Mathematical simulation of direct reduction process in zinc-bearing pellets

A one-dimensional unsteady mathematical model was established to describe direct reduction in a composite pellet made of metallurgical dust. The model considered heat transfer, mass transfer, and chemical reactions including iron oxide reductions, zinc oxide reduction and carbon gasification, and it was numerically solved by the tridiagonal matrix algorithm （TDMA）. In order to verify the model, an experiment was performed, in which the profiles of temperature and zinc removal rate were measured during the reduction process. Results calculated by the mathematical model were in fairly good agreement with experimental data. Finally, the effects of furnace temperature, pellet size, and carbon content were investigated by model calculations. It is found that the pellet temperature curve can be divided into four parts according to heating rate. Also, the zinc removal rate increases with the increase of furnace temperature and the decrease of pellet size, and carbon content in the pellet has little influence on the zinc removal rate.

含锌冶金尘泥还原焙烧-磁选分离试验

为实现钢铁企业含锌冶金尘泥低碳环保高效的资源化利用,对铁含量为30.38%、锌含量为4.79%的含锌冶金尘泥进行还原焙烧-磁选分离研究。结果表明,该含锌冶金尘泥直接磁选难以实现锌铁有效分离,在焙烧温度950℃、焙烧时间20 min、磁选强度100 mT等条件下,磁选精矿铁回收率为79.50%、铁含量为57.00%、锌含量为2.45%,磁选尾矿锌回收率为71.06%、锌含量为9.92%、铁含量为16.81%,锌铁分离效果较好。磁选产物中精矿主要以单质Fe为主,尾矿主要由SiO_(2)与ZnO等物相组成。

冶金含铁尘泥制备的Mn–Ce掺杂Fe基催化剂及特性

针对冶金工业固废–含铁冶金尘泥组分复杂的特性,结合当前冶金烧结过程NO_x排放也是钢铁行业污染治理的重中之重的现状,提出对冶金含铁尘泥进行改性制备掺杂低温催化剂的思路,并制备了Mn–Ce掺杂的含铁尘泥基催化剂(Mn_(0.05)Ce_(0.1)/ADM,ADM分别代表acidolysis,dust和mud),研究结果表明在170~430℃宽温度区间内,Mn_(0.05)Ce_(0.1)/ADM催化剂NO_x脱除率达到90%以上,并表现出优异的SO_(2)和H_(2)O抗性,抗水抗硫性测试表明Mn_(0.05)Ce_(0.1)/ADM催化剂得益于Fe、Ce优异的抗水抗硫性,其活性组分具有较好的分散性和优异的介孔结构,并降低了表面结晶度. Mn掺杂使催化剂在牺牲一定Ce^(3+)浓度和高价态Mnx+离子的同时提高了Fe^(3+)的浓度,结果使其具有最均衡脱硝活性.此外,Fe–Ce–Mn间的协同作用改善了催化剂的表面酸性从而增加了Lewis酸性位点,进而促进静电极化激活NO_(2)和硝酸盐物种生成.研究结果可为冶金固废的高附加值利用及以废治污的思路提供一定理论参考.

微波焙烧对钢铁行业含锌冶金尘泥锌铁分离的影响

为推进钢铁行业含锌冶金尘泥的资源化利用,对铁含量为30.38%、锌含量为4.79%的含锌冶金尘泥进行微波还原焙烧-磁选分离试验研究。结果表明:含锌冶金尘泥未焙烧直接磁选以及常规马弗炉还原焙烧-磁选的方式均难以较好实现含锌冶金尘泥中锌铁的有效分离;在微波马弗炉700℃、15 min时,焙烧产物中主要存在的物相为单质Fe,焙烧产物在磁场强度为150 mT时,含锌冶金尘泥中锌铁能够达到较好的分离,所得磁选的精矿指标:锌含量为2.73%、铁含量为57.84%、铁回收率为88.67%,磁选的尾矿指标:铁含量为9.54%、锌含量为9.85%、锌回收率为61.72%。

