Environmental Aspects - Atmospheric emissions:
Technical solutions to reduce emissions

Atmospheric emissions are associated with all phases of the manufacturing process.

• Three main kinds of gaseous emissions,
• technical solutions to reduce harmful emissions,
• main measures to minimize dust

Three main kinds of gaseous emission occur :

• Emissions coming from ceramic conversion of the raw material in the kiln. The emissions are HCl (hydrochloric acid), HF (hydrofluoric acid), SO_x (sulphuric acid) and C0₂.
• Exhaust gas emissions from combustion processes (from drying and firing plants). The emissions are CO (carbon monoxide), CO₂ (carbon dioxide), NO_x (nitrogen oxides) and particles.
• Emissions due to the use of organic substances (additives). The emissions are VOC’s (volatile organic compounds).

Therefore technical solutions are used to reduce harmful emissions.
For gaseous compounds, the main measures are:

• use of raw materials that are low in sulphur, nitrogen, chloride and fluoride
• incorporation of inert additives in the clay body
• incorporation of fine limestone in the clay body to retain fluoride (and some sulphur)
• recirculation of low temperature carbonisation gases into firing zones of kilns (to combust CO and VOC’s).
• thermal after burners
• exhaust gas treatment by purification (gravel or lime filter)

The extraction of clay usually occurs very close to the plant so emissions (CO₂ and NO_x) from transportation are minimised.

Main measures to minimize dust:

• enclosure of dust producing processes
• use of a covered conveyor belt
• use of moist raw materials where possible,
• maintain cleanliness of kilns and kiln cars.
  

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