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

3.8.3 PCDDs/PCDFs, PCBs, PCNs and PAHs
Chapter 3
Graphite anodes were used almost exclusively for chlorine production before being replaced in
the 1970s by metal anodes. The graphite anode was composed of various types of particulate
coke mixed with a pitch binder. Some oxygen was liberated at the anodes with the chlorine, and
this oxygen attacked the graphite forming carbon monoxide and carbon dioxide. This electrode
wear was the cause of a graphite consumption of approximately about 2 kg per tonne of chlorine
produced from sodium chloride and 3 – 4 kg per tonne of chlorine produced from potassium
chloride. The graphite residue produced was contaminated with PCDDs/PCDFs and other
halogenated organic compounds such as chloroform, polychlorinated benzenes (PCBs) and
naphthalenes (PCNs), mainly derived from the reaction between chlorine and the pitch binder
containing polycyclic aromatic hydrocarbons (PAHs). Before the 1970s, the spent graphite was
usually not incinerated but dumped in available pits near the site or unsecured local landfills [ 1,
Ullmann's 2006 ], [ 240, Otto et al. 2006 ], [ 242, Lutz et al. 1991 ]. [Müllmagazin, 1991],
[Ullmann’s, 1996] Table 3.36 shows some examples of contaminated chlor-alkali sites.
WORKING DRAFT IN PROGRESS
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