Innovations driving clinker reduction

Innovations driving clinker reduction
27 November 2020

Advances in clinker reduction and the emergence of new and innovative technologies to produce supplementary cementitious materials (SCMs), was the subject of another highly engaging Cemtech Live Webinar this week.

Interestingly, many of the innovations are being pioneered by niche players, scientists and small-scale cement producers, rather than the global majors.

For example, one notable breakthrough technology, known as G-ASH™, which stands for ‘granulated activated sand by heating’, has been quietly developed and commercialised in the Philippines by a new entrant called Big Boss Cement. The fledgling south Asian producer has devised a process to transform volcanic debris or sand into a product theoretically capable of delivering 100 per cent clinker substitution.

The product is generated by heating a natural pozzolana, such as sand, with proprietary additives (patent pending) at a relatively low heat of <500°C in an activation chamber. At present a blended cement (Type 1P) is produced with 20 per cent clinker replacement, but the manufacturer claims full substitution of clinker will be possible once the regulations are revised.

Another solution comes from the usage of calcined clays, particularly LC3 (Limestone Calcined Clay Cement), which was considered in detail during a previous Cemtech webinar. In her excellent presentation on the topic, Prof Karen Scrivener, who leads the LC3 project at EPFL (Switzerland), spoke about the benefits of adding limestone to calcined clays to create a superior product that would easily permit 40 per cent clinker reduction levels. At this level of substitution, global CO2 emissions could amount to 400Mta, a huge contribution to the global emissions reduction target.

According to EPFL, the first commercially active LC3 project is already up and running in west Africa. The plant, constructed by mid-sized emerging player, OYAK (Turkey), through its Cimpor subsidiary, uses rotary kiln technology supplied by IPIAC to calcine clays resulting in a product with a low energy consumption of 550kcal/kg.

OYAK’s regional industrial strategy also includes setting up the first calcined clay plant to use flash calcining technology, which is expected to be commissioned next year.

As well as being among the first producers with a greenfield calcined clay project, it is also looking to invest in Cabo Verde for the extraction of pozzolanic material such as volcanic rocks to further its SCM usage.

At the heart of this strategy is smart economics: by developing low cost SCMs, the company can substitute high-cost clinker imports, making the company far more competitive in the market while simultaneously reducing its CO2 footprint.

Progress from cement majors
While these are all signs that the cement industry is moving in the right direction, the lack of publicly-announced strategies from the cement majors regarding the usage of SCMs and calcined clays is notable. This is not to say that investment in these solutions is lacking, but rather that the much of the activity is in early stages or taking place under the radar. In due course, the announcement of such projects from majors would showcase its viability as a method of reducing carbon emissions and may even influence its further adoption.

The cement majors will be determined to make rapid progress in these areas and often have the most to lose, not just in terms of reputation and industrial strategy, but also pressure from the financial markets, where investors have become highly focussed on carbon reduction, especially in the cement sector.

LafargeHolcim, for example, recently launched a EUR850m sustainability-linked bond to mature in 2031. Bond investors will be entitled to a coupon higher than 0.5 per cent should the company not meet its emissions objective of reaching 475kg net CO2/t of cementitious material by 2030. Therefore, amongst the calls for sustainability improvements from society and government, there will now be added pressure from the financial sector.

We can expect to see a lot of movement in this area in the next few years as cement producers small and large seek to adopt new and innovative solutions.

Further resources for more information on SCMs and calcined clays:
Cement Plant Environmental Handbook 2nd Edition
Cemtech Live Webinar presentations – Clinker reduction advances in Asia
Cemtech Live Webinar presentations –  Advances in clinker reduction technologies

Published under Cement News