电解锰渣浆液烟气脱硫性能及机制

电解锰渣是电解锰生产过程中产生的锰矿石酸浸渣,富含锰、铁等活性组分,理论上可催化氧化SO₂实现烟气脱硫,同时脱硫后的电解锰渣可资源化利用,然而目前尚未见电解锰渣矿浆脱硫的研究报道。本文研究了工艺参数对电解锰渣浆液脱除SO₂性能的影响,探究了电解锰渣浆液烟气脱硫的过程机制。结果表明：锰渣粒径为200目（<75μm）、锰渣浆液初始浓度5000mg/L、气体流量400mL/min、进口SO₂体积分数0.20％、反应温度50℃、反应时间180min的条件下,电解锰渣浆液脱硫率最高可达93.87%。脱硫前后电解锰渣XRD、SEM、XPS表征结果表明,MnO₂、MnO、Fe₂O₃等活性组分参与SO₂反应,且浆液中的Mn²⁺、Fe³⁺等过渡金属离子液相催化氧化SO₂生成H₂SO₄,实现烟气脱硫。     

铁强化电解锰阳极液体系中氧化锰矿烟气脱硫和锰浸出工艺

结合电解锰生产工艺,以氧化锰矿为原料,以电解锰生产过程产生的电解阳极液废水配置烟气脱硫浆液,在其中添加FeSO₄强化电解锰阳极液体系下氧化锰矿烟气脱硫及浸锰能力,探讨铁强化氧化锰矿烟气脱硫和浸锰的工艺条件对烟气SO₂脱除和锰浸出的影响机制。研究发现FeSO₄的加入,通过FeSO₄与MnO₂之间的氧化还原反应以及产物三价铁离子和二价锰离子的协同催化作用,可同时提高锰矿烟气脱硫效率和锰的浸出率。锰矿粒径越小,脱硫及浸锰效率越高。温度升高,氧化锰矿浆液烟气脱硫率逐渐下降,浸锰率则先升高后下降,并在60℃时达到最大。浆液液固比和烟气流量的增大均会导致烟气脱硫率的下降,但会提高氧化锰矿浸锰率。进口SO₂浓度过高会导致脱硫率下降,但更有利于浸锰。采用5级逆流吸收对7%的烟气进行铁离子强化氧化锰浆脱硫,得到最终SO₂出口浓度293μL/L,溶液Mn²⁺浓度为44.72g/L,满足电解要求。铁强化电解锰阳极液体系有效回收利用了电解锰生产废水,不仅集脱硫浸锰工艺为一体,且可实现脱硫和浸锰效率的同时提升,为电解锰行业的清洁生产和资源综合利用提供理论依据和技术参考。     

基于α-FeOOH催化H2O2蒸气的低温烟气脱硝实验

针铁矿是分布广泛、储量丰富的铁氧化物，其主要成分为α-羟基氧化铁（α-FeOOH）。为了探究针铁矿在催化H₂O₂烟气脱硝反应中的性能，本文通过沉淀-水解法制备了α-FeOOH，并在自行搭建的实验台上开展了α-FeOOH催化H₂O₂的低温烟气脱硝实验研究，深入分析了H₂O₂流量、H₂O₂浓度、汽化温度、反应温度和共存气体浓度等工况参数对脱硝性能的影响。采用离子色谱（IC）分析了单独脱硝反应和同时脱硫脱硝反应后的含氧酸成分，结合各项表征分析技术考察了催化剂反应前后的理化特性和稳定性。实验结果显示，随着汽化温度和反应温度的升高，NO的脱除效率先增加后降低；增加H₂O₂浓度对脱硝效率有明显的促进作用。当汽化温度为140℃、反应温度为160℃时，以2.5mL/h注入10mol/L的H₂O₂脱硝效率达到80%。当SO₂浓度为1000μL/L时，脱硝效率提高至86.4%。离子色谱分析结果显示，单独脱硝反应和同时脱硫脱硝反应后含氧酸产物为HNO₃和H₂SO₄。反应前后催化剂的表征结果显示，α-FeOOH在脱硝反应后依然具有良好的稳定性，显示出针铁矿在低温烟气脱硝工艺中的潜在应用前景。     

