A snowball picks up more and more snow when it rolls down a snow-covered slope, increasing its volume and surface area. When it eventually comes to a halt, it has turned into a large lump of compacted ice crystals, which shows us: Mass attracts more mass. This process in physics, the “snowball effect,” brings variety to cold winter days, but leads to production losses and machine damage in the manufacture of building materials. And it also happened at Klaus Hoch- und Tiefbau GmbH & Co. KG in Wehringen near Augsburg, Germany. The traditional company has its own quarry plant in Königsbrunn and produces high-quality crushed sand using off-spec particle sizes.
To produce this sought-after and expensive construction material, off-spec particle sizes are crushed to a maximum grain size of 4 mm and then reused in road construction or for the production of particularly fine-grained concrete. However, machine breakdowns used to occur time and again because the fine and moist material started to clump together during the crushing process, quickly clogging the machine and machine outlet. The solution was to keep the outlet clear using water, which led to high wear on the machine due to sand friction. So it was not a viable solution.
High degree of crushing for fine particle shapes
This is why the construction materials manufacturer turned to the experts at BHS-Sonthofen. Before the order was made, extensive testing was performed using the input material at the Sonthofen test center. In the end, the customer opted for the BHS rotor impact mill of type RPM 1113, a high-performance crusher with a vertical shaft. This BHS rotor impact mill offers a high degree of crushing and achieves an excellent fine fraction size measuring from 0 to 4 mm. This makes the mill suitable for the crushing all mineral materials with low to medium abrasiveness. The BHS rotor impact mill of type RPM 1113 has been redesigned for the special requirements of Klaus Hoch- und Tiefbau in order to meet the special properties of crushed sand.
Constant production volume with reduced expenditure of time
The fine material is discharged immediately due to the very steep outlet of the BHS rotor impact mill, which means there is no chance of clumping in the machine. The machine housing is a redesign of the standard model but in a larger version. It has two enlarged openings in the discharge area through which the material can run off smoothly – without caking. The crusher achieves a throughput of 38 metric tons per hour with a particle size of 0 to 4 mm, maintaining the same production volume, yet requiring less time compared to the previous plant. A particularly positive aspect is that previously unused material can be processed sustainably and economically in this way. In addition, BHS-Sonthofen also took over the technical integration of the machine in the quarry plant and provided the control solutions for the BHS rotor impact mill. Digital metering of the input material ensures that the machine always delivers optimum crushing performance even at full capacity – with virtually no dust formation.
The system has been in operation at the quarry plant since the spring of 2021 and has since been running without any machine downtime due to clogged outlets. “The machine delivers excellent results and shows hardly any wear, even at high production volumes,” reports Arthur Jagosch, the engineer responsible for purchasing and quarry plant at Klaus Hoch- und Tiefbau. “What’s more, it is easy and convenient to maintain the machine and make adjustments to it.” For this reason, Klaus Hoch- und Tiefbau has decided to increasingly use the BHS rotor impact mill for sand production in the future: A second machine is already being planned. BHS-Sonthofen considers this success proof that the company should offer the modified BHS rotor impact mill of type RPM 1113 to other customers in the construction materials industry, as well.