Inorganic Chemicals Industry ›› 2022, Vol. 54 ›› Issue (7): 110-116.doi: 10.19964/j.issn.1006-4990.2021-0655

• Environment·Health·Safety • Previous Articles     Next Articles

Study on crystallization process and mechanism of phosphogypsum in wet process phosphoric acid system

HE Lei1(),ZHU Ganyu2(),ZHENG Guangming3,WU Wenfen2,ZhANG Jianbo2,LI Fang3,LI Huiquan2,4,CHEN Wen1()   

  1. 1.Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China
    2.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
    3.Yidu Xingfa Chemical Co. , Ltd.
    4.School of Chemical Engineering, University of Chinese Academy of Sciences
  • Received:2021-10-27 Online:2022-07-10 Published:2022-07-14
  • Contact: ZHU Ganyu,CHEN Wen E-mail:790391438@qq.com;gyzhu@ipe.ac.cn;chenwen63@126.com

Abstract:

Calcium sulfate crystallization restricts the quality of phosphogypsum in the process of wet process phosphoric acid.Fine calcium sulfate crystallization can not only improve the phosphorus yield,but also be conducive to the resource utilization of phosphogypsum.Aiming at the regulation of calcium sulfate crystallization in the process of phosphogypsum formation,the variation of phase morphology of calcium sulfate with reaction time was systematically investigated under the condition of adding n-octanol.The crystal structure change and growth law of phosphogypsum were studied comprehensively.The results showed that the residual phosphorus in phosphogypsum at 7 h was 0.36%,in which the aqueous soluble phosphorus was 0.18%,and the yield of phosphorus was 98.79%.Phosphogypsum was growed with(002) as the main crystal plane,and the crystallization process was divided into three stages:phosphate rock acidolysis,calcium sulfate crystal particle growth,crystal crushing and secondary crystallization.Uniform calcium sulfate dihydrate slab crystallization was helpful to improve the washing performance and washing effect of phosphogypsum.By studying on the crystallization regulation and change process of phosphogypsum.It was provided reference and basic support for the selection of process parameters and the control of calcium sulfate crystal form in the actual production of wet phosphoric acid.

Key words: wet process phosphoric acid, phosphogypsum, calcium sulfate crystallization, regulation

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