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  Global Journal of Environmental Science and Technology 2011, 1: 1
  Research Article
Treatment of the ammonium chloride recovered from rare-earth wastewater by the reaction between ammonium chloride and sulfuric acid
  Haiming Huanga, b, Bo Yanb, Xianming Xiaob  
a Center for Environmental Engineering Design, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
b State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences , Guangzhou 510640, China


In order to dispose the ammonium chloride (NH4Cl) recovered from rare-earth wastewater, a series of experiments were conducted to examine the feasibility of converting the recovered ammonium chloride to ammonium sulfate, a product that could then be reused in the mining of rare-earth. Experimental results showed that the NH4Cl conversion efficiency rises on lowering the NH4Cl:H2SO4 molar ratio and on increasing the reaction temperature and initial concentration of the NH4Cl mass. Reaction time influences the increase of the NH4Cl conversion efficiency, but declines to negligible levels when its duration exceeds 1 h. The NH4Cl conversion efficiency of adding concentrated H2SO4 before ammonium chloride is higher than that of adding ammonium chloride before concentrated H2SO4. Stirring and maintaining a negative pressure during the course of reaction too exert an influence although slightly on the conversion. Based on these findings, a process was designed to convert the ammonium chloride recovered from the rare-earth wastewater to ammonium sulfate. An economic evaluation of this process revealed that a payoff of $1.445 million per year is possible.

  Ammonium chloride; Ammonium sulfate; Conversion efficiency; Rare-earth wastewater  

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