Deactivation by SO2 of MnOx/Al2O3 catalysts used for the selective catalytic reduction of NO with NH3 at low temperatures

Low loaded alumina supported manganese oxides exhibit a high activity and selectivity for the selective catalytic reduction (SCR) of NO in the temperature range 383–623 K. The impact of low concentrations of SO₂ on the activity of these catalysts has been investigated. Upon SO₂ addition to the flue gas, the catalysts lose their high initial activity in a few hours due to stoichiometric SO₂ uptake. Analysis of the deactivated samples by mercury porosimetry, FTIR, TPR and TPD shows that the deactivation is not due to the formation of (bulk or surface) Al₂(SO₄)₃ or deposition of ammonium sulphates. Comparison of the results with unsupported Mn₂O₃ and MnO₂ provides evidence that formation of surface MnSO₄ is the main deactivation route. This process is independent of the oxidation state of the manganese and the presence of oxygen in the gas stream. The formed sulphates decompose at 1020 K and are reduced by H₂ at temperatures above 810 K. This means that regeneration of the catalysts is not very feasible. The results restrict practical application of these catalysts to sulphur free conditions.     

硫酸锰室温固相球磨制备四氧化三锰

利用软锰矿吸收硫酸镁热解尾气二氧化硫制得硫酸锰,再与碳酸氢铵室温下固相球磨反应,制备出前躯体碳酸锰,经热分解获得四氧化三锰。分别考察了物料比、球磨时间、球料比等因素对硫酸锰转化率的影响,采用XRD对产物进行了分析。结果表明,在n（碳酸氢铵）∶n（硫酸锰）=3.5∶1、球磨时间为40 min、球料质量比为5∶1时,硫酸锰的转化率可达99.8%,将固相产物在1 000 ℃热解1 h后所制备的四氧化三锰纯度为99.9%。该工艺操作简单,产品纯度高,成本低,为硫酸锰制备四氧化三锰提供了新的途径。     

Catalyst screening for oxidative desulfurization using hydrogen peroxide

Oxidation of a mixture of thiophene, benzothiophene and dibenzothiophene with hydrogen peroxide using supported Pd, Cr₂O₃, unsupported manganese oxides and a commercial Co-Mo/Al₂O₃ as catalysts has been studied in a mixture of hexadecane and acetonitrile. Based solely on the conversion of each organic sulfur compound, the ranking of catalyst efficiency found was: supported Pd > Cr₂O₃ ≈ manganese oxides ≈ Co-Mo/Al₂O₃. The influence of the calcination temperature on synthesized manganese oxides was also investigated. Mn₃O₄, amorphous manganese compounds, Mn₂O₃ and MnO₂ showed a similar catalytic activity independent of the hydrogen peroxide concentration. According to these preliminary results, it seemed that the catalyzed decomposition of the hydrogen peroxide competes with the oxidative desulfurization, however, at short reaction time (10 min) conversions at around 60–70% of thiophene were reached.     

Oxidative leaching kinetics of molybdenum-uranium ore in H2SO4 using H2O2 as an oxidizing agent

The processing of molybdenum-uranium ore in a sulfuric acid solution using hydrogen peroxide as an oxidant has been investigated. The leaching temperature, hydrogen peroxide concentration, sulfuric acid concentration, leaching time, particle size, liquid-to-solid ratio and agitation speed all have significant effects on the process. The optimum process operating parameters were: temperature: 95°C; H₂O₂ concentration: 0.5 M; sulfuric acid concentration: 2.5 M; time: 2 h; particle size: 74 μm, liquid-to-solid ratio: 14 ∶ 1 and agitation speed: 600 rpm. Under these experimental conditions, the extraction efficiency of molybdenum was about 98.4%, and the uranium extraction efficiency was about 98.7%. The leaching kinetics of molybdenum showed that the reaction rate of the leaching process is controlled by the chemical reaction at the particle surface. The leaching process follows the kinetic model 1 ? (1?X)^1/3 = kt with an apparent activation energy of 40.40 kJ/mole. The temperature, concentrations of H₂O₂ and H₂SO₄ and the mesh size are the main factors that influence the leaching rate. The reaction order in H₂SO₄ was 1.0012 and in H₂O₂ it was 1.2544.     

