Online Particle Sizing Proves Critical for the Production of ‘Greener’ Slag Cements

Zementwerk Berlin is relying on Malvern Instruments’ Insitec online particle sizing systems to efficiently manufacture high performance, ‘environmentally friendly’ slag cements. The real-time data supplied by the online systems supports fully automated, close loop control of the finished grinding circuits that produce both conventional Portland and slag cements. Particle size data and precise control have proven crucial to the commercialization of newer cement grades incorporating blast furnace slag.

“Achieving fully automated, closed loop control of the grinding circuit has been enormously beneficial,” said Mr Thomas Schuster, Lab Manager, Zementwerk Berlin. “We can switch between different product grades around three to nine times faster than when we only had offline Blaine measurements for plant control. This has had a major impact on plant throughput but it’s perhaps with slag cements that we see the biggest benefit. Here we have found the Insitec essential for the production of high quality products.”

At its site in Berlin, Zementwerk Berlin mills clinker and blast furnace slag to produce 11 different grades of cement. The size of cement particles determines the rate of hydration during product use. This in turn impacts both the early and developed strength of the cement. Effective particle size control is therefore crucial for successful cement manufacture. Replacing a proportion of fresh cement with a waste material such as blast furnace slag produces cements with a lighter CO2 footprint. However, implementing this strategy, while at the same time maintaining cement performance, requires a sound understanding of how to optimize the particle size of each cement component.

Zementwerk Berlin first purchased an Insitec in 2001. Using the resulting data the company implemented fully optimized closed loop control on its first grinding circuit. In 2010 a parallel circuit was installed, primarily to grind blast furnace slag, for entry into the slag cement market. This benefited from a duplicate online analyzer and control system from the outset. A third analyzer, purchased in 2014, has been used to upgrade the original installation although the first Insitec remains reliable and in good working order.

“The Insitec systems are a trusted and integral part of our plant. This is especially true when it comes to the optimal inclusion of slag. Our view is that real-time data are invaluable when it comes to producing slag cements with comparable performance to conventional products.”