Mercury reactions in copper roasting gas cleaning system

Reactions of mercury in copper roasting gas have been studied. The study in cludes characterisation of dust from a bag house filter which collects dust from a copper roasting process and equilibrium calculations to predict the reactions in a copper roasting gas cleaning system. Mercury was Found toge ther with roasted chalcopyrite particles in the characterised dust samples. Characterisation indicates the presence of HgS and mercury bromine. The re sults from the equilibrium calculations show that mercury is totally vapori sed as Hg degrees during roasting. Depending on gas atmosphere and temperat ure, different mercury species will, according to equilibrium calculations, be stable in the roast gas studied. HgBr2 and HgCl2 are thermodynamically favoured at decreasing temperatures in the system studied. A minor part of the present mercury will form HgS(s) at low temperatures if no leakage air is added. In the case where Br and Cl are removed from the calculations, Hg S will be the dominating species at low temperatures.