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1.
Rongrui Deng Hao Xiao Zhaoming Xie Zuohua Liu Qiang Yu Geng Chen Changyuan Tao 《中国化学工程学报》2020,28(8):2208-2213
Long-term high temperature in conventional vanadium extraction process would cause particles to be sintered and wrapped, thus reducing extraction efficiency of vanadium. Based on the purpose of directional conversion and process intensification, this work proposed a combination of low temperature sodium roasting and high efficiency selective oxidation leaching in vanadium extraction. The investigation of the reaction mechanism suggested that the structure of vanadium slag was changed by roasting, which also caused the fracture of spinel. The addition of MnO2 promoted the directional oxidation of low-valent vanadium into high valence. It also found that Na2S2O8 could oxidize low-valent vanadium effectively in leaching. The leaching efficiency of vanadium reached 87.74% under the optimum conditions, including a roasting temperature of 650 °C, a roasting time of 2.0 h, a molar ratio of sodium-to-vanadium of 0.6, a MnO2 (roasting additive) dosage of 5 wt% and a Na2S2O8 (leaching oxidant) dosage of 5 wt%. This percentage is 7.18% higher than that of direct roasting-and-leaching under the same conditions. 相似文献
2.
钒铬还原渣是钠化提钒过程的典型危险固体废弃物,其资源化利用需求迫切。中国科学院过程工程研究所提出钒铬还原渣硫酸酸解-钒铬初步分离-铬/钒/铁络合深度分离技术路线,并在攀钢集团建成万吨级示范工程。本文重点考察钒铬还原渣酸解液中钒铬初步分离原理及工艺,研究了H2O2和Na2S2O8两种氧化剂对沉钒效果的影响,并通过实验确定了最佳工艺条件。结果表明:以H2O2为氧化剂时,H2O2与钒摩尔比为0.75、氧化温度为60℃、初始溶液pH为2.0、氧化时间为60min、水解温度为95℃、水解时间为2.5h的条件下可得到84.2%的沉钒率;以Na2S2O8为氧化剂时,Na2S2O8与钒摩尔比为0.65、氧化温度为90℃、氧化时间为45min、沉钒初始溶液pH为2.5、沉钒温度为90℃、沉钒时间为2.5h的条件下可获得93.1%的沉钒率。过硫酸钠氧化过程温和,沉钒率高,铬损失小,更适合工业推广应用。采用SEM获得了沉淀产物的微观形貌,煅烧后得到V2O5产品,采用XRF获得了产品组成,通过X射线衍射确定得到的V2O5产品为正交晶型。 相似文献
3.
通过煅烧-碱浸法从钒铬还原渣中分离回收钒铬,考察了煅烧反应过程并探讨了煅烧-碱浸条件对浸出钒的影响。结果表明:煅烧过程中Cr(Ⅲ)和V(Ⅳ) 反应生成中间产物CrVO4,随后CrVO4分解为Cr2O3和V2O5;相同浓度条件下,在V2O5浸出效果方面NaOH要优于Na2CO3,提高浸出介质浓度和延长浸出时间有利于V2O5的浸出,而浸出温度对V2O5浸出无明显影响,钒铬还原渣在850℃煅烧1.5 h后经3 mol·L-1 NaOH在90℃浸出1.5 h,滤渣中的Cr2O3质量分数高于96%,钒、铬的浸出率分别为87.3%和小于1%,另外,利用酸性铵盐法能够沉淀滤液中97%的钒。 相似文献
4.
Compared with traditional sodium or calcification roasting process for vanadium extraction from raw vanadium slag (V-slag), ammonium sulfate (AS) roasting could reduce about 470℃ roasting temperature and avoid Cl2, HCl, sodium-containing waste-water and waste gypsum discharging. To reduce the amount of AS added in vanadium extraction process, an efficient AS two-stage cyclic roasting and acid leaching process was proposed. The result of TG analysis indicates V-slag could be decomposed in 275-380℃ using AS roasting process. Using 2.03:1 total mass ratio of AS to V-slag, 90.86% V and 80.54% Ti could be extracted after 380℃ roasting for 30 min and 8% initial concentration of H2SO4 leaching at 70℃ for 100 min. XRD analysis indicates V-containing spinel phase in the 1st stage leaching residue would be efficiently decomposed by the cyclic two-stage roasting and leaching process. Furthermore, the valence of V(III) in raw V-slag was not changed after the 1st AS roasting stage, but a part of V(III) in the 1st leaching residue was oxidized to V(V) after 2nd roasting process. 相似文献
5.
