Lead Concentration in Hong Kong Roadside Dust after Reduction of Lead Level in Petrol

Samples of roadside dust were collected from 30 sites in Hong Kong.The total concentrations of 10 metals in the samples were analyzed,and the correlation coefficients among the metal contents and the annual average daily traffic(AADT)in 1986 were determined.Pb was found to have a significant correlation(P<0.01)with AADT.No correlation was found between Al, Ba,Cd,Cr,Cu,Fe,Mn,Ni,and Zn with respect to AADT.A general decrease in the level of Pb in roadside dust in the past few years has been observed since the reduction in the level of lead in petrol.1989 Academic Press,Inc.

Study on the volatilization kinetics of lead in carbon- containing pellets made of Zn- Pb- bearing dusts

This study investigated the volatilization kinetics of lead in pellets made of Zn-Pb-bearing dusts mixed with coal powder,in a nitrogen atmosphere and in the temperature range between 1 100 ℃ - 1 300℃ ,and showed that the reduction temperature has a significant effect on the volatilization rate of lead and that neither the particle size of the coal powder nor the extra carbon content has any effect on the volatilization rate. The obtained activation energy for the volatilization of lead is 88.74 kJ/mol. The volatilization rate of lead is controlled by both the lead evaporation reaction and the diffusion of gaseous lead through the gas boundary layer covering the surface of the reduced liquid lead.

Wetting agent investigation for controlling dust of lead-zinc ores

The purpose of this project is to control the pollution of dust,which occurred in a typical lead-zinc mine.Two kinds of surfactants and water glass were chosen as the wetting agents to study the behaviours of suppressing the dust.The performances of the wetting agents of various sizes and water content of dust and their compositions among different weting agents were investigated. Firstly,the chemical compounds,dispersity,water content,bulk density and other relevant physico-chemical properties of the choiced dust of lead-zinc ore were mensurated.A great number of down-ward penetrating tests were conducted to different partical sizes of dust and to analyze the dust wetting behaviour respectively.The optimal compositions of wetting agents were obtained in accordance with different water contents and partical sizes of the dust after analyzing and statisting the achieved experimental data. The data show that the efficiency of chemical dust suppression of weting agents is much better than that of water.The results of the research work prove that the partical size and the water content of the dust are very important factors to the dust suppression.The results are also proved validly by the dropping experiment,which takes the penetrating diameter and penetrating time as the major factors.The superfine dust is much more difficult to be wetted.Since increasing the water content of dust is the best approach to control it,the choice of wetting agents for improving dispensation is significant.

Alkaline leaching of metal melting industry wastes and separation of zinc and lead in the leach solution

In this work, a thorough examinations on the extractability of zinc and lead present in the steelmaking dusts using alkaline leaching process and the effectiveness of the zinc and lead separation in the resultant leaching solutions using sulfide precipitation method were made. It was found that only about 53% of zinc and over 70% of the lead could be leached out of the dusts, while the other 47% of zinc and 30% of lead were left in the leaching residues. The zinc and lead in the resultant leaching solution can be effectively and selectively separated. When the weight ratio of sodium sulfide (M.W. = 222-240) to Pb was kept at 1.8, the lead in the solution could be precipitated out quantitatively while all the zinc was remained in the solution. The zinc left in the solution can be further recovered by the addition of extra sodium sulfide with a weight ratio of sodium sulfide to the zinc over 2.6. The resultant filtrate can be recycled to the leaching of dust in the next leaching process.

Volatilization of zinc and lead in direct recycling of stainless steel making dust

The volatilization of zinc and lead from the stainless steel making dust pellets in the direct recycling procedure was conducted by using a thermo-gravimetric analyzer and a Tamman furnace in the nitrogen atmosphere respectively. The results show that the temperature has a significant effect on the volatilization rates of zinc and lead, and the carbon content in the pellets has no effect on the volatilization process. The volatilization of zinc is controlled by the chemical reaction between zinc oxide and carbon monoxide, while the volatilization of lead is controlled by the evaporation from liquid phase to the atmosphere. The volatilization of zinc and lead mainly happen at about 1 000 ℃ according to non-isothermal experiment.

