Underground Mining

Nimble mineworker

Posted on 08 April 2016 by Yvonne Wirth/Thorsten Block, Images by Thorsten Block

Since 2016, a Bell B30E 4x4 has been working as a special-purpose vehicle at the natural-stone company Trierer Kalk-, Dolomit- und Zementwerke.

Since the start of the year, a Bell B30E 4x4 has been working as a special-purpose vehicle, specifically for the underground extraction of dolomite, at the natural-stone

A Bell B30E 4x4 has been working in the Josef-Stollen pit at TKDZ Wellen since January 2016. The two-axle vehicle has been specially adapted to underground mining requirements.

company Trierer Kalk-, Dolomit- und Zementwerke ("TKDZ GmbH Wellen" for short). In barely eight months, the two-axle vehicle based on the current Bell Equipment E-Series was adapted to the specific requirements of tunnel mining. It is driven by an MTU Series 6R 1000 diesel engine rated at 246kW.

High-quality dolomite rock has been mined in Wellen an der Obermosel near Trier for over 140 years. For decades, extraction took place overground and underground, and the adjoining firing plant in place there until 2006 processed the material into dolomite,

The two-axle vehicle's smaller curve radius, due to the concept involved, speeds up circulation and protects the underground around the dolomite pillars.

limestone, cement and later also fireproof products. The current Josefstollen pit was opened up in the mid-1960s, and it is from here that all TKDZ raw materials have come since 1965 following the end of overground mining. Since 2007 the company has relied on three articulated dumpers made by construction machinery specialist Bell for this work. Last year it was decided to replace the oldest Bell B30D, which had already clocked up 12,000 operating hours.

The company opted for a two-axle special-purpose vehicle – the Bell B30E 4x4 – which has been in service since early 2016. The necessary power for underground use is delivered by an MTU Series 6R 1000 engine rated at 246kW. It is based on the Mercedes-Benz OM 936 engine and was developed specifically for off-highway applications in the agricultural, construction and industrial sectors. Working all year round on an alternating single shift, each machine clocks up as many as 1500 operating hours a year.

The loading area in the Josef-Stollen pit is very narrow due to the room-and-pillar method employed in dolomite mining.
It takes the 4.5 m³ wheeled loader five load cycles until the 32 t payload of the Bell B30E 4x4 is reached. The compact dumpster for the stone spares the vehicle from having to move.

Demanding underground extraction

The overground plant has since been producing diverse stone powders and grits, which are used as high-quality mineral primary materials in the chemical industry or as rigorously controlled and certified fertilizers, bedding material and feed in agriculture and animal husbandry. With a total of 45 employees, TKDZ currently achieves an annual production of several hundred thousand tonnes of raw stone and filler materials. Both plant sections used for overground mineral and powder processing are


The far shorter dumpster on the Bell B30E 4x4 now allows full use of the 70° tipping angle at the primary crusher chute. With the previous 6x6 earthworks dumpster, the hydraulics still had to be automatically limited.

supplied directly from the two levels of the now 400-hectare Josefstollen pit via a conveyor system. Here mining is done by blasting based on the "room and pillar" process: this process involves the stone being removed from a regular grid-like pattern of rooms measuring around 5.5m across and six metres high before being loaded by heavy-duty loader. What remains are pillars measuring around 5.5 x 5.5m, which act like hundreds of pieces of scaffolding to keep the rock stable. This sophisticated process, which also ensures highly selective extraction of the in-situ rock, places high demands on the drivers of the loading and transport fleet comprising two 4.5-cubic metre wheeled loaders and three 30t dumper trucks. In addition to loading the head in the narrowest of spaces and only in the glow of the work lighting, the articulated dumper drivers in particular need much more than just a good sense of direction on the routes leading to the unloading point at the chute of the underground primary crusher. These routes can be up to 2,500m long, depending on the mining point and advancement. Man and machine face stiff challenges on the tight turns around the pillars at the loading and tipping points in particular, and even in the wider main pit with an average downhill gradient of ten percent.

With flatter "wheel houses" than its D-Series predecessor, the new dumpster geometry of the Bell B30E 4x4 allows a greater volume and better tipping.

Hard at the limit

It's not just the articulated dumpers that take things to the limit when working underground. So do the MTU engines. After its first two weeks of operation with some 3000t of stone transported already, equivalent to around 100t per day, the MTU engine is living up to all expectations: the six-cylinder engine rated at 246kW has consumed just 6.7l of fuel per hour on average. Although it is considered a lightweight engine, the 6R 1000 has extraordinary an power density. With its exhaust gas recirculation and selective catalytic reduction, the drive unit meets the requirements of the EU Stage IV emissions standard without a diesel particulate filter. Even the dusty air is unable to halt the progress of the MTU engine as special filters protect it against the dust produced when stone is mined.

Exceptionally mobile

The Bell B30 4x4 is exceptionally nimble: with an inner curve radius of just 3,5m and an overall length of 9,3m, it is much better at negotiating the turns than the previously

Good experience underground: TKDZ Operations Manager Matthias Wulf, driver Hans-Werner Scheuer, Andreas Reinert, Sales Manager Bell Germany.

used machines, which ensures fewer manoeuvring movements and faster circulation. After a total of five load cycles, the increased payload is reached. Plus the whole process has been speeded up dramatically thanks to the higher but shorter dumpster for the stone. In addition to this, the 70-degree tipping angle can now be used to the full at the tipping point. But these aren't the only improvements: as well as a statutory fire extinguishing system for underground operation, the dumpster equipment has been enhanced and the payload optimised. With its increased height, extended unloading chute and lockable pendulum-type rear flap, the dumpster can now carry around 20 instead of 18.50 cubic metres of stone – plus the dumpster form has been slightly adapted to the limited clearance outline of the Josefstollen pit. The installation of a 40t rigid axle with E4 rock tyres now allows a payload of 32t. With all these modifications, the Bell B30 4x4 is ideally prepared for underground operations.

Point of Contact

Edwin de Heij
+31 78 63957 03

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