CUT-Pozz: a new low-hanging fruit

Carbon Upcycling has already partnered with CRH, Cemex, and Holcim in its quest to commercialise low-carbon SCM production...

Global Cement (GC): Please could you introduce Carbon Upcycling Technologies?

Tiffany Duffy (TD): Carbon Upcycling Technologies was founded in Calgary, Canada, in 2014 to develop clean-tech solutions for construction. It has patented the MACE process to Mechanically-Activate and Chemically-Exfoliate inert by-products and minerals, transforming their reactivity.
The 'mechanical activation' part reduces the particle size to increase surface area. The 'chemical-exfoliation' part sequesters waste CO₂ within the material. The result is very fine, reactive materials that can be used as supplementary cementitious materials (SCMs). We call them
CUT-Pozz products.

The process can take CO₂ directly from flue gas, which is a key difference compared to other approaches to CO₂ capture and utilisation. The elevated temperature of the flue gas aids sequestration and there is no need for additional heat sources.

GC: What scale is the process at currently?

TD: Once the laboratory research was completed, the company developed a pilot-scale MACE reactor. It comprises a pressured catalytic ball mill that operates in a batch-wise process at 20t/day.

This has since been developed into a continuous 50t/day demonstration-scale process similar to a vertical roller mill. These are already being installed at some of our cement sector partners' sites in 2023, including with Cemex in the UK, which will use recycled glass as the feedstock. Another is coming for CRH in Mississauga, Ontario, Canada, where shale and clay will be used. Two other 50t/day projects, also in North America, will follow later in 2023 and there will be more in 2024. The next step will be up to 200t/day, followed by a 10-fold increase to 2000t/day (0.7Mt/yr) in 2025.

So far, the MACE process and equipment has been designed and manufactured entirely by Carbon Upcycling. However, it will become necessary to develop partnerships with established vertical roller mill manufacturers as we scale up.

GC: What kinds of materials can be used?

TD: Carbon Upcycling has so far tested more than 40 different minerals and by-products. The most suitable for the cement and concrete sector are off-spec fly ashes and recycled glass. Clays are also very interesting. Indeed, the process leads to a clay-based SCM that is as reactive as a calcined clay, but without the energy penalty associated with clay calcination. Unusual slags like EAF and BOF slag, will also become more interesting as steel producers transition away from blast furnaces.

GC: How much CO₂ is sequestered?

TD: This depends on the material that is being upcycled. For materials with a low calcium oxide and magnesium oxide content, CO₂ take-up can be less than 10% of the material by weight. When we have greater proportions of calcium and / or magnesium oxide - for instance in some of the less common slags, the volume take up can rise to 20 - 30% by weight. The CO₂ absorbed becomes quite significant.

However, absorbing CO₂ from the flue gas is just one of the ways that CUT-Pozz products reduce emissions. They reduce the amount of CO₂-intensive clinker used by more than conventional SCMs do. For example, instead of using 20 - 25% of relatively inert fly ash, we might add up to 50% CUT-Pozz fly ash. This is because CUT-Pozz products are very fine and highly reactive, contributing greatly to strength development, particularly early on. We can then use less cement in the concrete as well as less clinker in cement, and still develop the same strength as before. This cuts CO₂ emissions even further. We also see lower water demand for a number of CUT-Pozz products. This provides another environmental benefit, indeed one that will become crucial as climate change develops.

GC: How will cement producers employ CUT-Pozz products in the market?

TD: We presume that CUT-Pozz products will be commonly made at the cement plant as the footprint of the plant, even for 2000t/day, will not be burdensome. Capital and operating costs are also very manageable compared to other decarbonisation solutions. Indeed, CUT-Pozz products will be cost-comparable to clinker.

The exact solution for an individual cement plant or ready-mix producer will depend on the materials available and the building standards that apply in the market. CUT-Pozz products could extend production in a sold-out market such as the US. Elsewhere, it might be desirable to absorb as much CO₂ as possible to stave off rising clinker production costs (i.e.: fuel bills), as well as to avoid CO₂ costs or taxes in markets such as the EU.

GC: Where do CUT-Pozz products have the most potential?

TD: The earliest movers towards CUT-Pozz products are Europe and North America, where we already have commercial projects. But this is not the whole story. There are cement and SCM supply issues in several markets, notably some countries in the Middle East and North Africa. Making your own CUT-Pozz SCM offers advantages in terms of supply security at a time when the SCM market is becoming more strategic.

GC: What are some barriers to the roll-out of CUT-Pozz products?

TD: It is unfortunately still the case that standards are focused on the ingredients of particular blends, rather than their performance in use. This limits the extent to which novel approaches can be rolled-out in a number of markets. Thankfully, we see a gradual transition towards performance-based standards that will open the door for all kinds of novel solutions, including CUT-Pozz products. This is clearest in Europe, closely followed by North America.

GC: What contribution will CUT-Pozz products make to our sector by 2030?

TD: We would like our technology to help the sector sequester at least 18Mt of CO₂ by 2030. If we can partner with just some of the largest producers and sequester 10 - 15% of their CO₂ emissions, while enhancing their products, this is well within reach. We already have really exciting partnerships with CRH, Cemex and Holcim - and are in discussion with others too.

Our ultimate goal is to have a Carbon Upcycling MACE installation colocated in every cement plant worldwide. It represents a very low-capex approach to decarbonisation. Indeed, I would call CUT-Pozz products the 'new low-hanging fruit!'

GC: Thank you for your time today Tiffany.

TD: You are very welcome indeed.

About Tiffany Duffy

Tiffany Duffy has been the Director of Business Development for Carbon Upcycling Technologies, overseeing its development in North America, since August 2022.

A civil engineer with 15 years' experience, Tiffany has held various roles in the sale and development of cementitious materials, including at Stronghold Digital Mining, PNA Construction Technologies, Charah Solutions and Titan America.