Behavior of Pb During Coal Combustion: An Overview

Abstract

Despite the progress in understanding heavy metals behavior during coal combustion, mitigation of heavy metals emissions is still a tough challenge due to a complex character of this phenomenon. Several lists of potentially toxic elements have been presented; in most cases, Pb belongs to the elements with the greatest environmental and human-health concern. The review paper is focused upon the behavior of Pb during coal combustion. with particular attention paid to decreasing its emissions. It summarizes the dominant parameters affecting its redistribution among coal combustion streams. As gaseous emissions can quite easily pass through the particulate control device, attention was paid primarily to Pb distribution between condensed and volatilized phases. A crucial factor enhancing Pb volatility is the presence of organic or inorganic chlorides, which is discussed in detail, including their chlorination mechanisms and interactions with other fuel/flue gas species. Components decreasing Pb volatility and promoting the formation of condensed phases are also discussed (higher levels of moisture, Na, O2 etc.). Factors enhancing Pb volatility, as well as factors facilitating Pb retention, are discussed with the view of fluidized-bed combustion, pulverized-fuel combustion, or co-combustion of coal with wastes.

Coupling Plant Biomass Derived from Phytoremediation of Potential Toxic-Metal-Polluted Soils to Bioenergy Production and High-Value by-Products—A Review

“…The above-reviewed examples indicate that the concept of linking phytoremediation and thermochemical biofuel production is a potential and promising pathway toward sustainability, valorizing the polluted biomass into metal-free biofuels and by-products, while allowing the recovery of HMs. Besides the benefits of producing bioenergy from polluted biomass, the generation of potentially toxic streams must be minimized [91,92], which has focused the investigation of sorbents, demineralization, and leaching techniques in order to remove or immobilize HMs.…”

Distribution and Mode of Occurrence of Co, Ni, Cu, Zn, As, Ag, Cd, Sb, Pb in the Feed Coal, Fly Ash, Slag, in the Topsoil and in the Roots of Trees and Undergrowth Downwind of Three Power Stations in Poland

“…Due to the temperature of evaporation of the elements [148], this could occur in such an order: Cd, Pb, Zn, Sb, As, Cu, Ni, and Co. The volatility of the elements is variable, i.e., different at the initial stage of coal combustion in a power station, and different during the main stage of combustion [2,3,[149][150][151]. It is probable that most of the vapors of the analyzed elements condensed on the surface of microspheres and unburnt organic matter; then they crystallized in forms showed in Figure 4, i.e., euhedral ferrospinels, dendrites, magnetite, Ti-magnetite, and hematite.…”

Spatial Macroscale Variability of the Role of Mineral Matter in Concentrating Some Trace Elements in Bituminous Coal in a Coal Basin—A Case Study from the Upper Silesian Coal Basin in Poland

“…The volatility of the elements varies, i.e., it is different at the beginning and during the main stage of combusting in Power Plants. For each element of different modes of occurrence, the variability depends on the coal rank and working conditions, especially the temperature of combustion [40,96,97]. Coefficients of enriching elements of high volatility (e.g., As, Hg, and Zn) in fly ash and bottom ash are low, which indicates the elements were released into the atmosphere together with flue gases [17,23,[98][99][100].…”