Robert Shenk
Head of Green Cement Solutions Cement Project / Upgrades – FLSmidth
Robert Shenk, FLSmidth, provides an overview of what ‘green’ cement plants could look like in the near future.
A decade from now, the cement industry will already look very different than it does today. As the realities of climate change continue to hit home, social pressure on heavy emitters will increase and financial pressure will follow, forcing cement producers to act. There will be no more time to hide behind targets or roadmaps; global tolerance will have been exhausted. The cement industry has a responsibility to follow through on all the things it has promised.
As a leading supplier to the industry, FLSmidth feels this responsibility keenly. The company has solutions available now and more in development, but the priority is communicating these solutions to cement producers. Because if you cannot visualise what a cement plant will look like – if you do not believe in it – it is not going to happen. This article is an overview of the cement plant of the near future, from the quarry to dispatch. It may not look so different from a plant you would see today, but it is. The difference is in the way it is operated, what is being put into it, and some of the supporting technology.
Quarry
While total transformation of the quarry is not foreseen in the near future, there will be some key differences. First, the electrification of material extraction and transport – switching from diesel to electricpowered vehicles in the quarry is a relatively simple way to reduce carbon emissions in this part of the cement process. In fact, a recent pilot project at a Swedish quarry realised a 98% reduction in carbon emissions through the use of electric machinery.1 Furthermore, the quarry may become a lonely place because many of these electric vehicles will also be fully autonomous.
This electrification will require additional power sources, but in the next decade, more cement plants are expected to take control of their energy supply by building wind and solar installations on site. This will ensure that they have the clean energy needed to power not just their quarry operations but increase electrification throughout the plant.
Besides the quiet from electric engines, quarries may not appear as busy as in the ‘peak clinker’ years, thanks to the increased uptake of supplementary cementitious materials (SCMs), including calcined clay, which is discussed in further detail later in the article.
Crushing
Crushing operations will be smarter and more efficient, taking advantage of Industry 4.0 technology to conserve energy and maximise availability. Machine learning-driven vision systems will help prevent blockages, while an emphasis on hard-wearing parts and easy maintenance will ensure minimum downtime.
Stockpile management
More efficient blending will enable greater chemistry control and grinding efficiency – so the emphasis on this section of the plant will be on advanced stockpile visualisation technologies. The equipment might look the same, but quality control will be vastly refined thanks to the use of software programmes like QCX/BlendExpert™ Pile and Mill, which help cement plant operators gain greater control over their raw mill feed. 3D modelling and fast, precise analysis provide the greatest possible insights into stockpile composition, enabling the optimisation of blending with minimal effort. All of this means that the raw material will be prepared to maximize the utilization of SCMs.
Raw grinding Raw grinding operations will be focused on vertical roller mills, which are able to achieve greater energy efficiency, increased productivity and high availability. Additionally, the control potential for VRMs (when the main drive is equipped with a VFD) is far superior than for ball mills or even hydraulic roller presses. This enables a greater degree of optimisation, which in turn improves kiln stability and facilitates increased use of alternative fuels and the use of more diverse raw materials.
Pyroprocess
The biggest changes to the plant will be seen in the kiln. First, less clinker will be produced in proportion to cement production, replaced in increasing quantities by SCMs. Secondly, the fuel make-up will continue to evolve, taking advantage of advanced burners and other combustion technologies to co-fire a mix of alternative fuels including waste products, biomass, newly engineered fuels from waste streams, oxygen enrichment (so-called oxyfuel injection) and even hydrogen. Precision dosing will enable careful kiln control to maximise clinker quality, while solutions like the HOTDISC® Combustion Device will enable a wide range of fuels to be used. It is worth noting that 100% fossil fuel replacement is possible with existing technologies, but it may take another decade or more for the waste streams to catch up with demand. In addition, the green cement plant of the future will have to consider how green these alternative fuels actually are.
Waste heat will also be utilised, not just in the pyroprocess but also in other areas of the plant, for example to replace hot gas generators. Waste heat from the clinker production process will be captured and used to offset the remaining energy demands of the plant.
