CO2 Low-Carbon Cement Production With Activated Clay: thyssenkrupp Builds First Industrial Plant In Cameroon
- Technology from thyssenkrupp reduces carbon dioxide emissions in cement production by up to 40 percent
- New cement plant in Kribri, Cameroon, thus saving annually 120,000 tons of CO2 a
thyssenkrupp will equip a cement plant with a plant for the production of calcined clays for the Dutch company Cimpor Global Holdings for the first time. The technology developed by thyssenkrupp makes it possible to reduce the CO2 emissions generated by cement production by up to 40 percent. For this purpose, part of the cement clinker is replaced by calcined, i.e. thermally activated, clay. Cimpor Global Holdings is using the technology called "polysius activated clay" on an industrial scale for a new plant that is being built near the Cameroonian coastal city of Kibri. After the planned completion in autumn 2021, the plant will save more than 120,000 tons of CO2 annually .
The production of the important building material cement is an energy-intensive process in which large quantities of carbon dioxide are released due to the process. "At thyssenkrupp, we are convinced that CO2 -neutral cement production is possible in principle and in several steps," said Pablo Hofelich, CEO of the Cement Technologies division. “On the technological side, we have come a long way in many areas. We offer our customers products that protect the environment and at the same time bring economic benefits. In this way, CO2 and nitrogen oxide emissions can be significantly reduced and the use of raw materials, water or fossil fuels such as coal and gas can be reduced. "
As an EPC partner, thyssenkrupp is responsible for the engineering, procurement, construction and commissioning of the new system. It will produce 720 tons of activated clay every day. For Cimpor Global Holdings, it is the second project that uses calcined clays.
Activated clay lowers CO2 footprint and energy consumption significantly
CO2 is naturally contained in limestone, the main component of cement. Around 790 kilograms of process-related CO2 emissions are generated during the production of a ton of cement clinker . About two thirds of this is accounted for by the limestone used, which inevitably releases carbon dioxide through a chemical reaction. At the same time, the process requires large amounts of energy because the limestone and other additives have to be burned at temperatures of more than 1,400 degrees Celsius to manufacture the cement clinker.
With polysius activated clay, thyssenkrupp has developed a technology with which around a third of the cement clinker can be replaced with activated clay. The clay is heated to around 800 degrees Celsius - far less heat than is required in the production of clinker. The significant energy savings in the production of thermally activated clays and the changed chemical composition reduce the CO2 emissions per ton of cement produced by up to 40 percent.
Less dependence on expensive clinker imports
Clay as a substitute is available in huge quantities worldwide - especially in developing countries with an increasing demand for cement, for example in Southeast Asia and large parts of Africa and Latin America. So far, the clay has often been disposed of as a waste product in mining. With polysius activated clay technology, thyssenkrupp offers an innovative solution for the industrial use of clay as a substitute material and a sustainable and cost-effective alternative to conventional cement clinker.
"Our technology is not only more environmentally friendly, it also offers our customers such as Cimpor Global Holdings economic advantages," adds Dr. Luc Rudowski, Head of Product Management & Innovation in the Cement Technologies business unit. “Limestone is scarce in many regions and clinker has to be imported at a high price. In addition, stricter environmental regulations and emissions taxes are forcing cement producers in more and more countries to rethink. You need an alternative that is inexpensive while ensuring high cement quality. This is exactly what polysius activated clay technology does. ”
Climate-neutral cement production is getting closer
In addition to the technology for producing thermally activated clays, thyssenkrupp is also working on other products and processes for the “green” cement plant of the future . Oxyfuel technology is one example . A significant amount of CO2 emissions and energy can be saved by using activated clays ; Limestone is still needed, at least in parts, because it is essential for the strength behavior of the concrete.
With the pure oxyfuel process, thyssenkrupp has developed a solution with which the CO2 escaping from the limestone can be captured and used during clinker production. Pure oxygen is supplied instead of the ambient air during the burning process. Because this prevents nitrogen from entering the process, highly concentrated CO2 is created . This gas can be separated and stored or reused much more easily, for example as a raw material for chemical production.
Source: thyssenkrupp AG