探究了稀土精矿和稀土尾矿硫酸铵焙烧水浸稀土工艺.研究发现,氟碳铈矿预活化焙烧处理后与硫酸铵混合焙烧,稀土矿物转变为可溶性硫酸稀土盐,预活化焙烧处理有助于提高硫酸铵焙烧过程中稀土矿物向硫酸盐的转变,进而提高稀土浸出率,稀土浸出率最大达到90％.稀土尾矿煤基还原焙烧-磁选铁富集稀土,该过程不仅得到了铁精矿和富稀土渣,尾矿中氟碳铈矿得到活化分解有利于硫酸铵焙烧过程中的物相转变.针对选铁后的富稀土渣分别考虑了硫酸铵配比、焙烧温度和焙烧时间对稀土浸出率的影响.得出富稀土渣最佳硫酸铵焙烧条件:硫酸铵配比为4∶1,焙烧温度350℃,焙烧时间45 min,80℃热水浴浸出时间2h,浸出液液固比10 mL.g-1,La、Ce、Nd最高浸出率分别为82.83％,76.53％,77.14％.
The technology of (NH4)2SO4 roasting water bath leaching was used for extracting rare earth from rare earth concentrate and rare earth tailings,respectively.Bastnaesite was transformed into soluble sulfate by roasting with (NH4)2SO4.Preroasting bastnaesite played a positive role in turning bastnaesite into sulfate rare earth,then increasing the leaching rate.The highest leaching rate of Ce reaches 90％.High-grade magnetite concentrate and rare earth slag were obtained by coal-based reduction roasting and magnetic separation.Roasting process also benefited phase transition of rare earth.The main influence factors on the leaching rates of rare elements in roasted products were investigated including amount of ammonium sulfate,roasting temperature and roasting time.The optimized experimental conditions were obtained as following:4∶1 of (NH4)2 SO4 to slag mass ratio,350 ℃ of roasting temperature for 45 min,80 ℃ of water bath leaching temperature for 2 h and 10 mL · g-1 of leaching liquid-solid ratio,the highest leaching rates of rare earth(La,Ce,Nd) reach 82.83％,76.53％,77.14％,respectively.
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