焙烧制度对稀土精矿中铁、铝等杂质浸出行为的影响

Effects of roasting system on the leaching behavior of iron and aluminum impurities in rare earth concentrates

  • 摘要: 以来自赣南某稀土冶炼企业的离子型稀土精矿为原料,应用电感耦合等离子体发射光谱仪、X射线衍射分析技术等手段,考察了焙烧温度、焙烧气氛对稀土精矿中铁、铝等杂质元素浸出的影响规律,并揭示了其作用机制。结果表明:氧化焙烧能降低铁、铝等杂质元素的浸出,特别是当焙烧温度超过1 300 ℃后,铁、铝浸出率不足5%,而还原焙烧不利于铁、铝等杂质固化,这是由于在氧化焙烧条件下,稀土精矿中铁、铝、硅等元素由易溶解的非晶物相转化为难溶的结晶物相,使得铁、铝等杂质多以含铝多元硅酸盐的形式被固化,从而抑制了铁、铝的浸出。无论是氧化焙烧,还是还原焙烧,在实验所考察范围内,焙烧温度对稀土浸出率影响不大。

     

    Abstract: With the ion-adsorption rare earth concentrate from a smelting enterprise in southern Jiangxi as raw material, the effects of roasting temperature and roasting atmosphere on the leaching of iron, aluminum impurity elements was investigated by means of Inductively coupled plasma spectrometer(ICP), X-ray diffraction analysis(XRD). Its mechanism was revealed. The results show that oxidizing roasting reduces the leaching of iron and aluminum impurities, especially when the roasting temperature exceeds 1300 ℃, the leaching rate of iron and aluminum is less than 5%. However, reducing roasting is not conducive to the solidification of impurities. It is due to the transformation of iron, aluminum and silicon from easily soluble amorphous phase to insoluble crystalline phase under oxidizing roasting conditions for the leaching decrease of impurities, such as iron, aluminum and the like, which are solidified in the form of aluminum-containing polybasic silicate, thereby inhibiting the leaching of iron and aluminum. Whether oxidizing roasting or reducing roasting, the roasting temperature has little effect on the leaching rate of rare earth in the experimental range.

     

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