Estimating perfluorocarbon emission factors for industrial rare earth metal electrolysis
Estimating perfluorocarbon emission factors for industrial rare earth metal electrolysis
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估算工业稀土金属电解的全氟化碳排放因子
DOI：
10.1016/j.resconrec.2018.04.018
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
Shan Yuli
中科院分区：
文献类型：
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作者：
Cai Bofeng;Liu Helin;Kou Fan;Yang Youming;Yao Bo;Chen Xiping;Wong David S;Zhang Lizhi;Li Jianzhong;Kuang Guochun;Chen Liqu;Zheng Jinwen;Guan Dabo;Shan Yuli
稀土金属在新材料中得到了广泛的应用，近三十年来其产量急剧增长。在以熔氟电解技术为特征的生产过程中，全氟化碳（PFC）排放量很大，因此应在温室气体（GHG）排放清单中充分核算。然而，在《2006年IPCC国家温室气体清单指南》中，目前还没有办法计算稀土金属生产过程中PFC的排放。本研究旨在通过对稀土金属电解废气中PFC浓度的现场监测和实验室分析，确定工业稀土金属生产的排放因素。连续FTIR测量和时间积分样品（在现场使用高精度美杜莎气相色谱-质谱分析）在24-60 h周期内从中国的三家稀土公司进行，涵盖多种稀土金属/合金的生产，包括Pr-Nd， La和Dy-Fe。该研究证实，PFC排放是在电解过程中产生的，通常以CF4（约90% wt检测到的PFC）、C2F6（约10%）和C3F8（<1%）的形式产生；痕量的c- c4f8和c4f10也被检测到。一般来说，PFC排放因子随稀土金属的生产和不同设施的不同而变化，cf4的排放范围为26.66至109.43 g/t-RE， C2F6的排放范围为0.26至10.95 g/t-RE， C3F8的排放范围为0.03至0.27 g/t-RE。稀土电解的排放强度换算成总PFCs为211.60至847.41 kg CO2-e/t-RE，与工业铝电解相比（对于大多数稀土生产）或类似（镝-铁生产）。
Rare earth (RE) metals have been widely applied in new materials, leading to their drastic production increase in the last three decades. In the production process featured by the molten-fluoride electrolysis technology, perfluorocarbon (PFC) emissions are significant and therefore deserve full accounting in greenhouse gas (GHG) emission inventories. Yet, in the ‘2006 IPCC Guidelines for National Greenhouse Gas Inventories’, no method currently exists to account for PFC emissions from rare earth metal production. This research aims to determine emission factors for industrial rare earth metals production through on-site monitoring and lab analysis of PFC concentrations in the exhaust gases from rare earth metal electrolysis. Continuous FTIR measurements and time-integrated samples (analysed off-site by high-precision Medusa GC–MS) were conducted over 24–60 h periods from three rare earth companies in China, covering production of multiple rare earth metals/alloys including Pr-Nd, La and Dy-Fe. The study confirmed that PFC emissions are generated during electrolysis, typically in the form of CF4(∼90% wt of detected PFCs), C2F6(∼10%) and C3F8(<1%); trace levels of c-C4F8and C4F10were also detected. In general, PFC emission factors vary with rare earth metal produced and from one facility to another, ranging from 26.66 to 109.43 g/t-RE for CF4emissions, 0.26 to 10.95 g/t-RE for C2F6, and 0.03 to 0.27 g/t-RE for C3F8.Converted to 211.60 to 847.41 kg CO2-e/t-RE for total PFCs, this emissions intensity for rare earths electrolysis is of lower (for most RE production) or similar (Dy-Fe production) level of magnitude to industrial aluminium electrolysis.