Analysis of Iron Impurity and Its Occurrence Form in Red Clay of Guangdong Province
QIU Bo-xin1, LUO Hong-jie2*, WANG Fen1, ZHU Jian-feng1, LIU Yi-jun3, HAO Yao-rui1
1. Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, School of Material Science and Engineering, Shaanxi University of Science and Technology, Xi’an 710021，China
2. Fundamental Science Institute of Cultural Heritage Conservation, Shanghai University, Shanghai 200444, China
3. Monalisa Group Co., Ltd.，Foshan 528211，China
Abstract：The centuries of development of fine white porcelain in China has made the shortage of high-quality clay mineral resources increasingly serious. How to remove impurities of low-/medium-quality clay minerals and effectively utilize them have been attracted many attentions from potters, artists and material researchers. Iron, as a common impurity in minerals, plays a key harmful role in ceramic productions. One of the key technologies of improvement of low-/medium-quality clay minerals is to remove iron impurities. However, the unclear understanding of occurrence forms of iron in clay minerals limits the development of purification technology. The red clay in Guangdong province has a wide distribution and large storage. However, the high iron content restricts its further utilization as a high-quality resource. In this work, the occurrence forms of iron impurities in the red clay from Meizhou city, Guangdong province were investigated. Three types of impurities (red, yellow and gray green, respectively) in the red clay were selected and separated elaborately via washing and sieving processes. X-ray fluorescence spectrometer, scanning electron microscope equipped with energy disperse spectroscopy, transmission electron microscope equipped with selected area electron diffraction, visible-near infrared spectroscopy and first derivative spectra of visible absorption spectra were exploited to analyze the mineral assemblages, chemical composition, microstructure and spectral characteristics of the separated clay minerals. The occurrence forms of iron were identified. The results showed that iron was the key element that affected the appearance of the red clay. The clay minerals in the three samples were mainly composed of kaolinite and illite. In the red and yellow impurities, iron was absorbed or clamped on the surfaces of laminated clay minerals in the forms of hematite-goethite aggregate. In gray-green impurity, the iron was in the form of ions locked in Fe-Mg muscovite structure. The results also found that during the separation of red clay minerals, iron impurities were separated together with clay minerals from the red clay in the forms of both free and structural irons. This work is helpful for the selection of purification methods for southern red clay and for improving the processing efficiency and quality of low-grade clay.
Key words：Red clay; Iron impurity; Occurrence forms; Selected area electron diffraction
邱柏欣，罗宏杰，王 芬，朱建锋，刘一军，郝瑶睿. 广东省红粘土中铁杂质及其赋存形式分析[J]. 光谱学与光谱分析, 2021, 41(05): 1551-1558.
QIU Bo-xin, LUO Hong-jie, WANG Fen, ZHU Jian-feng, LIU Yi-jun, HAO Yao-rui. Analysis of Iron Impurity and Its Occurrence Form in Red Clay of Guangdong Province. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2021, 41(05): 1551-1558.
[1] Liu R, Yan C, Wang H. Journal of Nanoscience and Nanotechnology, 2015, 15(9): 7385.
[2] LI Bao-sheng, WEN Xiao-hao, David Dian, et al（李保生, 温小浩, David Dian, 等）. Chinese Science Bulletin（科学通报）, 2008，(22): 2793.
[3] WU Hui-jun, LI Zhen, WU Jian-fang, et al（武慧君, 李 珍, 吴剑芳, 等）. Acta Mineralogica Sinica（矿物学报）, 2013, 33(3): 427.
[4] Zhou C, Liang Y, Gong Y, et al. Ceramics International, 2014, 40(9): 14579.
[5] Sathy Chandrasekha. Applied Clay Science, 2006, 33(3-4): 269.
[6] Brigatti M F. Handbook of Clay Science. Elsevier Science, 2013. 11.
[7] HU Da-qian, HAN Chun-yuan, MA Rui, et al(胡大千，韩春元，马 瑞，等). Acta Petrologica Sinica（岩石学报）, 2012, 28(9): 3042.
[8] Vermeer A, van R, Koopal L et al. Langmuir, 1998，(4115)：4210.
[9] CHENG Chang-bing, CHEN Qiong, ZHOU Liang-zhong（程昌炳, 陈 琼, 周良忠）. Chinese Journal of Magnetic Resonance（波谱学杂志）, 1995, 12(6): 593.
[10] Viscarra R, Rossel R, McGlynn A, et al. Geoderma, 2006, 137(1-2): m70.
[11] Edward A, Cloutisa M J, Gaffeyb, et al. Fuel, 1995, 74(6): 874.
[12] Katsuya O. Applied Spectroscopy, 2019, 73(7): 781.
[13] YUAN Xiao-kang, LI Xu-sheng, HAN Zhi-yong，et al(苑晓康，李徐生，韩志勇，等). Geological Journal of China Universities（高校地质学报）, 2017, 23(2): 350.
[14] ZHONG Qian, LIAO Zong-ting, LAI Meng, et al（钟 倩, 廖宗廷, 赖 萌, 等）. Journal of the Chinese Ceramic Society（硅酸盐学报）, 2020, 48(1): 104.
[15] Lu M，Xia G H，Cao W, et al. Applied Clay Science，2017: 354.
