Use of EAF slag - CemStar®

In 1994, Texas Industries developed a system which enables the use electric arc furnace (EAF) slag of the steel industry as an input in cement kilns, reducing the use of limestone. The slag that contains tricalcium silicate (C3S in cement chemist notation) can more easily be converted to free lime than limestone. The CemStar® process allows replacing 10 to 15% of the clinker by EAF-slags, reducing energy needs for calcination and avoiding CO2 emissions related to fuel use and calcination. An additional advantage of the CemStar® process is the eliminated need for slag grinding, as slag can be added to the kin as 5 cm lumps. Depending on the location of injection it may also save heating energy.

Development Status Products

Use of EAF slag - CemStar®Costs & Benefits

Parent Process: Alternative Raw Materials
Energy Savings Potential

As the calcination energy demand is estimated to be 1.9 GJ/t-clinker, substituting 10% of clinker with steel slag will reduce energy consumption by 0.19 GJ/t-clinker. 

CO2 Emission Reduction Potential

Replacing 10% of clinker by steel slag can reduce CO2 emissions by approximately 11%


Equipment costs are mainly for material handling and vary between US $200,000 and $500,000 per installation. Total investments are approximately double the equipment costs. CemStar® charges a royalty fee.

Use of EAF slag - CemStar® Publications

Energy Efficiency Improvement Opportunities for the Cement Industry

The U.S. Environmental Protection Agency’s (EPA) energy guide, Energy Efficiency Improvement and Cost Saving Opportunities for Cement Making, discusses energy efficiency practices and technologies that can be implemented in cement manufacturing plants. This ENERGY STAR guide provides current real world examples of cement plants saving energy and reducing cost and carbon dioxide emissions.

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