Parallel processing
In order to achieve the required emissions reductions, all cement plants will be using some source of SCM to reduce clinker content in their final product. Calcined clay will be one of the key resources, as a widely available raw material with similar properties to clinker – albeit with the advantage of a much lower carbon footprint. The technology for this will be well proven within a decade, and in fact will be further improved (from an environmental standpoint) through electrification.
Other sources, such as ponded ash and mine tailings, will also be in use where it makes sense to do so – i.e. where the resources are in sufficiently close proximity to the plant to make it economically viable. Having provided a valuable direction for waste streams for decades, by the 2030s, the cement industry’s unique position as a ‘waste consumer’ will be well known and well utilised. Cement plants will work closely with other industries and local governments to develop the necessary infrastructure to process waste into SCMs, to the benefit of all.
Some of this processing may happen onsite at the cement plant, necessitating a kind of parallel processing line that meets at the cement mill. For instance, you might have a flash calciner on site to process calcined clay. Alternatively, the SCMs might be pre-processed off-site, and be delivered to the plant ready to use, or to the concrete batching facility for addition there.
Concrete recycling
In addition to well established and emerging SCMs, it is expected that in a decade from now, the infrastructure will be in place for greater concrete recycling. Instead of only reusing crushed concrete as road-based aggregate, concrete recycling could also entail creating aggregates for new concrete and even a fine cement paste concentrate for making eco-friendly cementitious binders. This process is already being explored and will likely be taken up by vertically integrated cement producers who will see the environmental and economic sense in it. Recycling concrete is a fantastic way to close the loop and achieve a truly sustainable approach to manufacturing.
Cement mills
Like the raw mill, cement plants will continue to move towards more efficient grinding technologies and away from ball mills. Vertical roller mills will be equipped with variable speed drives and enable the flexibility needed by the cement plant of the future, which is more likely to require regular recipe changes to accommodate the use of a variety of SCMs. Through utilization of the most efficient technology, precious kWs shall be preserved for additional decarbonization measures.
Hot gas generators will be decarbonised, either through electrification or by using waste heat from elsewhere in the plant. Advanced blend control applications will help ensure a larger clinker substitution, while maintaining quality targets.
Material transport
In many areas around the plant and for loading, unloading and dosing, material transport will move from mechanical to pneumatic. This not only ensures a clean and safe environment, it also enables higher capacity conveying with greater precision and control.
Packing and dispatch
Flexibility will be required here, as in the cement mill, to accommodate the variety of cement mixes produced. Automated packing, palletising and loading technology will not only facilitate the quick and easy packing of a variety of products, but will also help to remove the safety risks of manual operation.
Process and quality control
Across the plant, digitalisation will increase precision and efficiency, utilising data to optimise performance in a way that people alone simply cannot achieve. The ECS/ProcessExpert™ system shall provide all of the advanced control for the operator to simply switch across various raw mixes, fuel blends and cement blends. These improvements will result in a reduction in power consumption and related emissions, as well as an improvement in product quality that – together with the use of SCMs – enables the clinker factor to be pushed to new lows.
In the laboratory, fully automated sample preparation and analysis allows for unmanned operation 24/7, removing the potential for human error and ensuring the highest quality of analysis. Where online analysers are installed in the process, these are automatically checked against reference samples and bias-corrected to achieve optimal performance.
Maintenance
Advanced condition monitoring will be a core component of plantwide proactive maintenance strategies and, when managed correctly, could eliminate unplanned downtime altogether. In addition, service agreements with equipment suppliers will help achieve maximum equipment performance to enhance productivity and reliability. In all likelihood, the responsibility for maintaining asset health will become an ongoing partnership between the supplier and the cement plant, with the supplier much more involved on a day-to-day basis than is the case currently. These proactive maintenance models will allow “subscribe and save” models to be implemented to ensure the required parts are on-site when needed by the operations.
In addition to more comprehensive care of machinery, to minimise damage – the parts that do need changing regularly will be handled more responsibly. For example, reconditioning will be promoted over replacement, and wear parts that can be recycled and reused will be.
