Inorganic Chemicals Industry ›› 2023, Vol. 55 ›› Issue (5): 78-84.doi: 10.19964/j.issn.1006-4990.2022-0638

• Environment·Health·Safety • Previous Articles     Next Articles

Study on preparation of desulfurizer and byproduct gypsum from calcium carbide slag by cyclone separation

YANG Yue1(), ZHU Ganyu1(), ZHANG Jianbo1, MENG Ziheng1, LIU Xinhui2, YANG Jing3, YAN Kun1, PENG Zonggui2, WANG Qiujian3, LI Huiquan1,4   

  1. 1. CAS Key Laboratory of Green Process and Engineering,National Engineering Research Center of Green Recycling for Strategic Metal Resources,Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China
    2. Huaneng Qinbei Power Generation Co., Ltd., Jiaozuo 454650,China
    3. Beijing Genyuan Environmental Protection Co., Ltd., Beijing 101300,China
    4. School of Chemical Engineering,University of Chinese Academy of Sciences,Beijing 100049,China.
  • Received:2022-11-01 Online:2023-05-10 Published:2023-05-15

Abstract:

Calcium carbide slag is a solid waste from the process of producing acetylene by calcium carbide,which is a good raw material to replace limestone in the preparation of low carbon desulfurizer.However,there are some problems in the application process,such as high impurity content and difficult separation of coarse particles.To solve the above problems,multistage cyclone impurity separation was used to separate the impurities and large particles of calcium carbide slag.The efficiency of cyclone separation of calcium carbide slag reached 93.97% under optimized conditions.Scanning electron microscopy(SEM),X-ray diffractometry(XRD),X-ray fluorescence spectrometer(XRF) and X-ray photoelectron spectroscopy(XPS) were used to characterize the morphology,composition and phase equality of calcium carbide slag.The changes of composition and particle size before and after the cyclone were systematically analyzed,and the occurrence form and distribution law of impurities in calcium carbide slag were discussed in detail.The results showed that calcium in calcium carbide slag was mainly existed in the form of calcium hydroxide,and the content was not different before and after cyclone separation.The impurities mainly included ferric oxide,aluminum oxide,magnesium oxide,silicon dioxide,sulfur,carbon,and water-soluble chloride ions.After cyclone separation,silicon dioxide and aluminum oxide were enriched in fine slag and exist in the form of aluminosilicate.Ferric oxide and carbon were enriched in the coarse slag,and carbon was existed in the form of elemental carbon and carbonate.The contents of chlorine and magnesium were low and uniformly distributed,aluminum and silicon were concentrated,aluminum and sulfur were concentrated,and aluminum and sulfur particles are embedded in calcium carbide slag particles.Using calcium carbide slag cyclone fine slag as desulfurizer for flue gas desulfurization,the water content of desulfurized gypsum by industrial by-product was 13.20%,and the mass fraction of calcium sulfate dihydrate in gypsum was 90.01%.The above research could provide reference for the resource utilization of calcium carbide slag.

Key words: wet calcium carbide slag, cyclone separation, occurrence of impurities, desulfurization gypsum

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