In the Lower Rhine gravel plant Rheinberg, by Lake Haferbruch, Heidelberger Kieswerk Niederrhein GmbH & Co. KG – a subsidairey of Heidelberger Sand und Kies GmbH – is producing a wide delivery range from gravel and sand for concrete, road, garden and landscaping work (Fig. 1).
After materials that contain sand and gravel are extracted from the lake, they are classified in bigger grain sizes (fraction 2/32) and sand, both by using a Metso screening plant. The sand draining machine (0/2) had already withstood 15 years of weathering and harsh industrial conditions, and recently had to be replaced with a new machine.
The decision to replace it was made in mid-February and just 5 weeks later, the structurally identical model was installed into the otherwise unchanged steel construction (Fig. 2). As the old dewatering machine had dealt with a total of approx. 6 million tonnes of material in its one and a half decades, the beams and outer walls were rusted beyond repair (Fig. 3). Restoring the machine or replacing some of the crossbeams would not have been economically viable.
The new Metso linear vibrating screen type H1E 3000/2000 (length 3 m, width 2 m) with two imbalance drives is the identical successor of the old installation. According to Justus Mische, Metso sales manager MSE Germany, it would also have been possible to replace a unit of any length and width, and with different requirements. The exchange went according to plan: on the morning of March 28th, the old machine was lifted out of the steel construction by crane (Fig. 4), and shortly after, a team of the facilities' workers in cooperation with Metso employees fitted the new installation exactly into the place of the old unit (Fig. 5), without having to change the existing construction at all.
Beforehand, the original flat panel screening media has been flitted to the new screen. The design of the cross and side beans of the screening plant would also have allowed for the installation of modular Trellex LS screen media. After just one hour, the new machine stood in place of the old one (Fig. 6).
Further Metso machines passed their prime this year. This includes a screening machine that had damage to the side wall; by screwing on steel plates, it was temporarily repaired. In this case, it wasn’t immediately necessary to replace the whole side wall. This is something that can usually be carried out when the damage is discovered early, as the area can be reinforced with additional metal sheeting.
As linear vibrating screens perish quickly in the harsh sand and gravel surroundings, Karl-Heinz Schürmann is impressed by the quality and endurance of the spherical roller bearings in his old – and now new – screening plant. “With the unit we get sand and gravel in the ratio 60:40, often even 50:50. Normally, 180 tonnes of sand, and 330 tonnes of material altogether, are processed per hour, without straining the machine. The automatic system control will stop the process when the risk of with imminent overload increases,” he explained.
The company also supplies their internal concrete factories in Lintorf and Bottrop, but the company primarily serves customers in the whole Ruhr region, as far as Münster.