铁酸锌气体还原的热力学分析

根据热力学原理,计算并分析了含锌冶金粉尘中的重要成分ZnFe2 O4在CO- CO2气体还原过程中的热力学行为. ZnFe2 O4的气体还原遵循逐级还原规律,且ZnFe2 O4很容易被CO还原到ZnO和Fe3 O4.较高温度条件下,ZnO的气体还原易于FeO的还原.随着反应温度升高,锌完全反应和挥发所需要的CO含量不断降低,当反应温度从1100 K升高到1400 K时所需的CO体积分数由0.4降低到0.01以下.要达到还原分离金属锌的目的,不必将铁氧化物还原到金属铁,而只需将铁氧化物还原到Fe3 O4或FeO,同时满足锌的还原条件即可.在高炉炉身中上部,由于发生锌的还原反应和内部循环,给高炉生产带来危害,因此应减少和控制高炉的锌负荷.     

A novel hydrothermal method for zinc extraction and separation from zinc ferrite and electric arc furnace dust

A novel hydrothermal process was developed to extract zinc from pure zinc ferrite (ZnFe₂O₄) nanopowder and zinc-containing electric arc furnace (EAF) dust using hexahydrated ferric chloride (FeCl₃·6H₂O) as a decomposing agent. The effects of solid FeCl₃·6H₂O to ZnFe₂O₄ ratio by mass (R_F/Z), hydrothermal reaction temperature, and time on zinc extraction were systematically investigated. In the results, when the hydrothermal reaction is conducted at 150℃ for 2 h with R_F/Z of 15:20, the efficiency of zinc extraction from ZnFe₂O₄ reaches 97.2%, and the concentration of ferric ions (Fe3+) in the leaching solution is nearly zero, indicating a high selectivity for zinc. In addition, the zinc extraction efficiency from the EAF dust reaches 94.5% in the case of the hydrothermal reaction performed at 200℃ for 10 h with the solid FeCl₃·6H₂O to EAF dust ratio by mass (R_{F/EAF dust}) of 15:10. Zinc and iron separation is achieved by adjusting the pH value of the leaching solution according to the different precipitation pH values of metal hydroxides.     

CO还原氧化锌速率的研究

电弧炉粉尘直接还原回收新工艺中,粉尘中的锌被还原挥发进入气相并于收尘系统中被氧化,分离出这部分含锌较高的物料可采用传统的方法回收锌.而含锌物料中ZnO成分不断变化．为探索其还原过程的规律,首先采用化学纯ZnO进行CO还原实验,研究还原过程的有关规律,这一还原反应也是其它冶金过程中常见的和十分重要的反应．经实验研究发现,氧化锌还原速率与CO的浓度和温度有关,在还原温度为910～1200℃,CO浓度控制在15%～100%(体积分数)范围的实验条件下,建立了还原过程的动力学方程,确定了条件恒温下还原过程的动力学参数表观活化能为251.57kJ/mol,并与CO和CO     

锌冶炼中酸浸渣的锌铅分离

研究了含亮铅锌矿经沸腾炉焙烧的挥发氧化物酸浸处理的浸渣的锌、铅分离，使用添加剂ＬＨＹ后，常压下用硫酸浸取，在实验条件下，锌的浸取率达９８％以上，而铅仍以硫酸铅的形式留在浸渣中，从而有效地将锌、铅分离，而其中稀有元素铟的浸出率也较高。     

CaO--TiO2--Fe2O3三元系中Ca3TiFe2O8的生成机理

钒钛磁铁矿是烧结矿重要的原料之一,Ca3TiFe2O8作为钒钛烧结矿中矿物被发现之后,其生成机理尚不明确.本文采用X射线衍射分析、元素能谱分析和TG--DSC分析相结合的方法,研究了Ca3TiFe2O8的生成机理以及不同温度、CaO与TiO2含量下Ca3TiFe2O8的生成规律.实验结果表明,Ca3TiFe2O8由Ca2Fe2O5和CaTiO3反应生成,即CaO和Fe2O3反应生成Ca2Fe2O5;其后,与CaTiO3反应生成Ca3TiFe2O8.反应时间越长,Ca3TiFe2O8的生成量越大,但反应温度对Ca3TiFe2O8生成的影响并不明显.另外,还发现 CaO含量越高,Ca3TiFe2O8越易于生成,而且等摩尔 Fe2O3和 CaO下只要存在 TiO2,就会有Ca3TiFe2O8生成.     

