Anders Josefsen, Senior Vice President and Head of Projects and Upgrades, FLSmidth, discusses the evolving role of cement plants in society – from producing a key ingredient in building critical infrastructure to enabling a circular economy.

The role of cement is evolving. The industry has always been a pillar in the communities in which it operates – as an employer and as the producer of one of the world’s most widely-used products. But it has not always been the most popular of neighbours. It has had to work hard to win the trust of locals, to ensure that the benefits of its presence outweigh the disadvantages – and that those disadvantages are reduced year by year. Today, the fact remains that the industry continues to be one of the world’s largest emitters of CO2, and initiatives to decarbonise need to go beyond traditional energy savings and optimisation.
No stone is left unturned in the quest to minimise the environmental impacts from cement production, and one area in which the industry is making progress is as a valuable outlet for waste. Because of the high temperatures required to produce clinker, cement’s key ingredient, as well as the stringent regulations controlling emissions, the cement plant is well suited to co-process municipal and industrial waste, which cannot otherwise be recycled, thereby displacing traditional fossil fuels – mostly coal. In fact, we see more and more cases of producers, encouraged by local authorities, playing a beneficial role in disposing of waste that would otherwise prove problematic – including hazardous medical waste, and even solvents.

Not waste incineration, but co-processing
In waste-to-energy plants where waste is incinerated to produce electricity, there is a by-product: residues that need dealing with. In a cement plant, waste is burned in the kiln or calciner, producing the heat needed for calcination, and the remaining residues become part of the end-product. This – together with the advanced air pollution control technology and the fact that you do not need to invest in new incineration plants – is why waste-derived fuels work well in the cement industry.
In Europe, co-processing of alternative fuels such as biomass, meat and bone meal and household waste, is common practice, representing nearly 50 per cent of the fuel used in cement production. It is made easier by the availability of the required infrastructure to sort, manage and optimise waste streams, backed by sophisticated EU waste legislation. However, in regions where waste management infrastructure is not well developed, the cement industry can play an important role by helping to build waste-to-energy partnerships and address the mounting waste challenge.
This has been demonstrated recently in countries like Indonesia, where INDOCEMENT is investing in technology to co-process alternative fuels that would otherwise be landfilled. Similarly, in Vietnam, a partnership has sprung up between waste handling start-up TONTOTON and FLSmidth to help Vietnamese cement producers utilise non-recyclable plastic waste in their process. Equipment like our HOTDISC® Combustion Device enables such waste to be burned without pre-processing, significantly broadening the horizons on what can be fired in a kiln or calciner, and reducing the costs involved.

Reduce, reuse, recycle
It is true that co-processing of waste is not a magic bullet. Depending on the composition of the waste, it emits CO2 when used as a fuel. However, it does provide a useful path for non-recyclable waste that would otherwise be landfilled, littered, or burnt in the open air, as happens in many countries, causing a litany of environmental and health hazards for local communities.
The sheer quantities and varieties of non-recyclable waste are astounding – by-products from agriculture, mining, power generation, and even from construction. According to the United Nations, greenhouse gas emissions from plastics are projected to increase to approximately 6.5 gigatonnes in 2050. That represents 15 per cent of the whole global carbon budget.1
With 23 per cent of the world’s waste generation, the East Asia and Pacific region leads the statistics, reports the World Bank in their ‘What a waste 2.0’ report. The Middle East and North Africa region is producing the least in absolute terms, at six per cent. But, especially for low-income countries, materials that could be recycled account for only 16 per cent of the waste stream.2
Solid waste management is also a financial burden to municipalities in low-income countries, which are estimated to spend about 20 per cent of their budgets on waste management, on average. Yet over 90 per cent of waste in low-income countries is still openly dumped or burned.3

Closing the loop in concrete
Construction and demolition waste is one of the largest sources of waste by volume. At an annual growth rate of four per cent, it is projected to be a $143 billion business by 2028. In this lies an opportunity to close a loop. Why make more of something when you can reuse what you already have? Scientists and companies in the cement value chain, including FLSmidth, are exploring ways to break concrete down into its core components, including a fine cement paste concentrate suitable for making eco-friendly cementitious binders. This would help reduce the clinker factor – the amount of clinker that needs to be produced to meet cement demand – as well as provide a new pathway for old concrete. An economical and environmental approach to manufacturing.
According to the International Energy Association, the integration of emerging technologies such as lowering the clinker-factor in cement and carbon capture, will provide some of the largest cumulative CO2 reductions in the 2-degree Celsius Scenario (2DS).
Today, an office building has an expected lifespan of 20 years, and a residential building a lifespan of 30-50 years. That is extremely short and underlines the need for upcycling. If the industry is to support accelerating urbanisation, the winners of the construction industry will be the ones who see opportunities in waste that can be used again and again. And they will be the ones getting the building-licences from government authorities.

From trash to treasure…
Mine tailings are also an area of interest. This waste product – the leftovers after the most valuable minerals are extracted during the mining process – is a significant environmental and economic burden to mine operators, and a safety risk to them and their local communities. Great pools of these tailings are left wherever mines are or have been in operation – adding up to some 282 billion tonnes worldwide that could contaminate local soils and groundwater. However, as the old adage goes, ‘one man’s trash is another man’s treasure’, and mine tailings could prove to be a valuable opportunity for cement producers.
Research suggests that tailings may hold some of the same properties as traditional supplementary cementitious materials (SCM). This would not only make a significant impact on waste in our communities, but would also save the extraction of the raw materials usually used in cement production.
The cement industry has provided a similar pathway for waste from coal-fired power generation. Fly ash has been used as an SCM for decades. Even now, as coal-fired power plants are phased out, there is the opportunity to harvest stored fly ash – that was previously landfilled – to both relieve the environmental burden and reap the benefits of a lower clinker factor and improved cement strength.

…and from pollutants to new building materials
Carbon capture is essential to achieving a sustainable global cement industry. The development of new solutions is progressing rapidly. Some are ready for deployment now; others require additional research and development. However, one solution that is already on shelves today is Carbon8 Systems’ Accelerated Carbonation Technology (ACT), which FLSmidth offers to the cement industry. The containerised system – the CO2ntainer – captures CO2 direct from process gases and combines it with cement bypass dust to form a lightweight aggregate. The solution contributes to the decarbonisation of a plant while valorising the residues produced and saving the associated landfill costs. It is a circular decarbonisation solution.
The cement industry has a lot to offer to society, both now and well into the future. This push to decarbonise combined with increasing opportunities to contribute to circularity in society is an exciting journey that will fundamentally change the way the industry will operate and be perceived. Ensuring all these opportunities are pursued will require a number of regulatory changes and financial incentives. A worthwhile investment in light of clear benefits to society.

1 https://news.un.org/en/story/2021/10/1103692
2 https://datatopics.worldbank.org/what-a-waste/
3https://openknowledge.worldbank.org/handle/10986/30317