Your waste

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The treatment and recovery of waste in the cement process
After appropriate pre-processing and conditioning your waste will be co-processed in the cement kilns of Holcim. The main ingredients to form cement are Ca (from limestone), Si and Al from clay (aluminum silicates) and Fe from additives. Waste contains these elements in one or the other form. Co-processing destroys the compounds in your waste making the essential elements of the waste (Ca, Si, Al, Fe) available for cement production. In this way the mineral part of your waste is recovered in cement production. Any residual energy content in the waste is recovered for maintaining the temperatures for waste decomposition and forming the compounds for cement.

Recovery of raw material

From a natural quarry in the vicinity of the cement plants limestone (for CaCO3) and clays (for SiO2, Al2O3) are mined. These materials are mixed with correctives (Fe2O3, Al2O3) to give the right mix of Ca, Si, Al and Fe in the raw mix for cement production. The mineral part of waste can substitute material usually mined from a quarry when correcting the mixing ratio of all materials appropriately and respecting appropriate feeding conditions.

To recover materials for cement production mineral waste should contain the following materials: lime, limestone, silica, iron, or alumina. These wastes can be from various industrial sectors like the iron and steel industry, smelting-works, galvanization works, aluminium industry, car industry, aircraft construction, chemical industry, food and water processing industry, glass industry etc.

Energy recovery in the kiln
For energy recovery your waste is used at high temperatures at the main burner and at the base of the pre-heater tower. The following wastes can be used for energy recovery:

  • Solid waste

 

  • Shredded packaging waste
  • Shredded plastic and textile waste (fluff, etc.)
  • Hydrocarbon residue
  • Sawdust impregnated with pasty waste (supplied by platform)
  • Crushing rejects
  • Sewage sludge
  • Polluted soil
  • Animal meal
  • Seeds
  • ...

 

  • Liquid and pasty waste

 

  • Solvents
  • Emulsions, detergents
  • Waste oil
  • Waste water
  • Oil tank sludge and viscous hydrocarbon residue
  • ...

Waste materials that are not suited for co-processing in clinker kilns and which we will not use are the following:

  • anatomical hospital waste
  • asbestos-containing waste
  • batteries
  • bio-hazardous waste
  • electronics metals scrap
  • explosives
  • high-concentration cyanide waste
  • mineral acids
  • radioactive waste
  • unsorted municipal waste