ZnO不同微结构/ZnFe_2O_4复合薄膜光生电荷热动力学与光电性质研究

采用不同方法分别制备出ZnO纳米颗粒、纳米线、纳米棒、纳米管4种微结构,以ZnFe2O4为无机染料敏化剂在ITO透明导电玻璃上制备成ZnO不同微结构/ZnFe2O4异质结.XRD检测结果表明,所有复合结构中两种组分都达到了良好的结晶状态;而且,各复合薄膜体系都呈现出了异质结复合结构的光吸收特性,但光吸收性质差异不明显.稳态表面光电压谱测试结果表明,各异质结构都呈现出优于单一组分的光伏响应特性;而且,4种异质结构光伏性质呈现出:ZnO纳米管/ZnFe2O4ZnO纳米棒/ZnFe2O4ZnO纳米线/ZnFe2O4ZnO纳米颗粒/ZnFe2O4的特点.在较弱正外电场诱导下,复合薄膜仍然保持稳态下的光伏响应特性;随着外电场逐步提高,ZnO纳米颗粒/ZnFe2O4光伏性质增加非常明显,在+2V电压诱导下,ZnO纳米颗粒/ZnFe2O4已接近ZnO纳米管/ZnFe2O4的光伏响应强度,并明显高于另外两种异质结构的光伏性质.从光阳极微结构、自由电荷扩散长度、空间电荷区厚度、载流子参数、内建电场和能级匹配几个方面,详细讨论了ZnO/ZnFe2O4异质结中光生电荷分离的影响因素以及光生电荷传输机制.     

电弧炉粉尘直接还原炉渣氧化和脱硫能力计算热力学

电孤炉炼钢粉尘中含有多种重金属，若填埋弃置会对环境造成污染．将粉尘与还原剂碳粉混合制粒后返回电弧炉，并补充硅铁还原粉尘中难还原的金属，有价金属还原后回收于钢液中，不仅能生产不锈钢或特种钢，而且能保护环境．制粒时使用木质磺酸钙作为粘结剂，而木质磺酸钙中含有硫，可能影响钢材质量，影响程度取决于冶炼过程中炉渣的条件．经改变初始熔铁、球团、硅铁和石灰加入的量比关系进行实验，采用X射线荧光分析仪检测炉渣成分进行计算热力学研究，确定了1550℃时CaO-MgO-FeO-Fe     

氨法处理高炉瓦斯灰制取等级氧化锌研究

以氨-碳酸氢铵混合液为浸出剂浸出高炉瓦斯灰中的有价金属锌,经净化、蒸氨、煅烧得到等级氧化锌,对相关工艺参数进行优化选择。结果表明,最佳浸出条件为:[氨水]/[NH4HCO3]=2、液固比为4、总氨浓度为5mol·L-1,浸出时间为3h,此条件下锌浸出率为82.55%;最佳净化条件为:锌粉用量为1.5g·L-1、净化时间为2.5h,此条件下铅的脱除率为97.70%;最佳蒸氨条件为90℃下蒸氨至终点溶液pH值为6~7,此条件下蒸氨后锌的沉淀率可达99.95%。沉淀物在500℃下煅烧1h,得到纯度为96.03%的氧化锌粉末,达到了HG/T2527—94的一级标准。     

采用聚氨酯模板法制备花形纳米氧化锌

以乙酸锌(Zn(CH3COO)2)为锌源,尿素(CO(NH2)2)为碱源,非离子型聚氨酯(PU)为模板,采用水热法制备碱式碳酸锌(Zn5(CO3)2(OH)6)前驱体.在400 ℃进一步煅烧前驱体2 h,即获得氧化锌粉末.用粉末X射线衍射和扫描电镜研究产物的形貌和结构.结果表明:以PU为模板制备的氧化锌可以获得由纳米片状结构组成的花状形貌,PU的加入可以有效减小氧化锌的晶粒尺寸.进一步研究反应物的组成、反应温度及反应时间对产物结构的影响,发现当体系中碱源(OH-)和锌源(Zn2+)的摩尔比为4,水热反应时间为18 h,反应温度为150 ℃时,前驱体可以获得最完整的花状形貌,并且煅烧后氧化锌的花形形貌不变.     

