Calcined clays: making a global impact

Calcined clays: making a global impact
01 April 2022

This week FLSmidth announced that it would be supporting the largest calcined clay installation in the world in Ghana for CBI Ghana at its Accra plant. It is a good time to look at how many of these calcined clay projects are now underway and how much investment is being placed in this carbon reduction technology.

CBI Ghana's project instantly excites because it is billed as currently the largest calcined clay project in the cement industry. The grinding capacity will increase by 120 per cent from the present 0.6Mta cement capacity. This means that the calcined clay installation will have a grinding capacity of 0.72Mta and the plant will have an overall grinding capacity of 1.32Mta. The main aim will be to reduce the CO2 emissions at CBI Ghana as well as produce a high-quality product that is of no less a quality than OPC. FLSmith has estimated a 30-40 per cent reduction in CO2 emissions per tonne of cement produced compared with OPC. 

Africa seems to be ripe for calcined clay excavation as Malawi also reported this week that the country’s Limestone Calcined Clay Cement (LC3) project, a public-private project initiative, is now underway. Participants will include Lafarge, Shayona Cement and Cement Products Ltd. The project will see a decrease in the use of fire bricks with LC3 bricks for house building. It is also expected to reduce imported clinker requirements. The use of the EcoKiln or vertical shaft brick kiln passed feasibility studies in 2013 under CCODE, GIZ and TARA. Lafarge already produces DuraCrete (CEMIII 32.5N) in Blantyre.

Thyssenkrupp Industrial Solutions was one of the first companies to announce it would build an industrial-scale cement plant that uses activated clay in Kribi, Cameroon. Cimpor Global Holdings and OYAK Çimento AS are behind the project which aims to save more than 120,000tpa of CO2 emissions and will produce 720tpd of polysius activated clay. The project consists of a flash calciner and grinding plant for calcined clay. The plant also has a separate 100tpd grinding unit for cement. Aumund has received a bulk material handling equipment order for the project.

Cimpor Global Holdings also has a calcined clay project with Oyak in Abidjan, Côte d'Ivoire. The project started in August 2020 and produces DeOHclay (CEMII/A-M (Q-L 42.5N and CEM IV/B (Q) 32.5N. Kaolinite clay is put through the dehydroxylation process to form metakaolinite at 600-700˚C. The Abidjan site has a rotary kiln and dryer, and operates at 0.3Mta of calcined clays and 2400tpd of cement grinding capacity. Raw clay characteristics define the specific heat consumption and electrical energy rates, and these range between 550-750kcal/kg and 18-23kWh/t, respectively. 

HeidelbergCement has not invested as heavily in calcined clays as it has in carbon capture technology, but the Ghacem subsidiary in Ghana is building a US$100m cement plant in Kumasi, Ashanti region. This 1.5Mta cement plant will use calcined clays as an additive. The plant is scheduled to be commissioned in the 1Q23.

Cemex has also started activated clay production at its kiln at Assiut Cement plant in Egypt. The project aims to develop a tailor-made quality enhancer admixture to improve the reactivity of cement.

In India ACC and Ambuja are at the forefront of calcined clay development and have begun a project with the Indian Institute of Technology Delhi to develop calcined clays. The aim of this scheme is to target 50 per cent lower emissions in the next-generation of cement production.

Europe is not without its supporters of calcined clay and Vicat is looking use calcined clays at its Argilor site in Xeuilley, France. The EUR40m project requires a new calciner with 85 per cent alternative fuel usage and has had EUR13m funding from ADEME. FLSmidth is constructing the 400tpd flash calciner as well as a dryer crusher, calcination tower and gas emission abatement technology. CO2 emissions will target 87kg CO2/t of cement produced, cutting CO2 emissions by 16 per cent, according to Vicat. FLSmidth expects commissioning to be completed by the end of 2023. 

Holcim France has awarded Sinoma Construction Co Ltd the French SPL clay calcination EPC general contract project, located in Normandy. The cement factory will add the new clay calcination line next to the clinker production.

Aalborg (Cementir group) in Denmark also produces FUTURECEM which is a synergy between calcined clay limestone and the properties of OPC. 

South & Central America
South American projects are headed by Cementos Argos that has a 0.45Mta calcined clay production line in operation at its Rioclaro cement plant, Colombia. The investment cost US$78m and cuts CO2 emissions by 38 per cent while lowering energy consumption by 30 per cent.

Votorantim Cimentos is similarly investing in this technology through its Loma Negra subsidiary in Argentina. The Olavarría plant a calcined clay line has been operational since 2019 and produces 0.2Mta of product.

Central American involvement has seen Cuba launch a plant in 2020 at the Marta Abreu University in Las Villas to produce low-carbon LC3 cement. It has a small production of 4tpd that is being expanded to 8tpd.

While this is only a selection of the many plans for calcined clay production, there is a clear emphasis on projects in Africa. Much of this is because of the growing population, the cost of importing clinker and available resources of raw materials. There is a mixture of projects that are choosing flash calciner technology and rotary kiln and dryer technologies. Most emission savings on CO2 are between 30-50 per cent. Europe will likely be attracted to more calcined clay installations shortly as the market price for EU-ETS emission credits increase. ICR research did not come across calcined clay investments for the cement sector in southeast Asia, but ICR would be pleased to hear of any.


Published under Cement News