(BAT) Reference Document for the Production of Chlor-alkali ...

Chapter 4
thermal treatment: Distillation/retorting is carried out in specially designed units. The
mercury is recovered as metallic mercury.
The choice of the appropriate decontamination technique depends on the location of the
mercury, its concentration and its chemical state for each category of material. For example,
ultrasonic vibration with recovery of the released mercury is effective with certain types of
pore-sized activated carbon but not at all with others. Retorting is technically difficult or
uneconomic for wastes with high water or organic content, low mercury content, or with
mercury in a state (e.g. mercury sulphide) that is inappropriate for this technique. Retorting is
used by many mercury cell chlor-alkali plants during normal operation. Some of these plants
have their own retorting unit which can be used during decommissioning while others use the
services of an external retorting company [ 59, Euro Chlor 2010 ], [ 94, Euro Chlor 2009 ].
After appropriate decontamination, materials such as steel structures, copper or aluminium bus
bars can often be recycled as raw materials [ 94, Euro Chlor 2009 ]. In the case of a conversion
to the membrane cell technique, the brine system and the processing systems for chlorine and
hydrogen can often be reused after appropriate decontamination (see Section 4.1.2).
Table 4.7 provides an overview of contaminated solid materials arising during decommissioning
and possible decontamination techniques.
WORKING DRAFT IN PROGRESS
164 December 2011 TB/EIPPCB/CAK_Draft_1