Preparation of high purity cadmium with micro-spherical architecture from zinc flue dust

This research has focused on the treatment of zinc flue dust by an acid leach process, combining an environmentally suitable impurity removal process to recover cadmium. Optimum conditions were found as follows： H2SO4 concentration 90 g/L, liquid/solid ratio 6：1, leaching temperature 60 ℃ and leaching time 1.0 h. Under these conditions, 95.8% cadmium was recovered. FeAsO4 and Fe（OH）3 precipitates with FeCI3 are found to be highly effective to obtain a high degree of separation of heavy metals and the oxyanions of arsenic from the leachate. The overall separation of arsenic and other heavy metals and precipitate settling rates are optimum at n（Fe）/n（As） ratio of 3：l and pH 6. The removal rates ofFe, Pb and Cu from the solution were greater than 98.9%, and As removal rate was 99.6%. A solvent extraction with P204 was used for the separation of zinc and cadmium. Optimum conditions are obtained as follows： 20% P204 （volume fraction） diluted with kerosene at room temperature, pH 3.0, and varying organic/aqueous （O/A） phase ratio 1：1. The extraction rate of zinc is 99.2% under these conditions. Spherical cadmium particles showing nearly uniform size were produced by hydrogen reduction at 310 ℃ and the crystal structure was cubic. In addition, the purity of the recovered cadmium powder is more than 99.99%.

Selective leaching of arsenic from copper converter flue dust by Na2S and its stabilization with Fe2(SO4)3

The alkaline leaching of arsenic (As2O3) by Na2S, together with its precipitation by Fe2(SO4)3 was studied. Response surface methodology based on central composite design was employed to quantify and qualify the effect of pertinent factors and to develop statistical models for optimization purposes. Based on the obtained results, 89% of arsenic is removed from the dust under following optimum predicted conditions: Na2S concentration of 100 g/L and solid to liquid ratio of 0.163 g/mL at 80 °C. It is found that solid to liquid ratio and Na2S concentration are the significant factors influencing the leaching process. In the precipitation process, more than 99.93% of arsenic from the leaching solution is removed in the form of amorphous ferric arsenate, at pH 4.8 when Fe3+ to arsenic and H2O2 to arsenic molar ratios are set at 5:1 and 4:1, respectively. Also, Fe3+ to arsenic ratio and pH are the most significant factors, and the interaction between these terms is significant.

Indium recovery from zinc oxide flue dust by oxidative pressure leaching

Indium was recovered from zinc oxide flue dust(ZOFD)with sulfuric acid by oxidative pressure leaching in an autoclave, and the effects of different technological conditions on indium leaching were studied.Potassium permanganate and hydrogen peroxide were used as oxidants.The atmospheric pressure leaching experiments were also carried out.The experimental results show that the leaching rate of indium can be effectively improved by oxidative pressure leaching.The optimum conditions of pressure leaching are determined as sulfuric 5.10 mol/L acid,leaching time 150 min,temperature 90℃,and the H2O2 dosage of 0.5 mL/g or 2.5%KMnO4.The leaching rate of indium is more than 90%,which is increased by 13%compared with that of atmospheric pressure leaching process without oxidant under the optimum conditions.

Leaching of gallium from corundum flue dust using mixed acid solution

In order to extract gallium from a high-silica-content flue dust generated in corundum production,a mixed acid solution of H2SO4 and HF was used for leaching,and test parameters of the leaching process were optimized.Experimental results show that the leaching rate of gallium was only 38%when H2SO4 was used as leaching agent.Composition analysis results of micro areas in this corundum flue dust indicate that the content of gallium in silica-enriched phases was high;this portion of gallium was insoluble in H2SO4 solution.The leaching rate of gallium increased significantly with addition of HF due to corrosion of silica.Effects of reaction time,temperature,and concentrations of HF and H2SO4 on leaching rates of gallium were investigated.The leaching rate of gallium reached 91%when this corundum flue dust was leached in a mixed acid solution of H2SO4 and HF for 4 h,at a temperature of 80°C,with a liquid-to-solid ratio of 5:1(mL/g).The optimal concentrations of H2SO4 and HF in the mixed acid solution were 1.5 and 6.4 mol/L,respectively.

