Waste derived raw materials
Protecting natural materials
Cement manufacture is based on the production of clinker, which is produced using quarried materials such as limestone and shale.
Major components of clinker are lime (CaO), silica (SiO2), alumina (Al2O3) and iron oxide (Fe2O3). Such mineral components can be found in varying concentrations in a number of waste streams, allowing replacement of natural resources.
Waste streams containing valuable minerals can be carefully selected for recovery and treatment as waste derived raw materials for cement manufacture, with each product carefully blended to meet the specific requirements of different cement plants.
Sapphire Energy Recovery has identified over 80 types of waste suitable for such use, including:
- Mill scale arising from the steel industry and water treatment cakes containing suitable iron and/or alumina content.
- Alumina rich catalyst material from the petrochemical industry and blended materials from the manufacturing processes.
- Roadsweepings and gully washings.
- Waste sludge and residue from paper making and recycling processes which are suitable for calcium replacement.
- Ash arising from co-incineration processes that have a range of compatible mineral properties.
In addition to saving finite resources, using some of these materials also reduces emissions of carbon dioxide from the cement making process.
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