Oxygen-assisted zinc recovery from electric arc furnace dust using magnesium chloride

Electric arc furnace(EAF)dust is an important secondary resource containing metals,such as zinc(Zn)and iron(Fe).Recover-ing Zn from EAF dust can contribute to resource recycling and reduce environmental impacts.However,the high chemical stability of ZnFe_(2)O_(4)in EAF dust poses challenges to Zn recovery.To address this issue,a facile approach that involves oxygen-assisted chlorination using molten MgCl_(2)is proposed.This work focused on elucidating the role of O2 in the reaction between ZnFe_(2)O_(4)and molten MgCl_(2).The results demonstrate that MgCl_(2)effectively broke down the ZnFe_(2)O_(4)structure,and the high O2 atmosphere considerably promoted the sep-aration of Zn from other components in the form of ZnCl_(2).The presence of O2 facilitated the formation of MgFe_(2)O_(4),which stabilized Fe and prevented its chlorination.Furthermore,the excessive use of MgCl_(2)resulted in increased evaporation loss,and high temperatures pro-moted the rapid separation of Zn.Building on these findings,we successfully extracted ZnCl_(2)-enriched volatiles from practical EAF dust through oxygen-assisted chlorination.Under optimized conditions,this method achieved exceptional Zn chlorination percentage of over 97%within a short period,while Fe chlorination remained below 1%.The resulting volatiles contained 85wt%of ZnCl_(2),which can be further processed to produce metallic Zn.The findings offer guidance for the selective recovery of valuable metals,particularly from solid wastes such as EAF dust.

Extraction of Zinc from Electric Arc Furnace Dust by Alkaline Leaching Followed by Fusion of the Leaching Residue with Caustic Soda

Extractability of zinc from two types of electric arc furnace (EAF) dusts containing 24.8% and 16.8% of zinc respectively (denoted as Sample A and Sample B) were tested using direct alkaline leaching followed by fusion of the resulting leaching residues with caustic soda. The experimental results show that the extraction of zinc is heavily dependent on the contents of iron in the dusts. The higher iron content, the lower extraction of zinc is obtained. 53% and 38% of zinc can be extracted when both dusts were directly contacted with 5mol·L^-1 NaOH solution for 42h. The remaining zinc left in the leaching residues, which supposed to be present as zinc ferrites, can be further leached when the residues were fused with caustic soda. Quantitative extraction of zinc can be obtained from the leaching residue of Sample A while only 85% from Sample B. The extractability of zinc from dusts wit hvarious contents of iron is compared. The production flowsheet for zinc from the dusts using the process proposed is discussed.

Zinc leaching from electric arc furnace dust in alkaline medium

Physical and chemical properties of electric arc furnace （EAF） dust from Tianjin seamless Pipe Company were measured and analyzed. The zinc leaching tests in alkaline medium were carried out under variation of leaching agent concentration, leaching temperature, leaching cumulative time and solid-to-liquid ratio. The thermodynamics and kinetics of the zinc leaching process were also analyzed. The results show that the EAF dust contains 10% （mass fraction） zinc and the median particle size is 0.69 μm. The zinc recovery of 73.4% is obtained tinder the condition of 90 ℃, 6 mol/L NaOH, and 60 min leaching time. With the increase of concentration of NaOH and the cumulative time, zinc leaching will be significantly increased. The kinetics study demonstrates that the leaching reaction is chemically controlled and the reaction activation energy is 15.73 kJ/mol.

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（RF/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 RF/Z of 15：20,the efficiency of zinc extraction from ZnFe2O4 reaches97.2%,and the concentration of ferric ions（Fe^3＋） 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（RF/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.

