砷酸钙与碳粉混合共热解过程解析

研究了砷酸钙与碳粉体系共热解反应过程。利用热重分析仪监测不同升温速率下,砷酸钙与碳粉质量比为4∶1混合物在氩气气氛、加热区间温度30～1 200℃过程中的失重情况,并采用XRD表征各失重阶段残余物。结果表明,混合体系失重过程分为三个阶段:第一失重阶段,温度240～325℃,Ca_2As_2O_7·H_2O脱水生成Ca_2As_2O_7;第二失重阶段,温度560～668℃,Ca_2As_5O_7到Ca_3(AsO_4)_2的晶型转变及Ca_5(AsO_4)_3OH和Ca(OH)_2失水生成Ca_5(AsO_4)_3和CaO;第三失重阶段,温度904～1 120℃,碳还原砷酸钙反应生成CaO和砷蒸气。动力学模型拟合结果表明:相边界反应动力学模型能较好地解释砷酸钙与碳粉共热解第三个失重阶段的反应机制。     

氢氧化钠分解氟化钙的热力学分析

根据热力学计算结果,绘制出25℃下NaOH分解氟化钙的Ca-F-H_2O体系溶解组分的lgc-pH图。根据计算结果和所绘制的热力学平衡图对氢氧化钠分解氟化钙进行分析,结果表明:当pH4时,F~-迅速减少,Ca~(2+)迅速增加,氟化钙不能稳定存在;当4≤pH≤12时,氟化钙能够稳定存在;当pH12时,Ca~(2+)迅速减少,F~-迅速增加,氟化钙开始分解产生Ca(OH)_(2(aq));当pH继续升高到14.4时,Ca(OH_(2(aq))达到饱和,开始形成Ca(OH)_(2(s))沉淀。     

钙盐沉钒的热力学研究

根据同时平衡原理以及质量守恒定律,绘制了在不同的游离总钙浓度下Ca-V(Ⅴ)-H2O体系25℃时的热力学平衡图,并进行了热力学分析。结果表明,随着溶液pH值的增大,体系中依次出现V2O5、Ca(VO3)2、Ca2V2O7、Ca3(VO4)2、Ca3(VO4)2+Ca(OH)2、Ca(OH)2六个沉淀稳定区。当沉钒反应平衡后液游离总钙浓度为0.01mol/L时,在pH=5.1~9.8范围内,钒以Ca(VO3)2形式沉淀,钒浓度最低可降至2.2×10-3 mol/L;在pH=9.8~10.3范围内,钒以Ca2V2O7形式沉淀,钒浓度最低可降至1.2×10-2 mol/L;在pH=10.3~12.6范围内,钒以Ca3(VO4)2形式沉淀,钒浓度最低可降至2.4×10-4 mol/L,沉钒效果最佳。当游离总钙浓度为0.01~1.0mol/L时,理论最佳沉钒pH值基本维持在11.0~12.6。     

Fe—As—H_2O系电位—pH图及湿法炼锌除砷过程分析

本文通过绘制的Fe—As—H_2O系的电位—pH图,着重以湿法炼锌中中和水解及针铁矿两种沉铁方法为例,对除砷过程进行热力学分析。认为中和水解法除铁时,较高的温度和pH值有利于砷的脱除,砷主要被Fe(OH)_3胶体吸附除去。而以空气氧化中和呈针铁矿除铁时,低温或较高的pH值沉铁,有利于砷的脱除,砷主要是FeAsO_4与FeOOH共沉淀而除去。     

A hydrometallurgical method of energy saving type for separation of rare earth elements from rare earth polishing powder wastes with middle fraction of ceria

This study described a hydrometallurgical method to investigate the separation of rare earth elements(REEs)from rare earth polishing powder wastes(REPPWs)containing large amounts of rare earth oxides with a major phase of CeO_2 and minor phases of La_2O_3,Pr_2O_3,and Nd_2O_3 using a process devised by the authors.The suggested approach consisted of five processes:the synthesis of NaR E(SO_4)_2·xH_2O from rare earth oxides in Na_2SO_4-H_2SO_4-H_2 O solutions(Process 1),the conversion of NaR E(SO_4)_2·xH_2O into RE(OH)_3 using NaO H(Process 2),and the oxidation of Ce(OH)_3 into Ce(OH)_4 using air with O_2 injection(Process 3),followed by Processes 4 and 5 for separation of REEs by acid leaching using HCl and H_2SO_4,respectively.To confirm the high yield of NaR E(SO_4)_2·xH_2O in Process 1,experiments were carried out under various Na_2SO_4 concentrations(0.4–2.5 mol/L),sulfuric acid concentrations(6–14 mol/L),and reaction temperatures(95–125 oC).In addition,the effect of the pH value on the separation of Ce(OH)_4 in HCl-H_2 O solutions with Ce(OH)_4,La-,Pr-,and Nd(OH)_3 in Process 4 was also investigated.On the basis of above results,the possibility of effective separation of REEs from REPPWs could be confirmed.     

