PROCESS FOR DECOMPOSING WASTE RARE EARTH LUMINESCENT MATERIALS BY TWO TIMES OF ACIDOLYSIS

摘要

A process for decomposing waste rare earth luminescent materials by two times of acidolysis comprises the following steps: firstly, red powders (Y₂O₃:Eu) in the waste rare earth luminescent materials are dissolved by hydrochloric acid preferentially, and the obtained solution are filtered to obtain a yttrium-europium-rich type rare earth chloride solution and filter residues; the filter residues mainly contain green powders and blue powders, and the filtrate is treated by Na₂SO₄ to remove Ca²⁺ as a precipitation of CaSO₄ by settling and separation, so as to obtain the yttrium-europium-rich type rare earth chloride solution; the filter residues and alkali are mixed to conduct alkali fusion at a high temperature to decompose the green powders and the blue powders so as to obtain sodium metaaluminate, magnesium oxide, barium carbonate and rare earth oxide; the alkali fusion product is washed by water and filtered to obtain a sodium metaaluminate solution and filter residues containing rare earth oxide; hydrochloric acid is adopted for secondary acidolysis, then Mg²⁺ and Ba²⁺ in the waste rare earth luminescent materials are removed by adopting Na₂SO₄ and are settled and separated as MgSO₄ and BaSO₄, and a rare earth chloride solution containing europium, terbium and cerium is obtained. According to the process, the using amount of caustic soda in alkali fusion can be reduced greatly, the extraction amount of rare earth chloride can be reduced, the effect of energy conservation and emission reduction is obvious, and the production cost is low.