Thermodynamic modelling of the multiphase pyrometallurgical processing of electric arc furnace dust

Electric arc furnace (EAF) dust is produced when automobile scrap is remelted in an electric arc furnace and about 10–20 kilograms are generated per ton of steel. The major elements present in the dust are usually zinc, iron and calcium with smaller amounts of numerous other elements such as lead, copper and nickel. Typically, in the pyrometallurgical EAF dust treatment processes, the lead and zinc are separated as a crude zinc oxide while the iron is generally not worth recovering. Copper and nickel are usually not recovered as they report either to the oxide residue or to any metallic iron that is produced. In the present research, the recovery of the non-ferrous metals in a multiphase system consisting of gas, slag, matte, metal and solid carbon phases was investigated. The equilibrium compositions of the various phases, resulting from the smelting of the dust, were calculated using the SOLGASMIX module of Outokumpu HSC Chemistry. The effects of the following operating variables were investigated; carbon additions, sulphur additions, nitrogen and oxygen additions, temperature and dust composition. The thermodynamic modelling results show that the majority of the non-ferrous metals can be recovered, with the zinc and lead concentrating in the gas phase and the nickel and copper concentrating in the matte phase.     

Alkaline leaching of zinc from electric arc furnace steel dust

Electric arc furnaces (EAF) generate about 10–20 kg of dust per metric ton of steel, which constitute a hazardous waste, known as EAF dust. This dust contains a remarkable amount of non-ferrous metals, which include zinc, cadmium, lead, chromium and nickel that could be recovered, reducing the environmental impact of the leachable toxic metals, and generating revenue. In this paper, different alkaline leaching techniques were tested in order to dissolve the zinc present in an EAF dust: (i) conventional agitation leaching; (ii) pressure leaching; (iii) conventional leaching following a microwave pretreatment and (iv) leaching with agitation provided by an ultra-sonic probe. Temperature and sodium hydroxide concentration were the variables tested. The highest zinc recovery from the EAF dust, containing about 12% of zinc, was about 74%. This was achieved after 4 h of leaching in a temperature of 90 °C and with a sodium hydroxide concentration of 6 M of the leaching agent.     

用硫酸浸出河北某高炉瓦斯泥中锌

河北某瓦斯泥锌含量为8.74%、铁品位为27.4%,含锌矿物主要为红锌矿,含铁矿物主要为赤铁矿。为回收瓦斯泥中锌等有价元素,对其进行了硫酸浸出试验。结果表明,常温下,硫酸浓度为0.5 mol/L、液固比为6 mL/g、反应时间为15 min、搅拌速度为300 r/min条件下,可以获得锌浸出率为95.21%的指标,浸渣中锌品位降至0.5%。试验结果可以为该类瓦斯泥矿硫酸溶解浸出提供技术依据。     

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%。     

Recycling EAF dust by heat treatment with PVC

This study investigated whether polyvinyl chloride (PVC) can be used as an additive for the treatment of electric arc furnace (EAF) dust. The PVC powder was mixed with the dust in order to test the synchronous treatment of two resources: waste PVC and EAF dust. The mixture was made into pellets and subjected to heat at various temperatures. The effects of the heat treatment and heating rate were investigated. The PVC emitted hydrogen chloride gas by pyrolysis and generated chlorides of zinc, lead, and cadmium in the pellets. These chlorides can be recovered by volatilization or leaching after the heat treatment. The residual pellet of this process contained over 45% iron, and it is expected that the residual pellet can be injected into the electric arc furnace.     

电弧炉粉尘的治理

电弧炉粉尘含有某些重金属元素 ,堆放填埋对环境造成污染。至今已有约 2 0种方法处理这类粉尘回收有价金属 ,尤其是近几年来出现的 Ausmelt,Met Wool,Enviroplas,All Met,IBDR- ZIPP,Modified ZINCEX,Cashman,Rezada和 Rerra Gaia等技术正逐步趋于成熟。不锈钢和特种钢电弧炉粉尘中有价金属的综合回收虽未标准化 ,但越来越受到人们的关注。     

不同碱浸工艺处理氧化锌矿的对比研究

氧化锌矿资源化利用是当前锌冶炼行业重要关注点。通过超声波辅助和常规机械搅拌碱浸处理氧化锌矿对比实验,考查实验因素温度、时间、初始碱浓度、超声波功率/搅拌速率等对锌浸出率的影响。结果表明,超声波辅助浸出效果优于常规浸出,在较优实验参数超声波功率400 W、温度65℃、时间40 min、初始碱浓度4 mol/L、液固比10∶1下重复实验,Zn平均浸出率为91.62%。超声波辅助浸出可大幅缩短反应时间。超声波在浸出提取锌的过程中发挥重要作用。      

