Extraction of tungsten and vanadium from spent selective catalytic reduction catalyst for stationary application by pressure leaching process

Choi, In-Hyeok; Moon, Gyeonghye; Lee, Jin Young; Jyothi, Rajesh Kumar

doi:10.1016/j.jclepro.2018.06.196

Cited by 58 publications

(17 citation statements)

References 19 publications

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“…中国煤炭资源主要分布于内蒙古、山西、陕西、新疆等西北地区，目前已经形成内蒙古鄂尔多斯、陕西榆林、宁夏宁东、新疆准东等多个千万 t 级大型煤-电-化一体化能源基地 [1] ，有力支撑了中国经济社会快速发展对电力、基础化学品等重大产品的迫切需求。但目前煤-电-化转化过程中，大约占原煤质量 30%的 Al、 Si、 Fe 等无机组份主要以固废形式从主流程中输出。上述基地每年集中产生约数亿 t 粉煤灰、电石渣、气化渣等典型煤基固废，并主要以粉煤灰制备建材 [2] 、废催化剂回掺 [3] 、电石渣制备水泥 [4] 、脱硫石膏制备纸面石膏板 [5] 等建工建材方式利用，但受限于运输半径及周边市场容量，固废资源综合利用率低于 40%。近 60%煤基固废以堆存、填埋为主，资源浪费严重，环境风险与经济压力巨大。国外煤基固废的传统利用方式为水泥、混凝土等建材化利用领域 [6,7] ，近年来的研究转向地质聚合物合成、稀贵元素提取等途径 [8] [9] 和 Al、 Si、 C 分质利用 [10] 等方面的研究；针对电石渣，主要开展了电石渣活性调控制备氧化钙、轻质碳酸钙 [11,12] 、活化除杂制备脱硫剂 [13] 等研究；针对废脱硝催化剂，主要开展了 V、 W 组分分离回 http://www.resci.cn 收 [14] 以及载体重构循环回用研究 [15] 。综合上述情 [16,17] 。电石渣排放主要集中在新疆、宁夏等中西部大型能源基地，仅 40%左右可应用于水泥等建材行业 [18] 结构 [19] 。通过上述分析可以发现电石渣具有良好的资源属性，是作为烟气环保脱硫的优良材料 [20] http://www.resci.cn 式主要包括干粉进料和水煤浆进料 [21,22] 。有机组分以甲醇、烯烃等高附加值产品形式产出，无机组分经熔融态水淬得到气化粗渣和气化滤饼，其中气化粗渣占比约为 60%~80%，气化滤饼占比约为 20%4 0%。因其含碳量高 [23,24] ，目前主要以堆存为主，少部分气化粗渣低掺量用于建工建材利用 [25] ，另有少废 SCR 催化剂是能源行业产生的典型难处理多金属危险废物 [26] ，其中含有活性元素 V、 W 等重金属及烟气中沉积的 As、 Hg 等毒性组分，堆放、填埋处理过程中的浸出毒性易造成水体和土壤等污染 [27] 。目前，国内废 SCR 催化剂年产生量达到 50 万 m 3 ，大部分以掺混形式利用，其 Ti、 W、 V 等组分有效利用率仅 70%左右，因而其高效循环已成为当前研究的热点和重点 [28,29] 。废 SCR 催化剂的主要有价组分为 TiO2、 V2O5和 WO3 [30] ，具体组成和主要矿相结构如表 4 所示 [31] 。以上分析结果表明废 SCR 催化剂中含有 0.53%V2O5、 [31] 。通过稀碱重构调控恢复钛钨载体的孔结构，对不同碱浓度下得到的浸出渣孔结构性能分析，随着 NaOH 浓度的增大，比表面积和孔容逐渐增加 [31] 。NaOH 浓度增加至 2.5~3.0 mol/L 时，比表面积增至 110.50 m 2 /g 以上，孔容增至 0.59 cm 3 /g 以上，孔道结构达到新鲜钛钨粉的性能，图 3 气化灰渣不同矿相形貌及赋存状态 [20,34,35] [ 9 ] 相玉琳, 焦玉荣, 王立鹏. 可溶性有机质改性气化渣对黑沙蒿生…”

Section: 引言unclassified

Recycling and product chain of coal-based solid waste

LI¹,

HU²,

LI³

et al. 2021

资源科学

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：Large-scale recycling of coal-based solid waste has important practical significance for the sustainable development and ecological environment protection of the large-scale energy bases in northwestern China. In this study, the typical energy bases in northwestern China were taken as a research object. The principle of collaborative location of solid waste and industry in the region was applied in the analysis. Key technologies such as the use of coal-based solid waste to produce chemicals, environmental protection materials, and building materials were proposed. The key product chains of typical coal-based solid waste recycling such as calcium carbide slag, gasification slag, and spent catalysts were established. The results show that coal-based solid wastes such as calcium carbide slag, gasification slag, and spent catalyst can be used to prepare desulfurizers, water glass, catalysts, and other products with good performance through separation of impurities, phase control, and catalyst carrier refactoring. The products can be directly used in the production process of coal-electricity-chemical enterprises in the region. In the coal-based solid waste 90% of calcium, aluminum, and silicon can be effectively used, and the recycle rate of vanadium, wolfram, and titanium can reach over 90% . Residual carbon can be separated. The utilization efficiency of coal and water resources of the recycling product chain can be increased to 36% and 27%, respectively, which can reduce the emissions of three types of typical solid waste by more than 98%. The process can provide a new way for large-scale utilization of solid waste, and can realize the high efficiency utilization of coal and secondary resources in coal energy bases.

