The Role of Mineral Matter in Concentrating Uranium and Thorium in Coal and Combustion Residues from Power Plants in Poland

Henryk R. Parzentny,Leokadia Róg

doi:10.3390/min9050312

Abstract

Based on the results of tests on feed coal from the Lublin Coal and Upper Silesian Coal Basin and its fly ash and slag carried out using X-ray diffraction and X-ray fluorescence analysis, atomic emission spectroscopy, and scanning electron microscopy, it was found that in feeds, coal Th is associated with phosphates and U with mineral matter. The highest Th content was found in anhedral grains of monazite and in Al-Si porous particles of fly ash of <0.05 mm size; whereas in the slag, Th is concentrated in the massive Al-Si grains and in ferrospheres. U is mainly concentrated in the Al-Si surface of porous grains, which form a part of fly ash of <0.05 mm size. In the slag, U is to be found in the Al-Si massive grains or in a dispersed form in non-magnetic and magnetic grains. Groups of mineral phase particles have been identified that have the greatest impact on the content of Th and U in whole fly ash and slag. The research results contained in this article may be important for predicting the efficiency of Th and U leaching from furnace waste storage sites and from falling dusts to soils and waters.

Highlights

The identification of groups of minerals that have the greatest influence on trace elementals content in coal makes it easier to forecast the efficiency of various chemical and mechanical procedures for purging ecotoxic elements; it has an influence on more conscious forecasts concerning the quantities of elements released into the environment following coal combustion [4,5,6,7,8].Combustion of hard coal in thermo-electric power stations provides people with electricity and heat, and raises concerns about the possibility of environmental pollution
Considering the share of grains in the composition of the whole fly ash and whole slag (Table 1), it was found that a group of non-magnetic particles of
Clarke, which is concentrated most likely in apatite and crandallite and in monazite.The average Th and U content in feed coals from the LCB and U in feed coals from the Upper Silesian Coal Basin (USCB) is higher, and the average Th content in the USCB feed coals is lower than the hard coal Clarke values

Summary

Introduction

The identification of groups of minerals that have the greatest influence on trace elementals content in coal makes it easier to forecast the efficiency of various chemical and mechanical procedures for purging ecotoxic elements (e.g., refs. [1,2,3]); it has an influence on more conscious forecasts concerning the quantities of elements released into the environment following coal combustion [4,5,6,7,8].Combustion of hard coal in thermo-electric power stations provides people with electricity and heat, and raises concerns about the possibility of environmental pollution. [1,2,3]); it has an influence on more conscious forecasts concerning the quantities of elements released into the environment following coal combustion [4,5,6,7,8]. Dust from the thermo-electric power stations (TPS), as well as the combustion residues generated and remaining at these plants, are a threat to the environment, due to the ecotoxic trace elements present in them. The highest content of trace elements in combustion residues is recorded in the smallest particles of fly ash On the surface of the fly ash particles, there are condensed elements of high volatility, which include. There are no legal regulations concerning the content of these elements in the combusted fuel and in the eluates from combustion residue dumps [16,17]

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