Carbon capture
While carbon capture has a critical role to play in the future of the cement industry, it is unlikely that it will be in widespread use in the early 2030s. It is also considered to be a last resort technology as opposed to a go-to solution. However, given the limitations on what can be achieved within the bounds of the existing cement process, carbon capture will be necessary if the cement industry is to achieve net zero cement production. To this end, FLSmidth is working on a number of very interesting projects. The first deals with the problem of kiln gas bypass dust, which can occur with the use of fossil fuels and typically has to go to landfill. In collaboration with Carbon8, FLSmidth offers a solution to carbonate bypass dust, sequestering a small amount of CO2 from the plant, and creating a usable aggregate product that can be incorporated into concrete. Another, entirely different, carbon capture solution may come to cement plants from FLSmidth’s partnership with Chart Industries. This Cryogenic Carbon Capture Technology captures CO2 from exhaust gas at very high rates and produces it as a highpurity liquid ready for storage and use. This technology is undergoing trials now and will be in place for full-scale industrial application by 2030, for use in new and existing cement plants. FLSmidth shall also leverage its experience on oxyfuel combustion and electrification in collaboration with its carbon capture partners to insure the lowest cost for carbon capture.
Drivers for change
Achieving the kinds of changes discussed in this article will be challenging. While digital transformation and performance optimisation make good business sense and can be implemented very easily from the inside, changing the cement mix requires more of an ‘outside-in’ approach. Change in this area will be driven by policymakers and by customers, who must demand more eco-friendly cement. It is important to keep talking to the people defining the codes and writing the standards to ensure that they understand that solving this problem is as much in their hands – perhaps even more – than it is in the hands of cement producers. Switching to a performance-based perspective on standards will make all the difference.
Similarly, eliminating fossil fuels from the process is not something the cement industry can do alone. Developing waste streams suitable for cement kilns and ensuring there is sufficient renewable power generation are endeavours that must be shared with other industries.
The vision
Cement producers must begin to consider how the changes outlined above could work in their plants, and the measures that need to be taken to meet emissions targets.
The cement industry has pioneered new technologies, set itself very high standards, and has done so before climate change agreements obligated it to. Collectively, the industry has incredible power to make a difference in the global campaign to reduce warming. As often declared in superhero movies, “with great power comes great responsibility”. When reflecting on the ambitious goals of the cement industry and the requirements for Green Cement Solutions, the lyrics from one of my favorite bands come to mind – “And nothing else matters.”
Expanding the scope of industry partnerships
For decades, suppliers and cement manufacturers have had a relatively transactional relationship. This is already changing, with greater emphasis on service and partnership – in part thanks to the enabling force of digitalisation, but also due to skills shortages across the industry. Within a decade, the mid- and long-term service partnerships that are beginning to take shape now will likely be the norm, having proven to be the best way to sustainably maximise availability and productivity. Cement plants that dedicate resources to continuous optimisation will reap the benefits – and those which do not will fall behind.
This greater sense of partnership will also expand the role of equipment suppliers up and down the supply chain. They are more likely to be involved in conversations with concrete producers, for example, to enable and improve the adoption of SCMs. They may even be asked to assist with pilot projects to prove the viability of new cement mixes to end users – developers, architects, and local governments. The concept of ‘full-flowsheet support’ will grow in length and breadth as the OEM takes on greater responsibility for customer success.
Digitalisation’s role in optimisation
Digital tools offer incredible potential to increase cement plant efficiency and thereby reduce emissions. By gathering and interpreting data from across the plant, digital tools from online condition monitoring to advanced process control enable cement producers to gain a deep understanding of their process and equipment. Armed with this knowledge, producers can:
– Optimise operating parameters to improve product quality
– Reduce energy and fuel consumption
– Get advanced warning of potential disruptions
– Implement a proactive maintenance strategy
– React quickly to changes in the fuel or product mix
In short, digitalisation can provide the insight cement producers need to be more productive, more competitive and more sustainable.
References / 1 https://www.volvoce.com/global/en/this-is-volvo-ce/what-we-believe-in/innovation/electric-site/