Latest developments in screening at work at world center of marble

The white marble quarries now operated by William Vennai SpA in the Italian Alps have proved to be a source of the highest quality material, providing marble for the statues of the great Michelangelo himself amongst others. These are considered to be amongst the oldest and 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, they are capable of producing annually an amount equal to about 60,000 tons of marble blocks, rising to 100,000 tons through commercial connections with affiliated companies such as the Major Excavation Fantiscritti Marmi srl Scarl and E.T.A. Scarl.

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

Precise quarrying methods

In order to supply such a prestigious and valuable resource, the marble has to be extracted precisely. This quarrying of the marble is explained by William Vennai SpA head of excavation, Pau Abbot: "The cultivation (of the marble) takes place under the open sky and underground. We always use natural fractures in the marble mass and always try to follow the marble strand so to offer greater aesthetic appeal and structure.”

However, although many techniques have remained the same, new 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 whereas to produce a block 10m x 10m it took three days of work it now takes only 4 hours,” Paul continues.

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 using special inflatable ‘pillows’ or hydraulic jacks using 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 consistent high quality. The ‘perfect’ block represents only 20% of the production; the remaining 80% consists of semi-formed blocks as well material that does not possess the desired homogeneous structure due to contamination with metamorphic rock, rubble and other materials. Earth and gravel are always present which needs to be removed in order to preserve the quality of the marble. In order to effectively and efficiently remove contaminants (which themselves are valuable products) from non-block marble production, a mobile screen was acquired. In this case a Sandvik QE341.

New distributor for Sandvik Construction in Italy

William Vennai SpA’s Sandvik QE341was acquired from Sandvik’s authorized distributor in Italy, CGT. Compagnia Generale Trattori (CGT) S.p.A became Sandvik’s distributor for Mobile Crushers and Screens as well as Surface Drilling in January 2016. The company now supplies the comprehensive range of Sandvik equipment as well as providing full aftermarket care, spare parts and dedicated customer service related to the two product lines.

CGT SpA, a Caterpillar dealer since 1934, possesses representation throughout Italy with 28 direct branches. These provide integrated sales, rental and servicing solutions in both the energy and earth moving fields. CGT is part of the Tesa Group, which employs approximately 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, Sales Manager for Sandvik Mobiles in Southern Europe, says that working with such an established and respected company has opened up new opportunities enabling growth to be taken to the next level. "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."

Italian launch to great acclaim

In order 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 of the customer day, "240 companies, totalling approximately 600 people, walked through the gates of the event and the level of interest was what struck us most of all." He continued, "Companies from all over Italy visited the event including many of the major players in the Italian construction industry. All of which were extremely impressed with the recent innovations."

Eugene Lyons, Global Sales and Marketing Director for Sandvik Mobile Crusher and Screeners, was highly impressed by CGT's customer event, "It was great to see the appetite for the equipment and the great turn out." He continued, "As we are aware, the Italian Market has been quite stagnant in previous years, however 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 that the unique properties of the machine would be ideally suited to removing contamination from marble for William Vennai SpA.

The QE341 is a heavy duty scalper with class leading open scalping area delivering enormous rates of production. This means that production of 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 2-way or 3-way split configurations, as well as the ability to interchange side conveyors thereby demonstrating the ultimate flexibility of the unit. The screen-box jack up facility allows easier access to the bottom deck for maintenance and screen media changes.

As operational user friendliness is seen as vital for enhanced use, the QE341’s electrical control system incorporates a number of features to improve both the operational effectiveness and machine safety. This simple, easy to use system possesses a color-coded numerical push buttons, combined with a visual display unit enabling the operator to view engine and plant status. Prestart warnings on all plant functions, and an auto stop-start facility, together with a three mode selector function (set-up, operation and tracking facility), all ensure that safety, as well as ease of operation, are paramount at all times. The unit is also fully radio controlled as standard, with quick-set times inbuilt with sequential start-up. Other key customer requirements include:

• Screen angle working range (11° – 17°) allows material to cascade more effectively
• Jack-up screen mechanism to allow better access to bottom deck for maintenance.
• Wider screen box outlets for unrestricted oversize material flow
• Apron feeder c/w one piece wear resistant hopper
• 4700 x 1446mm / 15’ 5” x 4’ 9” double deck screen
• Top deck media - mesh, punch plate, grizzly or tines
• Bottom deck media - mesh or cascade fingers
• Three adjustable, hydraulic folding conveyors
• Hydraulic folding walkways
• Hydraulic drive oil cooler
• CAT C4.4 engine

An essential tool

Erich Padlocks, a partner of William Vennai said of the new screen: "Acquiring the QE341 was a necessity in order to maximize and improve the quality of our end product. 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 with me personally 30 years. We place so much emphasis on our relationship that now our quarries only use CAT 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 maximize production of some of the world’s most sort after marble.

For more information, contact:

Melissa Baker
Marketing Communications
Mobile Crushers and Screens, Sandvik Mining and Rock Technology
Office Phone: +44 (0)1283 818164
Email: melissa.baker@sandvik.com