冶金企业重点爆炸性粉尘分析

以某钢铁企业为例,从粉尘防爆角度出发,重点研究了企业6处地点的粉尘情况,包括焦粉、矿粉、煤粉和焦煤粉。通过粉尘爆炸性筛选实验判定粉尘是否具有爆炸性,并分析得到粉尘的爆炸压力(P_(ex))和爆炸压力比(PR),结果表明,6处粉尘均达到粉尘爆炸性判定标准,均为爆炸性粉尘。该钢铁企业重新评估以上6处地点的粉尘爆炸风险,采取相应的防控措施,确保企业的生产安全和稳定。

Research status and development of extraction process of zinc-bearing dust from ironmaking and steelmaking—a critical review

Almost 29.57–38.46 million tons of zinc-bearing dust were produced in Chinese iron and steel enterprises annually.The recovery of Zn and other metals in zinc-bearing dust from ironmaking and steelmaking could improve economic efficiency.However,zinc-bearing dust was classified as hazardous waste,and the volatile metals(like Zn,Na,Pb,etc.)in zinc-bearing dust limited the direct reusing in a blast furnace.Therefore,the formation process,fundamental characteristics,and current extraction process of Zn from zinc-bearing dust,associated with thermodynamics and kinetics of the pyrometallurgical process,hydrometallurgical process,and pyro-hydrometallurgical process,were analyzed.It is indicated that industrialized pyrometallurgical processes are undergoing high energy consumption and pollution such as rotary kiln and rotary hearth furnace process.The vacuum carbothermal reduction process can realize low carbon emission and no waste produced in the process.The hydrometallurgical leaching processes in strong acid,strong alkali,and ammonium solutions result in serious liquid pollution and equipment corrosion.The pyrometallurgical process involves complex kinetics and lacks kinetic research on semi-industrialization and industrialization.Water-soluble components in zinc-bearing dust can be removed by water leaching.The kinetics of the strong acid leaching is mainly controlled by the leaching kinetics of Fe_(2)O_(3) and ZnFe_(2)O_(4),while the alkali leaching and weak acid leaching are controlled by the kinetics of ZnO leaching.Zn in the zincbearing dust can be extracted by a low-temperature sodium roasting–weak acid leaching process that reduces equipment corrosion and environmental pollution.

铊在冶金过程中的迁移和富集

铊是一种典型的稀有分散元素,其毒性远高于Hg、Cd、Cu、Pb、As等元素。虽然铊在地壳中含量很低,但是经过冶金过程富集后,冶金副产物中的铊含量远高于地壳丰度。世界上铊的主要生产来源为锌、铅、铜的烟道粉尘,有色冶金部分以锌、铅、铜冶炼过程为例,黑色冶金就钢铁冶金各工序中铊元素含量、相关化学反应和富集走向进行综述。本文介绍铊在冶金过程的迁移行为和富集走向,为铊元素开路和固废资源化利用提供相关研究支撑,以实现绿色冶金的目标,并服务于国家生态文明战略。

火法处理钢铁粉尘中有价元素研究现状及展望

针对国内外钢铁冶金粉尘的化学组成和各有价元素的赋存状态,本文比较了国内外提取钢铁冶金粉尘有价元素的工艺现状,并基于热力学基本原理,着重分析了火法处理工艺的影响因素及存在的问题。在此基础上,围绕钢铁冶金粉尘协同资源化问题,提出高效利用粉尘自身所含碳素资源,采用火法富集—湿法分离提取—尾渣资源化工艺是我国冶金行业未来实现钢铁冶金粉尘全量资源化的一条有效途径。

汉钢冶金粉尘在烧结工序综合回收利用的研究

汉钢烧结厂通过冶金粉尘清洁运输、分类堆储及消化,建立了冶金粉尘应对调整模型,实现了钢铁企业冶金粉尘在烧结工序的综合回收利用,这一创新举措不仅有效地降低了烧结工序生产成本,实现了冶金粉尘的清洁运输,还为冶金行业提供了可持续发展的解决方案。

钢铁行业尘泥回收利用及处理技术分析

在总结钢铁行业尘泥主要来源及污染特征的基础上,对钢铁行业现有钢铁尘泥综合利用及处理技术进行详细分析,深入探讨了物理法、湿法、火法和火法—湿法联合处理的工艺原理以及在实际应用中的优缺点,并对未来钢铁行业尘泥处理的发展方向进行展望,以期为相关人员提供参考。