铅冶炼场地粉尘重(类)金属的迁移转化

粉尘是铅冶炼场地土壤重(类)金属的来源之一,但粉尘中重(类)金属的迁移转化机制尚不明确。本文系统研究了此过程中重(类)金属的地球化学行为和解离机制。实验结果表明,两类粉尘样品中Pb、Zn、Cd和As的总量和浸出均超过标准,其中,两类粉尘中约有80%的Pb、Zn为生物可利用态,底吹炉粉尘中70%以上的As为弱酸提取态,而还原烟化炉粉尘弱酸提取态的重金属为Cd,占比为60%。Pb同位素结果显示,表土中97.12%的Pb来自冶炼过程中排放的粉尘。XRD和MLA结果表明,粉尘中的主要矿物为PbSO_(4)、ZnSO_(4)和CdSO_(4),表土中的矿物主要是石英、方解石、白云石和白云母。利用地球化学模型对主要矿物进行拟合发现,在酸性条件下,Pb、Zn和Cd的解离主要依赖于硫酸盐矿物,而As的解离与氢氧化铁的吸附作用有关。

铅蓄电池厂房负压取值方法的模拟分析

铅蓄电池厂房的负压取值,既涉及铅烟、铅尘等污染物向外部环境的泄漏风险,又影响到通风系统的能耗和投资。针对铅蓄电池厂房设计现状,结合实际的工程实例和相关行业规范,提出了一种具有实用性的计算方法,用于确定铅蓄电池厂房的负压取值范围。利用专业工程软件COMSOL模拟铅蓄电池厂房的室外压力场,并与理论计算结果进行对比分析。结果表明,该负压计算取值方法具有一定的可行性和合理性,可以有效地减少污染物的排放,提高厂房的环保性能,同时还能降低前期设计成本,具有显著的经济效益和环保价值。该方法可为铅蓄电池厂房的设计和优化提供便利及参考。

粗铅冶炼过程中砷镉铊的走向分布及治理措施

在粗铅冶炼工艺中,铅精矿和其他含铅物料中的砷、镉、铊分布于各工序环节,不利于有价金属资源的回收,而且加大了冶炼废弃物的处理难度,另外还对人体健康和环境造成负面影响。现有文献对于砷、镉、铊在粗铅冶炼过程中的分布及趋向还未见报道,本文根据某冶炼企业实际生产情况,统计了2021年及2022年分别为期14d的两套物料平衡数据,对砷、镉、铊在各冶炼工序的分布进行了分析,得到以下结论。砷的分布情况:在底吹炉工序中,约85%砷进入高铅渣,约9%砷进入烟灰,约6%砷进入硫酸净化污酸系统;在还原炉工序,约70%以上砷形成铅铜锍进入粗铅,约20%砷进入还原炉烟灰,10%以下的砷通过还原渣进入烟化炉。镉、铊的分布情况:高度富集于底吹炉和侧吹炉烟灰中,其中底吹炉烟灰中富集比例为85%~95%,只有5%~15%进入高铅渣转至还原炉工序,极少部分进入硫酸系统。企业采用开路底吹炉烟尘方式减少粗铅冶炼系统中砷、镉、铊的含量,开路标准是烟尘含镉超过20%时从收尘系统开路,当烟尘含镉低于15%停止开路,取出的烟尘可直接作为回收镉的原料外售。本文分析结果及解决方法可为同类企业控制冶炼系统中砷镉铊的分布提供参考。

铅基固废资源区域分布及环境属性分析

铅基固废是含铅的固体废物,主要来源于锌、铅、铜冶炼过程和废旧铅酸蓄电池回收,含有大量有价金属,同时对环境有一定的污染,因此摸清铅基固废的来源结构、产量及区域分布显得尤为重要。本文在实地企业调研的基础上分析了锌、铅、铜主要冶炼技术及其产生的铅基固废,根据单吨精炼金属的固废产出比及精炼金属产量测算了铅基固废产量,基于锌、铅、铜产量分布描绘铅基固废的区域分布,依照铅基固废污染元素含量和铅基固废产量测算有价元素的产量,以期为铅基固废处置技术开发研究及产业布局提供基础支撑。

