Uranyl Minerals from Abandoned Podgórze Mine (Sudetes Mountains, SW Poland) and Their REE Content

Marcin Daniel Syczewski,Jan Rohovec,Šárka Matoušková,Rafał Siuda,Jan Parafiniuk

doi:10.3390/min12030307

Marcin Daniel Syczewski, Jan Rohovec + Show 3 more

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https://doi.org/10.3390/min12030307

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Abstract

The Podgórze uranium deposit is located near Kowary in the Sudetes Mountains, SW Poland. The mine is located in the Karkonosze-Izera block, largely comprising Cambrian to Devonian metamorphic rocks intruded by the Variscan Karkonosze granite. Uranyl minerals from the Podgórze mine can be divided into three assemblages. The first one is associated with heavily ventilated mining galleries. The next assemblage is related to the outflow of water from fissures in the walls of the mine galleries. The last assemblage appears in the mine dump, where there is increased activity of other weathering products. The main purpose of this paper is to determine the mineralogical characteristics of uranyl minerals from the abandoned Podgórze uranium mine and reconstruct the physicochemical crystallization conditions based on the concentrations of rare earth elements (REEs) in these minerals. The results of thermodynamic modeling show that the aqueous species of uranyl ion in the mine water are represented by UO2HAsO4 (aq), UO2CO3(OH)3−, UO2CO3 (aq), and UO2OH+. The content of REEs and their distribution patterns were used to determine the crystallization conditions of uranyl minerals. Uranyl carbonates and arsenates have generally low concentrations of REEs compared to uranyl silicates, phosphates, and hydroxides, which have higher concentrations. The differences in REE concentration patterns may be related with the oxidizing nature of water circulating in the subsurface part of the deposit.

Highlights

Uranium can be released into the environment during the oxidation of uraninite [1,2]
The main purpose of this paper is to determine the mineralogical characteristics of uranyl minerals from the abandoned Podgórze uranium mine and reconstruct the physicochemical crystallization conditions based on the concentrations of rare earth elements (REEs) in these minerals
The Podgórze uranium deposit is located near Kowary in the Sudetes Mountains, SW Poland (Figure 1)

Summary

Introduction

Uranium can be released into the environment during the oxidation of uraninite [1,2]. This process starts with the decomposition of primary mineralization in polymetallic deposits with the oxidation of unstable phases, such as ferric sulfides, in aerobic conditions [3]. The water in weathering environments is enriched in various components, and some are considered dangerous and toxic to the environment [6]. In such zones, various secondary minerals can crystallize. In low-pH conditions, uraninite is unstable and uranium is leached. Uranium changes the oxidation state from 4+ to 6+

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