钢铁企业粉尘颗粒污染物特点及除杂技术

钢铁冶炼过程中会产生大量烟气,经过除尘处理后得到冶金粉尘,该粉尘中存在着碳、钙、铁等有价元素,可通过资源化利用技术对其进行分离、回收。利用烧结对冶金粉尘进行回收,虽可以获得较可观的经济效益,却无法避免对烧结烟气污染物控制所造成的不利影响,要尽量降低粉尘中杂质所带来的有害影响就需要提前将其从冶金粉尘中分离出来,分离环节至关重要,因此根据钢铁冶金粉尘的特点,从粉尘杂质分离角度进行着重分析与研究。

试论冶金企业的环保除尘技术

金属冶炼过程中会产生大量的烟尘和废气,采用湿式除尘和静电除尘等技术可以有效去除这些烟尘和有害气体,降低对大气环境的污染。通过采用环保除尘技术,可以有效减少废气中的污染物排放,保护环境和人民的健康,并同时推动冶金行业的转型升级,促进行业的绿色发展。因此,相关企业应该加强环保意识,积极引进和推广环保除尘技术,为冶金工业的可持续发展作出贡献。

Integration of preparation of K,Na-embedded activated carbon and reduction of Zn-bearing dusts

Large amounts of solid wastes and flue gases are generated in iron and steel production process,probably leading to serious environmental pollution without duly handle.An innovative and green process of simultaneous reduction of zinc-bearing dusts and activation of low-rank coal was developed and its mechanism was clarified in this paper.Under the optimal conditions,the reduced zinc-bearing dusts containing low harmful elements(0.02%Zn,0.015%K and 0.03%Na)could be made as high-quality burden for blast furnace while the low-rank coal was transferred into K,Na-embedded activated carbon,which can be used as effective adsorbent for purification of SO_(2) and NO-containing flue gases.The solid wastes were successfully utilized to treat the flue gases through the process.The synergetic activation and reduction mechanism in the process was revealed.The coupling effect between reduction reactions of metal oxides in the dusts and activation reaction of carbon in the coal promoted the simultaneous reduction and activation process.In the meanwhile,part of the potassium and sodium from the zinc-bearing dusts could be adsorbed by the activated carbon and played a catalytic role in the activation process.

Leaching process of germanium oxide dust

A thermodynamic analysis on the acid leaching process of germanium oxide dust and discussion on the behaviors of main substances of the dust in the leaching process were carried out. The effects of temperature, acid concentration, leaching time and stirring speed on the leaching rate of germanium were investigated. Based on the characteristic of the dust, the kinetics and reactive mechanism of acid leaching were studied. The results show that the leaching of the dust by acid belonged to ＂the unreacted core shrinking model＂ of producing solid outgrowth layer. The chemical reaction was controlled by inner diffusion process. The apparent activation energy of leaching process was 12.60 kJ/mol. The leaching reaction of germanium was determined to be mainly second order reaction. The optimum conditions were the reaction temperature of 363 K, the leaching time of 2.5 h, the stirring speed of 120 r/min, the solid-to-liquid ratio of 1/8 and the acid concentration of 120 g/L. Under these conditions, the leaching rate of germanium can come up to more than 87%.

冶金粉尘对铁矿粉高温性能影响研究

烧结矿的质量与铁矿粉的高温性能密切相关,烧结生产过程中配加冶金粉尘是钢铁企业处理冶金粉尘的一种重要方式,而冶金粉尘的加入势必影响铁矿粉的高温性能,进而影响烧结矿的质量,因此,研究冶金粉尘添加对铁矿粉高温性能的影响具有重要意义。本文通过对比3种冶金粉尘(烧结除尘灰、高炉炉灰与杂料)与铁矿粉理化性能差异,并采用微型烧结试验研究了冶金粉尘对混合铁矿粉同化性及液相流动的影响。结果表明:烧结除尘灰、高炉炉灰和杂料粒度均小于混合矿,其中烧结除尘灰粒度最细;烧结除尘灰、高炉炉灰和杂料配比的增加均会降低混合矿最低同化温度和黏结强度,提高混合矿的流动性,对最低同化温度下降程度影响最大的是杂料,对流动性指数增加程度最大的是高炉炉灰;3种冶金粉尘对混合铁矿粉黏结强度的影响效果比较接近。

