Migration of natural radionuclides in the extraction process of the ion-adsorption type rare earths ore

Abstract

The ion-adsorption type rare earths ore contains natural U, 232Th and 226Ra. The production of this kind of rare earth concentrate will produce a lot of waste residue and wastewater. It may cause the radioactive pollution and the wastage of radioactive resources. In this paper, a quantitative analysis on the migration and enrichment of natural radionuclides in the extraction process of the ion-adsorption type rare earths ore was developed. The column leaching, impurity removal, precipitation and roasting process were carried out according to the actual extraction process conditions. The related results about RE and Al did accord with the actual production index. For natural radionuclides, most of the radionuclides in the raw ore were retained in the tailings, and only 3.31% natural U, 0.08% 232Th and 0.62% 226Ra migrated into leaching liquor because the partial release of the exchangeable phase and carbonates phase. The radionuclides in the leaching liquor were finally distributed in the impurity slay (about 0.30% natural U, 0.057% 232Th and 0.016% 226Ra), the precipitated liquor (about 1.89% natural U, 0.012% 232Th and 0.59% 226Ra) and the rare earth concertrate (about 1.03% natural U, 0.009% 232Th and 0.019% 226Ra). Moreover, the radionuclides contents in impurities slag and rare earth concentrate were greatly improved than it in the raw ore, being 79.18mg·kg−1 natural U, 122.59mg·kg−1232Th, 1.83×10−6mg·kg−1226Ra in impurities slag and 284.07mg·kg−1 natural U, 19.95mg·kg−1232Th, 2.31×10−6mg·kg−1226Ra in rare earth concentrate. These part of the radionuclides might could be further enriched by optimum solubilizing, and then recycled by extraction in an economic way. What's more, the radioactive specific activities in the different types of samples were much lower than the specific activities threshold of radioactive waste, and would have little harm to the human body. The research of the migration and enrichment of natural radionuclides in the extraction process had provided accurate and reliable data support for the radioactive pollution prevention and the recovery of radionuclides.