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

Chapter 4
However, the soil washing plant was not able to sustain adequate reliable operations and Orica
decided to suspend the operations in 2011 [ 247, Orica 2011 ].
At a mercury cell chlor-alkali site in Squamish/British Columbia (Canada), a total of 150 kt of
mercury-contaminated soil and sludge were excavated from 1999 – 2003. While the heavily
contaminated soil was stabilised and shipped for disposal, the less severely contaminated soil
was washed on site and reused as backfill [ 264, British Columbia Ministry 2009 ].
In the United States, a full-scale decontamination was carried out in 1993 at a waste processing
and recycling facility with approximately 10 000 m 3 of soil. The washing consisted of screening,
separation and froth flotation. The concentrations of mercury could be reduced from 100 mg/kg
to 1 mg/kg [ 266, US EPA 2007 ].
Cross-media effects
Some raw materials and energy are consumed for the construction and operation of the washing
system.
Additional emissions may result from the mobilisation of pollutants which have negative effects
on health and safety. Washing implies generating a contaminated waste water stream that has to
be treated. Any recovered metallic mercury or mercury-containing wastes from the treatment of
exhaust gases and waste water require further treatment and/or safe disposal.
Technical considerations relevant to applicability
Soil washing requires the excavation of soil which may be restricted by existing buildings and
underground equipment.
Economics
{Please TWG provide information.}
Driving force for implementation
The driving force for implementation of this technique is environmental legislation.
Example plants
Orica mercury cell chlor-alkali site in Sydney (Australia) [ 247, Orica 2011 ];
Nexen mercury cell chlor-alkali site in Squamish/British Columbia (Canada); in
operation 1960 – 1991, capacity unknown [ 264, British Columbia Ministry 2009 ];
Several full scale and pilot applications in the United States [ 266, US EPA 2007 ].
Reference literature
[ 247, Orica 2011 ], [ 264, British Columbia Ministry 2009 ], [ 266, US EPA 2007 ]
WORKING DRAFT IN PROGRESS
TB/EIPPCB/CAK_Draft_1 December 2011 265