氧化钠等组分促进CaCl₂的分解。PbO和CdO不直接与CaCl₂反应,而是主要与CaCl₂分解生成的HCl反应生成挥发性氯化物。动力学结果表明,Pb和Cd的氯化挥分行为受界面化学反应控制,Pb氯化挥发的表观活化能为84.54 kJ/mol,Cd氯化挥发的表观活化能为44.96 kJ/mol。盆栽实验表明,制备的土壤调理剂能改善土壤环境,促进香葱对营养物质的吸收,改善香葱品质,添加CaCl₂能降低产品中的重金属含量,提高有效钙含量。研究提供了一种综合利用粉煤灰的方法。     

闪锌矿表面铅活化及黄药吸附的密度泛函理论研究

采用密度泛函理论对闪锌矿Pb2+替换活化和PbOH+吸附活化开展了模拟研究,同时研究了铅活化对闪锌矿表面黄药吸附的影响.计算结果表明,PbO H+吸附活化比Pb2+取代活化在能量上更容易发生.Pb2+活化的闪锌矿表面,黄药的S与表面Pb作用距离略大于铅硫原子半径之和,相互作用较弱;而在PbO H+活化的闪锌矿表面,黄药...     

含铅固废资源化循环过程中PbSO4分解机理

简要总结了当下含铅固废的资源化循环技术现状,针对含铅固废原料复杂性,提出了还原固硫混合熔炼清洁循环新方法,介绍了新工艺反应原理,并详细探究了含铅固废主要组分PbSO4的分解机理,阐明了PbSO4的分解行为与物相转化历程,同时,分离、收集并分析了PbSO4分解气体产物。结果表明,PbSO4分解属于多步、逐级分解过程,初始分解产物为PbO?PbSO4;在N2中PbSO4的分解率及含硫气体产物分解压P(SO2)和P(SO3)均比空气中的大,气体产物以SO2为主;同时,高温和低氧分压会加快PbSO4分解进程。     

铅酸单液流电池石墨毡正极的电化学氧化处理

以1.0mol/L甲基磺酸为电解液,石墨毡和石墨板分别为正负极,通电氧化石墨毡,氧化程度为400mA·h/g。借助循环伏安法和恒电流充放电法测试PbO2/Pb(Ⅱ)电对在处理前后的石墨毡电极上电化学活性和电池的充放电性能,利用FT-IR、SEM表征处理前后的石墨毡表面官能团和形貌变化。结果表明,处理的石墨毡表面相对粗糙,形核活化能和羟基官能团含量相对增加。氧化的石墨毡电极提高PbO2/Pb(Ⅱ)电对循环伏安特性,10mA/cm2电流密度时,氧化的石墨毡电极电池库伦效率、电压效率、能量效率有所增加,分别为94.85%、86.37%和81.92%。     

报刊文摘

在无捕收剂浮选条件下方铅矿的表面状态用X射线光电子光谱法研究了在硫化钠溶液中,不同pH值下的方铅矿表面形成的化合物状态。研究指出,在碱性溶液中,PbS表面形成Pb(OH)_2(pH=10.5—10.7时为最高),当pH=12时它被溶解;当用硫化剂处理时,它转为PbS。研究发现,有适于浮选的元素硫和多硫化物结构的形成。 1991,N0.4,16—20     

含铅离子模拟废水沉淀处理理论分析及产物表征

采用氢氧化钙、碳酸钠和硫化钠处理含铅废水,在测定铅离子浓度、pH值、ξ电位、上清液浊度等指标的基础上,结合溶液化学平衡分析及沉淀产物结构表征,探讨了沉淀剂用量对铅离子去除率的影响及沉淀剂作用机理.研究结果表明:氢氧化钙用量为理论计算量的2.5倍时,铅离子去除率达到最高值,为76.10％;碳酸钠用量为理论计算量的1.5倍时,铅离子去除率达到最高值,为99.80％;硫化钠用量为理论计算量的1.5倍时,铅离子去除率达到最高值,为99.70％.尽管硫化铅溶度积很小,而铅离子去除率比理论值低,其原因可能是溶液饱和度过高,某些沉淀物直径小于0.45 μm,从而透过滤膜所致.X射线衍射和热重分析表明,氢氧化钙与含铅废水作用生成的沉淀物为PbO和Pb5O8;碳酸钠与含铅废水作用生成的沉淀物为PbCO3;而硫化钠与含铅废水作用生成的沉淀物为PbS,PbSO4和Pb10( CO3)6(OH)6O,这对污泥处理处置以及回收利用有指导意义.     