A review on hydrometallurgical extraction and recovery of cadmium from various resources

Cadmium is a toxic metal, which is primarily produced as a by-product from mining, smelting and refining of sulphide ore concentrates of zinc. Secondary cadmium is recovered from spent Ni–Cd batteries. Some cadmium is also recovered from zinc sinter plant fume, EAF dust, cadmium containing alloys, cadmium containing fluorescent materials, etc. In all cases cadmium is associated with some other impurities depending on the source. The hydrometallurgical processing is very effective for treating such materials because it can control the different levels of impurities. The most common lixiviant used to dissolve the desired metals is sulphuric acid. In the present paper, the hydrometallurgical processes have been described for the recovery of cadmium from various resources using sulphuric acid as the main lixiviant. The leach solution obtained has been purified using cementation or solvent extraction methods. The metal is then produced from the purified solution by electrowinning or precipitation with zinc dust and melting.     

以硫化钙为还原剂焙烧还原提取锰除尘灰中的锰

研究了以硫化钙为还原剂焙烧还原提取锰除尘灰中的锰, 考察了焙烧时间、焙烧温度、物料配比、搅拌速率、浸出温度、液固比、浸出时间和H₂SO₄浓度对锰除尘灰中锰及铁浸出率的影响。结果显示, 焙烧还原工艺最佳条件为：锰除尘灰与还原剂硫化钙质量比4.12∶1、焙烧还原温度600 ℃、焙烧还原时间1.0 h, 酸浸工艺最佳条件为：搅拌速率300 r/min、H₂SO₄浓度3 mol/L、液固比8∶1、浸出温度80 ℃、浸出时间25 min, 最佳工艺条件下锰、铁浸出率分别为98.18%和76.83%。     

铜烟尘加压浸出工艺研究

采用加压酸浸工艺处理铜烟尘, 研究了反应温度、反应时间、初始硫酸浓度、液固比、氧压等对铜、锌浸出率的影响。最佳浸出工艺条件为：初始酸度0.5 mol/L、液固比10∶1、反应温度115 ℃、反应时间2 h、搅拌转速500 r/min、氧压0.4 MPa, 此时Cu、Zn浸出率分别为95.4%和97.6%, Fe、As浸出率分别为6.6%和14.0%, 同时Pb、Ag等有价金属在浸出渣中得到富集, 实现了有价金属的综合回收。     

废镀锌板炼钢粉尘加压硫酸浸出试验研究

对废镀锌板炼钢粉尘加压硫酸浸出工艺进行了研究, 并与常压酸浸进行了对比。探讨了初始硫酸浓度、浸出时间、液固比、浸出温度对浸出率的影响。结果表明, 采用加压浸出技术可使常温弱酸下不溶的铁酸锌和难处理的硅酸锌高效浸出。在釜内压力0.6 MPa、浸出温度140 ℃、液固比6∶1、搅拌速度500 r/min、硫酸浓度120 g/L、浸出时间1.5 h条件下, 浸出矿浆无胶体形成、过滤性能良好, 锌、铁浸出率分别为98.35%和3.51%, 铅几乎全部进入渣相, 浸出液中硅含量仅为0.06 g/L, 实现了粉尘中锌与杂质的有效分离。     

含富铟铁酸锌锌浸渣中铟的微波强化酸浸

常规酸浸很难高效浸出富铟铁酸锌中的铟,为了探索提高铟浸出率的低耗、高效工艺,以广西柳州锌品厂含富铟铁酸锌的锌浸渣为对象,进行了微波助浸工艺及工艺参数研究。结果表明:微波直接酸浸工艺具有简单、高效的特点,其铟浸出率明显高于常规酸浸和微波预处理+常规酸浸工艺,与微波预处理+微波酸浸工艺的铟浸出率十分接近;搅拌速度、硫酸初始浓度、液固比、浸出温度、浸出时间对铟浸出率均有显著影响;在搅拌速度为550 r/min、硫酸初始浓度为1.5 mol/L、液固比为10 mL/g、浸出温度为75℃、浸出时间为90 min情况下,对锌浸渣进行微波直接酸浸铟,铟浸出率可达77.0%,较常规酸浸铟浸出率高19.9个百分点。     

电炉含锌粉尘在微波场下脱锌的试验研究

微波能是一种清洁型能源，可以对物料进行选择性体加热。利用电炉含锌粉中和煤粉吸收微波能力强的特点，试验研究了微波加热还原电炉含锌粉尘的脱锌效果。结果表明，在大气条件下，脱锌率可达到80％左右；脱锌率随着配煤最、煤粉粒度和微波功率的增加而提高。     