Ca(Ⅱ)-Mg(Ⅱ)-Glu~(2-)-CO~(2-)_3-H_2O体系热力学平衡分析

研究了CaCO_3、MgCO_3在L-谷氨酸钠溶液中的浸出行为,根据同时平衡原理,分析了Ca(Ⅱ)-Mg(Ⅱ)-Glu~(2-)-CO~(2-)_3-H_2O体系中Ca(Ⅱ)和Mg(Ⅱ)的配合平衡热力学。计算结果表明,在7pH12条件下,溶液中的c(Ca~(2+))_T、c(Ma~(2+))_T随pH增大而降低,且会降到很低。     

基于磷酸盐沉淀分离电镀污泥中铬铁的热力学研究

电镀污泥酸性浸出液中的铬铁分离是影响铬资源化回收的一大技术难题。目前已开发的磷酸盐选择性沉淀法分离效果好、操作简单,是一种具有发展前景的铬铁分离工艺。研究有关该体系沉淀过程的相关理论对于寻找最佳工作条件具有重要的指导意义。通过热力学计算,绘制了25℃时Cr~(3+)-Fe~(3+)-PO_4~(3-)-H_2O系和Cr~(3+)-Fe~(2+)-PO_4~(3-)-H_2O系的热力学平衡图,并考察了磷酸盐加入量和溶液中总铁浓度等相关参数对分离效果的影响。结果表明:在酸性溶液中,采用磷酸盐沉淀法分离Cr~(3+)和Fe~(3+)是不可行的;而在Cr~(3+)-Fe~(2+)-PO_4~(3-)-H_2O系中,CrPO_4(s)单独稳定区的存在,为Cr~(3+)和Fe~(2+)的分离提供了一条途径;通过热力学分析,获得了Cr~(3+)和Fe~(2+)分离的最佳工作窗口。结合已有研究,进一步验证了理论计算的准确性。     

几种钴矿石的浮选研究

自然界中含钴矿物约有30多种。按化学组分可分为:硫化物、砷化物、硫砷化物及氧化物,但其中具有工业价值的一般不超过10种。常见的钴矿物有:砷钴矿CoAs_2,辉砷钴矿CoAsS,钴毒砂(CoFe)AsS、砷钴镍铁矿(CoNiFe)As_2、方钴矿Co_3S,方硫钴镍矿(CoNi)_3S_4,钴华Co_3(AsO_4)_2·8H_2O和钴土矿(CoOMnO)Mn_2O_3H_2O等。     

碱性萃取分离钨铝过程的热力学分析

针对碱性萃取分离钨、铝过程,根据同时平衡和物质守恒定律,应用现有的热力学数据绘制了25℃时W/Al-H_2O系的溶解组分浓度-pH图,Na_2CO_3-NaHCO_3-H_2O系R-pH图(R为萃取剂中(R4N)2CO_3与(R4N)2CO_3+R4NHCO_3物质量比例),利用热力学平衡图对碱性萃取钨铝分离过程进行研究。结果表明:[W]T,[Al]T分别为0.5,0.1 mol·L-1,溶液pH为11.5~14.0时钨、铝分别以WO_4~(2-),Al(OH)-4存在;pH为4.0~11.5时铝部分以Al(OH)3(am)沉淀析出,钨以阴离子形态存在溶液中;Na_2CO_3-NaHCO_3-H_2O系中,NaHCO_3含量增加,溶液pH值降低。试验表明,Al(OH)-4能与季铵盐形成萃合物存在有机相中,不会出现沉淀或影响萃取;季铵盐对WO_4~(2-)的结合能力强于Al(OH)-4;碳酸氢型萃取剂参与钨萃取反应降低萃余液溶液pH值,萃余液pH值低于11.46时铝水解产生氢氧化铝沉淀。串级试验表明,控制萃余液pH为11.59,通过12级逆流萃取,钨、铝的萃取率分别为99.17%,1.20%,说明碱性萃取工艺能够高效地分离钨铝。     