加压热解半焦特性及有害元素演化行为研究

通过固定床加压热解模拟实验,考察了不同煤焦特性及有害元素演化行为;借助FactSage热力学计算对有害元素在热转化过程中的形态进行了分析。结果表明,加压显著提高煤焦比表面积和总孔容积,为反应物扩散提供有利条件。较高的反应温度导致矿物质熔融或表面烧结,阻塞煤焦孔隙,不利于内部产物扩散。加压热解过程中,70%以上的Hg、As和Se挥发进入气相中,表现出高挥发性;F、Cd和Pb的挥发率随温度升高显著增大。热力学计算结果显示,当温度高于800℃时,主要生成HF(g)、Hg(g)、AsH_3(g)、H_2Se(g)、Cd(g)、PbS(g)和Pb(g)等有害元素化合物。     

FeO/SiO2=1.6，CaO/SiO2=0.6含铅渣的挥发特性及动力学分析

高温下含铅渣中易挥发组分的挥发对其物理化学性能测定的准确性和冶炼过程顺行都至关重要。为揭示FeO/SiO2=1.6,CaO/SiO2=0.6的PbO-FeO-CaO-SiO2-ZnO含铅渣系的高温挥发特性及PbO含量变化对该体系铅渣挥发特性的影响规律,本文采用热重-差热分析,建立了不同PbO含量的含铅渣高温挥发动力学模型;并结合挥发后渣化学元素、XRD检测及热力学计算,揭示铅渣高温挥发规律。研究结果表明：高温下该铅渣体系剧烈失重的主要是由含铅物质挥发所致。该体系不同含铅量渣挥发趋势一致,在700℃~1450℃高温段其挥发最显著。含40%PbO渣的挥发率最高达33.59%,这与挥发后渣900-1100℃水淬物相几乎检测不到Pb2ZnSi2O7、Pb2FeSi2O7含铅相是一致的;高铅渣挥发本征动力学分析可知,FeO/SiO2=1.6,CaO/SiO2=0.6的PbO-FeO-CaO-SiO2-ZnO系含铅渣的高温挥发机理函数符合Avrami-Erofeev方程,挥发过程受PbO随机成核和随后气泡生长控制。因而,在实际冶炼过程中控制铅渣的形核长大过程可抑制高铅渣的挥发率。     

磷酸抑制城市污泥高温过程中重金属挥发的研究

以榆林市城市污水厂剩余污泥为研究对象,在分析污泥中重金属总量的基础上,研究焙烧温度对重金属总量和形态分布的影响,并对污泥及底灰浸出稳定性进行分析。结果表明,污泥中重金属以Cu、Zn为主,还含少量Pb、Cr及微量Cd。磷酸与重金属元素在高温下生成Cu_5Zn(OH)_6(H_2O)(PO_4)_2、Ca_(19)Cu_2(PO_4)_(14)及Zn_3(PO_4)_2·4H_2O等稳定磷灰石类矿物相,对重金属挥发有一定抑制作用。常温下,Cu、Cr形态较稳定,高温焙烧后,不稳定形态含量增加,Zn在常温或高温下不稳定形态含量均很大。磷酸预处理会降低污泥底灰中Cu、Cd、Pb的浸出量,但会增加Zn、Cr的浸出量。     

Current situation and future trend of China rare earth luminescent material industry