含锌高炉瓦斯泥浸出过程动力学研究

为研究高炉瓦斯泥硫酸浸出锌过程的动力学,以河北某高炉瓦斯泥为原料进行了硫酸浸出试验,分别考察了浸出温度、硫酸浓度对浸出过程锌浸出率的影响。随着浸出温度的升高和硫酸浓度的增加,锌浸出率逐渐提高,浸出速率降低。采用Avrami动力学模型对锌浸出过程进行模拟,结果表明,浸出过程符合n=0.160 4的Avrami动力学模型,反应表观活化能为10.02 kJ/mol,说明浸出过程受扩散控制,因此要提高浸出效率,应加强扩散效应。提高硫酸浓度或升高反应温度,加速了溶液中的反应过程和传质过程,锌浸出率提高。试验结果为湿法浸出过程动力学以及固废资源化利用后续研究和生产实践提供了一定的理论依据。     

Hydrometallurgical process development for the production of a zinc sulphate liquor suitable for electrowinning

This study deals with the development of an innovative hydrometallurgical process for zinc recovery from Waelz Oxide, a concentrate of zinc and lead oxides obtained pyrometallurgically from the treatment of EAF dusts.Its main objective is the production of a zinc sulphate liquor to be used as feedstock in electrolytic processes. The process requires different stages to achieve this goal. The first stage consists of a double-sulphuric-acid-leaching, achieving a 88% lixiviation of the zinc present in the Waelz Oxide. After the leaching, to fulfil the strict requirements of an electrolysis feed, some purifying stages, such as oxidation, removing more than the 99% of the iron present in the leach liquor, and cementation to remove cadmium, lead and copper were investigated. Finally, if the concentration of some metallic impurity is above the accepted level for electrolytic processes, an additional purification stage could be considered.Through this process, sulphate zinc liquors with a zinc purity of around 99.75%, containing less than 135 ppm of metallic impurities, could be obtained.     

湿法炼锌渣柠檬酸浸出回收钴、锌和镍

研究了用柠檬酸从湿法炼锌净化渣中回收有价金属的工艺方法.采用单因素浸出试验,探讨了净化渣中有价金属浸出的行为规律.分别考察了柠檬酸浓度、浸出温度、液固比、搅拌速度、pH值和浸出时间对有价金属浸出率的影响.结果表明:在柠檬酸浓度0.8 mol/L、浸出温度60℃、液固比10:1、搅拌速度200 r/min、pH 1.0、...     

国外电弧炉烟尘处理技术现状及发展

综合介绍了国外电弧炉烟尘处理的主要工艺——威尔兹、转底炉直接还原、ZINCEX、EZINEX及MRT(HST)工艺的发展现状。经综合评价后指出：采用先火法后湿法的联合工艺，可以一次回收电弧炉烟尘中全部的铁与锌等有价金属，并得到优质高纯的产品，是将来的发展方向。     

从某烟灰中选择性浸出锌的试验研究

以冶炼烟灰为原料选择性浸出锌, 考察了液固比、pH值、浸出温度和浸出时间对锌和砷浸出率的影响。试验结果表明: 在液固比2∶1、浸出pH值4.0、浸出时间90 min、浸出温度25 ℃条件下, 锌浸出率可达93.92%, 砷浸出率仅4.12%。     

硫酸浸出转底炉高锌铅粉尘的研究

研究了硫酸浸出转底炉高锌铅粉尘提取锌的工艺条件和参数。最佳浸出工艺条件为: 搅拌速度400 r/min, 硫酸浓度为1.0 mol/L, 浸出温度为25 ℃, 固液比为1∶8, 浸出时间为0.5 h。在此条件下, 锌的浸出率可达96%以上。采用针铁矿-氧化水解法除铁、过硫酸铵深度除铁锰、锌粉置换除杂的方法对浸出液净化处理, 得到高纯度硫酸锌溶液, 该溶液可直接电解制取锌或制取碱式碳酸锌和氧化锌。     

某含锌烟尘中性-酸性两段浸出试验

为回收某废镀锌板炼钢烟尘中以氧化锌为主的锌,对其进行了中性-酸性两段浸出试验。首先通过条件试验确定了中性浸出时的适宜工艺参数为始酸浓度0 g/L、液固比9 mL/g、搅拌强度200 r/min、浸出温度25 ℃、浸出时间80 min,酸性浸出时的适宜工艺参数为始酸浓度20 g/L、液固比9 mL/g、搅拌强度500 r/min、浸出温度25 ℃、浸出时间80 min,然后按所确定的工艺参数进行中性浸出液为产出液、酸性浸出液返回中性浸出作业的闭路流程试验,试验稳定后锌的浸出率达到90.36%,浸出液中锌的含量为10.14 g/L,铁含量仅为0.56 g/L。