超低排放燃煤电厂中SO3的迁移及脱除特征

燃煤烟气中的SO₃会对机组运行及大气环境造成不利影响。为研究燃煤电厂SO₃排放特征，本文采取异丙醇吸收法对某300MW超低排放机组污染物控制装置进出口SO₃采样，以分析SO₃在燃煤机组中的迁移及脱除特性。结果表明：炉膛燃烧过程以及选择性催化还原装置（selective catalytic reduction，SCR）均将部分SO₂转化为SO₃，炉膛燃烧生成SO₃的质量浓度为SO₂的0.86%，SCR内SO₂/SO₃转化率为0.45%。烟气经过空气预热器，SO₃浓度降低了5.7%；静电除尘器（electrostatic precipitator，ESP）脱除SO₃效果较差，主要由于ESP内烟温在110℃以上，H₂SO₄酸雾凝结量较少；双级湿法脱硫装置（wet flue gas desulfurization，WFGD）对SO₃脱除效率达到81.3%，比国内单级脱硫装置SO₃脱除效果高30%～50%；湿式静电除尘器（wet electrostatic precipitator，WESP）脱除SO₃效率为23.0%。机组烟囱排放SO₃质量浓度为2.025mg/m³（标准），SO₃排放因子EF为0.034kg/t。     

Microbial removal of sulfur dioxide from a gas stream

A study of the feasibility of utilizing the Thiobacillus ferrooxidans or Desulfovibrio desulfuricans bacterium for microbial removal of sulfur dioxide from flue gases has been carried out. Sulfur dioxide may be readily reduced to H₂S by contact with sulfate-reducing microorganisms in which Desulfovibrio desulfuricans were dominant in the first stage. The H₂S was then oxidized to sulfur by the ferric sulfate in a second stage where ferrous ions were regenerated. These results were compared to microbial oxidation of SO₂ from flue gases to sulfate by Thiobacillus ferrooxidans. The mechanisms for the reduction of SO₂ to H₂S in the presence of Desulfovibrio desulfuricans and the oxidation of SO₂ to H₂SO₄ in the presence of ferric sulfate and Thiobacillus ferrooxidans are discussed. Sulfuric acid or gypsum CaSO₄ · 2H₂O are byproducts from microbial flue gas desulfurization.     

硫酸-糖蜜酒精废液浸出软锰矿的动力学(英文)

The kinetics of reductive leaching of manganese from low grade pyrolusite in dilute sulfuric acid in the presence of molasses alcohol wastewater was investigated. The shrinking core model was applied to quantify the effects of reaction parameters on leaching rate. The leaching rate increases with reaction temperature, concentrations of H 2 SO 4 and organic matter in molasses alcohol wastewater increase and ore particle size decreases. The leaching process follows the kinetics of a shrinking core model and the apparent activation energy is 57.5 kJ·mol –1 . The experimental results indicate a reaction order of 0.52 for H2SO4 concentration and 0.90 for chemical oxygen demand (COD) of molasses alcohol wastewater. It is concluded that the reductive leaching of pyrolusite with molasses alcohol wastewater is controlled by the diffusion through the ash/inert layer composed of the associated minerals.     

