Latest screening innovations in the marble capital

The white marble quarries now operated by William Vennai SpA in the Italian Alps have been a source of the highest quality material, providing marble for the statues of the great Michelangelo himself, among others.

The quarries are among the oldest, most prestigious in the entire area, with the company having quarried the marble since its incorporation in 1924.

Located in the marble basin of Fantiscritti, Vennai can produce annually an amount equal to about 60,000 tonnes of marble blocks, rising to 100,000 tonnes through commercial connections with affiliated companies such as the Major Excavation Fantiscritti Marmi SRL Scarl and ETA Scarl.

The extracted marble is classified as ordinary white (white Carrara C extra, Bianco Carrara, and Bianco Carrara CD C D) and, to a lesser extent, Bardiglio Nuvolato. These are extremely valuable materials that – together with the Statuary of Torano, the Veins, the Crimson and Calacata, and Carrara marble – have helped to make this one of the most prestigious marble producing areas in the world.

Precise methods

To supply such a prestigious and valuable resource, the marble has to be extracted precisely.

“The cultivation of the marble takes place open cast and underground,” Paulo Gianni, an excavator operator at William Vennai, said. “We always use natural fractures in the marble mass and always try to follow the marble strand, so as to offer greater aesthetic appeal and structure.”

{{quote-A:R-W:300-I:2-Q:"The Italian market has been quite stagnant in previous years, but now we are seeing added enthusiasm, new projects and great confidence."-WHO:Eugene Lyons, global sales and marketing director for Sandvik mobile crushers and screens}}Although many techniques have remained the same, modern technology is also playing its part.

“Diamond wire saws have replaced the old helical wire ones, allowing a radical lowering of work times, so much so that where it took three days of work to produce a block 10m x 10m, it now takes only four hours,” Gianni said.

After using horizontal and vertical drilling holes or joints with jackhammers, holes are screwed to the diamond wire, which is connected to a powerful cutting machine. This scrolls down automatically during cutting phases or rotates the point of axis, according to various requirements.

When the marble block is separated from the mountain, complete detachment is facilitated with special inflatable “pillows” or hydraulic jacks on powerful excavators to a specially prepared “bed” of debris, to provide a safe resting place for the extremely valuable end product.

However, the marble is not all of a consistently high quality. The “perfect” block represents only 20 per cent of production; the remaining 80 per cent consists of semi-formed blocks and material that does not possess the desired homogeneous structure, due to contamination with metamorphic rock, rubble and other materials. Earth and gravel is always present and needs to be removed to preserve the quality of the marble.

To effectively and efficiently remove contaminants (which themselves are valuable products) from non-block marble production, a Sandvik QE341 mobile screen was acquired.

Launch to acclaim

William Vennai’s Sandvik QE341 was acquired from Compagnia Generale Trattori (CGT) SpA, Sandvik’s authorised distributor in Italy.

CGT has been Sandvik’s distributor for mobile crushers and screens and surface drilling since January 2016. The company now supplies the comprehensive range of Sandvik equipment and provides full aftermarket care, spare parts and dedicated customer service related to the two product lines.

CGT SpA, a Caterpillar dealer since 1934, has 28 direct branches throughout Italy that provide integrated sales, rental and servicing solutions in both the energy and earthmoving fields. CGT is part of the Tesa Group, which employs 1600 people and has a controlling interest in several other companies.

It is also the Caterpillar dealer for the Balkans and Malta, focusing on the construction, energy and logistic markets.

Norbert Lentschig, the sales manager for Sandvik mobiles in southern Europe, says working with such an established and respected company has opened new opportunities for growth.

“We are delighted to work with such a trusted distributor. Its industry expertise and local customer knowledge, combined with strong aftermarket support, has enabled us to get closer to our Italian customers such as William Vennai SpA.”

To mark and celebrate its distributorship, CGT held its first customer event dedicated to Sandvik equipment in 2016, with one of the major attractions being the QE341.

Andrea Elli, marketing manager for CGT, said about 600 people from 240 companies “walked through the gates … and the level of interest was what struck us most of all.

“Companies from all over Italy visited, including many of the major players in the Italian construction industry. All of them were extremely impressed with the recent innovations.”

Eugene Lyons, global sales and marketing director for Sandvik mobile crushers and screens, was highly impressed by CGT’s customer event.

“It was great to see the appetite for the equipment and the great turnout,” he said.

“The Italian market has been quite stagnant in previous years, but now we are seeing added enthusiasm, new projects and great confidence. Our partnership has great potential for the future, in the short-, medium-and long-term.”


Ideal mobile solution

One of the pieces of equipment demonstrated was the QE341 scalper/ screener.

CGT could immediately see the machine’s innovative properties would be ideally suited to removing contamination from marble for William Vennai.

The QE341 is a heavy-duty scalper with an open scalping area that can deliver enormous production rates. This means even the most hard wearing of materials is facilitated through a wear-resistant steel apron feeder, with massive stockpiling capability with over-wide conveyors to maximise delivery.

With a one-piece, wear-resistant rigid hopper, it features a robust crusher-style chassis and has been designed to be compatible for two-way or three-way split configurations. The ability to interchange the side conveyors further demonstrates the flexibility of the unit.

The screen box jack-up facility allows easier access to the bottom deck for maintenance and screen media changes.

As user-friendliness is seen as vital for enhanced use, the QE341’s electrical control system incorporates numerous features to improve operational effectiveness and machine safety. This easy to use system possesses colour-coded numerical push buttons, combined with a visual display unit enabling the operator to view engine and plant status.

Pre-start warnings on all plant functions and an auto stop-start facility, together with a three-mode selector function (set-up, operation and tracking facility), ensure safety and ease of operation. The unit is also fully radio-controlled as standard, with quick-set times in-built with sequential start-up. Other key features include:

  • A screen angle working range (11° to 17°) that allows material to cascade more effectively.

  • A jack-up screen mechanism to allow better access to bottom deck for maintenance.

  • Wider screen box outlets for unrestricted oversize material flow.

  • An apron feeder combined with a one-piece wear-resistant hopper.

  • A 4700mm x 1446mm double-deck screen.

  • Top deck media comprising mesh, punch plate, grizzly or tines.

  • Bottom deck media comprising mesh or cascade fingers.

  • Three adjustable, hydraulic folding conveyors.

  • Hydraulic folding walkways.

  • A hydraulic drive oil cooler.

  • A Caterpillar C4.4 engine.

“Acquiring the QE341 was a necessity to maximise and improve the quality of our end product,” Erich Lucchetti, a partner of William Vennai, said.

“We could only really choose Sandvik – above all, for the quality of the machines, and then for our relationship with CGT, a relationship established over time and dating back 30 years.

“We place so much emphasis on our relationship that now our quarries only use Caterpillar machines. In future, if we require screening (or crushing equipment), we will put our faith in CGT again and choose Sandvik as well.”

The QE341 has all the attributes required to help maximise production of some of the world’s most sought-after marble.

In Australia the QE341 mobile scalper/ screen is available through Precisionscreen (New South Wales, Australian Capital Territory, Queensland, Victoria, South Australia, Tasmania and the Northern Territory) and Porter Group (Western Australia).

The QE341’s successor – the QE342 mobile screen – will be launched at Hillhead 2018 towards the end of June.


Source: Sandvik Rock & Technology

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