Mechano-chemical activation of clays for Supplementary Cementitious Material production

The innovative meca® clay technology marks the first industrial-scale application of mechano-chemical activation of clays or clay-containing materials for use as supplementary cementitious materials (SCMs). This groundbreaking technology not only revolutionizes sustainable cement production but also offers significant environmental and economic advantages, positioning it as a key driver for the future of the industry.

Operation
The meca® clay technology employs mechano-chemical activation of clays. Based on the Polysius® Charger technology, it combines grinding and activation in one system. It uses decarbonized electrical energy instead of thermal energy and fossil fuels. The process enhances the internal free Gibbs energy of clays to make them suitable as SCMs.

Environmental purpose
The primary environmental objective of meca® clay technology is to substantially reduce CO2 emissions in cement production. Traditional methods are carbon-intensive due to limestone calcination and fossil fuel usage. By eliminating the need for thermal energy and fossil fuels, meca® clay technology offers a cleaner alternative, reducing the CO2 footprint by up to 48 %. The CO2 reduction assumes that up to 48% less clinker can be used in the production of a a CEM II/C-M compared to a CEM I production. Additionally, it produces no air pollutants, enhancing environmental sustainability.

Driving force for implementation
The implementation of meca® clay technology is driven by the urgent need for climate neutrality in cement production. thyssenkrupp Polysius and SCHWENK Zement have collaborated to develop this technology, addressing the industry's environmental challenges. Their partnership aims to industrialize the production of activated clays, demonstrating the technology's feasibility and efficiency.

Performance
The meca® clay technology has demonstrated promising results in cement mortar and concrete formulations. Pre-industrial tests by SCHWENK Zement and thyssenkrupp Polysius have confirmed its excellent quality and performance. The technology is adaptable, activating various clays, including illitic and calcareous types and even marls. It also requires lower water demand and achieves high compressive strength.

Advantages and innovative features
• Versatility: meca® clay can activate any type of clay, making it suitable for a wide range of applications.
• Single process system: Grinding and activation occur in a single system, streamlining the production process.
• Fully electrified: The process is entirely powered by electrical energy, eliminating the need for fossil fuels.
• Environmental benefits: Significant reduction in CO2 emissions and elimination of air pollutants.
• Economic efficiency: The technology can be economically viable depending on electricity availability and pricing.
• Color control: The patented process allows for simple color control of activated clays.
• Renewable energy storage: The Polysius® Charger enables renewable energy storage, enhancing the sustainability of the activation process.

Environmental Added-Value
The environmental benefit of meca® clay technology is its ability to produce hydraulic binders with reduced thermal energy, utilizing decarbonized electrical energy. This innovation lowers the carbon footprint of cement and concrete production, aiding global climate change efforts. By providing a sustainable alternative to traditional methods, meca® clay technology supports greener construction practices and promotes environmental stewardship.

Link to the technique (Basic Information)

www.thyssenkrupp-polysius.com

Relevant alternative technique

Thermal clay activation (calcination):
Clay calcination involves the thermal activation of clay minerals, primarily kaolinite, by heating them to temperatures typically between 600 °C and 900 °C. This process transforms the clay into a reactive material that can be used as a supplementary cementitious material (SCM) in concrete production. The method begins with the selection of high-kaolinite clay, which contains more than 40 % kaolinite. The clay is then heated in a kiln or calciner to the required temperature, followed by cooling and grinding to produce a fine powder.

Compared to the Polysius meca® clay method, calcined clay shows different features. The thermal energy consumption for the calcination process is significant, which could offset some of the CO2 reduction benefits if the energy used is not from renewable sources. The effectiveness of the calcination process depends on the quality of the raw clay material, and variations in kaolinite content can affect the performance of the final product. Furthermore, the calcination process itself generates CO2 emissions, which need to be considered in the overall environmental impact. In addition, emission abatement measures may be necessary.

Participant Companies

• Under construction

Technology readiness level (TRL) 8

Environmental purpose of the innovative technique

Decarbonisation

Material efficiency (Reduction of raw material consumption or waste generation)

Reduction of emissions to air (including noise and odour)

Relevant industrial sector

Cement, lime, magnesium oxide production

IED activity

3.1a Production of cement, lime and magnesium oxide: production of cement clinker in rotary kilns