industry and environment - DTIE

Chemicals management
Figure 1
Drum-emptying plant for liquid waste
Figure 2
Drum-emptying plant for solid waste
avoid settling. The mixture is finally pumped to
15,000 m 3 storage tank farms. Capacity is increased
by 40,000 m 3 external storage facilities in
Copenhagen.
For safety reasons, the plant is completely
flushed with nitrogen to reduce the oxygen level
(which must be under 8%). Thus the gas phase in
the plant cannot explode.
The plant has been in operation since 1990. It
has a treatment capacity of approximately 3.5
tonnes of packaged liquid waste per hour, or
approximately 7000 tonnes per year for one shift.
Approximately 10% of this amount is steel scrap,
which is recycled.
The drum-emptying system for solid
waste
The solid portion of the packaged waste was still
incinerated in the rotary kilns directly in the packaging,
as it could not be treated in the drum-emptying
system for liquid waste. However, Kommunekemi
still had a distinct need for plant to
empty, homogenize and continuously feed the
packaged solid waste.
In 1996 an automatic system for handling and
emptying solid and pasty packaged waste was
built. In principle, this plant (Figure 2) is similar
to the liquid plant. However, it is of course of
much heavier construction.
The waste is transferred from storage areas to a
roller conveyor. Again, individual waste is identified
by bar codes and the process control system
ensures that it has been approved for treatment.
Waste and packaging are transferred to the
plant by a sluice flushed with nitrogen. A batch of
waste, typically five to seven pallets with packaged
solid waste, is crushed in the crushing chamber,
where viscosity is adjusted up or down by mixing
in special waste fractions. From the crushing
chamber the batch is pumped, using heavy piston
pumps, through the front shield and into the
rotary kilns.
At this plant there is no separation of steel scrap
for recycling, as the mixture is unable to pass a
sieve in the same way as at the “liquid plant”. The
steel is oxidized during incineration and then
incorporated in the bottom slag from the rotary
kilns.
For safety reasons, the plant is completely
flushed with nitrogen to reduce the oxygen level
(which must be under 8%). Thus the gas phase
cannot explode.
The treatment capacity of the drum-emptying
plant for solid waste is 1.5 tonnes of waste per
hour, or similar to approximately 12,000 tonnes
annually in five shifts.
Improved environment and safety
conditions
Establishment of the automatic drum-emptying
systems has resulted in a number of improvements
in environmental and safety conditions at Kommunekemi:
◆ Occupational health and safety problems related
to manual handling and emptying of packaged
waste have been reduced to a minimum;
◆ Employees’ contact with hazardous substances
UNEP Industry and Environment April – September 2004 ◆ 53