Photographic paper and film as well
as other suitable combustible silver containing
materials are incinerated in a 1.3 metre
diameter refractory lined rotary kiln incinerator.
The kiln combustion conditions are maintained
by instrumentation and control systems,
with operational data logging and retrieval
by an on-line computer.
Material is charged into a static primary
combustion chamber, where material is ignited,
before moving into the rotating kiln. Combustion
air is drawn into the ash discharge end
of the kiln, flowing counter-current to the
burning material, and is drawn through into
the primary chamber.
Material and ash move along the kiln by
a combination of the rotation and the inclination
of the kiln. Ash is discharged from the
end of the kiln. The counter-current airflow
ensures that ash is well burned and cool
before discharge.
Combustion is sustained by the calorific
value of the raw material. No fuel is used.
Wet materials can be dried by directly using the waste heat
generated within the combustion process.
The exhaust gases are quenched by water
spray for temperature control. Lime and activated carbon are injected
into the raw gas stream to aid the absorption
of acid gases and dioxins. The exhaust gases are cleaned
by a dry filter plant, conforming to BAT
as specified by the UK’s EA, before
discharge to atmosphere through a 35 metre
exhaust stack.
Emissions to atmosphere are continuously
monitored by a particulate monitoring system
and data is automatically logged into an
on-line computer. Frequent additional sampling
of the exhaust stack also monitors for emissions
of gaseous and fume products. |