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Section: 引言unclassified

Recycling and product chain of coal-based solid waste

LI¹,

HU²,

LI³

et al. 2021

资源科学

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show abstract

“…In the previous report 7 , one reason for the low leaching efficiency of vanadium and tungsten in alkali-roasted feedstock by water leaching is the formation of insoluble compounds including calcium tungstate and calcium vanadates in the alkali roasting of spent SCR catalyst. Detrimental effect of insoluble formation for extracting vanadium was significant.…”

Section: Resultsmentioning

confidence: 99%

“…Owing to stringent regulations for NO x emissions and increasing global demands of SCR catalysts, studies on the recycling of spent SCR catalysts have reported their high potential as a new secondary source 4–8 . Direct leaching of metal in spent SCR catalysts using acid or alkaline agent has revealed as inadequate for effective extraction of vanadium and tungsten 7 . This seems to be due to the characteristics related to the formation of vanadium and tungsten of SCR catalyst.…”

Section: Introductionmentioning

confidence: 99%

Alkali fusion using sodium carbonate for extraction of vanadium and tungsten for the preparation of synthetic sodium titanate from spent SCR catalyst

Choi

Moon

Lee

et al. 2019

Sci Rep

Self Cite

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Alkali fusion method to extract vanadium and tungsten from spent SCR catalyst and to simultaneously prepare synthetic sodium titanate for the purpose of preparation of feedstock for TiO 2 manufacturing by hydrometallurgical processing was investigated. Based on the Na 2 O-TiO 2 phase diagram and experimentally obtained results, appropriate alkali-fusion temperature and molar ratio (MO x /Na 2 O + MO x ) were determined to prepare soluble vanadium, tungsten salts, and sodium titanate. As results, the extraction efficiency of vanadium and tungsten was >99% and sodium titanate as feedstock for making TiO 2 was obtained under the following alkali fusion conditions: Temperature, 950 °C; reaction time, 20 min; molar ratio, 0.5. When the molar ratio (MO x /Na 2 O + MO x ) was less than 0.5, complete liquidized product (eutectic melt of the feedstock and Na 2 CO 3 ) was obtained at the given conditions. This method, compared to conventional alkali roasting, is advantageous for rapid synthesis of water-soluble compounds for leaching of vanadium and tungsten, and for use as feedstock for the preparation of TiO 2 by hydrometallurgical route.

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“…Burying the spent SCR catalyst underground as hazardous waste will lead to serious environmental pollution [13]. At the same time, vanadium and tungsten as rare metals which can be recovered and applied in chemical industry as secondary energy [14]. Therefore, recycling SCR catalysts can not only solve the pollution problem of hazardous waste, but also produce tremendous economic benefits [15].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Roasting Parameters for Recovery of Vanadium and Tungsten from Spent SCR Catalyst with Composite Roasting

Wang

Yang

2021

Processes

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Every year, large amounts of selective catalytic reduction (SCR) catalysts with losing catalytic activity and failing to be regenerated need to be regenerated, which will result in acute pollution. Recycling valuable metals from spent SCR catalysts can not only solve environmental problems, but also save resources. The process of sodium roasting and water leaching is able to effectively extract vanadium (V) and tungsten (W) from spent SCR catalysts. To improve the efficiencies of V and W, different sodium additives were first investigated in the roasting process. The results revealed that the process of NaCl-NaOH composite roasting and water leaching showed superior leaching efficiencies of V and W, which can reach 91.39% and 98.26%, respectively, and simultaneously, it can be found that adding low melting point NaOH promoted mass transfer as compared with the melting points of different sodium additives. Next, a single-factor experiment was conducted to investigate different roasting conditions, such as roasting temperature, roasting time, mass ratio of sodium additive and catalyst, and mass ratio of NaCl and NaOH, on the leaching efficiencies of V and W. Then, a three-level and four-factor orthogonal experiment and a weight matrix analysis were used to optimize the roasting parameters. The results showed that roasting temperature had the most significant effect on the leaching efficiencies of V and W, and the optimal roasting conditions were as follows: the roasting temperature was 750 °C, the roasting time was 2.5 h, the mass ratio of sodium additive and catalyst was 2.5, and the mass ratio of NaCl and NaOH was 1.5. Under the optimal roasting conditions, the leaching efficiencies of V and W were 93.25% and 99.17%, respectively. The results of XRD analysis inferred that VO2 coming from the decomposition of VOSO4 in spent SCR catalysts may first oxidize into V2O5 and then react with sodium additives to produce NaVO3. The formation of titanium-vanadium oxide ((Ti0.5V0.5)2O3) was a part reason of hindering the leaching of vanadium. With the increase of roasting temperature, TiO2 converted into Na2Ti3O7, which indicated that the main structure of the catalyst was destroyed, and simultaneously, more characteristic peaks of sodium metavanadate and sodium tungstate appeared, thus enhancing the leaching of V and W. Finally, it can be seen that the process of NaCl-NaOH roasting and water leaching remained higher leaching efficiencies of V and W and lower roasting temperature by comparing with leaching efficiencies of V and W in different processes of recycling SCR catalyst. The process of NaCl-NaOH composite roasting and water leaching provided a strategy with a highly efficient and clean route to leach V and W from spent SCR catalyst. The orthogonal experiment and weight matrix analysis in our study can be used as a reference to optimize the reaction conditions of a multiple indexes experiment.

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Extraction of tungsten and vanadium from spent selective catalytic reduction catalyst for stationary application by pressure leaching process

Cited by 58 publications

References 19 publications

Recycling and product chain of coal-based solid waste

Recycling and product chain of coal-based solid waste

Alkali fusion using sodium carbonate for extraction of vanadium and tungsten for the preparation of synthetic sodium titanate from spent SCR catalyst

Optimization of Roasting Parameters for Recovery of Vanadium and Tungsten from Spent SCR Catalyst with Composite Roasting

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