Identification of Technogenic Magnetic Particles and Forms of Occurrence of Potentially Toxic Elements Present in Fly Ashes and Soil

Małgorzata Wawer

doi:10.3390/min10121066

Abstract

Solid fossil fuel power plants are the main source of energy in Poland. In 2018, the most important energy carrier was hard coal with a share of 57.9%, followed by lignite with a share of 18.1%. In addition to CO2, NOx and SOx, the combustion of fossil fuels produces dusts containing, among others, potentially toxic elements (PTEs), e.g., Pb, Zn, Cu, Cr, Cd. Although the currently operating power plants have efficient filter systems, the total dust emission in Poland in 2017 amounted to 341,000 t, of which approximately 36,000 t was from the power plants. PTEs present in the power plant dust are often accompanied by technogenic magnetic particles (TMPs)—mainly iron oxides and hydroxides formed in high-temperature technological processes as a result of the transformations of iron minerals contained in raw materials and additives. The presence of magnetic iron minerals (e.g., magnetite, hematite, maghemite, metallic iron) in the tested ashes from hard coal and lignite power plants was confirmed by scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) analysis. The sequential extraction analysis showed that most of the analyzed PTEs found in dust after hard coal combustion were mainly related to amorphous and crystalline FeOx or in the residual fraction and in dust after lignite combustion, mainly in the most mobile fractions.

Highlights

Current trends and new regulations implemented in the European Union force the gradual reduction in fossil fuels as traditional energy sources, contributing to the diversification of these sources and increasing the share of low-carbon and renewable energy
This research covered fly ash of the power plant after burning hard coal and lignite, as well as soil samples collected in the forest near the power plant
This study showed that the power plant dusts contained technogenic magnetic particles produced during high-temperature processes

Summary

Introduction

Current trends and new regulations implemented in the European Union force the gradual reduction in fossil fuels as traditional energy sources, contributing to the diversification of these sources and increasing the share of low-carbon and renewable energy. The European Commission supports an increase in financing for low-carbon energy, which will lead to the phasing out of support for fossil fuel projects, including natural gas [1]. Despite these arrangements, new coal-fired power plants and power units are still being designed and opened in Poland, and it is not expected that this source of energy will be abandoned in the near future.

Objectives

Methods

Results

Conclusion