Agglomeration and bonding mechanism of typical metallurgical solid wastes

The agglomeration of solid wastes is a key factor for subsequent utilization,while the difficulty in agglomeration and high cost have become common problems in the recycling process.The disk pelletizing process was adopted,based on the optimization method by liquid binder addition,and the influence mechanism of the ratio of typical solid wastes as blast furnace dust(BFD)and sludge generated by oxygen converter gas recovery(OGS)was explored.Meanwhile,the effect of binder solution concentration on the quality of green pellets was studied.Derived from the contact angle detection and infrared spectrum analysis,the liquid bridge model was established to study the bonding mechanism.The results showed that OGS had stronger adsorption effect with binder,and the hydrophilicity of BFD was better.When the concentration of binder was higher than 0.2 wt.%,the contact angle between the binder and BFD was bigger than that with OGS,while the capillary force between particles reduced with larger contact angle.The increment in the binder concentration increased the viscous force between particles and the maximum separation distance.The ultimate drop strength and compressive strength were related to the type of viscous force,and the compressive strength reflected the strength of the force between particles intuitively,while the drop strength represented the comprehensive forces of green pellets.Reasonable combination of BFD and OGS was available for pelletizing process,while the ratio of BFD should not exceed 32.0%,and binder C was added in the form of solution with the addition amount of 0.4 wt.%,which can reduce the cost of binder by 20–30¥/t.

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。

含锌冶金尘泥特性分析及锌铁分离

为实现含锌冶金尘泥节能、环保、低碳的资源化利用,对原料进行水分、粒度、化学成分、物相组成、SEM-EDS等物理化学特性分析。结果表明:含锌冶金尘泥的水分为3.43%、水分容易脱除,颗粒大小不一、细小颗粒会聚集成团和黏附于大颗粒表面,具有回收利用价值的成分主要为锌和铁,含量分别为5.06%和29.24%,其中锌主要以ZnFe_(2)O_(4)的形式存在于细小颗粒中、铁主要以Fe2O3的形式存在。含锌冶金尘泥的锌铁分离试验研究表明:直接磁选和常规焙烧—磁选的锌铁分离效果均不理想,微波焙烧—磁选可以达到较好的锌铁富集分离效果;在微波焙烧温度700℃、焙烧时间10 min的条件下,磁选精矿产率为61.67%、铁含量为54.39%、锌含量为2.62%,磁选尾矿锌含量为12.15%、铁含量为9.74%,磁选精矿和磁选尾矿均能实现较好的资源化回收利用。

含锌尘泥球团直接还原过程中渣相行为与固结强度关系研究

通过表征不同直接还原温度下碱性含锌尘泥球团外观形貌、物相组成、微观结构及抗压强度变化,并结合FactSage热力学计算,分析了碱性尘泥球团直接还原过程中渣相行为及其对球团固结强度的影响。结果表明,随着还原温度升高,碱性尘泥球团体积先膨胀后收缩,对应抗压强度也先减小后增加,碱性氧化物一直参与球团渣相的形成过程并最终形成复杂的含钙化合物渣相。固相反应是渣相形成的基础,其中间产物Ca 2SiO 4良好的固溶性促进了钙铁和钙镁低熔点物相的固相生成,铁氧化物的初步还原产物FeO有利于液相生成,促进球团中物相的迁移和重新排列,球团体积收缩,强度明显提高。

超声强化含锌尘泥浸出机理及动力学

采用低共熔溶剂为浸出剂,进行了含锌尘泥超声浸锌试验。分析了超声功率、温度、液固比、搅拌速率、反应时间等对锌浸出率的影响。结果表明:在超声功率90 W、温度40℃、液固比7 mL g、转速250 r min、浸出时间80 min条件下,锌超声浸出率可达98.48%。超声强化浸出过程受混合固体产物层的控制,表观活化能为11.23 kJ mol。