Uncompromising secondary crushing

There is no hiding their enthusiasm when the “decision makers” at Vogelsberger Basaltwerk GmbH & Co. KG, VBW, describe their latest addition. The optimally designed Sandvik CS550 installed at the plant in February is a powerful and reliable high-throughput unit that delivers precision and quality at the secondary crushing stage.

The Büdingen-Rinderbügen quarry in Wetteraukreis/Germany, has been supplying the basalt that is characteristic of the Vogelsberg landscape since 1963. The basalt is currently quarried and reduced to gravel, chippings and fine flint, as well as crushed sand, by Vogelsberger Basaltwerk GmbH & Co. KG, VBW, part of the Dressler Verwaltungsgesellschaft mbH group of companies. The basalt grit is used by VBW to produce construction materials to meet the requirements of several customers in the region.

Bernd Krempel joined Dressler as co-director at the beginning of 2016. One of his most important tasks, together with operations manager Dieter Pracht and foreman Heiko Schlögel, is continuous optimization of the basalt plant process. The first step of the modernization programme was to replace the secondary stage crusher – a 1650 cone crusher that had been in operation since 1984 – with the aim of improving capacity and product quality. Always satisfied with the service and support from Sandvik, VBW’s decision makers favoured replacing the crusher with a Sandvik CH-series Hydrocone, even though they knew this decision would also impact operation of their primary crusher. However, at just the right time for  VBW, Sandvik announced the new CS550 that was even more ideal for their requirements.

A perfect fit

Just to recommend, never mind purchase, a brand new innovation requires a deep, mutual trust. With no lack in trust between the consultancy partner, stationary crusher specialist Hubertus Kirschbaum from Sandvik Mining and Rock Technology’s sales team in Essen and those involved at VBW, the advice was spot on. Results of quarry testing in Sweden of the pre-series models of the brand new Sandvik CS550 spoke for themselves. This latest, innovative cone crusher from the 500-series not only complements the two existing Sandvik CH550 and CH540 models, it’s also an ideal alternative for the popular CH660. The Sandvik CS550 uses a range of familiar components from the proven CH crushers and operates at higher pressure levels compared to traditional CS-crushers, has low-maintenance and many safety features and is less sensitive to material feed variations, for example, a secondary crusher from the CH series.

The reliable and powerful secondary crusher with its high reduction ratio comes with a completely redesigned crusher chamber, which essentially guarantees the enhanced quality demanded at the secondary crushing stage. To meet the demands of the customers, the C (coarse) crushing chamber is designed for intake of materials with a feed size of up to 350 mm, while the EC (extra coarse) crushing chamber can handle up to 430 mm.

German customers were given the first opportunity to inspect the new crusher at close hand at an event in September 2016, when Bernd Krempel and Dieter Pracht where able to closely monitor the assembly and disassembly of the CS550 that was on show. Already impressed by the well thought-out design, which gave an indication of the potential productivity and simplified maintenance and servicing, any final doubts they might have had were quickly dispelled when making process simulations with Sandvik’s Plant Designer program, featuring data from their own basalt. The crusher was commissioned, and installed in February 2017 as a replacement for VBW’s outdated predecessor (1650 crusher).

Putting theory into practice

The eminent suitability of the CS550 as a viable alternative to the CH-series for secondary stage crushing at VBW quickly became clear. The large C-chamber intake to match the jaw crusher in the primary stage quickly “swallows” the crushed material of 250 to 350 mm in feed size, and thus offers the possibility to produce large volumes of the final grain fractions even at the secondary stage, while ensuring a high reduction ratio and an excellent shape of the end product. Between 250 and 300 t of material per hour can be processed, with seemingly no effort, to the target particle size of 0/56 mm, with the proportion of the preferred particle size of <32 mm being around 80 %. The wide range of additional settings, together with additional, larger throws of 24/28/32, 32/36/40 and 40/44/48 mm provides excellent processing flexibility if this should be needed. The reduction of fine material that is required is a strikingly positive feature compared to the old crusher. The Sandvik CS550 also clearly meets VBW’s requirements in terms of oversized particles (>32/X).

“It’s quite the guzzler!”, says Managing Director Bernd Krempel happily after just a few weeks’ operation, which he describes as being the first successful step in their modernization step, which will undoubtedly be followed by more: “There is still more potential. We are pushing our primary crusher to its performance limits and the downstream CS550 manages with just 80 to 130 of its 330 kW.” A major change compared to the previous situation, since the old crusher always required the 250 kW that was provided. Why is this possible? Because the modern IE3 motor only draws as much energy as it needs. Depending on the feed material, as well as the defined throw and the closed side setting, the crusher can handle up to 700 t/h.

The CS550 is currently set to operate in low output mode, due to the primary crusher limitation. Operators select the smallest possible throw of 24 mm to suit the situation at hand. Even at this level, the plant is achieving a 20 % increase in production following the upgrade. However, this will only work if all of the plant components keep pace. This is not a problem for the downstream vertical shaft crusher that is used for producing fine grit, since it is now supplied with the perfect secondary material from which to produce the required 5/8 fraction. Rough final grain fractions of up to 32 mm can be removed directly after the secondary crusher thanks to their outstanding quality and classified in accordance to the required spectra.

Overall, the new secondary crushing stage therefore allows a more efficient process with a significant reduction in the recirculating load, while at the same time relieving the tertiary stage of some of its load. This allows the operators more time to quality assure the product. This was an essential element of the modernization plan.

Automation, control and ease of access

Of course, the Sandvik CS550 comes as standard with a modern crusher control system. It uses Sandvik’s latest automation and control system and is state-of-the-art in terms of automation and machine/process control of the crusher, supplying a wealth of valuable data. It optimizes operation in correlation to throughput and reduction ratio and adapts the crusher to suit different operating conditions, thereby ensuring that an optimum level of consumption is always achieved in terms of energy efficiency. The Hydroset system regulates the positioning of the main shaft and at the same time offers overload protection to permit the passage of uncrushable items.

Service partnership paves the way

As already mentioned, VBW and Sandvik were once again in contact when it came to the new secondary crusher in terms of the replacement investment, not least because of their longstanding service partnership. However, service of the future will not look the same as it did in the past - the new digital possibilities will change the face of the collaboration. However, the partnership itself will continue to endure, because solutions like this that are designed to make everyday working life more convenient are highly valued by those in the business. The ease of maintenance and servicing of all Sandvik 500-serie crushers delivers this trump card. For example, backing compound is no longer used when installing the crushing chamber, making them much easier to replace when needed - particularly since a Sandlock lifting device is available to make replacement of the cone and crushing mantle significantly easier and safer. Inspection openings in the lower section, manufactured from polyurethane, simplify access to trouble spots and an offline filter system ensures permanent lubricant filtration. The quality of the lubricating oil can thus be consistently maintained “as new” for years, despite the difficult environmental conditions. This in turn reduces wear on the main machine components and saves costly oil changes every year. The user-friendly operating concept of the motor is enhanced by a hydraulically-operated pivoting motor base, which simplifies re-tensioning of the belts and it also keeps it at a constant tension.

Well equipped to meet demand

Dressler’s rock and stone division has taken an important step for the future by investing in the Sandvik CS550 secondary crusher for VBW and, since February, is therefore in a much better position to meet increased demand, demonstrated by an impressive 20 % increase in throughput capacity, even with the remaining limitations in terms of the overall concept. The higher reduction ratio in the secondary stage means more final product to bypass tertiary crushing and less recirculation results in reduced wear and less downtime.


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