电感耦合等离子体原子发射光谱法测定铜、铅、锌矿石,煤烟尘中锗

采用酸溶分解样品,经蒸馏锗与共存离子分离消除干扰,运用CP-AES法测定铜、铅、锌矿石、煤烟尘中锗含量;试验结果表明,在6.0 mol/L的盐酸体系中,锗以四氯化锗的形态从盐酸溶液中能蒸馏完全;Ge校准曲线的线性范围为0.10~50.00μg/mL,校准曲线线性相关系数为0.99997;方法检出限为0.0106μg/g,测定范围10~50000 g/t,结果相对标准偏差(RSD,n=11)为0.2%~3.4%;加标回收率97%~107%。本法测定结果与国标方法-原子荧光光谱法测定值均一致。

Direct Reduction Process of Pellet Containing Carbon with Addition of Zn-Pb-Bearing Iron and Steel Plant Dust

The study on direct reduction process of pellet containing carbon with the addition of Zn-Pb-bearing iron and steel plant dust shows that the reduction time and pellet basicity have obvious effect on the evaporation of lead and final metallization degree of pellet.The reduction temperature has significantl influences on the lead and zinc evaporation ratios and on final metallization degree of pellet. The optimum process parameters obtained are reduction temperature of 1 250 ℃,reduction time of 25 min and pellet basicity of 0.9.

湿法炼锌协同处置富氧顶吹炼铅烟尘分离回收镉的生产实践

针对富氧顶吹炼铅工艺铅烟尘中镉不断富集的难题,为充分发挥铅锌冶炼联合工艺流程的优势,利用湿法炼锌中的浸出工序实现烟尘中镉与铅的分离,再采用锌粉置换、净化,实现镉的分离和回收。结果表明:在初始硫酸浓度为20 g/L、液固比4∶1、浸出温度70℃、浸出时间3 h的优化条件下,铅烟尘硫酸浸出段镉浸出率为85.7%;烟尘中铅、银进入浸出渣,可返回铅系统实现铅的回收,浸出液可采用铜渣除,氯控制氯离子浓度小于200 mg/L;除氯后液并入锌冶炼湿法浸出、净化流程回收镉,实现镉的资源化利用,使铅烟尘中镉形成有效开路,整个工艺经济环保、可操作性强。

铅渣合并焙尘常压浸出回收锌的研究

针对氧化锌烟尘浸出后所产铅渣含锌过高的问题,研究利用焙尘浸出的Fe3+离子来回收铅渣中的锌。通过采用一段先对焙尘浸出,二段补酸后加铅渣继续浸出的浸出方式,在一段焙尘浸出液固比5∶1 mL/g,二段补加60 g/L的酸后加入焙尘浸出渣1.2倍量的铅渣继续浸出,反应温度85℃,反应时间2 h的条件下,能有限浸出铅渣中的锌,锌的浸出率可达87%~88%,铅渣含锌降低至4.5%左右。

高砷铅阳极泥还原熔炼高效脱砷工艺

传统铅阳极泥处理工艺为还原熔炼产贵铅-氧化精炼产银阳极板-电解精炼生产银粉,冶炼过程中锑元素基本以Sb_(2)O_(3)形态与As_(2)O_(3)共同进入烟尘中,采用加压浸出工艺处理含砷锑烟尘回收锑。整个工艺流程长、成本高、综合回收率低,而且废水产生量大,既不经济也不环保。本文利用转炉在高温还原熔炼过程中配入工业氢氧化钠进行高效脱砷处理,砷以砷碱渣形式与贵铅进行分离,生成的贵铅采用真空精馏技术梯级回收有价金属。验证试验结果表明,在加入的氢氧化钠与贵铅合金中砷含量的质量比2:1、反应时间4 h、反应温度1100℃的条件下,砷的脱除率可达95%以上。该工艺与真空精馏技术联合,金、银、铋、锑的回收率均有一定程度提高,而且缩短了流程,减少了锑渣、烟灰、废水等的产生,不但节约了熔炼成本,而且减轻了环保压力,具有良好的示范效应和推广价值。

湿法铟回收工艺中双氧水代替氯酸钠除锡工艺研究

在国内外铅锌联合冶炼企业中,铟回收工艺主要采用氯酸钠除锡法。然而,此方法在除锡过程中会产生氯气,给生产过程带来安全环保方面的隐患。为了解决这一问题,本文研究了一种使用双氧水替代氯酸钠除锡的工艺。这种新工艺具有诸多优点,不仅提高了除锡效果,还避免了氯气产生,从而消除了铟回收生产过程中的安全环保隐患。同时,使用双氧水除锡还能将产出锡渣作为中间产品外售,增加了企业经济效益。本文介绍了双氧水除锡工艺的实验条件和实施步骤,并对比了新工艺与原工艺在实验数据和生产实践中的应用效果。应用结果表明,新工艺具有显著的优势,值得在相关企业中推广应用。