Na2S2O3是湿法脱硫过程外排废液中最主要的副盐,降低Na2S2O3的生成量对绿色生产具有重要意义。首先采用Plackett-Burman实验筛选出影响Na2S2O3生成量的关键因素,即pH、单质硫浓度、温度。在此基础上运用响应曲面法,以Na2S2O3生成量为目标函数,进行三因素三水平的优化设计分析。研究结果表明,pH对Na2S2O3的影响最大,其次是温度和单质硫浓度,因子间交互作用的影响很小。得到最优的操作条件为pH 8.25,单质硫浓度0.47 g/L,温度31.80℃,PDS浓度90 mg/L,氧硫比1.2 mmol/mmol,此时Na2S2O3生成量为1.838 mmol/L。从Na2S2O3反应动力学和多硫离子的平衡反应两方面对各因素的影响规律进行了解释。最后对实际生产过程进行分析,发现实验得出的pH过低,不利于吸收过程的稳定,现有单质硫熔融分离方法不利于降低脱硫液中的单质硫含量,加速了副盐的生成等问题,对此提出了改进意见,并取得了显著效果。 相似文献
6.
介绍了当前电子废弃物中常用的浸金方法及其优缺点, 分析了电子废弃物中硫代硫酸盐法浸金的研究现状。针对这一研究现状, 本文采用碱性Na2S2O3溶液中添加Cu2+的方法, 对废旧IC(integrated circuit)芯片中金的浸出进行了试验研究。通过对IC样品进行机械预处理、粒度分析、解离度分析、化学预处理和浸金试验, 探讨了Na2S2O3浓度、Cu2+浓度、NH3浓度、浸出温度、浸出时间和反应液固比6个因素对金浸出率的影响。试验得出最佳浸金条件为:Na2S2O3浓度0.3mol/L, Cu2+浓度0.03mol/L, NH3浓度0.5mol/L, 添加3.5g/L的Na2SO3作为稳定剂, 浸取温度50℃, 浸取时间2.5h, 液固比10:1, 在最佳浸出条件下, 金的最高浸出率为92.25%。与传统方法相比, 该方法具有浸出速度快、浸出液无毒、操作简单等优点, 是一种具有开发潜力的电子废弃物浸金方法。 相似文献
7.
Margarita Hincapi Prez Gustavo Peuela Manuel I. Maldonado Octavio Malato Pilar Fernndez-Ibez Isabel Oller Wolfgang Gernjak Sixto Malato 《Applied catalysis. B, Environmental》2006,64(3-4):272-281
Alachlor, atrazine and diuron dissolved in water at 50, 25 and 30 mg/L, respectively were photodegraded by Fe2+/H2O2, Fe3+/H2O2, TiO2 and TiO2/Na2S2O8 treatments driven by solar energy at pilot-plant scale using a compound parabolic collector (CPC) photoreactor. All the advanced oxidation processes (AOPs) employed mainly compared the TOC mineralisation rate to evaluate treatment effectiveness. Parent compound disappearance, anion release and oxidant consumption are discussed as a function of treatment time. The use of Fe2+ or Fe3+ showed no influence on the reaction rate under illumination and the reaction using 10 or 55 mg/L of iron was quite similar. TiO2/Na2S2O8 showed a quicker reaction rate than TiO2 and a similar rate compared to photo-Fenton. The main difference found was between TiO2/Na2S2O8 and photo-Fenton, detected during atrazine degradation, where pesticide transformation into cyanuric acid was confirmed only for TiO2/Na2S2O8. 相似文献
8.
