Critical temperature for rapid release of mercury from coal after high temperature: A review

The emission of mercury during high-temperature processing of coal under different conditions poses a great threat to the natural environment and human health in recent years. Extensive research has been conducted on the emission of mercury in coal under high temperature. This review discusses the progress of the mercury emission characteristics of various types of coal under high temperature. The effects of temperature, heating time, heating rate and oxygen concentration on mercury emission are summarized. And the measures to reduce the mercury emission from coal are also prospected. The results show that the Hg release rate gradually increases with increasing temperature, especially in the range of 200-500 degrees C. Moreover, the increase of heating time, heating rate and oxygen concentration will promote the emission of mercury. This review also focuses on the effects of reaction pressure and mercury form changes on mercury removal. The lower the reaction pressure, the higher the removal rate of mercury. The oxidation of elemental mercury and the formation of particulate mercury are easy to control. In addition, the development of new adsorbents in the future will contribute to the detection and removal of mercury. (C) 2020 Elsevier Ltd. All rights reserved.