Research on leaching rate enhancement and organic matter removal in wet-process phosphoric acid

In the process of wet-process phosphoric acid leaching, the product phosphoric acid appears black due to the incomplete carbonization of some organic matter. A novel type of catalytic oxidation wet-process phosphoric acid purification technology was proposed in this work. During the leaching process, the oxidant (H₂O₂) and catalyst (MnO₂) was added to form the peroxides such as ·OH and HO₂· in the transformation process, which can enhance the removal rate of organic matter and strengthen the leaching rate of phosphate rock. The different reaction conditions that affected the leaching rate of wet-phosphoric acid and the removal of organic matter were investigated. The results indicated that 96.9% of phosphate rock were leached under the optimum conditions of H₂O₂ dosage 0.08 ml/g, MnO₂/P mass ratio of 0.04, 80℃ and for 40 min. At the same time, the TOC remove rate reached 79%. The analysis mechanism showed that H₂O₂ will form H₃PO₄ · H₂O₂ peroxide with H₃PO₄ in the solution, and MnO₂ will react with it like Fenton to generate a large amount of ·OH, and then fully oxidized the black organic matter into CO₂ and H₂O. Organic matter “wrapped” on the surface of the phosphate rock is broken by ·OH, which promoted the leaching of phosphoric acid and enhanced the removal of organic matter.     

Preparation of nanosized Mn3O4/SBA-15 catalyst for complete oxidation of low concentration EtOH in aqueous solution with H2O2

A new heterogeneous Fenton-like system consisting of nano-composite Mn₃O₄/SBA-15 catalyst has been developed for the complete oxidation of low concentration ethanol (100 ppm) by H₂O₂ in aqueous solution. A novel preparation method has been developed to synthesize nanoparticles of Mn₃O₄ by thermolysis of manganese (II) acetylacetonate on SBA-15. Mn₃O₄/SBA-15 was characterized by various techniques like TEM, XRD, Raman spectroscopy and N₂ adsorption isotherms. TEM images demonstrate that Mn₃O₄ nanocrystals located mainly inside the SBA-15 pores. The reaction rate for ethanol oxidation can be strongly affected by several factors, including reaction temperature, pH value, catalyst/solution ratio and concentration of ethanol. A plausible reaction mechanism has been proposed in order to explain the kinetic data. The rate for the reaction is supposed to associate with the concentration of intermediates (radicals: OH, O₂⁻ and HO₂) that are derived from the decomposition of H₂O₂ during reaction. The complete oxidation of ethanol can be remarkably improved only under the circumstances: (i) the intermediates are stabilized, such as stronger acidic conditions and high temperature or (ii) scavenging those radicals is reduced, such as less amount of catalyst and high concentration of reactant. Nevertheless, the reactivity of the presented catalytic system is still lower comparing to the conventional homogenous Fenton process, Fe²⁺/H₂O₂. A possible reason is that the concentration of intermediates in the latter is relatively high.     

湿法磷酸浸出强化及有机质去除研究

在湿法磷酸浸出过程中由于部分有机物碳化不彻底，使产品磷酸呈现黑色。本文提出了一种新型的催化氧化湿法磷酸净化技术，即在湿法磷酸浸出过程中引入氧化剂（H₂O₂）及催化剂（MnO₂），基于转化过程中形成的·\mathrm{O}\mathrm{H}和\mathrm{H}{\mathrm{O}}_{\mathrm{2}}·等过氧化物实现对有机物的去除与浸出过程的强化。重点考察不同反应条件对湿法磷酸浸出率及有机质去除的影响。结果表明，浸出时间为40 min、反应温度为80℃、H₂O₂用量为0.08 ml/g、催化剂与磷矿的质量比为0.04时，磷矿浸出率可达96.9%；同时测定得到的TOC去除率达到79%。分析机理可得，H₂O₂会与溶液中的H₃PO₄形成H₃PO₄·H₂O₂过氧化物，MnO₂与之发生类Fenton反应，产生大量·\mathrm{O}\mathrm{H}，进而将黑色有机物充分氧化为CO₂和H₂O，打破有机物对磷矿颗粒表面的“包裹”，促进磷酸的浸出和有机物的去除。     