采用臭氧氧化结合湿法喷淋硫代硫酸钠溶液的方法开展模拟烟气同时脱硫脱硝实验研究。结果表明,采用臭氧氧化结合Na2S2O3-NaOH溶液湿法喷淋可以实现NOx和SO2协同脱除:在O3/NO摩尔比为1.1~1.2时,溶液中Na2S2O3浓度的增加会提高系统的NOx脱除效率,烟气中SO2的存在会促进NOx的脱除,当SO2浓度为1030 mg·m-3、2.0%Na2S2O3溶液作为喷淋液时可实现较高的SO2脱除效率,同时NOx脱除效率可达70%以上;喷淋液pH在2.5~9范围内变化时提高浆液pH有利于NOx的脱除,当pH 9时脱硝效率可达75%。180 min连续同时脱硫脱硝实验结果表明,硫代硫酸钠可有效促进NOx的脱除,并实现SO2较高的脱除效率,同时可实现系统同时脱硫脱硝连续稳定运行,喷淋吸收后烟气中NOx的主要转化产物为NO2-, 该方法作为一种有效的同时脱硫脱硝技术,具有一定的工业应用推广前景。 相似文献
9.
A process of simultaneous desulfurization and denitrification of flue gas was conducted in this study. The flue gas containing 200 mg·m-3 NO, 1000-4000 mg·m-3 SO2, 3%-9% O2, and 10%-20% CO2 was first oxidized by O3 and then absorbed by ammonia in a bubbling reactor. Increasing the ammonia concentration or the SO2 content in flue gas can promote the absorption of NOX and extend the effective absorption time. On the contrary, both increasing the absorbent temperature or the O2 content shorten the effective absorption time of NOX. The change of solution pH had substantial influence on NOX absorption. In the presence of CO2, the NOX removal efficiency reached 89.2% when the absorbent temperature was raised to 60 °C, and the effective absorption time can be maintained for 8 h, which attribute to the buffering effect in the absorbent. Besides, both the addition of Na2S2O3 and urea can promote the NOX removal efficiency when the absorbent temperature is 25 °C, and the addition of Na2S2O3 had achieved better results. The advantage of adding Na2S2O3 became less evident at higher absorbent temperature and coexistence of CO2. In all experiments, SO2 removal efficiency was always above 99%, and it was basically not affected by the above factors. 相似文献
10.
Research on leaching rate enhancement and organic matter removal in wet-process phosphoric acid
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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. 相似文献
11.
R. S. G. Ferreira P. G. P. de Oliveira F. B. Noronha 《Applied catalysis. B, Environmental》2001,29(4):209-283
The nature of the vanadium species present on V2O5/Al2O3 catalysts was investigated by using solid state 51V NMR, diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD) and temperature programmed reduction (TPR). 51V NMR and DRS analyses indicated the presence of V5+ in tetrahedral symmetry at low vanadium loading. A surface polymeric vanadium species and/or the bulk crystalline V2O5 were mainly observed at high vanadium loading as also detected by XRD. The positions of the absorption edges determined through the UV–VIS spectra allowed distinguishing between various tetrahedral symmetries. After TPR, the average oxidation state of vanadium depended on the vanadium content. The nature of vanadium species was related to the catalyst behavior on the benzene oxidation reaction. The catalysts containing high vanadium content were more active suggesting that a high amount of V4+ is responsible for the higher activity. 相似文献
12.
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·OH和HO2·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·OH,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。 相似文献
13.
在玻璃鼓泡反应器中进行Na2S2O8和H2O2两种混合氧化剂吸收SO2和NO的实验研究,结果表明:在Na2S2O8氧化剂中加入H2O2可以促进脱硫脱硝,考虑溶液的成本以及系统的整体脱硫脱硝总效率,选取质量分数为2%的H2O2和10%的Na2S2O8混合液具有较高的性价比。基于数值模拟的方法,将扭带引入鼓泡反应器中,研究扭带直径、厚度和扭率对鼓泡反应器脱硫脱硝效率的影响。数值模拟结果表明,与普通鼓泡反应器相比,加入扭带促进脱硫脱硝的效果。脱硫脱硝效率随着扭带直径和扭带厚度的增大而增大,随着扭带扭率的增大而减小,当扭带的直径从16mm增加到24mm时,系统的脱硫率和脱硝率分别增加了3.88%和3.45%;当扭带的厚度从0.2mm增加到1mm时,系统的脱硫率和脱硝率分别增加了4.27%和1.62%;当扭带的扭率从0.25增加到0.75时,系统的脱硫率和脱硝率分别降低了3.91%和1.90%。 相似文献
14.