The flue dust emission of the coal fired power plants in Zhejiang Province attains target

According to statistics, the average dust collection efficiency of flue gas emission in the large and medium- sized power plants in Zhejiang Province at present has attained higher than 97% which surpasses the 95% standard as stipulated by the Ministry of Electric Power. The dust collection efficiency of the Beilungang Power Plant has already attained 99.92%. In recent years, Zhejiang Electric Power Corporation has stipulated that all the newly constructed generating units shall be equipped with high efficiency electrostatic precipitator (ESP) while the existing power plants shall speed up their renovation work for their dust collectors. In combination with the fourth stage project of the Taizhou Power Plant, the improvement work of the dust

Recovery of gallium from phosphorus industry flue

The flue dust generated during electric furnace production of elemental phosphorus was investigated for the recovery of gallium. Then the flue dust was slurried with water and blended with concentrated sulfuric acid, followed by ageing. The gallium in the dust was thereby converted to soluble sulfate. The factors affecting the dust curing were investigated to understand the process chemistry of the pretreatment. The optimal curing conditions are determined as follows: the mass ratio of dust to water and acid is 1∶1∶1, ageing temperature and time are 200 ℃ and 2 h, respectively. Almost all the gallium available to acid dissolution in the dust, about 90% gallium, can be extracted by leaching the cured dust at 80 ℃ for 1 h.

Study on the System for Separating Sulfurfrom Flue Gas and Dust

This paper describes the structure of the system for separating sulfur from flue gas and dust. In the paper, the velocities of turbulent flow and laminar flow inside the tower, the total of liquid membrance, and the additional flow of rotation fogged fluid are calculated, and the separation of rotation air-solid affected by tower is analyzed. The velocity distribution in quasi free vortex area is obtained from experiment. The minimum separated particle diameter is computed. The paper also studies the chemical reactions of flue gas containing sulfide with the dynamic fogged sulfur separating agent and discusses the main factors related to the effect of separating sulfur and dust. At last, the applications of separating sulfur in industrial stove and collecting dust in environmental engineering are introduced.

基于YOLOv3的袋式除尘器滤袋破损自动检测方法

干式除尘装置中袋式除尘器的滤袋在长时间使用后会出现破损,造成能源消耗增加、除尘效率降低、污染环境等严重问题。为此,本文采用在除尘舱室处搭建粉尘烟雾检测摄像头,并基于YOLOv3算法检测袋口烟雾的泄漏情况。试验检测步骤:①根据真实除尘舱室尺寸设计袋式除尘器袋口烟雾泄漏实验室平台,采集不同洞口烟雾泄漏的图像数据;②使用软件标注这些图像数据;③搭建Darknet深度学习框架,采用YOLOv3算法对图像数据进行训练,并依据模型计算结果识别破袋情况。结果表明:模型对于批量图像的识别准确率能达到91%以上,对于连续视频的识别准确率可达95.65%。本文系统可以减少除尘器运行中的人工检测,降低工厂人力资源成本和工人劳动强度,可以避免生产中的安全隐患和损失,可以为工厂的生产安全及定期维护提供技术指导,也为全厂智能化生产提供了有效的方案。

铜冶炼烟尘金属分离及资源回收研究进展

以铜冶炼烟尘为研究对象,分析其理化及矿物学性质,对比铜冶炼烟尘金属分离与回收方法,包括碳热还原法、硫酸浸出法、碱性浸出法和湿法-火法联合工艺,总结各方法的原理、典型工艺、现状和存在问题,阐述非常规冶金方法在铜冶炼烟尘金属分离中的应用,展望铜冶炼烟尘资源回收的发展方向。研究结果表明:铜冶炼烟尘中砷、铜、锌含量受冶炼工艺、原矿品质的影响,不同元素赋存形态存在差异。碳热还原法可以通过金属砷酸盐和氧化物分解的方式释放砷,从而实现砷与其他有价金属的分离;硫酸浸出法可以高效浸提铜冶炼烟尘中的金属,实现多元素的回收;碱性浸出法可选择性浸提砷;湿法-火法联合工艺结合了火法工艺选择性分离砷和湿法工艺高效提取金属的优点,对于复杂高砷铜冶炼烟尘处理具有优势。铜冶炼烟尘兼具资源属性和环境风险,实现清洁生产及多金属资源化利用仍是关键,砷的无害化处置与锌、铜、铅等有价金属的高效协同回收工艺及分离机制、全过程物质流与环境效应是铜冶炼烟尘资源回收的发展方向。

