Displaying items by tag: LC3

There was fantastic news for fans of novel cements this week, when Cementos Argos announced the completion of work on a new 0.45Mt/yr calcined clay production line at its Rio Claro plant in Colombia. This artificial pozzolanic material, developed and promoted by the Swiss-led LC3 consortium in recent years, can dramatically lower cement CO₂ emissions by replacing slag and/or fly ash in cement mixes. The Rio Claro plant is the first major cement plant to install such a line following smaller trials in Switzerland, India and Cuba.

Suitable clays are more widely available than slag and fly ash, alleviating some of the difficulty and cost of obtaining supplementary cementitious materials. They also need to be calcined at just 800°C, offering massive savings in terms of fuel costs, CO₂ emissions and embodied energy compared to Ordinary Portland Cement (OPC) production. Karen Scrivener from the École Polytechnique Fédérale de Lausanne (EPFL), the leading academic party in the LC3 consortium, explained that calcined clays are at their best when in ternary (three-way) blends alongside clinker and limestone in the September 2019 issue of Global Cement Magazine. “It has long been known that calcined clays can be pozzolanic,” she explained. “When used alone, the maximum substitution level is around 30%, which gives a moderate saving in CO₂ emissions. However, if we substitute a further 15% of the clinker with limestone, we get a significant reduction in CO₂ emissions, with a product that has almost identical properties to the blend that contains just the calcined clay.”

While the exact composition of Rio Claro’s new products is unclear, it will enable Cementos Argos to produce ternary cement blends with CO₂ emissions 38% lower than OPC. Energy consumption is also cut by 30%, which provides secondary benefits in terms of reduced off-site CO₂ emissions. At the plant’s launch, Cementos Argos’ President Juan Esteban Calle clearly stated that calcined clays were the way forward, announcing, “With this project we are sowing the seeds of the Argos of the future. It starts today with a new production line at Rio Claro. In our commitment to climate change, this project makes us very proud.”

The response from Argos’ consumers will be keenly watched, especially in Europe. Just this week LafargeHolcim and Vicat, along with France’s Technical Association of the Hydraulic Binders Industry (ATILH), called on the European Commission and European Committee for Standardisation to hurry up and publish ternary cement standards across the European Union (EU). At the moment these producers are primarily concerned with CEMII / C-M and CEM VI cements. These classes of cement comprise a range of ternary blends that contain clinker and limestone, plus a third component, be it slag, fly ash, natural pozzolans or calcined clay. They claim that placing low-clinker cements on the market could reduce the amount of CO₂ emitted by 127kg/t, around 20% of the 656kg/t average in Europe at present.

Frustrated with the delays at Commission level, cement producers have now taken things into their own hands. The plan is to establish the same standard within each EU Member State at the national level, rather than waiting in vain for standards from ‘on high.’ One pressing driver for this behaviour is the rapid approach of the Phase 4 of the EU Emissions Trading Scheme (ETS) in January 2021. In Phase 4 it is likely that EU cement producers will be allocated only 80% of the free allowances they have become accustomed to. They will have to buy the remainder at market prices, currently Euro25.1/t of CO₂ (17 February 2020). This will represent a massive new expense for some producers. The opportunity to sell cement that emits only 58% of the CO₂ of OPC is clearly exceedingly attractive as a way to reduce outgoings. CO₂ emissions will be reduced, of course but, as usual, the way to make companies do things is to hit them in the wallet.

Indeed, on this point, Vicat seemed to almost goad or ‘troll’ its competitors in Europe this week by announcing that it has never sold any EU ETS allowances and is sitting atop a 5Mt CO₂ reserve worth Euro120m. This is sufficient to last it until 2030 at current prices. The key part of that last sentence is ‘current prices,’ which are subject to change. In its press release, Vicat was keen to point out that it is not resting on its laurels, highlighted by its advocacy for ternary blends and continued development of alternative fuels. This may be wise, considering that EU ETS allowances will likely cost more once Phase 4 kicks in.