Manganese leaching during high concentration flue gas desulfurization process with semi-oxidized manganese ore was studied in this paper. It was found that there were different reaction pathways among which MnO_2,Mn_2O_3 and MnCO_3 in semi-oxidized manganese ore during flue gas desulphurization and manganese leaching.High SO_2 concentration facilitated redox reaction between MnO_2 and SO_2, and high concentration of H_2SO_4 accelerated MnCO_3/Mn_2O_3 leaching from semi-oxidized ore. Kinetics study showed that manganese leaching in flue gas desulfurization process with semi-oxidized ore was controlled by a mixed-control model, that is the surface chemical reaction and mass diffusion dominated both the oxidation of SO_2 and manganese leaching process. The apparent activation energy was 13.05 k J·mol~(-1) and the reaction orders with respect to SO_2 and H_2SO_4 concentration were 1.38 and 0.10, respectively. Finally, a semi-empirical rate equation based on shrinking core model was derived to describe the process. 相似文献
15.
在亚熔盐生产线达产达效期间,对钒渣液相氧化、液固分离、钒酸钠结晶、三效蒸发等工序进行了研究。结果表明,在纳微曝气氧化及规模放大效应共同作用下,亚熔盐示范工程可实现较低温度(140~180℃)和较低压力(0.6~1.0 MPa)下钒和铬的高效同步提取,钒和铬的转化率分别为93%和85%;对不同原料来源的钒渣,纳微曝气亚熔盐技术均体现出优异的浸出性能;全自动立式压滤机采用三级逆流洗涤方式,保证了尾渣含水率低于30wt%,钒含量低于0.15wt%,铬含量低于0.05wt%;选用OSLO冷却结晶器进行钒酸钠结晶,钒酸钠结晶率达到61.5%;通过在三效系统蒸汽接口处增设减温减压器,实现循环碱液浓度由试生产初期的45wt%提高至50wt%。利用亚熔盐产线对传统钠化焙烧工艺废水处理过程中产生的钒铬泥进行钒铬浸出,在反应温度175℃、反应压力0.65 MPa、进出料速度0.25 t/h的工作条件下实现了钒铬泥中钒和铬的高效浸出,钒和铬的浸出率分别为93.68%和96.76%。当溶液中铬浓度达到25~30 g/L后,铬酸钠结晶工序可保证将每次液相氧化反应溶出的铬全部结晶析出,铬酸钠的结晶率为17.65%。 相似文献
16.
以铜冶炼废渣[简称铜渣,主要成分为铁橄榄石(Fe2SiO4)]为原料,采用钠化焙烧的方法脱除废渣中的硅,研究了以氢氧化钠为钠化剂对铜渣脱硅的影响。首先采用正交实验探究了焙烧温度、矿碱质量比、焙烧时间等因素对铜渣脱硅的影响顺序,在此基础上采用单因素实验研究了铜渣脱硅的适宜工艺条件。结果表明:铜渣脱硅影响因素由大到小的顺序为焙烧温度、矿碱质量比、焙烧时间。铜渣脱硅的适宜工艺条件:焙烧温度为650 ℃,矿碱质量比为1∶1.75(氢氧化钠理论量的4.17倍),焙烧时间为180 min。在此条件下铜渣钠化焙烧所得产物的水浸渣中二氧化硅的质量分数降至1.74%,脱硅率达到94.5%。焙烧产物及其水浸渣的X射线衍射分析表明,铜渣钠化焙烧脱硅的机理是铁橄榄石转化为铁酸钠和硅酸钠,铜渣中的铁最终以四氧化三铁的形式存在,硅以硅酸钠的形式脱除。 相似文献
17.