Carbothermic reduction behaviors of Ti-Nb-bearing Fe concentrate from Bayan Obo ore in China

To support the development of technology to utilize low-grade Ti-Nb-bearing Fe concentrate, the reduction of the concentrate by coal was systematically investigated in the present paper. A liquid phase formed when the Ti-Nb-bearing Fe concentrate/coal composite pellet was reduced at temperatures greater than 1100℃. The addition of CaCO₃ improved the reduction rate when the slag basicity was less than 1.0 and inhibited the formation of the liquid phase. Mechanical milling obviously increased the metallization degree compared with that of the standard pellet when reduced under the same conditions. Evolution of the mineral phase composition and microstructure of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet at 1100℃ were analyzed by X-ray diffraction and scanning electron microscopy-energy-dispersive spectroscopy. The volume shrinkage value of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet with a basicity of 1.0 was approximately 35.2% when the pellet was reduced at 1100℃ for 20 min, which enhanced the external heat transfer to the lower layers when reduced in a practical rotary hearth furnace. The present work provides key parameters and mechanism understanding for the development of carbothermic reduction technology of a Ti-Nb-bearing Fe concentrate incorporated in a pyrometallurgical utilization flow sheet.     

Enhanced photocatalytic activity of sponge-like ZnFe2O4 synthesized by solution combustion method

A kind of cubic ZnFe2O4 with spinel structure was synthesized by an improved solution combustion method via a facile and environmentally friendly pathway and their photocatalytic activity under visible light radiation was investigated. The particle synthesized under the ignition temperature of 573 K has a pure phase. While a small amount impurities, a-Fe2O3 and ZnO, were formed in the sample during the combustion process at higher ignition temperature of 623 K. The synthesized ZnFe2O4 has a sponge-like porous structure and wide absorption in the visible-light region. The impurities a-Fe2O3 and ZnO formed in the sample probably enhance the reduction and oxidation ability and promote the separation of photo-generated electrons and holes. Comparing with ZnFe2O4 synthesized by the conventional solid state reaction, the ZnFe2O4 derived by solution combustion method showed the better photocatalytic activity under visible light radiation.     

氧化锌法式圆炉燃烧系统及结构优化

 氧化锌的生产可分为火法和湿法两种工艺,法式氧化锌生产工艺是火法间接氧化锌生产的一种重要工艺。本文以浙江某厂的一台氧化锌法式圆炉为研究对象,采用数值模拟方法对该窑炉的加热工艺及结构进行优化,并通过改造实施进行验证,有效提高了氧化锌法式圆炉的热效率,增加了窑炉的使用寿命。通过对法式圆炉燃烧井及燃烧空间的数值模拟,对比分析了燃烧器型式及燃烧井结构的变化对窑炉温度场、流场及气体浓度场等的影响,据此提出了合理的优化改造意见,模拟结果与实测数据吻合良好。依据模拟结果对法式圆炉进行节能技术改造,首先将燃烧器型式由大气式改为预混式,并采用空燃比例调节装置,控制天然气和助燃空气的比例及混合程度;其次将炉窑燃烧井由竖直结构改为扩口结构。技术改造之后,生产每吨氧化锌的天然气单耗由240Nm³降至192Nm³,日节约天然气360Nm³;内外坩锅寿命由3个月提高至6个月;每个生产周期氧化锌平均产量由7.5t/d提升至8.0t/d,单台窑炉的年经济效益可达50万元人民币。     

ZnFe~Ⅲ类水滑石制备过程研究

以ZnSO4、FeSO4为原料,采用共沉淀和氧化的两步法合成了ZnFeⅢ二元类水滑石化合物,详细探讨了原料配比、pH及氧化处理条件等因素对合成产物物相的影响,借助XRD,FTIR,N2吸附等手段对合成物物化性能进行表征。研究结果表明:以Zn(NO3)2、Fe(NO3)3为原料,改变合成条件只能得到碱式碳酸锌或碱式硝酸锌;而以FeSO4、FeSO4为原料,采用共沉淀和氧化的两步法可得到晶相单一、结晶度良好的ZnFeⅢHTLcs。两步法制备ZnFeⅢ类水滑石的最适宜的条件为:n(Zn2+)/n(Fe2+)=2.0～3.0,pH=6.0～7.0,氧化温度为25℃,该条件下合成的ZnFeⅢHTLcs有较高的热稳定性,热分解温度为600℃;有较窄的粒径分布,中值粒径为1.24μm,平均粒径为1.28μm;吸附等温线类型为Ⅱ型,比表面积为23.08m2/g。     

ZnO/Fe2O3光催化降解苯酚

用浸制法制备,ZnO/Fe2O3为光催化剂,日光灯为灯源,以苯酚降解为探针反应,考察了不同ZnO负载量对ZnO/Fe2O3为光催化剂的活性的影响,并考察不同光源,催化剂用量,苯酚的初始浓度,溶液的PH值和降解温度对苯酚光催化降解过程的影响.结果表明,ZnO负载量的最佳量为3%,最佳的工艺条件是苯酚浓度是20mg/L,催化剂用量为0.05g,PH值为13时在常温下用日光灯光照射,能较好地降解苯酚.     

