Prediction of Chinese Coal Ash Fusion Temperatures in Ar and H₂ Atmospheres

Abstract

The ash fusion temperatures (AFTs) of 21 typical Chinese coal ash samples and 60 synthetic ash samples were measured in Ar and H2 atmospheres. The computer software package FactSage was used to calculate the temperatures corresponding to different proportions of the liquid phase and predict the phase equilibria of synthetic ash samples. Empirical liquidus models were derived to correlate the AFTs under both Ar and H2 atmospheres of 60 synthetic ash samples, with their liquidus temperatures calculated by FactSage. These models were used to predict the AFTs of 21 Chinese coal ash samples in Ar and H2 atmospheres, and then the AFT differences between the atmospheres were analyzed. The results show that, for both atmospheres, there was an apparently linear correlation and good agreement between the AFTs of synthetic ash samples and the liquidus temperatures calculated by FactSage (R > 0.89, and σ < 30 °C). These models predict the AFTs of coal ash samples with a high level of accuracy (SE < 30 °C). Because the iron oxides in coal ash samples fused under a H2 atmosphere are reduced to metallic iron and lead to changes of mineral species and micromorphology, the AFTs in a H2 atmosphere are always higher than those with an Ar atmosphere.

Measurement and simulation of flow properties of coal ash slag in coal gasification

“…As can be seen from 47,48 To observe more directly the distribution of composition for these coal ash slag samples, we used FactSage to draw the pseudo-ternary diagram (SiO 2 -Al 2 O 3 -CaO-Fe 2 O 3 with an SiO 2 /Al 2 O 3 weight ratio of 1.7) in Figure 3. Since over 90% of the mineral matter in coal ash slag is derived from the oxides of aluminum, silicon, calcium, and iron, the SiO 2 -Al 2 O 3 -CaO-Fe 2 O 3 pseudo-ternary diagram can well describe the distribution of composition for these coal ash slag samples.…”

Prediction of temperature of critical viscosity for coal ash slag

“…Analysis of coal ash compositions shows that they consist mainly of SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO, and MgO, 11,12 so that the properties of coal ashes at high-temperature might be modeled by a five component SiO 2 …”

“…12 This test involved heating a sample cone of specified geometry at a rate of 5 K/ min in an Ar atmosphere. The following specific temperatures are recorded for each sample, corresponding to specific shapes of the ash cones: Initial deformation temperature (IDT), softening temperature (ST), hemispherical temperature (HT), and flow temperature (FT).…”

Mineral melting behavior of chinese blended coal ash under gasification condition

“…[15] Furthermore, the possible major mineral reactions in ash also can be interpreted through phase diagram theory. Main chemical components (SiO 2 , Al 2 O 3 , CaO and Fe 2 O 3 ) of most Chinese bituminous coal ashes usually comprise more than 90% of the total.…”