New pyrometallurgical process of EAF dust treatment with CaO addition

The non-carbothermic zinc pyrometallurgical processing of electric arc furnace(EAF) dust was investigated on a laboratory scale. The main objective of this process was to convert highly stable zinc ferrite(Zn Fe2O4), which accounts for more than half of total zinc in the EAF dust, into Zn O and Ca2Fe2O5 by Ca O addition. The EAF dust was mixed with Ca O powder in various ratios, pressed into pellets, and heated in a muffle furnace in air at temperatures ranging from 700 to 1100°C for a predetermined holding time. All Zn Fe2O4 was transformed into Zn O and Ca2Fe2O5 at a minimum temperature of 900°C within 1 h when sufficient Ca O to achieve a Ca/Fe molar ratio of 1.1 was added. However, at higher temperatures, excess Ca O beyond the stoichiometric ratio was required because it was consumed by reactions leading to the formation of compounds other than Zn Fe2O4. The evaporation of halides and heavy metals in the EAF dust was also studied. These components could be preferentially volatilized into the gas phase at 1100°C when Ca O was added.

Ultrasound effects on zinc recovery from EAF dust by sulfuric acid leaching

In this work, an ultrasound-assisted leaching process was studied for the recovery of zinc from electric arc furnace （EAF） dust, in which zinc was mainly present in the form of franklinite （60%）. HydrometaUurgy is emerging as a preferred process for the recovery of a va- riety of metals, and the use of ultrasound could offer advantages over the conventional leaching process, especially for the dissolution of franklinite. Franklinite is a refractory phase that is difficult to leach and represents the main obstacle in conventional hydrometallurgy proc- essing. Atmospheric leaching with different sulfuric acid concentrations （0.2-2.0 M） at two temperatures （323 and 353 K） was performed. The tests were conducted using both conventional and ultrasound-assisted leaching. After the leaching tests, the solid residues were charac- terized by scanning electron microscopy （SEM） and X-ray diffraction （XRD） techniques, whereas the leach liquor was analyzed by induc- tively coupled plasma spectroscopy OCP）. The use of ultrasound facilitated the dissolution of franklinite at low acid concentrations and re- suited in a greater zinc recovery under all of the investigated operating conditions.

基于动态事件触发机制的电弧炉弧流参数建模及控制

国内冶金工业交流电弧炉弧流参数控制存在很大局限性,大多依据经验设定电抗器、变压器和弧流参数等工作点,缺乏全流程弧流参数智能化控制。为解决铍铜合金冶炼全流程弧流参数控制问题,本文从能量角度建立电弧炉冶炼过程多目标优化模型,并在弧流控制全流程引入动态事件触发机制(Dynamic Event-triggered Mechanism,DETMs)对模型进行优化,在电气特性和工艺指标的约束下,制订具有弧流、弧压和电抗协同作用的冶炼控制策略。研究结果表明:①从能量传导角度搭建多目标优化模型符合铍铜合金冶炼过程特点,温度约束条件较为容易观测,在一定程度上反映电弧电阻的动态变化;②引入DETMs解决了模型多个局部弧流变化阶段间的衔接问题,改善了目标值变化滞后导致冶炼时间延长问题;③FCPs触发弧流目标值的效果优于人工\时序触发机制,组成了具有较强的跟踪能力和鲁棒性能的弧流控制系统,实现了弧流目标值超前变化、局部稳态阶段耗时缩短。

冶金含锌粉尘中有价组分湿法回收利用的研究进展

冶金含锌粉尘是钢铁冶金过程中产生的一种有害固体废弃物,含有多种有价组分,极具回收利用价值。主要对含锌高炉灰(BFD)和含锌电炉灰(EAFD)中的有价组分湿法回收利用研究的最新进展进行综述,并对其未来研究进行了展望。

含锌电炉尘制备ZnO及其光催化还原Cr(Ⅵ)

Cr(Ⅵ)是一种强毒性重金属离子,对人类和生态环境危害巨大。光催化还原法去除Cr(Ⅵ)是一种绿色、经济且高效的一种方法。以含锌电炉尘为原材料,采用硫酸酸解、分步沉淀和煅烧法制备了ZnO复合材料。采用ICP和XRD对酸解液和产物进行了表征,并考查了产物对Cr(Ⅵ)溶液的光催化还原活性,同时研究了初始Cr(Ⅵ)浓度对光催化还原效率的影响。