电炉粉尘循环利用造泡沫渣

在实验室中研究了电炉粉尘和煤粉加入量及温度对泡沫渣高度的影响。结果表明,在电炉渣中加入0－30％的电炉粉尘和3％－12％的煤粉（质量分数）时,随粉尘煤粉加入量的增加以及温度的提高,泡沫渣的最大发泡高度增加;在加入电炉粉尘造泡沫渣过程中,随温度升高,渣中ZnO的还原挥发速度加快,反应6min,Zn的挥发率大于97％,在本实验条件下,反应3min,渣中pb小于0．02％,温度对PbO的还原挥发速度无明显影响。     

ZnFe2O4与CaCl2氯化反应机理

利用CaCl2为氯源与含锌冶金粉尘的重要组分ZnFe2O4进行反应,并利用扫描电镜(SEM)和能量色散谱仪(EDS)分析了ZnFe2O4粉体与CaCl2反应面和反应产物微观形貌的变化,讨论了ZnFe2O4与CaCl2的反应机理.认为反应过程包括一个固液反应和气体挥发过程.ZnFe2O4颗粒被熔融CaCl2包裹,在固液界面发生氯化反应,生成的ZnCl2溶解在CaCl2液膜中,并在气液界面挥发逸出,而CaFe2O4的产物层不断增大,同时伴随着多个颗粒间的黏结和融合长大.     

Recovery of iron and calcium aluminate slag from high-ferrous bauxite by high-temperature reduction and smelting process

A high-temperature reduction and smelting process was used to recover iron and calcium aluminate slag from high-ferrous bauxite. The effects of w(CaO)/w(SiO₂) ratio, anthracite ratio, and reduction temperature and time on the recovery and size of iron nuggets and on the Al₂O₃ grade of the calcium aluminate slag were investigated through thermodynamic calculations and experiments. The optimized process conditions were the bauxite/anthracite/slaked lime weight ratio of 100:16.17:59.37, reduction temperature of 1450°C and reduction time of 20 min. Under these conditions, high-quality iron nuggets and calcium aluminate slag were obtained. The largest size and the highest recovery rate of iron nuggets were 11.42 mm and 92.79wt%, respectively. The calcium aluminate slag mainly comprised Ca₂SiO₄ and Ca₁₂Al₁₄O₃₃, with small amounts of FeAl₂O₄, CaAl₂O₄, and Ca₂Al₂SiO₇.     

Zinc oxide nanostructures and porous films produced by oxidation of zinc precursors in wet-oxygen atmosphere

Wet oxidation can be used to produce high quality zinc oxide(ZnO) nanostructures at moderately high temperatures with low requirements of equipment and experimental conditions.Zn precursor films were prepared by magnetron sputtering and controlled ZnO nanostructures were produced by oxidation of the Zn precursor films in wet O_2.The growth mechanism of the ZnO nanowires and nanobelts in wet oxidation was discussed based on the experimental results.Silver and nitrogen doping were realized in the wet oxida...     

新一代电炉炉底用捣打料技术特性及耐蚀机理探讨

采用显微分析及相图分析方法对新一代MgOCaOFe2O3合成砂炉底捣打料的技术特性及冶金性能进行了研究剖析,结果表明:该捣打料的主要晶相为方镁石,基质胶结相为低熔过渡型的C2F(C4AF)·在实际应用中C2F具有活化晶格加速烧结的作用,且C2F成氧化铁及CaO分解分别溶入方镁石形成RO相及反应生成高熔点C2S相,有较强的抗蚀性·并对捣打料与熔渣反应,在钢液中的行为,在炉底烧结及蚀损的机理进行了探讨·     

低品位氧化锌矿的浓硫酸焙烧

采用浓硫酸焙烧新工艺,提取低品位氧化锌矿中的锌、铁、铝.考查了反应温度、反应时间及酸矿摩尔比对低品位氧化锌矿中锌、铁、铝提取率的影响.利用扫描电镜(SEM)和X射线衍射分析仪(XRD)对熟料和尾渣的微观形貌进行了表征并分析了生成产物成分.在此基础上,通过正交试验,确定最佳反应条件.研究结果表明:最佳反应条件为反应温度6735K,反应时间120min,酸矿摩尔比16∶1.此时,锌的提取率可达9902%,铁、铝的提取率分别为2378%与7768%,硅、钙、铅等元素富集在渣中.