Turn clays, slag, ash, and fumes into green cement: what a 1Der!

Turn clays, slag, ash, and fumes into green cement: what a 1Der!

One person’s trash is another person’s treasure: it’s an old saying, but a new development is making it very applicable to the cement industry. That development is ‘green cement’: cement that uses by-products from other industrial processes called supplementary cementitious materials (SCMs).

SCMs include fly ash from coal combustion, clays and calcined clays, silica fume from silicon production, and blast furnace slag from steel manufacture. These SCMs reduce the need for clinker, the production of which is the most carbon-emitting step in cement production. Additionally, they lower the amount of industrial waste going to landfills.

As such, using SCMs can significantly reduce the overall environmental impact of cement production. Clays and calcined clays are particularly exciting: their low price, availability, and distribution in the world make them a valuable SCM for concrete technology.

However, more varied raw materials also means more variability in input quality. With their very diverse mineralogical composition, clays are a case in point. Furthermore, the composition of SCMs may not have been analyzed before they reach the factory floor. As a result, state-of-the-art analytical techniques and equipment are essential to maintaining output quality and preventing damage to machinery.

That’s where X-ray diffraction (XRD) comes in – in particular, the Aeris Cement edition and its 1Der detector, which futureproofs the instrument by ensuring accurate analysis regardless of the mineralogical composition of waste material.

XRD: A tried and trusted way to screen cement after passage in the kiln

XRD is the main technique for screening cement output quality, providing mineralogical and crystalline phase analysis. Most natural and synthetic materials are polycrystalline mixtures, made of different crystallographic phases. In cement production, the raw material feed, clinker, and industrial by-products are all examples of these polycrystalline mixtures.

The type and abundance of crystalline phases determine a material’s properties, from melting temperature and density to solubility and hydration kinetics. To assess these characteristics, XRD instruments use X-rays to probe the distances between atoms. The measured distances can then be compared with database values of the various mineral components using the Rietveld or PONCKS method for amorphous components.

For example, if XRD shows that a sample of cement clinker contains a high amount of free lime calcium oxide, this indicates that the kiln temperature is too low or the residence time in the clinker kiln is too short for the materials used in that batch. The operator can then adjust these parameters accordingly.

Upscaling XRD analysis to meet the increased need for green cement

With XRD, you can therefore control the quality of raw clay coming into the production line, perform process control on clay calcination, and monitor the amount of calcined clays in blended cement – all with a single instrument.

However, ensuring these screening processes are always reliable requires a powerful and flexible device. In addition, the throughput that XRD instruments need to handle will only increase as manufacturers shift toward producing green cement. The analysis must be fast enough to screen greater quantities of cement made from a greater variety of materials.

The Aeris Cement edition is a flagship solution to these challenges. Its speed and ease of use – thanks to a large touchscreen and intuitive user interface – allow technicians to screen higher throughputs without requiring extensive training. In addition, unlike traditional XRD instruments, the Aeris Cement performs Rietveld and PONCKS analyses automatically. Automation can be enhanced even further by using an external sample loading mechanism, such as a belt or robotic arm.

To explore the capabilities of the Aeris Cement Edition with 1Der detector even further, read our application note.

And don’t hesitate to get in touch with one of our experts to find out more!