电弧炉烟尘湿法提锌研究

江苏苏钢集团电弧炉炼钢烟尘含锌15.4%,并主要分布在铁酸锌中。对该炼钢烟尘进行浸出试验,结果表明:以氢氧化钠为浸出剂进行碱性浸出时,锌的浸出率仅为34.0%;以硫酸为浸出剂进行酸性浸出时,在搅拌转速为420 r/min,硫酸浓度为200 g/L,液固比为10∶1,反应温度为90℃,浸出时间为2 h的条件下,锌的浸出率达到98.7%。

交流三相电熔镁炉的最佳运行分析

针对电熔镁炉是具有大时滞、强非线性、多变量的复杂系统,现场控制需要一个准确的工作模型的情况,以电熔镁炉的电弧电阻与熔池电阻为切入点,分析了其工作机理,建立了熔池功率场数学模型;提出了针对不同阶段优化操作方法、合理布料和改变熔池形状可提高成品生产率及质量合格率;对方镁石在电熔镁砂熔体中的结晶过程的研究表明,在电熔镁炉外部增加温控手段是获取优质电熔镁砂的关键。

含锌电炉粉尘配碳球团的冶金特性

以某钢铁公司含锌电炉粉尘为原料,配入适当的无烟煤制成含碳球团,焙烧球团通过还原煤保护冷却至室温后进行化学分析·研究了1150℃～1300℃的范围内,温度、时间和内配煤量对锌、铁的还原速率以及球团抗压强度的影响·研究结果表明:锌、铁的还原率均随焙烧温度、焙烧时间以及内配煤量的增加而提高;抗压强度随焙烧温度、焙烧时间的增加而增高,但随内配煤量的增加出现极值点·焙烧球团最佳的工艺参数:焙烧时间为15min,内配煤量为13 04%,焙烧温度为1250℃·此时锌的还原率为98 43%,金属化率为94 51%,抗压强度为800 6N/球·

含碳球团还原法处理含锌电炉粉尘的试验分析

为综合利用含锌电炉粉尘，提出运用含碳球团的还原处理方法，并进行了扩大性试验，得到了还原焙烧法的合理工艺条件。试验表明：配碳的碳氧比C／O=1．2、还原温度1150℃、料层厚度30mm、加热时间65min可取得较好的效果；还原后的球团为半金属化球团，其w（TFe）为50％左右，金属化率60％～70％，球团的残Zn含量在2％以下，是较好的高炉原料；Zn的还原挥发率达到90％左右，收集粉中ZnO含量在90％左右；PbO含量在2％以下，已达到等级氧化锌的标准，实现了含锌电炉粉尘的无害化和资源化利用。

含锌电炉粉尘处理的扩大性实验

分析研究了运用配碳球团的直接还原技术处理的电炉粉尘，并完成了实验室扩大性实验；得到了还原焙烧法的合理工艺条件，即碳过量系数为1．2，还原温度为1150℃，料层厚30mm，加热时间60min。还原后的球团为半金属化球团，其ω（TFe）为50％左右，最高可达54．7N；金属化率60％～70％，最高可达88％；收集的粉尘含氧化锌达90％以上，球团中锌的还原挥发率大于90％，说明用配碳球团的直接还原技术处理含锌电炉粉尘是成功的。

低频矿热炉生产优势研究

针对矿热炉在工频冶炼中存在的缺点,通过阐述低频电源的工作原理及在矿热炉中的应用,剖析低频矿热炉增产及节电原理,并对其进行经济效益分析。实验结果表明,以低频电源技术改造工频矿热炉,是一个投资少,见效快的项目。它对资源的综合利用、环境保护、节能降耗都有着重要意义。

