Leaching Process of Ionic Rare Earth Ore under Combination of Leaching and Leaching Process
There was a large amount of residual ammonium salt in the tailings after leaching of ion-type rare earth by ammonium sulfate,causing pollution to the environment of the mining area for a long time after the clo-sure of the ore,which restricts the application of ammonium sulfate leaching agent and the efficient mining of ion-type rare earth.Through the laboratory column leaching simulation test,the combination optimization pro-cess of leaching and centralized leaching process was explored in small test conditions and verified in expanded test.Under the conditions of ammonium sulfate by adding 4.53 g·g-1 REO and magnesium sulfate by adding 120％of the molar amount of ammonium sulfate,the 2％(mass fraction)solution was prepared for leaching and leach-ing process successively.The rare earth leaching rates of ammonium+magnesium leaching in the small test and the expansion test are 96.81％and 98.61％,respectively.The magnesium ion concentrations in the mixed leach-ing solution are 57.24 and 77.34 mg·L-1,respectively.And the magnesium content in the rare earth carbonate concentrate obtained by ammonium bicarbonate precipitation is less than 15 mg·kg-1.Combined with pure water leaching in the pore volume of ore soil in the one-fold column,the leaching rate of ammonia nitrogen in the tail-ings of magnesium leaching and water leaching is about 90％,and the residual ammonia nitrogen content in the tailings is less than 200 mg·kg-1,meeting the requirements of green planting soil.The leaching-leaching integra-tion process has no impact on the quality of leaching solution while leaching reagent is used to wash and push the ammonium in ionic rare earth tailings to leaching.Under the condition of the same rare earth leaching rate,the dosage of leaching agent ammonium sulfate can be greatly reduced,and the leaching and leaching cycle can be shortened,which has good industrial popularization value.
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