This week thyssenkrupp Polysius and Schwenk Zement announced a new project for their meca-clay, low carbon cement process line at the Allmendingen cement plant in Germany in 2025. Leading multinationals have been among the first to highlight their development of calcined clay production, but there is a growing opportunity for African producers to play a significant role in the manufacture of limestone calcined clay cement (LC3).
While Europe has seen some calcined clay projects, the global location of kaolin sources indicates that Asia and Africa could well be the dominant regions for this type of low-carbon cement in the coming years, depending on local demand.
Kaolin's clinker reduction benefits
Metakaolin – the key incredient in calcined clay – is produced by heating kaolin (clay, paper sludge etc) to 650-750˚C to produce a highly reactive, pozzolanic material which can be used as a clinker replacement for cement. An LC3 cement consists of 30 per cent calcined clay, along with 15 per cent limestone and five per cent gypsum, with the remaining 50 per cent made up of clinker. The lower temperatures required to activate clays compared to limestone calcination represents a significant cost reduction for cement manufacturers, while LC3 blended cements are able to reduce CO2 emissions by as 40 per cent when compared to calcining Portland limestone.
Can African demand for LC3 expand?
Indications are that Africa will invest in LC3 production on a larger scale in the coming years. Only last week, Nova Cimangola announced that it was about to launch its LC3 production line in Angola with the assistance of Ecosolutions and IPIAC. This follows projects in West Africa by CBI Ghana, CIMAF in Burkina Faso, plus Cimpor and Oyak’s collaboration for a plant in Kribi, Cameroon. West African producers currently rely on costly clinker imports due to low availablity of domestic limestone for clinker production. Therefore many of these projects are driven by the economic benefits of clinker substitution.
The performance of the new LC3 brick factory for housebuilding in Malawi – a joint venture between the government, Terrastone brick company and Lafarge Cement Malawi set up in 2022 – is being eagerly awaited as the first such project in east Africa. Malawi is a perfect test environment for LC3 bricks as it has the highest urbanisation growth rate in the world at 6.3 per cent annually and has a high demand for urban settlements with 21,000 housing units needed every year over the next decade.
Africa's growing interest in calcined clay is unlikely to subside. A 2022 university study of kaolinitic clays for calcined clay cement pointed to their being abundant resources of the material in South Africa and, as early as 2019, AfriSam located viable reserves of kaolin on Bronkhorstspruit, Ottosdal, Western Cape and Eastern Cape. Therefore, it is possible that we could see the first South African LC3 project soon with leading cement producers such as AfriSam, Dangote Cement and PPC likely to exploit any potential for LC3 if it can be produced commercially at scale for a receptive market in South Africa.
