{"title":"电化学处理从碳化钨-钴结合废物中回收战略金属","authors":"P. Katiyar, N. Randhawa","doi":"10.4152/pea.2023410202","DOIUrl":null,"url":null,"abstract":"Scraped or end-of-life WC-Co bonded makes it an attractive resource. The conventional technologies to recover these metals entail energy-intensive pre-treatment steps, followed by their dissolution in a high volume of concentrated acids/alkali reagents. Recently, much attention has been given to the development of energy-efficient and environmentally friendly routes based on WC-Co direct electrochemical dissolution as anodes. However, the metals have a retarded dissolution, in NaOH alkali media, due to the formation of passive oxide layers, in the acidic electrolytes, and of hydroxides, on the anodic surface. The present study investigated WC and Co dissolution fundamentals in aqueous NH 3 , in order to develop a greener process, by the suitable addition of (NH 4 ) 2 CO 3 , (NH 4 ) 2 SO 4 and NH 4 Cl Preliminary PDP studies revealed the necessary concentration of NH 3 and additives, and their effect on the metals passivation tendency, for obtaining the best anodic dissolution parameters. The electrodissolution experiments in a specially designed cell achieved the maximum values, by adjusting those parameters. The highest dissolution of W and Co occurred under optimum conditions (10 V, 150 g/L NH 3 and 15% w/v NH 4 Cl). Co was deposited at the cathode, while H 8 N 2 O 4 W remained in the electrolyte and was recovered as H 2 WO 4 or YTO . Topographical analysis of the polarized surface by AFM has confirmed the pitting corrosion mechanism responsible for W and Co dissolution. A process flow chart for the newly developed single-step direct recycling methods of WC scraps has also been proposed. This process has produced pure saleable WO 3 powder and Co.","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":null,"pages":null},"PeriodicalIF":16.4000,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Recovery of Strategic Metals from Tungsten Carbide-Cobalt Bonded Waste by Electrochemical Processing\",\"authors\":\"P. Katiyar, N. Randhawa\",\"doi\":\"10.4152/pea.2023410202\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Scraped or end-of-life WC-Co bonded makes it an attractive resource. The conventional technologies to recover these metals entail energy-intensive pre-treatment steps, followed by their dissolution in a high volume of concentrated acids/alkali reagents. Recently, much attention has been given to the development of energy-efficient and environmentally friendly routes based on WC-Co direct electrochemical dissolution as anodes. However, the metals have a retarded dissolution, in NaOH alkali media, due to the formation of passive oxide layers, in the acidic electrolytes, and of hydroxides, on the anodic surface. The present study investigated WC and Co dissolution fundamentals in aqueous NH 3 , in order to develop a greener process, by the suitable addition of (NH 4 ) 2 CO 3 , (NH 4 ) 2 SO 4 and NH 4 Cl Preliminary PDP studies revealed the necessary concentration of NH 3 and additives, and their effect on the metals passivation tendency, for obtaining the best anodic dissolution parameters. The electrodissolution experiments in a specially designed cell achieved the maximum values, by adjusting those parameters. The highest dissolution of W and Co occurred under optimum conditions (10 V, 150 g/L NH 3 and 15% w/v NH 4 Cl). Co was deposited at the cathode, while H 8 N 2 O 4 W remained in the electrolyte and was recovered as H 2 WO 4 or YTO . Topographical analysis of the polarized surface by AFM has confirmed the pitting corrosion mechanism responsible for W and Co dissolution. A process flow chart for the newly developed single-step direct recycling methods of WC scraps has also been proposed. 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引用次数: 0
摘要
报废或报废的WC-Co粘合使其成为一种有吸引力的资源。回收这些金属的传统技术需要耗费大量能源的预处理步骤,然后将其溶解在大量的浓酸/碱试剂中。近年来,以WC-Co直接电化学溶解为阳极的节能环保路线的开发受到了广泛关注。然而,由于酸性电解质和阳极表面的氢氧化物形成了被动氧化层,金属在NaOH碱介质中溶解迟缓。本研究考察了WC和Co在nh3水溶液中溶解的基本原理,为了开发更环保的工艺,通过适当的(nh4) 2co3、(nh4) 2so4和nh4 Cl的加入,初步的PDP研究揭示了nh3和添加剂的浓度,以及它们对金属钝化倾向的影响,以获得最佳的阳极溶解参数。通过调整这些参数,在专门设计的电解池中进行电溶解实验,获得了最大值。在最佳条件(10 V, 150 g/L nh3和15% W / V nh4 Cl)下,W和Co的溶解率最高。Co沉积在阴极,而h8n2o4w留在电解液中,并被回收为h2wo4或YTO。用原子力显微镜对极化表面进行形貌分析,证实了W和Co溶解的点蚀机制。提出了新开发的单步直接回收WC废料的工艺流程图。该工艺生产出了纯可销售的三氧化二钒粉和钴。
Recovery of Strategic Metals from Tungsten Carbide-Cobalt Bonded Waste by Electrochemical Processing
Scraped or end-of-life WC-Co bonded makes it an attractive resource. The conventional technologies to recover these metals entail energy-intensive pre-treatment steps, followed by their dissolution in a high volume of concentrated acids/alkali reagents. Recently, much attention has been given to the development of energy-efficient and environmentally friendly routes based on WC-Co direct electrochemical dissolution as anodes. However, the metals have a retarded dissolution, in NaOH alkali media, due to the formation of passive oxide layers, in the acidic electrolytes, and of hydroxides, on the anodic surface. The present study investigated WC and Co dissolution fundamentals in aqueous NH 3 , in order to develop a greener process, by the suitable addition of (NH 4 ) 2 CO 3 , (NH 4 ) 2 SO 4 and NH 4 Cl Preliminary PDP studies revealed the necessary concentration of NH 3 and additives, and their effect on the metals passivation tendency, for obtaining the best anodic dissolution parameters. The electrodissolution experiments in a specially designed cell achieved the maximum values, by adjusting those parameters. The highest dissolution of W and Co occurred under optimum conditions (10 V, 150 g/L NH 3 and 15% w/v NH 4 Cl). Co was deposited at the cathode, while H 8 N 2 O 4 W remained in the electrolyte and was recovered as H 2 WO 4 or YTO . Topographical analysis of the polarized surface by AFM has confirmed the pitting corrosion mechanism responsible for W and Co dissolution. A process flow chart for the newly developed single-step direct recycling methods of WC scraps has also been proposed. This process has produced pure saleable WO 3 powder and Co.
期刊介绍:
Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance.
Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.