上海城市街道灰尘重金属铅污染现状及评价

对上海市区和郊区城镇中心街道灰尘中铅的含量水平进行了研究，并应用克里格插值法分析了市区街道灰尘中铅的空间分布特征，结果表明：市区街道灰尘中铅的含量为28～4443mg·kg^-1，平均含量为264mg·kg^-1，为上海土壤环境背景值的10．4倍；郊区城镇中心街道灰尘中铅的含量为155～364mg·kg^-1，平均含量为237mg·kg^-1，为环境背景值的9．3倍；市区内环线以内黄浦江两岸区域铅污染较为严重，平均含量为359mg·kg^-1；铅污染中心主要位于商业区和交通干道，平均含量分别为642和520mg·kg^-1．地积累指数法和铅污染指数法的评价结果表明：上海城市街道灰尘中铅污染整体上处于中度污染水平，其中，市区内环线以内黄浦江两岸区域街道灰尘中铅污染处于偏重污染水平．研究结果以期为上海市的城市环境污染防治和城市规划提供重要的科学依据.

钢铁厂含锌铅粉尘配碳球团的直接还原工艺

对钢铁厂含锌铅粉尘配碳球团直接还原工艺进行了研究.结果表明：生球碱度及还原时间对球团中铅挥发率和铁的金属化率有显著影响，而还原温度则对球团中锌、铅挥发率和铁的金属化率均有显著影响.在此基础上确定的最佳工艺参数为：生球碱度～0.9，还原温度和还原时间分别为1250℃和25min.

离子选择电极法测定电铅灰中氟与氯

提出了一种使用pH/电导率/离子综合测试仪检测电铅灰中氟和氯含量的离子选择电极方法。电铅灰试样用过氧化氢、柠檬酸和硝酸的混合酸溶解,硝酸与过氧化氢可以消除硫离子对氯离子测定的干扰,柠檬酸与氟总离子强度调节缓冲溶液可以消除电铅灰中铁、铝对氟离子测定的干扰。样品测试结果显示,方法的相对标准偏差(n=6)为:氟离子≤2.5%,氯离子≤2.4%。电铅灰中共存离子对氟离子和氯离子的测定无干扰。该方法用于电铅灰中氟和氯的同时测定,具有很好的可行性和实用性。

不同粒径降尘中痕量金属元素Cu、Pb、Zn、Cr的形态分析

运用Ｔｅｓｓｌｅｒ形态分类法和石墨炉原子吸收分光光度法研究了不同粒径降尘样品中痕量金属元素Ｃｕ、Ｐｂ、Ｚｎ、Ｃｒ的存在形态，讨论了不同存在形态的分布规律。结果表明，Ｃｕ、Ｐｂ、Ｚｎ、Ｃｒ在降尘中的主要形态按顺序分别为有机结合态、铁锰氧化物结合态、铁锰氧化物结合态、残渣晶格态，其活性顺序为Ｚｎ＞Ｐｂ＞Ｃｕ＞Ｃｒ；４种元素的可交换态、碳酸盐结合态、铁锰氧化物结合态在小颗粒中的分布均比在大颗粒中占优势，说明小颗粒中金属元素较为活泼，其环境危害性更大。

铅蓄电池生产企业的清洁生产审核

介绍了某铅蓄电池生产企业按照清洁生产审核程序的7个阶段开展的清洁生产审核工作,分别对企业含铅废气、含铅废水和含铅危险废物污染源进行了排查,采用铅平衡核算、与清洁生产标准进行指标对比等方法查找问题并进行原因分析,提出改进方案。实施清洁生产方案后企业废水产生量为0.10 m3/(kV.A.h)(以生产单位电功率铅蓄电池产生的废水量计),总铅产生量为0.35 g/(kV.A.h),铅尘处理系统除尘效率达98%以上,年减少含铅废酸液产生量50 t,年减排铅尘3.2 kg,年节约成本50万元以上。