HAMON电除尘器故障分析及应对措施

HAMON电除尘器可用于处理催化裂化烟气中的催化剂粉尘。由于催化裂化装置四年一修,电除尘器不能随时停运检修,因此针对HAMON电除尘器的运行情况进行研究,对于保障电除尘器及催化裂化装置的长周期稳定运行具有重要意义。在运行过程中,电除尘器出现电流和电压降低的问题。对故障原因进行分析,并在电除尘器停运后进行检查,发现:腐蚀泄漏导致电除尘器内部烟气湿度大。制定了检查、检修项目,更换了配件,同时结合冷态试验结果,调整了电除尘器的电流、电压、振打周期和振打力度。检修开工后,电除尘器入口粉尘质量浓度53.3 mg/m^(3),出口粉尘质量浓度4.8 mg/m^(3),远低于设计值(30 mg/m^(3))。检修开工至今超过2 a,电除尘器运行平稳,未出现任何故障,实现了长周期稳定运行。

高钛渣密闭直流电炉烟气除尘干法改造实践

以30 MVA高钛渣密闭直流电炉烟气净化回收系统为对象,分析了原湿法除尘流程的特点,给出了干法除尘改造方案,结合改造实施过程,论述了干法除尘系统的配置要点,并对改造前后的系统运行效果进行了对比。结果表明:烟气干法除尘净化回收系统能够适应密闭直流电炉的冶炼工况,无需进行污水污泥处理,减少了药剂和水电消耗,降低了运行成本;回收烟尘为干颗粒,可直进入配料系统二次冶炼;净化后的烟气含尘量降低到5 mg/m^(3)以下,达到了大气颗粒物超低排放标准。

pH对铜冶炼烟尘中重金属浸出行为的影响及其矿物学控制机理

以某废弃铜冶炼厂收集的铜冶炼烟尘作为样本,采用TCLP毒性浸出和宽溶液pH(3~13)范围浸出实验,研究了铜冶炼烟尘中重金属的释放行为及其矿物学控制机制。结果表明,TCLP浸出液中As、Cd、Cu、Pb和Zn浓度分别是我国《危险废物鉴别标准浸出毒性鉴别》(GB 5085.3—2007)中相应元素限值的704倍、82.7倍、2.08倍、3.1倍和3.26倍。在整个溶液pH处理范围内,As的释放率高达26.0%~28.1%。在酸性条件下Cd、Cu和Zn的浸出率明显较高,而Pb在pH 13.0时释放率较高。地球化学分析表明,在pH 5.5~11.5的溶液处理下,As的溶解度部分受新形成的Ca、Cu、Pb和Zn砷酸盐控制,而Cd、Cu、Pb和Zn的溶解度主要受碱性条件下氢氧化物沉淀形成控制。BCR顺序提取和XRD分析表明,浸出液中Cd和Zn浓度较高与其在灰尘中赋存活性态比例高一致。研究结果为烟尘处理或处置防止重金属污染提供科学指导。

光学成像烟气粉尘分析仪在催化装置的应用

催化装置烟气中催化剂粉尘浓度和分布如不能被准确监测,会导致烟机结垢,频繁停机检修。某催化装置应用了一种光学成像烟气粉尘分析仪来测定三旋分离器分离后烟气中的催化剂粉尘含量和分布,介绍了该光学成像烟气粉尘分析仪的工作原理、结构以及主要功能。实际应用表明:该分析仪能够实现准确测量烟气中的催化剂粉尘浓度和分布情况,为催化烟气粉尘测定提供新的方法。

高频燃烧红外吸收法检测铜冶炼烟灰中的硫

建立了高频燃烧红外吸收法检测铜冶炼烟灰中的硫分析方法。该试验过程中选择称量0.05~0.06 g样品,加入0.05 g纯铁助熔剂、0.15 g钨粒。将混合试样放入高频燃烧炉中,在富氧条件下高频感应加热燃烧,硫被转化为二氧化硫,气体通过高和低含量的二氧化硫红外检测室检测含量。标准加入法得到硫系数在0.95~1.05之间,该方法的检出限为0.003 3%,相对误差小于1.37%,相对标准偏差小于1.65%(n=11)。此方法操作简单、检测时间短、适合批量检测,结果准确,可满足快速检测的分析要求。