<正>Rare earth luminescent material is one of the most important application sectors of rare earths.China enjoys the exceptional advantage to develop rare earth luminescent material for its abundant rare earth resources.After several decades'endeavor,China's rare earth luminescent material industry,headed by rare earth phosphor for lamp and LED and high efficient rare earth energy-saving light source,has been gradually developed into a scale industry.China has become a major production base of rare earth phosphor for lamps and rare earth     

China rare earth market review

正June 1~10,2014Rare earth market remained weak.Quoted price of rare earth products was similar to that in May.There was no sign of recovery in downstream market.The market of NdFeB magnetic materials and phosphor was depressed.Catalyst,polishing powder and ceramic industries remained inactive.Demand from downstream industry was soft.Consumers purchased on their needs.Suppliers had strong intention to sell.Prices of rare earth products     

Annual Report analysis of Chinese rare earth-related listed companies in 2013

<正>Chinese rare earth-related listed companies have published their 2013 annual reports.It can be understood from their reports that production and operation activities of Chinese rare earth-related companies were still heavily affected by macro economy and industrial policies.They basically followed the steps of national economy.In 2013,world economy recovered slowly but the economy     

Market opportunities and challenges for rare earth polishing powder

正1.Status of rare earth polishing powder Rare earth polishing powder with high content of cerium oxide began to replace iron oxide for glass polishing and became one of the key materials in glass polishing process since 1940.Compared with traditional iron oxide,rare earth polishing powder has many advantages,such as fast polishing rate,high polishing quality and long service life.It can achieve good surface quality and improve operation conditions.For example,in lens polishing,the polishing work that cerium     

Baotou Research Institute of Rare Earths developed a new RE alloy preparation technology

正Pyrometallurgy Laboratory of Baotou Research Institute of Rare Earths had independently developed a new preparation technology of rare earth alloy for NdFeB.The alloy can remarkably enhance the coercivity of NdFeB magnet but also evidently reduce the production cost of the magnet.The new master alloy was prepared in the kA pilot-scale electrolytic cell by the independent technology.The rare earth master alloy can be used as the raw material for NdFeB.Compared     

Market and recycling of NiMH battery

<正>Market status and future trend of NiMH battery1.Global market of small NiMH battery Global market size of small NiMH batteries declined year on year since 2011.The trend will continue to 2018,at the rate of 5%to 10%annually.Demand for small NiMH batteries will be stable gradually.Many electrical apparatuses are powered by the built-in lithium battery today,which is the main reason for the shrunk market of small NiMH batteries.But,for some products,small NiMH     

China rare earth market review

正September 1-10,2014 Affected by the National Day holiday,rare earth transaction was stagnant and the market showed a weak steady state.As there was no good news for downstream market,some products with flat demand would likely rally slightly for some time to     

2014 second batch of rare earth quota released

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矿用防爆轴流对旋主要通风机叶片ANSYS模态分析及应用

高效节能矿用防爆对旋主要通风机的叶片是主要通风机运行的关键部件,叶片在运行时不断受到气流的作用力,从而使叶片产生振动,当叶片振动的频率与叶片的固有频率接近时,容易产生共振从而导致叶片的断裂。一旦叶片断裂时,对主要通风机的安全运行产生致命的影响,从而导致矿山、化工等企业发生重大事故,将会产生不可估量的损失。基于有限元分析软件ANSYS,对高效节能矿用防爆轴流对旋主要通风机叶片进行模态分析及产生对应的六阶模态频率,对主要通风机叶片的运行频率、固有频率及产生的共振问题进行了原理分析,并且解决了叶片频率共振的问题,从而为主要通风机叶片结构设计提供理论依据,并对主要通风机叶片的安全运行提供保障。     

2013 NdFeB export analysis

<正>China totally exported nearly 24,000 tonsof NdFeB products during 201 3,including 18,825 tons of permanent magnet,valued USD 1.34 billion at an average price of 71.4 USD/kg;3,277 tons of NdFeB magnetic powder,valued USD 1 01 million at an average price of 30.9 USD/kg;1,334 tons of strip casting ribbon,with total export value of USD 74million at an average price of 55.3 USD/kg;and 586