DefinePK

Abstract

Currently, complex compounds of lanthanide carbonates remain poorly understood, but this information is of no small importance for research in various fields of science. Processing of dumps of phosphogypsum to produce new marketable products and reducing their total amount is achievable by the carbonate conversion method. At the moment, the average level of beneficial use of phosphogypsum - waste processing apatite or phosphorite raw materials is not more than 2.0%. Moreover, the content in phosphogypsum of valuable components, for example, compounds of rare-earth metals, is comparable with the mass fraction of REE oxides in ores of natural deposits. Targeted extraction of rare earth metals from phosphogypsum will not lead to an improvement in the environmental situation, since the volume of the blade and its composition changes little. To reduce the amount of dump phosphogypsum can lead to its processing on a number of other commercial products. Of particular interest are methods for the conversion of phosphogypsum to produce ammonium or sodium sulfate and commercial calcium carbonate. Mathematical modelling showed the fundamental possibility of such an approach with the extraction of REEs in the form of carbonate complexes in solution by the reaction The presence of rare-earth metals in the chalk obtained by carbonate processing indicates kinetic difficulties in the dissolution of rare-earth phosphates. It should be noted that for both light lanthanides and heavy lanthanides, the degree of extraction into solution is consistent with the Gibbs energy changes calculated in this work. A lower value of Gibbs energy corresponds to a larger value of the degree of extraction (dependences for Nd and Eu); comparable Gibbs energies for holmium and europium lead to a small difference in the degree of extraction into solution for these elements. For heavy REM, there is a greater, compared with light, extraction into the solution, which can be explained by both thermodynamic and kinetic factors and requires separate experimental and theoretical studies.