An Experimental Comparison of the Ash Formed from Coals Containing Pyrite and Siderite Mineral in Oxidizing and Reducing Conditions

Abstract

Four coals containing iron mineral pyrite (FeS2) and siderite (FeCO3) were combusted in a laboratory drop tube furnace at temperatures of 1300, 1450, and 1600 °C under oxidizing and reducing conditions. Results for the behavior of pyrite mineral were in agreement with the established literature. The behavior of siderite mineral was determined and comparisons made. Coals containing pyrite minerals were determined to have potential to produce ash deposition and slagging at lower temperatures than coals containing siderite mineral. Reducing conditions were determined to lower the temperature at which ash deposition and slagging may occur for coals containing iron minerals compared to oxidizing conditions. With respect to ash deposition and slagging, it was determined that the iron levels in a coal are not definitive, but rather the iron mineral type (pyrite or siderite), mineral association (included or excluded), degree of association of included minerals, and the type of included alumino−silicate minerals have important roles.

Emission of inorganic PM10 from included mineral matter during the combustion of pulverized coals of various ranks

“…First, extensive fragmentation of the HLH lignite may take place during devolatilization, following similar phenomenon observed by Levendis et al [42] for other low rank lignites. Second, the temperature ($435°C [43]) at which the devolatilization of the HLH lignite commences is close to the decomposition temperature ($495°C [39]) of siderite. Thus, the fragmentation of inherent siderite due to the evolution of its decomposition gaseous products and that of coal due to volatile release may simultaneously take place.…”

“…3b). The presence of Fe in PM 1-10 is well-known as a result of a series of mineral reactions [39], followed by fusion and coalescence on the surface of burning char particles [40]. For the HLH lignite rich in siderite, the PSD of Fe in PM 10 exhibits a trimodal distribution, with peak diameters of $0.08, $0.25 and $4.1 lm, leading to $15% and $85% of total Fe in PM 10 being distributed in PM 1 and PM 1-10 , respectively (see Fig.…”

The melting potential of various ash components generated from coal combustion: Indicated by the circularity of individual particles using CCSEM technology

“…The major carbonates generally found in coal are calcite, siderite, dolomite and ankerite. Only siderite cannot be detected by CCSEM effectively because it has a similar Fe/O ratio with iron oxide, accordingly it is analyzed together with iron oxide in our research and other earlier studies [24,27,28], and will be named as iron oxide/siderite in this paper. The mineral analysis results from CCSEM are summarized in Fig.…”

Inhibition of lignite ash slagging and fouling upon the use of a silica-based additive in an industrial pulverised coal-fired boiler. Part 1. Changes on the properties of ash deposits along the furnace

“…The formation of iron oxide is a major route for the transformation of inherent iron in coal [25]. Finally, the dispersion of Mg is noteworthy.…”