为了解决Na2S2O3·5H2O存在的过冷度过大导致不结晶的问题,提高复合相变材料的循环稳定性并抑制相分离现象,以CaSO4和1-萘酚(C10H8O)为成核剂;聚丙烯酸钠(PAAS)和羧甲基纤维素钠(CMC)为增稠剂进行改良,通过步冷曲线和差示扫描量热法(DSC)对复合相变材料进行了研究。实验结果表明:加入质量分数为1%和5%的CaSO4、0.5%和3%的C10H8O对Na2S2O3·5H2O有较好的成核作用。萘酚体系在加入增稠剂后降温冷却时不出现结晶现象。对于CaSO4体系,增稠剂PAAS效果优于CMC,Na2S2O3·5H2O+1%CaSO4+2%PAAS复合材料相变温度47.7℃,相变潜热为200.4J/g;Na2S2O3·5H2O+5%CaSO4+2%PAAS复合材料相变温度48.2℃,相变潜热为213.4J/g;经过100次高低温循环后,1%CaSO4的复合材料相变温度47.6℃,相变潜热为192.4J/g,相较循环前相变潜热降低了3.99%。5%CaSO4的复合材料相变温度47.8℃,相变潜热211.2J/g,相比循环前下降1.03%。5% CaSO4体系较优于1% CaSO4体系,循环前后潜热值、相变温度变化不大,循环稳定性良好。 相似文献
18.
以海南万宁的钛铁矿和硫酸铵为主要原料,通过熔融反应法使钛铁矿中的钛转化为易溶于稀酸的硫酸氧钛,用稀硫酸浸取,达到提高钛浸取率的目的。考察了硫酸铵加入量、焦硫酸钾加入量、反应温度、稀硫酸浸取浓度对钛浸取率的影响。实验结果表明:硫酸铵和焦硫酸钾的加入量、反应温度对钛浸取率的影响较大。提高钛浸取率的最佳条件为:m(钛铁矿)∶m(硫酸铵)∶m(焦硫酸钾)=1∶6∶0.5,反应温度为450 ℃,保温时间为30 min,稀硫酸浸取浓度为2.32 mol/L,在此条件下钛的浸取率达到96.82%。 相似文献
19.
Zishuai Liu Yimin Zhang Zilin Dai Jing Huang Cong Liu 《Frontiers of Chemical Science and Engineering》2020,14(5):902
High-manganese containing vanadium wastewater (HMVW) is commonly produced during the vanadium extraction process from vanadium titano-magnetite. HMVW cannot be reused and discharged directly, and is harmful to the environment and affect product quality due to heavy metals in the wastewater. The wastewater is usually treated by lime neutralization, but valuable metals (especially V and Mn) cannot be recovered. In this study, an efficient and environmentally friendly method was developed to recover valuable metals by using a solvent extraction-precipitation process. In the solvent extraction process, 98.15% of vanadium was recovered, and the V2O5 product, with a purity of 98.60%, was obtained under optimal conditions. For the precipitation process, 91.05% of manganese was recovered as MnCO3 which meets the III grade standard of HG/T 2836-2011. Thermodynamic simulation analysis indicated that MnCO3 was selectively precipitated at pH 6.5 while Mg and Ca could hardly be precipitated. The results of X-ray diffraction and scanning electron microscopy demonstrated that the obtained V2O5 and MnCO3 displayed a good degree of crystallinity. The treated wastewater can be returned for leaching, and resources (V and Mn) in the wastewater were utilized efficiently in an environmentally friendly way. Therefore, this study provides a novel method for the coextraction of V and Mn from HMVW. 相似文献
20.
钒铅锌矿含有多种有价金属,V品位高,具有较高的经济价值。本工作采用硫酸浸出法从该矿中提取钒锌,对浸出过程热力学进行分析,通过条件实验研究硫酸浓度、液固比、浸出时间、搅拌速率、浸出温度等条件对钒、铅、锌等主要有价金属浸出率的影响。结果表明,在较高pH值及较高温度下,浸出液中V会出现水解,含V的水解产物留在浸出渣中影响V浸出率。得到最优浸出条件为:硫酸浓度200 g/L,液固比3:1,浸出时间30 min,搅拌速率200 r/min,浸出温度为30℃。最优条件下V浸出率可达97.90%,Zn浸出率为97.11%,Fe浸出率<1%,Pb浸出率<0.01%。动力学分析结果表明,浸出过程的反应速率受扩散过程控制。酸浸过程使V和Zn进入浸出液,Pb和Fe留在浸出渣中,所得浸出液可使用离子交换或萃取法分离V和Zn。浸出渣中含钒0.41wt%、锌0.61wt%、铁15.50wt%、铅47.70wt%,主要成分为PbSO4和FeO(OH),可返回火法炼铅系统。 相似文献