Production of micronised additives: Central dust extraction

Customer:	Clariant
Extracted material:	Additives for paints and plastics
Industry:	Chemical
Vacuum cleaner:	DS 2520 M-B1 as central extraction system with high-speed cyclone as pre-separator

Clariant AG is one of the world’s largest providers of specialised chemicals. The company develops and produces additives in the additive business field that improve the functional properties and performance of paints and plastics. The Gersthofen plant near Augsburg manufactures a broad range of wax-based additives, among other products. They ensure, for instance, that printed colours adhere well to base materials, that plastics are very easy to process, and that paints offer good scratch resistance.

Problem

One central work step in the Gersthofer wax plant is milling the waxes down to a size of just a few microns. The micropowder used in the Ceridust additive has maximum particle sizes of 15 to 35 µm, depending on type. Milling always produces, dust, which Clariant extracts with “in-line” suction. Otherwise, it would impact the grain size distribution and thereby the product quality of the micronised wax.

Solution

A type DS 2520 M-B1 Ruwac vacuum cleaner is used, here, not as a mobile device, but rather as a central extraction system. There are a variety of extraction points on the feeds and dosing units of the milling system, and these convey material to the extraction unit via a collector line. Ahead of the vacuum cleaner is a high-speed cyclone with continuous discharge, which separates out the larger particles and sends them to a waste container. A type B1 filter keeps out dusts with low particle content. The milling systems operate on average 16 to 17 hours a day, and the integrated 90 l collection container is equipped with automatic fill level monitoring.

As wax dust has a tendency to clog, Ruwac had to choose a filter material that would counteract this characteristic. For that reason a PTFE coating was selected. The retention rate for the medium conforms to usage category C, meaning it does not exceed a transmittance rate of 0.1%. The system is designed to conform with the requirements for DustEx zone 21. Under explosion protection regulations the vacuum is approved for use up to dust class M, which is suitable for dust with an exposure limit value of less than 0.1 mg/m3.