Ammann Group Offers Ammann RAH50 Drying Drum Retrofit

Ammann Group offers the Ammann RAH50 drying drum retrofit to improve fuel efficiency and recycling capabilities over old drying drums.

Ammann drying drum retrofits are designed to be compatible with equipment from Ammann or other manufacturers. Ammann dryers heat and dry raw materials of different compositions, material properties and moisture contents. They have exceptional wear resistance, are easy to maintain and highly efficient, according to the manufacturer. The Ammann RAH50 is a popular retrofit because it allows customers to work with recycled asphalt.

Christian Westphal, head of machine technology MTA Mischwerke SAW Schleswiger Asphaltsplitt-Werke GmbH & Co. KG, retrofitted a plant with an Ammann RAH50 drum. He explained how his new middle dryer ring works compared to a conventional new mineral drum.

“At first, I was rather skeptical because of the promised high RAP addition rates (up to 45%),” Westphal shared. “The promises have been kept regarding flexibility and RAP addition. The maintenance effort is, of course, slightly higher than with a pure new mineral drum, but it is lower than previously expected. Surprisingly, RAP caking is not a problem at all.”

Westphal spoke of the drum’s different applications. “In addition to the standard cold feed, the RAH50 drum gives us the flexibility to switch to hot recycling. It is already worthwhile for us to use the RAH50 middle ring addition from batch sizes of 50 tonnes. Switching to hot recycling is problem-free, taking into account the overrun from the dryer drum to the hot mineral silo. For permissible construction measures, RAP percentages of up to 45% are possible for base layers via the middle ring addition. This enables us, in consultation with the client, to recycle large quantities, which of course offers enormous advantages in terms of costs.”

Westphal also spoke of temperatures. “The addition of RAP to the RAH50 drum enables gentler heating compared to cold addition. When mixing the raw material with the RAP, we can run drum outlet temperatures of 160 to 170 degrees C. This is gentle on all plant components and also saves fuel. The frequency converter installed in the drive motors also allows us to vary the dwell time of the new minerals and the RAP, which means that all types of aggregate are dried very effectively.”

The Ammann dryer drums also offer wall thicknesses up to 15 mm and a frequency converter for energy-efficient operation. The drums are available with Amdurit wear protection and high-temperature steel.

For more information, visit www.ammann.com