Clinker substitution takes hold in Africa
Ghana's cement producers have struck out on a decarbonisation and low-carbon cement path. By using local resources for raw materials and reducing the clinker factor, cement manufacturers are targeting reduced imports of clinker and lower cement prices, as well as the benefits of CO2 reduction.
This week the Director-General of Ghana Standards Authority, Professor Alex Dodoo, confirmed that plans are underway to build factories that can manufacture a substitute for clinker. "We have published a few papers on how we can use local substitutes to replace a significant proportion, probably 50 per cent of the clinker we use, using clay. I am happy to note that two giants are actually establishing a factory to produce this, they would need the standards that will drive this," added Professor Dodoo.
Ghana spends over US$0.5bn annually on importing clinker, according to Professor Dodoo. Cement producers such as Continental Blue Investments Ghana Ltd (CBI) are taking action to change this strategy. Its new 405,000tpa clay calcination unit will be one of the first in Africa and will source local clay as a raw material to replace 30-40 per cent of the clinker in the final product. This will result in a 20 per cent reduction in CO2 emissions from cement production compared to current practices and a 30-40 per cent reduction of CO2 compared to standard production of ordinary Portland cement (OPC), including the production of imported clinker. Total emissions are forecast to be cut by 300,000t CO2e/year.
Higher clinker substitution rates
Clinker substitution is also a regular practice in South Africa where cementitious cements have become common place. The incorporation of pulverised fly ash (PFA) from coal-fired plants and ground granulated blastfurnace slag (GGBS) from steel plants have always been accessible by-products for South African cement producers. According to the Association of Cementitious Material Producers (ACMP), clinker substitution rates in South Africa have risen from 12 per cent in 1990 to 23 per cent in 2000 and 41 per cent in 2009, while the forecast is to surpass 60 per cent in 2030.
Introducing new cement standards
Modernising Africa's cement sector will result in innovations to reduce the clinker factor and the addition of new substitute raw materials. Dr Wolfram Schmidt, a senior researcher at the Federal Institute for Materials Research and Testing (BAM) in Germany, believes Africa will play a crucial role in the use of local raw materials for cement and concrete manufacture.
"The future of concrete technology will be invented in Africa. The continent is very rich in resources, but we’ve never considered it in the past for concrete technology.
"We need to find ways to bring these resources to standards because they’re the same materials which are already standardised," said Dr Schmidt.
Reducing clinker trade
Reducing clinker trade is also a proactive way to cut CO2 emissions and to produce more sustainable cement. In March 2022 the National Independent Clinker Verification report in Kenya claimed that it could not be justified that local cement producers were importing clinker while producing the same product locally and exporting it to other east Africa countries. Kenya’s Finance Bill 2023 is now proposing an additional 10 per cent duty on the export and investment promotion levy rate for imported clinker.
West Africa's largest cement market and producer
Clinker trade has been a central theme in Nigeria since the country became self-sustainable in cement production in 2017. The lack of local limestone resources in parts of Africa has been key to Dangote Cement’s strategy to export cement and clinker. The company has built its Onne and Apapa export terminals to supply the region with its products, including clinker. In 2021 Dangote Cement absolved to honour free trade agreements, and build new grinding plants in west and central Africa for its export business. The company has already found Senegal and Cameroon profitable export markets (0.197Mt in 2020), because these countries do not have large limestone reserves.
However, the longevity of Dangote Cement's successful export strategy will depend on its ability to reduce the clinker factor of its products as these markets, as well as its domestic market, will begin to see low-clinker cements become standard solutions in the coming years. Nigeria itself has an energy transition plan to reach 20 per cent clinker substitution in cement production by 2030 and 50 per cent by 2050.
Summary
Most African countries and cement producers are providing more sustainable products for their customers. Calcined clay cement production is expected to transform the industry in Ghana, and the introduction of AI to optimise products could result in further clinker factor reductions. New African standards and product labelling recording the clinker factor are likely to be introduced to help promote low-clinker cements. Changing the practices of African cement producers may not be instantaneous. However, economic and climate pressures in Africa are increasing the move towards a reduced clinker factor, higher rates of clinker substitution as well as reduced clinker trade.
