A unique Arocs 1833 for the "Happy Valley quarries"
Vehicle & Technology
A tanker adapted to French mining requirements: that's exactly what the technical bosses of Carrières de la Vallée Heureuse were looking for. And the result? A pretty unique Arocs 1833.
The quarries of Carrières de la Vallée Heureuse (literally "Happy Valley Quarries"), and the company of the same name have been owned by the Hénaux family for 137 years now. They can be found between Boulogne-sur-Mer and Calais and cover an area of more than 200 hectares. The plant is open from 4:30 a.m. to 6:30 p.m. and operates three different shift teams from Monday to Saturday morning in order to extract as many as 20,000 tonnes of limestone per day.
"The range of our products stretches from 0.2-millimetre granules to 7-tonne blocks of stone," says Bruno Devaux, Head of the company's Industrial Services business area. "Depending on the area, you find stone with different characteristics which thus allows us to serve various industrial sectors. Among these are steel processing plants, sugar refineries and gypsum manufacturers, plus the pharmaceutical and foodstuffs industries, and of course construction companies."
The products from Carrières de la Vallée Heureuse are used for example by ArcelorMittal in their furnaces as well as by the town of Wimereux, which uses stone to strengthen its sea defences as the limestone from the quarry is non-abrasive and thus particularly hard. Everything is transported by road or by rail; the latter thanks to a terminal with a rail connection.
Currently, 30 machines are in use at the quarry. You can normally also find two dumpers there, which get loaded by the wheeled loaders and diggers. These machines need to be refuelled with hundreds of litres of fuel on a daily basis and the latest models even need AdBlue. Refuelling takes place both in the morning and the late afternoon.
"We wanted to bring a further warehouse area back into operation but it is only accessible by road, and so we needed a truck which was road-approved and which could also be used problem-free in the quarry in order to supply fuel to our machines," explains Bruno Devaux, talking about the fundamental specifications of the vehicle.
Regarding the chassis, the company chose a two-axle Arocs 1833. The truck should be able to transport two tanks with a total capacity of 8000 litres, as well as a platform on which a 1000-litre tank for AdBlue or lubricants can be mounted. A true challenge. "The tank has to conform both to the French RGIE general regulations imposed on mineral-extracting industries, as well as the ECE-R111 regulation which prescribes a specific centre of gravity for tanks. A specific climbing ability is also required. Only the Arocs fulfils these criteria," continues Bruno Devaux. Upon delivery, though, the Arocs had a centre of gravity which was actually too high to be used as a refuelling vehicle. A few modifications were required in order to lower it. Laurent Meyrignac, Customer Advisor for the Mercedes-Benz Partner in Isques, thus had the Arocs equipped with two 9-tonne axles and an additional pack of leaf springs.
"Only the Arocs fulfils these criteria."
The regulations applicable to the mining industry also required the cab to be equipped with a protective cage. This cage is normally installed on the exterior, which was not possible in the case in question. Had it been mounted in this way, then the tanks would have had to be moved further back, thus subsequently reducing the length of the platform. The solution involved integrating the protective bar for the driver in the cab itself. "The vehicle was delivered in accordance with our specification and was thus a true prototype," says Bruno Devaux.
Brevet Carrosserie handled the project and were even subject to further restrictions. "We have three certifications: ISO 9001, ISO 14001 and ISO 18001. The latter obliges us to maintain particular safety standards. For the protection of the driver, the tanks can be filled from below. For the rare cases in which the driver has to climb onto a tank, there's a step with a folding handrail, which can be operated from below. What's more, the tanks feature automatic deactivation if a specific quantity is reached," tells Bruno Devaux.
For all those involved, this was an extremely complex project which took one and a half years to complete as a result of the many discussions that were necessary for it. But now, the little Arocs is a true gem worth 150,000 euros. "Mercedes-Benz followed our requirements where others wouldn't have even attempted it," affirms Bruno Devaux.
How the quarry works.
The excavation of limestone is carried out using controlled explosions. "We have our own team of explosives experts," explains Yoan Bétaz, Head of the Maintenance and Machine Planning department at Carrières de la Vallée Heureuse. The first step is 3D scanning of the face to be mined, after which the explosion depth is determined. The drillmaster can then locate the positions at which the holes should be bored. For an explosion whereby as many as 40,000 tonnes of stone are to be extracted, between 50 and 60 vertical holes are required. A wheeled loader or a 90-tonne digger then lifts the usable stone into a dumper with a load capacity of 60 tonnes.
The material is then transported to the jaw crushers and impact pulverisers, where the desired grain size can be obtained. These machines can break up stone with a maximum weight of 2.5 tonnes. Hoppers with dosing units make it possible to process products to the desired grain size and the precisely defined characteristics required. The stone-masonry firm which is located on the company premises also obtains their raw materials from the quarry.
"The depth of the quarry is currently 90 metres," says Yoan Bétaz. "We can still go another two mining faces deeper, which corresponds to a further 30 metres." Anyone tempted to look into the future of the quarry will quickly realise that Carrières de la Vallée Heureuse still have enough work for an entire century.
Photos: Hans Müller