With clinker factors of just 50 - 65% for CEMII / C-M, and 35 - 50% for CEM VI, Edelio Bermejo, director of research and development (R&D) at LafargeHolcim insists, "These cements are no longer at the research and development stage. They have been widely validated and we are ready to produce them, especially as their manufacture does not require modification of our facilities." The establishment of Cementos Argos’ Rio Claro calcined clay plant proves his point. We can expect to hear a lot more about these blends in the coming months. In the words of Bermejo, “The future is here!”

Charah Solutions has been steadily building up its fly ash distribution business in recent years with an eye on the supplementary cementitious materials (SCM) market. This week it opened the third of its new series of SCM grinding plants, at Oxnard in California, US. The unit sticks out because it is focusing on grinding natural pozzolans. The plant will receive natural pozzolan by truck and rail and then use Charah’s patented grinding technology to produce pozzolan marketed under its MultiPozz brand. The previous plants in this series mentioned natural pozzolans but this is the first to promote it explicitly.

The change is potentially telling because global demand for granulated blast furnace slag (GBFS) outstrips supply. Both performance benefits and environmental regulations are pushing this. It’s a similar situation for fly ash, also driven by trends to close coal-fired power stations in some countries. As Charles Zeynel of SCM trading firm ZAG International explained in the March 2019 issue of Global Cement Magazine, “...volcanic pozzolans are a potential SCM of the future. This is gaining traction, but it’s slow progress at the moment. This will be the answer for some users in some locations.”

The problem though is that natural pozzolans are down the list of preferred SCMs for their chemical properties after silica fume, GBFS and fly ash. The first is expensive but the latter two were traditionally cheap and easy to obtain if a cement or concrete producer had access to a source or a distribution network. Natural pozzolans are very much subject to variations in availability.

It’s no surprise then that Charah is promoting natural pozzolans in a Californian plant given that state’s environmental stance. It’s unclear where Charah is sourcing their pozzolan from but they are not the only company thinking about this in the US. Sunrise Resources, for example, is working on the environmental permits for a natural pozzolan mine near Tonopah in Nevada. As it described in its company presentation, California and Nevada are the most affected states in the fly ash supply crisis because they are, “...at the end of the line when it comes to rail deliveries from power stations in central and eastern USA.” It also estimated that California used 0.9Mt of pozzolan in its cement production of which about 90% is fly ash. The state produced 9.6Mt in 2015. Other companies are also mining and distributing natural pozzolans in the US as the website for the National Pozzolan Association (NPA) lists. Although, if this line-up is comprehensive, then the field is still fairly select. Most of these companies are based in the west of the country.

One last thing to consider is that various groups are tackling a potential future lack of SCMs for the cement industry by making their own pozzolanic materials through the use of calcined clay. These groups include the Swiss-government backed LC3 project and Cementir’s Futurecem products. Using clay should bypass the supply issues with natural pozzolans but the cost of calcining it requires at the very least an investment to get started.

As concrete enthusiasts often point out, a variant of pozzolanic concrete was used by the Romans to build many of their iconic structures, some of which survive to the present day. To give the last word to the NPA, “What is old is new again: natural pozzolan is back!” If environmental trends continue and steel and coal plants continue to be shut then it might just be right.

Cuba: The University ‘Marta Abreu’ of Las Villas (UCLV) has started operating a 7t/day limestone calcined clay cement plant. The unit will be run by the Geominera del Centro Company, according to the Cuban News Agency. Building materials produced at the plant will be used locally.

Fernando Martirena Hernández, director of the Centre for Research and Development of Structures and Materials (CIDEM), said it was the first plant producing low carbon cement in the world. The project is a collaboration between the university and the Swiss Agency for Development and Cooperation as part of the LC3 project. Similar plants are planned for 18 countries including India, China, Indonesia, Thailand, Guatemala, Mexico, Ecuador, Colombia, Peru, Ivory Coast, Cameroon and Senegal.