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

Chapter 4
Table 4.7: Overview of contaminated solid materials arising during decommissioning and
possible decontamination techniques
Material
Typical
Hg
content
in wt-%
Remarks
Possible decontamination technique
Mechanical
and physical
treatment
Chemical
treatment
Thermal
treatment
Sludge from storage
tanks and sumps
10 – 30 Wet Yes No Yes
Sludge from settling
catch pits, drains, etc.
Sulphurised or iodised
2 – 80 Wet Yes No Yes
charcoal from
hydrogen purification
10 – 20 Dry Yes ( 1 ) Yes No
Carbon from caustic
filters
Q 40 Wet Yes No Yes
Graphite from
decomposers
2 Porous Yes Yes Yes
Rubber/packing variable No remarks Yes Yes No
Brick work/concrete 0.01 – 0.1 Dry Yes Yes Yes
Ebonite-lined cell
components (anodes
covers, end boxes, side
walls, pipework)
Steel (cells,
decomposers, baffles,
H2 coolers, base plates,
Hg pumps, pipework)
variable
0.001 – 1
Plastic equipment < 0.1
Copper conductors 0.04
Cell sealant (layers
concrete)
Asphalt 1 – 20
Concrete and subfloor variable
Inhomogeneous
contamination
Surface
contamination
Surface
contamination
Surface
contamination
Yes Yes No
Yes Yes Yes
Yes ( 2 ) No No
Yes No Yes ( 3 )
0.01 No remarks Yes ( 1 ) No No
Inhomogeneous
contamination
Inhomogeneous
contamination
Yes No No
Yes No Yes
Wood variable No remarks Yes No No
Soil variable
Decomposer lagging
(thermal insulation)
Inhomogeneous
contamination
0.03 No remarks
Yes No No
WORKING DRAFT IN PROGRESS
Retort residues Q 0.1 Dry, porous
Wooden floor boards 0.05 – 0.08
Inhomogeneous
contamination
( 1 ) Washing with water is not effective.
( 2 ) Only washing with water is effective.
( 3 ) For flexible connections made of several copper sheets.
Source: [ 94, Euro Chlor 2009 ]
No treatment before disposal
When high concentrations of mercury are expected to be present in the workspace atmosphere,
the working area is confined and the ventilation air is treated (e.g. for high-pressure washing of
TB/EIPPCB/CAK_Draft_1 December 2011 165