Particle size analyser put Italian cement maker in control
21 Mar 2012
Tavernola, Italy – Cement producer Sacci SpA is employing an on-line laser diffraction particle size analyser to improve process control at its cement mill in Tavernola, Italy.
The analyser – an Insitec device from Malvern Instruments – provides the milling circuit that produces finished cement. This, reports the company, has enabled operators to focus on ’higher value’ work and improved product consistency.
The device is installed on the elevator conveyor that carries finished product to the storage silo. It automatically samples the cement via a two-stage sampling system which ensures a representative cut of the very large process flow. A full particle size distribution is produced every five seconds but rolling average data are used for process control.
This continuous data stream is said to give much finer control of the classifier, which is now varied within far tighter limits compared with using off-line measurement, leading to a more consistent product. Automating sampling, analysis and control has saved considerable operator time - time that is now being used to further other production goals.
“Before … we relied on off-line particle size data to control the milling circuit,” said Alessandro Mazzuc?o, plant quality manager. “The quality of the data was fine but the frequency of measurement, every two hours, wasn’t really high enough. Quite large changes were made after each measurement and so our product was not as consistent as we would have liked.”
At the plant, particle size data are used to automatically vary the speed of the classifier used to separate the milled cement into a fine product stream and a coarser recycle. In the past this control loop was driven by data measured in the laboratory using a Mastersizer 2000 laser diffraction particle size analyser – from Malvern. Now the data come from the on-line Insitec system.
“Being able to rely on this level of performance is crucial for 24/7 operations such as ours,” said Mazzuc?o. “Production has become far more consistent than when we relied on the off-line analysis of single samples, with much smaller process changes now made automatically on a more frequent basis.”