玻纤覆膜滤料研究进展及应用

袋式除尘器被广泛应用于工业除尘领域,其滤料的性能是影响除尘效果的关键因素。玻璃纤维覆膜滤料结合了玻璃纤维及PTFE薄膜材料的优点,为PTFE薄膜提供支撑力,PTFE薄膜孔径小能够实现对粉尘的表面过滤,因此被广泛用作工业除尘滤料。本文综述玻纤覆膜滤料的结构及组分特征、玻纤覆膜滤料在工业除尘领域的应用,分析各工业领域烟气产生特性并阐述玻纤覆膜滤料在各个行业的研究现状,并对玻纤覆膜滤料提出展望。

杂质锌对顶吹炉铜熔炼系统的影响

鉴于杂质锌对顶吹炉生产中产品质量和生产率的不利影响,系统研究了入炉精矿中锌含量对铜熔炼顶吹炉系统冰铜、炉渣、烟尘的影响。结果表明,随着入炉精矿中锌的平均品位由0.88%上升至3.59%:冰铜中锌含量由0.68%上升至2.16%,不利于后续降低吹炼渣及精炼渣中铜含量;电炉渣中的锌含量由2.02%上升至5.80%,将导致更多的含锌铁尖晶石固相在高温下析出,使炉渣熔化温度出现升高趋势;上升烟道烟尘中锌含量增至3.34%,含锌物相增加将引入高熔点、高黏度锌铁尖晶石,诱发半熔融状或致密坚硬的结瘤物产生,难以破碎清除;电收尘系统烟尘率由0.96%提升至6.88%,烟尘中锌含量由4.25%增至8.44%,增加电收尘系统负担,降低除尘效率。

粉尘浓度高对于电厂脱硫系统的影响分析与改造

为保障脱硫系统的高效稳定运行,阐述平海电厂吸收塔系统的工艺流程与反应原理,分析粉尘浓度高对脱硫系统的不利影响。提出优化的石膏一级脱水系统,用以解决排废水与产石膏之间的矛盾,通过新增一路直排到废水处理系统,提升吸收塔浆液品质,又保证石膏品质。实践表明,此技术改造方法可行。

烟气除尘技术在大气污染治理过程中的应用思考

在社会发展过程中,随着城市化进程的加快及工业的发展,废气排放总量不断增加,造成了严重的大气污染,因此大气污染治理十分必要,需要相关人员结合实际进行方案设计。而在实际治理环节,由于大气污染的类型较多、总量较大,治理存在一些难点,相关人员应通过烟气除尘技术对大气污染进行治理,实现对环境的保护。本文从大气污染治理入手,浅谈烟气除尘技术的必要性及优势。相关人员应结合大气治理的需要,合理安排烟气除尘技术,发挥其优势,实现对大气污染的治理。

负压大布袋除尘器在高纯硅冶炼烟气净化系统中的应用

本文就负压大布袋除尘器在高纯硅冶炼烟气净化系统应用情况展开了研究,介绍了负压大布袋除尘器技术的技术原理,通过负压大布袋除尘器与正压布袋除尘器对比,并结合实际应用情况表述了负压大布袋除尘器在应用中的优势,为高纯硅冶炼企业选择烟气净化设备提供参考.

燃煤焦化厂烟气脱硫吸收塔内过程优化及湿电除尘技术研究

为提高吸收塔脱硫效率,开展燃煤焦化厂烟气脱硫吸收塔内过程优化及湿电除尘技术的研究。选择某燃煤焦化厂内2×1 000 MW机组作为研究对象,建立燃煤焦化厂烟气脱硫喷淋塔几何结构模型,从反应区容积、喷淋浆液速度、喷淋负荷等多个角度分析烟气脱硫吸收塔的脱硫效率,得到结论:设置一三层、一二三层喷淋方式,且喷淋浆液速度为9 m/s,喷淋负荷在100%~160%之间,可以使燃煤焦化厂烟气吸收塔脱硫效果达到最佳。在此基础上,按照烟气预处理、电场荷电、湿式收集、连续清灰、排放与监控等步骤,进行湿电除尘技术的应用,实践证明此项技术的应用不仅能够高效去除烟气中的粉尘颗粒,达到环保标准的要求,还能够降低能耗、提高焦化厂的运行稳定性。