Investigation on the transfer-transformation behavior of beryllium during coal combustion

The thermodynamic equilibrium calculation was conducted to estimate the beryllium conversion in the combustion process of coal, and the high temperature vacuum tube furnace was used to research the beryllium compounds reaction with other solid substances and the coal combustion experiments by adding sorbents. X-ray diffraction (XRD), X-ray fluorescence probe (XRF) and inductively coupled plasma-mass spectrometry (ICP-MS) were used to reveal the transformation behavior of beryllium during coal combustion. The results indicate that the beryllium only reacts with aluminum compounds and the reaction resultants are BeAl₂O₄ and BeAl₆O₁₀, the solid-solid reaction experiments are in agreement with thermodynamic calculation results, but the actual reaction temperature is about 1000℃, far above the thermodynamic calculation temperature 650℃. Because beryllium reacts with Al₂O₃ in combustion, the release rate of beryllium in the coal sample added with Al₂O₃ reduces greatly by up to 33%. Moreover, the inhibition of illite to beryllium release for coal combustion with addition of illite is weaker owing to a higher reaction temperature of illite with beryllium than that of Al₂O₃. Kaolinite, because its reaction temperature with beryllium is too high, has the lowest inhibition effect.