Development of a radiochemical sequential procedure for the quantification of Th- and U-decay series elements in mining
- PDF / 1,164,144 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 96 Downloads / 136 Views
Development of a radiochemical sequential procedure for the quantification of Th‑ and U‑decay series elements in mining residues Claire Dalencourt1 · Jean‑Christophe Tremblay‑Cantin1 · Dominic Larivière1 Received: 16 September 2020 / Accepted: 2 October 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract This article discusses a new complementary method for gamma spectrometry for the assessment of natural radioactivity in mining residues. The proposed analytical strategy allows us to determine if secular equilibrium is achieved in the sample with an HF-free dissolution process and a robust sequential radiochemical procedure for U, Th, Ra, Pb and Po isotopes. Various mineralization strategies were investigated on certified mining residues to completely dissolve both refractory (Th, U) and volatile (Po) species, either via open vessel or microwave-assisted acid digestion with nitric and hydrochloric acids followed by an alkaline fusion on the undissolved solids. Then 5 naturally occurring radioelements (Th, U, Ra, Pb and Po) present in the digested sample were separated with 3 stacked selective resins (TRU, Sr resin and HRa), from which they were individually eluted. The single loading step, composed of HCl/HNO3, was optimized to ensure selective retention onto the resins without the need to alter the loading matrix by varying the pH or adding salt, acid, or solvents. The 5 eluted solutions containing individual fractions of the desired elements could then be analyzed by either ICP-MS/MS or alpha spectrometry. More than 92% of each analyte were recovered in certified reference materials with the proposed procedure (dissolution and extraction). Keywords TRU resin · Sr-resin · Ra-01 · AG50Wx8 · Mining residue · HF-free digestion
Introduction Radionuclides are ubiquitous—found in every constituent of the environment, and both anthropogenic and cosmogenic in nature. Humans are mainly exposed to radioactivity originating from either thorium (Th) or uranium (U) decay series [1–3]. The mobility of radionuclides from those series is dictated, amongst other parameters, by the speciation and the chemicophysical properties of the radionuclides. Anthropogenic activities, such as mining operations, can remobilize radionuclides and increase their distribution in the environment [4]. For these reasons, national and international regulators have implemented policies often requiring Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10967-020-07443-8) contains supplementary material, which is available to authorized users. * Dominic Larivière [email protected] 1
Radioecology Laboratory, Chemistry Department, Laval University, Quebec, QC G1V 0A6, Canada
proper monitoring of wastes and residues originating from mining operations. For example, the province of Québec (Canada) legislature defines radioactive material as any material containing radioactive nuclides for which the result of the following equation, calculated for 1 kg of material, is greater than 1:
Data Loading...
