离子型稀土尾矿残留铵缓释性分析

Analysis on slow-release of residual ammonium in ion-absorbed type rare earth tailings

为探究尾矿残留NH_(4)^(+)的缓释性,以江西信丰离子型稀土矿为研究对象,柱浸制备浸出尾矿,去离子水淋洗尾矿.按照淋洗→封存→再淋洗的步骤,考察了淋洗尾矿不同含水率(1.3%,15%,35%,250%),不同封存时间(15,30,60,120,180,195,210,240d)和不同传质机制(对流、扩散)下NH_(4)^(+)的淋出量.结果表明:尾矿再淋洗仍能淋出NH_(4)^(+),NH_(4)^(+)淋出量受含水率、封存时间和传质方式影响;含水率≥15%时,NH_(4)^(+)淋出量整体随时间推移而递增;同时间下,NH_(4)^(+)淋出量整体随含水率增大而增大;其他条件相同时,对流传质下NH_(4)^(+)淋出量大于扩散.尾矿再次淋出的NH_(4)^(+)是可交换态NH_(4)^(+)向水溶态NH_(4)^(+)转化的结果.

In order to explore the slow-release of residual NH_(4)^(+),ion-absorbed type rare earth ore from Xinfeng(Jiangxi Province)was taken as the research object.The leached tailings were prepared by column leaching,and then drip washing with deionized water.Follow the steps of drip washing→sealing and storing→re drip washing,NH_(4)^(+)amount in drip washed tailings with different water content(1.3%,15%,35%,250%),under different time(15,30,60,120,180,195,210,240d),different mass transfer mechanisms(convection,diffusion)were investigated.The results show that NH_(4)^(+)can still be washed out from the drip washed tailings after being sealed and preserved for a long time.NH_(4)^(+)washing amount is affected by water content,time and mass transfer mechanism.NH_(4)^(+)washing amount,as a whole,increase with time proceeding,when the water content is ≥15%,and increase with the increase of water content,in the same preserved time.When other conditions are the same,NH_(4)^(+)washing amount under convective is greater than diffusion.NH_(4)^(+)re-washed out from the tailings is the result of transformation of NH_(4)^(+)from exchangeable to water-soluble.