Carbon black is an extremely valuable industrial raw material consisting of tiny, mainly spherical, so-called primary particles. In most cases, these particles have a size of 10 to 300 nm, which is why they are also referred to as nanoparticles. Their specific surface area can be anything between 10 and 1000 m2/g. On the one hand, carbon black manufacturers can take advantage of these properties and influence them by means of the production process or by varying the process parameters. On the other hand, they also face challenges, especially with regard to the packaging process.
Cost-intensive with high health risk
Products with such low bulk densities as carbon black place very high demands on bagging technology in the packaging process. Many packaging solutions involve a large amount of air in the filled bags. These voluminous and unstable bags result in an untidy pallet appearance in two respects: since extreme dust is produced during filling, the bags are often contaminated with residues. In addition, the air-pumped bags can no longer be stacked precisely. Apart from losing valuable product, this also means paying for logistics and transport of bulky bags filled with up to 70 % air. However, high dust loads contaminate not only the bags themselves but also the production environment. Cleaning is exceedingly time-consuming and flying particles pose an immense health risk to employees. Technical rules for hazardous substances, in particular TRGS 900, describe the limit values for a large number of dust types.
Imerys Graphite & Carbon turned to Lübeck-based packaging machine specialist Greif-Velox Maschinenfabrik GmbH for support optimising the packaging process for carbon black in general while meeting the above-mentioned protection requirements. The solution: the highly efficient Velovac system. Ultra-lightweight materials with particle sizes of less than 200 mm and bulk densities from 10 to 450 g/l are bagged in a completely closed vacuum chamber. The product is sucked into the vacuum bags by creating an atmospheric vacuum. Any dust which escapes is sucked off and returned to the bagging process directly, saving product and air. Even without upstream compaction equipment, little or no air gets into the vacuum bags. Depending on the material to be packed, up to 400 % product compaction is possible.
Excellent sealing technology
After filling, the bags are hermetically sealed using patented methods for external valve cutting and ultrasonic sealing. The valve cutting technique has been optimised by Greif-Velox in a way that leads to more process reliability, better knife performance and increased productivity. The improved knife system is particularly durable; modern sensor technology provides users with dynamic predictions for upcoming maintenance cycles and warns of imminent failure or a deterioration in performance. In addition, an integrated self-regulating process is controlled by an intelligent algorithm, preventing operators from selecting the wrong pa-rameters. The cutting time is automatically adjusted to between 50 and 500 ms and the cutting pressure to between 2.6 and 5 bar. No unnecessary time is wasted after cutting, as no cooling is required and the bags can be processed immediately. The patented wafer closure prevents incorrect sealing. The cutting edge is additionally welded in line with the motto “better to be on the safe side”.
More stable, cleaner, safer, faster
Instead of seven precariously balanced layers, Imerys Graphite & Carbon now has secure pallets with 22 stable and steady layers each. The bagging capacity has been increased to 90 bags per hour and the costs for storage and logistics reduced by 75%. At the same time, dust pollution during bagging and transport has been completely eliminated. The entire process remains absolutely dust-free. The Greif-Velox Velovac system thus benefits Imerys and its customers right down the line.
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