The role of refractories in a sustainable fuel strategy

There is a growing need in the cement industry for innovative solutions that help solve the challenges facing the sector today. One of the most pressing of these is the industry’s carbon footprint, which accounts for about 7% of global carbon emissions. The industry is currently ‘not on track’ to achieve net zero goals by 2050, according to the most recent IEA report. In fact, direct CO2 intensity of cement production actually increased by about 1.5% per year between 2015 and 2021.

Annual declines in carbon intensity of 3% are now needed to get the industry back on the right path. This will require progress on a range of pathways – from reducing the clinker-to-cement ratio to deploying innovative technologies, such as carbon capture and storage.

The adoption of alternative fuels (AFs) is another critical route to lower carbon emissions and, in contrast to other solutions, has a long track record of success. Quickly increasing thermal substitution rates (TSRs) therefore offers cement plants an accessible way to reduce their carbon intensity.

That is not to say that AFs are without their own challenges. Notably, they can cause changes to the atmospheric conditions inside the kiln, which can, in turn, adversely impact the refractory.

Combining strengths in monolithic refractory technology and refractory bricks, Calderys and its Turkish subsidiary, Haznedar Durer, have developed a complete line of refractory solutions for the cement industry, including a new alumino silicate-based brick that can be used at plants with high TSR. It can be applied in most areas of the cement production process impacted by AF use.

Alternative fuels and the problem for refractories

Cement plants around the world are recognising the benefits of switching to AFs. The European industry leads the way, supported by a highly developed waste management industry and decades of experience utilising waste-derived fuels. TSRs are lower in other regions, but uptake is growing, as cement plants seek both to reduce carbon emissions and recognise the additional benefits that AFs can bring. These include lower fuel costs and more stable, local fuel sources, which are insulated from global shocks to fossil fuel supply chains.

However, the use of AFs often results in higher concentrations of alkali gasses in the cement production process. These react with traditional alumina-based refractories, risking premature failure of the lining and damage to the equipment. The usual response has been to apply specialised refractories containing silicon carbide and zircon, which have better resistance to alkali-rich environments.

Although effective, the use of silicon carbide and zircon is becoming more problematic. Demand for both minerals is growing, resulting in tight market conditions and spiking prices.

Consequently, prices for silicon carbide- and zircon-containing refractories are relatively high – a serious consideration for cement plants considering the switch to alternative fuels.

Supply is also vulnerable to disruption, which may slow or even stop production of the refractory, while cement plants also face competition from the larger steel industry for refractories containing silicon carbide.

With many cement plants operating in competitive market conditions, they simply cannot afford to rely on expensive refractories with a potentially constrained supply chain. It is also true that these refractories require significant energy inputs during their manufacture, and thus come with a higher environmental impact than traditional linings. With some cement companies looking beyond their direct (scope 1 and 2) emissions to those of their supply chains (scope 3), there are now serious questions being asked of refractory providers with regard to the environmental impact of their products.

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Read the article online at: https://www.worldcement.com/special-reports/23012023/the-role-of-refractories-in-a-sustainable-fuel-strategy/