含铅锌铁锰矿综合利用新工艺研究

针对湖南某含铅锌铁锰矿,开发了冷固球团-还原挥发-电炉熔分新工艺,先将矿粉与还原剂及粘结剂混合,造球后经低温固结,再送入回转窑还原。矿中铁还原为海绵铁;MnO2还原为MnO;同时铅、锌还原成金属态并挥发,在烟气中氧化并富集到烟尘中;还原后的金属化球团直接进入电炉,通过熔分得到生铁和锰渣。实现了含铅锌铁锰矿的综合回收利用。回转窑还原挥发后的金属化球团中铅、锌含量较低,不会影响电炉炉衬寿命和操作,回收铅锌的同时省去了铁锰粉矿进电炉前需造块的工序。试验结果表明,在焦粉加入量为20%,硅石用量2.5%,1 390℃下熔分90 m in,得到生铁和锰渣,生铁中铁品位为95.72%,锰渣中锰品位为31.53%。

铁合金矿热炉三相熔池功率平衡的控制

矿热电炉由于短网的长度与布置不同,短网压降不同,采用电流平衡的结果使得三根电极不能得到同样的功率,影响冶炼效果。文章提出三相矿热电炉的熔池功率平衡控制,为电炉控制提供了最佳的方案。

进口含锌物料的固体废物鉴别方法

基于已完成的进口含锌物料固体废物鉴别实践,系统地介绍了所遇到的进口含锌物料的申报品名、每种品名所占的比例、种类以及每种种类的特征、固体废物鉴别的关键方法和每种鉴别结果所占的比例,其中申报品名中锌精矿或锌矿砂所占比例为55.2%,而鉴别结果中锌精矿仅占3.4%。重点介绍了锌精矿、副产品氧化锌、电弧炼钢烟尘、冶炼渣、固体废物简单处理产物等含锌物料的鉴别方法:首先进行外观观察和必要的试验分析,包括肉眼观察物料的外观特征,利用烘箱测量含水率、X射线荧光光谱仪分析主要成分和含量、滴定法确认锌元素及典型重金属元素的准确含量,另外,利用X射线衍射仪及矿相显微镜确定物料的物相组成,对于粉末物料,还需利用激光粒度仪分析其粒度分布;其次,根据物料的外观特征和试验结果,通过资料对比、实地调研、专家咨询的方法,判断出物料的产生来源;最后,根据《固体废物鉴别导则》(试行)得出物料的固体废物鉴别结论。所进行的研究为进口含锌物料的固体废物鉴别和监管提供参考,对将含锌冶炼渣、含锌烟尘、含锌固体废物简单处理产物等固体废物堵在国门之外具有重要意义。

FeCl_2处理电炉炉尘的热力学计算

电炉炉尘中富含Zn、Pb、Cd等元素,简单地将这些炉尘倾倒野外或填埋,Pb、Cd等重金属元素的浸出会污染环境 ,而直接将炉尘返回钢铁厂内循环使用 ,Zn在高炉内富集会缩短炉衬寿命 ,而且这些元素向钢水的转移还会降低钢材品质。为减少电炉炉尘对环境的污染和实现其综合利用 ,必须寻求经济高效的新方法脱除炉尘中Zn、Pb、Cd等有害元素。通过热力学计算分析了采用FeCl_2去除电炉炉尘中Zn、Pb的可能性 ,比较了不同反应条件下的作用效果。计算结果表明,在 600～900℃下,炉尘中ZnO、ZnFe_2O_4 、CuO、PbO和CdO几乎全部转化为气相氯化物。对于CaO含量较高的炉尘 ,添加SiO2 有利于提高炉尘中有害元素的脱除效率,Zn的脱除率约 96 %～ 98%。当反应温度超过950℃。

基于10t矿热炉的煤气净化回收微差压控制系统

以某10t矿热炉煤气净化回收系统升级为背景,介绍了煤气净化回收系统的组成和回收过程,应用PI控制方法和炉口微差压、回流阀开度双闭环的控制方式,实现了煤气回收净化过程中的炉膛压力、文氏管压差的自动控制,并增加了数据采集、保存、输出和异地通讯等系统功能,有效提高了煤气回收的效果,提升了企业的自动化管理水平。