Use of electric knockers underground

Innovative strength and efficiency for conveyor system at a depth of 700 m

At a depth of 700 m, the ePKL reliably removes salt residues from chutes in the salt mine

The PKL and its compressed air-independent counterpart, which taps on an electrical impulse and can be used almost anywhere

A wide range of mounting solutions are available for the PKL: classic weld-on bracket (above), flexible vacuum mount or material-friendly adhesive bracket (left)

In bulk material handling in industrial practice, knockers are used to support material flow, loosen caking, break up bridges and prevent product jams. In cooperation with K+S and NetterVibration, an efficient and lucrative solution was found to flow problems on conveyor belts during the removal of salts in underground mining in the largest plant in northern Hesse.

The current K+S plant in Werra was created in 1997 through the merger of the four formerly independent plants in Hattorf, Wintershall, Unterbreizbach, and Merkers, resulting in a highly efficient production facility. Approximately 20 mio. t of raw salt are mined here each year. The underground mining area of the Werra plant is equivalent in size to the city of Munich, making it the largest site of K+S Minerals and Agriculture GmbH. The integrated plant, including production, wastewater management, workshops, rail operations, energy supply, administration, and training center, employs almost 4400 people (including craftsmen from the central technical department and approximately 300 trainees), almost half of whom work underground. The products refined from the raw salt are delivered to numerous countries worldwide. In addition to fertilizers for agriculture, the company also manufactures precursors for industrial applications and for the pharmaceutical, food, and animal feed industries.

Use of knockers in salt conveying

As is so often the case, technicians, plant managers, and maintenance personnel at K+S are faced with a familiar challenge when the bulk material is in an unfavorable condition, such as a tendency to stick or clump together, combined with the problematic surface properties of the conveyed material. To knock off stubborn deposits from conveyor pipes and belts, an impact is required, which in many companies is still carried out manually using a tried-and-tested hammer – with the associated inaccuracy and destructive force on the equipment.

In contrast, NetterVibration’s PKL series of pneumatic knockers have long enabled K+S to clean reliably and effectively while also protecting the material, without deformed or narrowed equipment further impairing the conveying of salts. Strongly adhering, hygroscopic salts are efficiently and reliably loosened by the impact of the PKL on its impact surface.

Advantageous use of electricity instead of
compressed air

The long-proven PKL pneumatic knocker now has an innovative sibling, the ePKL, which triggers a knock in response to an electrical impulse and can therefore be used anywhere, even in extreme cases in remote operating areas without a power supply, thanks to its battery operation. A compact control unit triggers single knocks or knocks at regular intervals as required.

Use of the ePKL on a remote chute

In the HERA shaft facility, conveyor belts transport the extracted salts. Due to their hygroscopic properties, clumping and caking occur in many places. This repeatedly led to a variety of conveyor system malfunctions, restrictions in material flow, and consequently to a reduction in the performance of the entire conveyor system.

K+S therefore launched a joint project with its long-standing partner NetterVibration to solve the problem at particularly critical, sensitive points, known as “dust chutes.” In mechanical engineering, a chute is a loading channel or similar conveyor device. In this case, it is a special type of pipe for the directed transport of salts.

Pneumatic roller vibrators of the NCR 22 type from NetterVibration had been used for a long time to knock off salt deposits and support the flow of material. Unfortunately, the very high mechanical stress led to increased wear and costly maintenance. The use of these devices 700 m underground with correspondingly long distances resulted in high maintenance costs, and in some cases there was no compressed air supply to the affected plant components located so far away.

After careful analysis and detailed planning by the NetterVibration field service in cooperation with K+S technicians, the customer decided to use the electric ePKL. The primary goal was to save the increased costs for setting up and maintaining a compressed air supply, especially since electrical connections were already available at the chutes.

Thanks to its robust design, the ePKL, including its control system, has proven to be ideally suited for demanding underground applications. It was easy to install and operates reliably on electricity alone. The directed impulse generated by the piston stroke protects the mechanics of the chute. A major advantage is the low maintenance requirement of the ePKL, which in this specific case is installed at transfer stations, i.e., at a conveyor belt intersection where employees cannot be on site every day for inspection or maintenance.

Since its installation, the ePKL has been working to the satisfaction of the K+S operations manager for knocking off raw salt and is only subject to general monitoring and visual inspection of the transfer station by maintenance personnel at longer intervals.

www.nettervibration.com