HEXADUR^® Wear Protection for HPGRs

Challenge and solution for the cement industry

The adoption of high-pressure grinding technology over the last 25 years has led to significant energy savings as well as reduced costs for wear material.

But the conventional welded rolls used predominantly today in high-pressure grinding roller presses (HPGRs) are subject to rapid and excessive wear. Depending on the abrasiveness of the feed material, hardfaced rolls need to be refurbished at more or less short intervals. They tend to become “softer” with repeated welding of the hardfacing, resulting in irreparable surface failures. After a certain number of refurbishments, the entire roller has to be replaced. The economical use of conventionally equipped HPGRs is therefore severely limited due to:

•    constantly decreasing grinding efficiency
•    cost-intensive plant downtime
•    frequent maintenance and repair
•    shorter replacement or refurbishment intervals.

While welded rolls do of course benefit from attractive initial pricing, their running costs make them increasingly uneconomical over time. Köppern responded to this challenge during the early 90’s by developing the innovative and unique HEXADUR^® wear protection system.

Our HEXADUR^® tires for HPGRs feature an extremely wear-resistant surface with a high content of hard phases in hexagonal tiles of different thicknesses (macro-profiling). The tiles are made of powder-metallurgical tool steel or metal matrix composites (MMC) with a high degree of wear resistance. They are then diffusion-bonded onto a high-strength base ring in a hot-isostatic pressing process (HIP), which provides strong resistance to damage.

During operation, the gaps between the tiles wash out slightly and fill up with compacted feed material. This builds up a honeycomb-like autogenous wear protection layer (APL), which also improves intake behavior as well as machine throughput by increasing the friction between the tire surface and the feed material.

The softer but tough steel in the gaps between the tiles largely prevents any local damage extending to neighboring hexagons. The tiles are tolerant to minor damage due to their ability to regenerate by smoothing out partial chippings.

Read more about comminution for the cement industry
Read more about HPGRs for the cement industry