Thermal Treatment

Application of combustible waste products in the production of cement and analysis of gasification and a new calzinator

Various wastes have been used as raw materials and fuels in a cement kiln installation by the use of a circulating fluidised bed system in combination with a calcinator. Product quality remains unchanged, emissions lie below statutory limit values and it has even been possible to reduce quantities of waste water.


Cement production involves the consumption of 2.3 billion Mg of raw materials and 150 million Mg of fuel worldwide.  A significant proportion of these base materials may be replaced by wastes, thereby allowing the conservation of raw materials and landfill capacity.

In order to evaluate and optimise the use of fuel-bearing secondary raw materials in cement kiln installations, this project involved the investigation of gasification in a circulating fluidised bed system and a new design of calcinator.  Tests have been conducted under production conditions using the following substitute fuels: waste wood, airworthy fraction of solids, bleaching earth, foundry sand, dry stabilizing material, acid sludge, oil-contaminated soils, sand trap residues and lime-bearing materials.  These fuels are gasified in the circulating fluidised bed system and burned in the cement kiln calcinator.  Spent ash is then processed in the raw material mill for use as an admixture in cement production.


  • The circulating fluidised bed system appears to be suitable for a wide variety of wastes.
  • Emissions of dust, SO2, NOx, Hg and ∑C in the kiln waste gas have been measured on a continuous basis.  All emissions fell below the statutory limit values, although in some cases this was only achieved by the application of optimisation measures.
  • The water consumption of the cement works has been reduced by approximately two thirds to 300,000 m3 per annum, and the discharge of water has been reduced by 80% to 130,000 m3 per annum.
  • On the basis of cost considerations, this process has proved to be of economic value for the test site considered.

Project Participants

Implementing Institutions

Rüdersdorfer Zement GmbH

Cooperation Partner

KHD Humboldt Wedag AG, Köln

Asea Brown Boveri AG (ABB), Germany

Wissenschaftlich-Technische Gesellschaft für Verfahrenstechnik Freiberg e.V. (FIA)

Clausthal University of Technology

TU Bergakademie Freiberg

Verein Deutscher Zementwerke e.V. / Forschungsinstitut der Zementindustrie (VDZ/FIZ)

Fraunhofer Institute for Building Physics (IBP)

Fraunhofer Institute for Environmental, Safety and Energy Technology (UMSICHT)

Forschungszentrum Karlsruhe GmbH

Lurgi Energie und Umwelt, Frankfurt/Main

Gesellschaft für umweltverträgliche Verfahrensinnovation mbH (GUV)

Institut für Sicherheitstechnik, Freiberg

Institut Fresenius GmbH

Institut für Baustoff- und Umweltschutztechnologie GmbH, Weimar

Institut Prof. Dr. Jäger, Weimar

NAFU Ingenieurbüro, Schöneiche

More Project Information

Project title: Development, technical investigation and optimisation of residue-free cement production as an integrated process with the simultaneous recycling of various residues

Project number: 01ZH943C/6

Project period: 1994 - 2001

Project region: Germany (Brandenburg)

Project contact::

Dipl.-Ing. Peter Scur
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Source: German National Library of Science and Technology Hannover (TIB)