尺寸形貌可控Y(NH_4)(C_2O_4)_2·H_2O和Y_2O_3的制备及其形成机制

以硝酸、氨水、硝酸铵、商业氧化钇及草酸为初始原料,加入分散剂聚乙二醇(PEG2000)及表面活性剂十二烷基苯磺酸钠(SDBS),采用改进的草酸沉淀工艺成功制备氧化钇前驱体Y(NH_4)(C_2O_4)_2·H_2O及经随后的焙烧工艺获得最终产品Y_2O_3粉体。具体工艺中,将一定浓度的小体积Y(NO_3)_3溶液滴入大体积氨水-硝酸铵混合溶液中形成Y(OH)_3溶胶,整个滴入过程体系pH值保持稳定,然后将85℃温度下的饱和草酸溶液滴加入上述制备的Y(OH)_3溶胶中,进行沉淀转化以制备钇草酸盐前驱体Y(NH_4)(C_2O_4)_2·H_2O,继而经焙烧工艺成功制备Y_2O_3粉体。X射线衍射技术(XRD)和扫描电子显微镜(SEM)表征表明:前驱体Y(NH_4)(C_2O_4)_2·H_2O具有立方晶体结构,有轻微的团聚,经950℃焙烧2 h后,尽管失去了O,C和H,立方相Y_2O_3产品完整地保留了前驱体的形貌特征。进一步,主要通过调整表面活性剂SDBS/分散剂PEG2000质量比及改变草酸沉淀转化终点pH值来考察其对Y_2O_3产品尺寸及形貌的影响。不同条件下制备的Y_2O_3粉体扫描电子显微镜(SEM)表征表明:精确控制实验条件,特别是控制草酸沉淀转化过程终点pH值,可制备出形貌和尺寸可控的Y_2O_3粉体,当草酸沉淀转化过程中终点pH值小于1.8时,制备的Y_2O_3粉体粒径在1μm以下。另外,基于前驱体Y(NH_4)(C_2O_4)_2·H_2O在空气气氛下的差示-热重(TG-DSC)分析结果,其热分解过程应为:Y(NH_4)(C_2O_4)_2·H_2O→Y(NH_4)(C_2O_4)_2→Y_2O_2CO_3→Y_2O_3。     

熔炼次数对M17返回料合金成分、组织和性能的影响

实验结果表明,M17铸造高温合金(%:0.16C、8.79Cr、5.79A1、4.93Ti、3.29Mo、15.20Co、0.78V、0.015B、0.073Zr、0.002S、0.001P、0.001 1O、0.001 0N)经25 kg真空感应炉返回重熔后,Si含量随重熔次数的增加而略有增加,合金中主要元素和其它杂质元素S、P、H的含量变化不大,而氧、氮略有增加;合金中初生碳化物由新合金中的草书体逐渐向返回合金块状转变,初生碳化物的遗传性堵塞合金凝固时的补缩通道,使返回料合金的疏松倾向增大,高温塑性下降较大。     

Shijiazhuang will Build the World's Biggest Replacingcopper-with-aluminum Cable Production Base

正Shijiazhuang City will build the world’s biggest replacing-copper-with-aluminum cable production base,the annual output value can reach 100 billion yuan,in the future it will develop replacing-copper-with-aluminum highend industry cluster.This piece of news was learned by the reporter at the Rare Earth highiron Aluminum Alloy[Nonferrous Business Opportunity:Aluminum alloy door]Cable Conductor New Technology Application Seminar held at the provincial capital.     

Chongqing is Preparing to Set Up Nonferrous Metal Exchange,in a Bid to Become the Transit Place of Kazakhstan Copper

正Since the beginning of Chongqing’s upgrading to a municipality directly under the Central Government,Chongqing City has established direct friendly relationship with Almaty,Kazakhstan,and carried out a series of cooperation in commerce and trade,and culture     

Guangxi Baise Extends Industrial Chain to Combat Loss in Aluminum Business

正"For each tonne of aluminum being produced,the upstream enterprise on the aluminum industrial chain will suffer loss about 2000yuan."Said Liang Xiao,Deputy Director of Pingguo Industrial Park Management Committee under the Guangxi Baise City,one of the four major aluminum industry bases in China,on August 11.Extending aluminum     

JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL ANNUAL CONTENTS Volume 21(2014)

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Chinalco Straightened Out Copper Assets,and Delegated Stock Equity of Yunnan Copper

正Immediately after the news that Chinalco transferred 58%stock equity of Yunnan Copper Group to its wholly-owned subsidiary China Copper Corporation Limited free of charge was disclosed on July 9,many individual investors couldn’t help but to think:Does it mean China Copper Corporation Limited will assemble assets for overall listing?At present,among main copper business companies under China Copper Corporation     

The Development and Reform Commission Encourages Private Capital to Enter Geological Prospecting Field

正At the press conference recently held by the National Development and Reform Commission under the theme"Deepen Reform in Investment AuditApproval System",when answering questions from reporters,Huang Min,Director of the Department of Fixed Assets Investment of the National Development and Reform Commission,said that in the future it would continue to intensify efforts in geological prospecting,and actively guide social capital to enter this field.     

Guangxi's first Nickel Industry Development Research Report Was Released

正Recently,Guangxi Metallurgical Research Institute,a subsidiary of Guangxi Nonferrous Metals Group,completed survey on laterite and related manufacturers in the region,by combining the current development status of laterite both at home and abroad,it compiled Guangxi’s first"Research Report on the Development of Guangxi Nickel Industrial Chain"which adopted laterite as the study subject.This report expounded on the current     

China’s Major Non-ferrous Metals Imports & Exports(End of September. 2014)

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China's Major Non-ferrous Metals Imports & Exports

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