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The retention of arsenic (As) during coal combustion facilitates As emission control. A fixed-bed experimental system was used to conduct devolatilization and char combustion experiments at 1100–1300 °C using three types of coal. Both processes contributed to the As release. As in coal was bound to carbonate, oxide, sulfide, and aluminosilicate (Als-As). During devolatilization, carbonate- and oxide-bound As and Als-As remained stable, while sulfide-bound As was completely decomposed. The gaseous As was partially retained as Char-As. During char combustion, Char-As was oxidized to As 2 O 3 , which was partially retained by minerals. Carbonate- and oxide-bound As reacted with silicon (Si) and aluminum (Al) to produce Als-As, which was the main As form in ash. As retention was significantly inhibited by the destruction of the lattice structure. As retention by char during devolatilization and minerals during char combustion promoted As enrichment in solid products and its removal. [Display omitted] [ABSTRACT FROM AUTHOR]

Biomass-coal blending combustion is an effective method for utilizing biomass; however, its pollutant emission requires attention. Herein, the effect of biomass-coal blending combustion on lead (Pb) transformation was explored. Combustion experiments were conducted in a fixed-bed reactor, using coal, corn stalk, rice stalk, bamboo flour and their mixtures as fuels, at 1000, 1100, 1200 and 1300 °C. The Pb release ratios were determined by measuring its content in the fuels and solid-phase combustion products. The distribution of Pb forms was analyzed using sequential chemical extraction. The results indicate that blending combustion significantly enhanced the release of Pb. At blending ratio 1:1, the release ratios increased by 1.54–27.2%, 5.30–15.6%, and 2.31–7.76% at 1000, 1100, and 1200 °C, respectively. The potassium (K) components in biomass, mainly KCl and K 2 CO 3 , had a significant promoting effect on Pb release. K compounds facilitated the release of residual Pb through reactions with aluminosilicates. The promotion effect weakened as the temperature increased due to the faster evaporation rate of K. When the mass fractions of K in the fuels were equal, K 2 CO 3 exhibited a stronger promoting effect. HCl had minimal impact on the transformation of Pb. The results are helpful for optimizing the combination of biomass and coal to control Pb emission from the blending combustion source. [Display omitted] • The effect of biomass-coal blending combustion on lead (Pb) transformation was studied. • The release of Pb in coal was promoted during blending combustion. • K compounds in biomass promoted the release of Pb, while Cl had little effect. • K 2 CO 3 and KCl could both react with aluminosilicate and release residual Pb. • K 2 CO 3 had a stronger promoting effect on Pb release than KCl. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dynamic transformation of Pb during coal devolatilization was studied. • Pb release and changes in distribution of Pb forms in solid products were analyzed. • Char-Pb was found to be an intermediate form during devolatilization. • Release of original residual Pb in coal was mainly promoted by H 2 S in the volatiles. • Mechanism of Pb transformation during coal devolatilization was proposed. The transformation of Pb during coal devolatilization affects its emission characteristics. Herein, devolatilization experiments were conducted at 1100–1300 °C in a fixed-bed experimental system using four types of coal samples. The occurrences of Pb in coal and devolatilization products were characterized. The release ratio of Pb first increased and then stabilized with time. The Pb release ratio and rate were higher at higher temperatures. Pb in some coal samples was completely released at 1100 °C. Pb in coal was mainly in carbonate- and oxide-bound, sulfide-bound, and residual forms. During devolatilization, carbonate-, oxide-, and sulfide-bound Pb gradually disappeared. Organic-bound and residual Pb first increased and then decreased owing to the conversion of gaseous Pb into Char-Pb by char, according to further form analysis of residual Pb and the experiments of char retaining PbCl 2 and PbO. The effects of different volatile components on residual Pb were compared, and H 2 S was found to significantly promote the release of residual Pb in coal. The transformation paths of Pb during coal devolatilization were proposed, including the release of original Pb in coal and the reversible conversion between gaseous Pb and Char-Pb. The results help understanding Pb emission and developing control techniques for coal-fired plants. [ABSTRACT FROM AUTHOR]