Readsorption of rare earth elements during leaching process of ion-adsorption-type rare earth ore

A leaching experiment on simulated rare earth ore pillars with uneven grade distribution was conducted because of the readsorption of rare earth elements in the in situ leaching process of ion-adsorption-type rare earth ore. Results show that the readsorption of rare earth elements in the barren layer is the main reason for the decrease in rare earth concentration in the leachate, decrease in rare earth recovery and extension of the leaching process. This limitation could be affected by the concentration of rare earth of the influent flow passing through the barren ore layer, and pH value of leaching agents shows minimal effect during leaching. The magnesium sulfate leaching process requires higher liquid-to-solid ratio than the ammonium sulfate leaching process. The former also has lower peak value of rare earth concentration and more significant tailing in the leaching curve. The readsorption of rare earth elements in the barren layer is more severe in magnesium sulfate leaching than in ammonium sulfate leaching. Thus, areas without ore belts should be avoided when magnesium sulfate is used for leaching.