CeO2表面氧化转移FCC烟气中SO2的反应过程

为提高Ce基脱硫助剂对石油加工过程中流化催化裂化（FCC）烟气深度脱硫效果,采用实验与密度泛函理论（DFT）探究了SO₂、O₂在CeO₂表面的反应过程。通过60℃、200℃反应温度下SO₂、O₂与CeO₂的反应,对反应前后CeO₂样品的XRD、IR、XPS谱图比较分析,探索S、Ce的价态变化和相对含量转变规律,从而推测SO₂可能的反应路径。基于密度泛函理论模拟构造了O₂单分子和SO₂、O₂双分子在CeO₂（111）和MgAl₂O₄（111）O空位表面可能产生的吸附构型;利用LST/QST方法搜索SO₂氧化反应过程,计算各步反应能垒。结果表明CeO₂（111）相比MgAl₂O₄（111）具有更好的SO₂催化效果,其中CeO₂在反应中起到了晶格O传递作用,并进一步推断SO₃的脱附过程是整个反应的速率控制步骤。     

MnO2/NaY复合材料的制备及其对SO2脱除性能

以NaY分子筛为载体，MnO₂为活性组分，采用沉淀法制备MnO₂/NaY复合脱硫材料；通过X射线衍射（XRD）、扫描电子显微镜（SEM）、氮气吸附脱附法（N₂-吸附脱附）、X射线光电子能谱（XPS）、热重分析（TG）等手段进行材料的物理化学结构表征；使用容量法装置测试复合材料的脱硫性能；考察MnO₂不同负载量及不同反应温度对MnO₂/NaY复合材料脱硫性能的影响。结果表明：MnO₂/NaY复合材料的孔容越大，其脱硫性能越好；多孔珊瑚状MnO₂脱硫性能优于棒状MnO₂；随着MnO₂负载量及反应温度的增加，MnO₂/NaY的脱硫性能先增加后降低，MnO₂/NaY-41%在400℃时的脱硫性能最好，第1h脱硫量达到114.56mg {{}_{\mathrm{S}\mathrm{O}}}_{{}_2} /g_材料；500℃时复合材料脱硫性能下降，是由于脱硫反应过程中MnO₂分解生成Mn₃O₄；MnO₂/NaY比纯MnO₂拥有更好的脱硫性能，反应温度为300℃和400℃时，MnO₂/NaY-41%较纯MnO₂的第1h脱硫量分别提高28.3%和56.1%。MnO₂/NaY-41%复合材料在中低温下的高效脱硫性能有望应用于船舶尾气的深度脱硫。     

IN SITU LEACHING OF URANIUM USING DILUTE SULFURIC ACID AND MOLECULAR OXYGEN

The technical feasibility of in situ uranium leaching using dilute sulfuric acid and molecular oxygen has been assessed and the important process parameters examined by use of laboratory high pressure leaching columns.

The dilute H₂SO₄/O₂ lixiviant was effective in leaching uranium from the ore samples tested. The leaching process was chemical reaction rate limited and can be represented using pseudo first-order kinetics. The leaching rate constant is proportional to the proton concentration of the lixiviant.

Much of the uranium was leached from the ore before decomposition of carbonate minerals by the acid was complete. Acid consumption per pound of U₃O₈ increased sharply as the uranium recovery level exceeded 70%. There appears to be a minimum oxygen pressure for effective uranium leaching. A pressure of 2758 KPa was adequate for the ore samples tested     

Sulfur resource recovery based on electrolytic manganese residue calcination and manganese oxide ore desulfurization for the clean production of electrolytic manganese

An environmentally friendly and resource-conserving route to the clean production of electrolytic manganese was developed, in which the electrolytic manganese residue(EMR) was initially calcined for cement buffering;then the generated SO_2-containing flue gas was managed using manganese oxide ore and anolyte(MOOA) desulfurization; at last, the desulfurized slurry was introduced to the electrolytic manganese production(EMP). Results showed that 4.0 wt% coke addition reduced the sulfur of calcined EMR to 0.9%, thereby satisfying the cement-buffer requirement. Pilot-scale desulfurization showed that about 7.5 vol% of high SO_2 containing flue gas can be cleaned to less than 0.1 vol% through a five-stage countercurrent MOOA desulfurization. The desulfurized slurry had 42.44 g·L~(-) Mn~(2+) and 1.92 g·L~(-1) S_2 O_6~(2-), which was suitable for electrowinning after purification, and the purity of manganese product was 99.93%, satisfy the National Standard of China YB/T051-2015.This new integrated technology fulfilled 99.7% of sulfur reutilization from the EMR and 94.1% was effectively used to the EMP. The MOOA desulfurization linked the EMP a closed cycle without any pollutant discharge, which promoted the cleaner production of EMP industry.     

