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Cement plants

Sector's classified installations

Nomenclature sections: 251525172520 - 167c
Standard orders: 25152517

Classified Installations Legislation references

Order of 3 May 1993 relative to cement plants
Circular DPPR/SEI of 3 May 1993 relative to the implementation of the order of 3 May 1993 on cement plants
Order of 20 September 2002 relative to hazardous waste incineration and co-incineration installations
Order of 20 September 2005 relative to greenhouse gases (CO2 quota disclosure etc.)
Reference document listing the Best Available Techniques (BREF) in cement and lime manufacturing industries pursuant to directive IPPC 96/61/CE.

Context, issues and problems

Cement is a basic material in the construction and civil engineering sectors. Worldwide cement production (over 1,500 million tons in 2005) has regularly increased since the early fifties and is currently soaring in rapidly developing regions such as Asia. European production represents approximately 12% of the worldwide production and there were nearly 252 plants manufacturing clinker or finished cement in 1995 (38 plants in France) as well as 68 crushing plants not equipped with furnaces (5 crushing plants in France).

Cement is a non-metallic and inorganic finely crushed powder obtained from limestone and clay. The basic chemical reaction begins with the decomposition of calcium carbonate (CaCO3) into lime (calcium oxide, CaO), accompanied by the release of carbon dioxide at approximately 900°C. This process, called calcination, is followed by clinkering during which the calcium oxide reacts at a high temperature (between 1,400°C and 1,500°C) with silica, alumina and ferrous oxide to form calcium aluminium silicates making up the clinker. This clinker is then crushed and mixed with gypsum and other components to obtain cement.

There are 4 major cement manufacturing processes: dry, semi-dry, semi-wet and wet processes. The choice of process largely depends on the condition of the raw materials (dry or wet). A significant part of worldwide production still relies on the wet process. In Europe however, over 75% of the production uses the dry process due to the availability of dry raw materials.

The cement industry consumes a lot of energy; its cost represents 30 to 40% of the production costs (excluding investment costs). The primary combustible used is coal but a broad range of products is also used such as petroleum coke, natural gas and fuel oil. In addition to these combustibles, the cement industry has been burning different types of waste for 10 years (used tyres subject to specific approval, industrial waste with a certain calorific value, animal meal etc.).

2Risks and nuisances / best available techniques 2

The major issue lies with pollutant emissions. The main emissions are furnace emissions; cement plants generate a lot of CO2 which is produced by the CaCO3 calcination reaction and the combustion.
The IPPC directive (Integrated Pollution Prevention and Control) contains the general list of air pollutants to be taken into account when setting limit emission values. The main pollutants are:

  • Nitrogen oxides (NOX) and other nitrogen compounds,
  • Sulphur dioxide (SO2) and other sulphur compounds,
  • Dust particles.

As well as:

  • Carbon monoxide (CO)
  • Volatile organic compounds (VOC)
  • Dioxins and furans (PCDD and PCDF)
  • Metals and metal compounds,
  • HF, HCL etc.

The main sources of dust emissions are therefore furnaces but also raw material crushing plants, clinker coolers and cement crushers. The design and reliability of modern electrostatic filters and bag filters has enabled the reduction of dust emissions to relatively low levels (under 10 mg/m3).
While dust reduction measures have been largely enforced for over 50 years and the reduction in SO2 is specific to each plant (it should be noted that a significant part of the SO2 is trapped in the process), the issue of NOX is a relatively new one for the cement industry. This process has been optimised and low NOx burners are being developed. These initial general measures shall probably be completed by additional and more complex measures applicable to processes such as non catalytic selective reduction etc.
The other nuisances or risks inherent in a cement plant relate to the noise, the treatment of special waste, transport and supplies, the risk of fire or explosion depending on the nature of the combustibles used.

Finally, it should be pointed out that all cement plants are associated with a nearby quarry for raw material supplies and, consequently, prevention and protection measures against the nuisances of this type of installation should be taken into account (landscape protection, dust particles, noise, blasting, protection of surface and underground water, waste, transport and supply etc.).

Ongoing actions in the sector