Vanadium – Valuable and toxic element in coal combustion ash: An overview

Abstract

The paper evaluates all important aspects related to V present in coal and its behaviour during coal combustion with particular attention paid to its potential extraction from ash and slag wastes. Due to great environmental benefits of co-combustion of coal and wastes, these alternative fuels and corresponding ash and slag counterparts were also taken into evaluation. Specifically, the paper summarizes V levels in world coals, in other related materials (alternative fuels, additives etc.) and in ash and slag residues including V speciation and discussion of its valence states. Theoretically predicted (equilibrium-based) calculations and species are compared with experimental results; due to a significant effect on mitigating CO2 emissions, attention is paid also to oxy-fuel combustion conditions. With the aim to extract V out of the ash and slag residues, physical, chemical, and biotechnological separation methods are discussed in detail along with dominant affecting factors. The paper includes also concluding remarks and highlights the most promising trends and limitations thereby providing suggestions for future research.