废旧混合锂电池正极材料还原酸浸行为研究

针对废旧混合锂电池正极材料中有价金属元素镍钴锰的高效分离浸出,设计开发了2种不同混合废料体系：LiCoO₂与Li （Ni_1/3Co_1/3Mn_1/3） O₂、LiMn₂O₄与Li （Ni_1/3Co_1/3Mn_1/3） O₂,研究了还原剂用量、硫酸初始浓度、浸出温度、液固比对浸出过程的影响。LiCoO₂与Li （Ni_1/3Co_1/3Mn_1/3） O₂混合废料较适宜浸出参数为：浸出温度80℃、反应时间90 min、H₂SO₄浓度2.3 mol·L^-1,液固比R=8 mL·g^-1、还原剂Na₂SO₃用量=1.2倍理论量;LiMn₂O₄与Li （Ni_1/3Co_1/3Mn_1/3） O₂组成的混合废料的较适宜浸出实验参数为：浸出温度60℃、反应时间90 min、H₂SO₄浓度2.3 mol·L^-1,R=8 mL·g^-1、还原剂Na₂SO₃用量=1.2倍理论量。得到的浸出规律为混合锂离子电池正极废料回收工艺的广泛适应性提供了参考思路。     

燃煤锅炉烟气中Na2SO4生成的化学动力学研究

准东煤燃烧过程中Na₂SO₄的形成会造成锅炉受热面沾污、尾部SCR催化剂失活等问题。烟气中Na₂SO₄形成及转化规律的研究对于预测和控制燃煤烟气中Na₂SO₄的形成有重要意义。发展了烟气中Na/Cl/S/O/H化学动力学模型,研究了烟气中Na₂SO₄的生成过程及转化机理,考察了含氧量、温度、SO₂浓度、H₂O浓度等因素对Na₂SO₄生成的影响。动力学计算结果表明,模型预测结果与实验数据吻合较好,验证了模型的准确性。烟气中的高氧气含量有利于Na₂SO₄的生成。高温加快化学反应的同时,抑制了Na₂SO₄的生成。SO₂和H₂O的影响效果受温度影响较大。反应路径分析表明,Na₂SO₄的生成路径有两个：一是依赖于SO₂直接氧化（NaCl→NaSO₃Cl→NaHSO₄→Na₂SO₄）,二是依赖于SO₂间接氧化（NaCl→NaO₂→NaSO₄→NaHSO₄→Na₂SO₄）。敏感性分析结果表明,Na₂SO₄的生成主要对系统中生成或消耗自由基的反应更为敏感。     

一种典型钒钛系SCR催化剂SO3生成特性研究

选择性催化还原（SCR）技术由于脱硝效率高、选择性好而被广泛应用于烟气氮氧化物排放控制;然而,目前广泛采用的钒钛系SCR脱硝催化剂会使烟气中SO₂氧化成SO₃,烟气中过高的SO₃对电厂安全运行会造成严重影响,也会对环境造成污染。以典型V₂O₅-WO₃/TiO₂催化剂为研究对象,系统研究了SCR脱硝过程中烟气流量、温度、O₂浓度、SO₂浓度等对催化剂表面SO₃生成特性的影响,并进一步对SO₃生成的反应动力学特性进行了分析。研究表明：催化剂表面SO₃生成反应中SO₂的反应级数为0.59,当O₂浓度大于3%时,O₂的反应级数为0,该反应的表观活化能为70.39 kJ/mol;实验条件下,烟气中SO₂浓度增加会使SO₃生成的反应速率提高;O₂浓度对催化剂表面SO₃生成影响并不显著;烟气温度对催化剂表面SO₃生成具有显著影响,高温会促进SO₃的生成。