The UK produces over 9 million tonnes of cement each year. To achieve this over 14 million tonnes of quarried materials are taken from the ground. These resources are finite, but the possibilities of replacing some of the requirements with mineral rich wastes are real.
There are some 20-25 million tonnes of mineral-based waste that could be re-used in the manufacture of cement.
Clinker is the base for cement production and is itself produced using quarried materials such as limestone and shale. The major components of clinker are lime (CaO), silica (SiO2), alumina (Al2O3), and iron oxide (Fe2O3).
These mineral components are not always found in optimum quantities in the natural feedstocks. They are found, however, in varying concentrations in waste streams such as air filter dusts and filtrates from water treatment and other industrial processes. If carefully selected, these materials contain the mineral ‘valuables’ as major constituents, and, depending on the origin, limited quantities of contaminants. The materials are recovered and treated as alternative raw materials according to cement work requirements and specifications.
Production of tailor-made Alternative Raw Materials for the cement industry
Based on the specific needs of each cement works, appropriate materials are pre-selected according to their chemical and physical constituents. In order to guarantee adherence to the ARM feedstock specification all input materials are subjected to comprehensive analysis by independent laboratories.
- Sustainable re-use of valuable resources (Al203, CaO, Fe2O3, SiO2)
- Reduction of disposed wastes
- Protection of natural resources for the future
- Increased control in the cement production process from predictable ARMs
Materials for Alternative Raw Materials
A range of over 80 types of waste, as identified by their European Waste Catalogue (EWC) classification, have been identified as suitable for ARM production. Some of these are:
- Filter residues from iron and non-iron metal production and treatment
- Filter residues from combustion, paper and sludge incineration
- Residues from ceramic, clay and sand productiones for the future
- Communal and industrial water treatment filter cakes
- Spent catalysts
- Brewing & food production filter mediums