, Volume 70, Issue 12, pp 2800–2806 | Cite as

Selective Dealkalization of Red Mud Using Calcium Oxide with Pressure Leaching

  • Xiaobo ZhuEmail author
  • Wang LiEmail author
  • Heng Zhao
  • Chuanxiang Zhang
Solution Purification Technology


Selective leaching of Na from red mud by using CaO with pressure leaching was investigated. The main factors studied were temperature, pressure, CaO dose, and leaching time. An L9(34) orthogonal test was carried out to analyze the importance of each factor and define optimal conditions. The leaching mechanism of sodium was investigated and analyzed using inductively coupled plasma–atomic emission spectrometry, x-ray diffraction, and scanning electron microscopy with energy-dispersive spectrometry. More than 85% of sodium could be dissolved under the optimal conditions. The order of influence of the investigated factors on the leaching efficiency of sodium was CaO dose > liquid-to-solid ratio > leaching time > leaching temperature/pressure. Cancrinite was decomposed from the red mud during the selective leaching process. The decomposition products silicon oxide and aluminum oxide reacted with calcium oxide, and the reaction products calcium silicate and calcium aluminate remained in the leaching residue. However, the other decomposition product, i.e., sodium oxide, was dissolved in the leaching solution. Other components in the red mud underwent almost no change in the process, representing an advantage compared with other processes that have been proposed.



The research is financially supported by the National Natural Science Foundation of China (51804103), Scientific and Technological Project of Henan Province (172102310679, 182102310846), Key Project of Scientific Research in Colleges and Universities from Henan Province (15A440014, 16A530006), and Doctoral Foundation from Henan Polytechnic University (B2014-012, B2014-009).


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Copyright information

© The Minerals, Metals & Materials Society 2018

Authors and Affiliations

  1. 1.College of Chemistry and Chemical EngineeringHenan Polytechnic UniversityJiaozuoChina
  2. 2.Henan Key Laboratory of Coal Reen ConversionHenan Polytechnic UniversityJiaozuoChina

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