Thermal Demercurization of Coal Sorbents

Abstract

The extraction of mercury in the vapor–gas phase from coal sorbents, used to capture mercury from industrial waste gases, was studied herein to develop a unified technology. The behavior of mercury compounds (Hg2Cl2 and HgCl2) under conditions of thermal demercurization in a fore vacuum and at atmospheric pressure was examined using partial pressure diagrams. It was established that the stable phases during the technological process are vaporous mercury and Cl2. As a result of technological research and extensive testing with developed equipment at 400–800 ◦C and pressure in the range of 0.13–91.99 kPa, it was established that mercury in a vacuum under these conditions almost completely enters the vapor–gas phase (99.4–99.97%). A similar degree of mercury extraction from a coal sorbent was achieved at 600–800 ◦C at atmospheric pressure. A study was conducted, and it was established that the sorbent after thermal demercurization—in terms of its sorption capacity for gold—was practically comparable to fresh, unused Norit sorbent.