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Graphic element Research > Growth > Research projects > Products & processes projects > Reducing waste in hard stone quarries
Graphic element Reducing waste in hard stone quarries
    04/02/2002
 

Reduction of the high levels of wastage in the excavation of hard stone such as Portuguese pink marble was the focus of a 27-month long BRITE-EURAM project funded by the European Commission, and co-ordinated by the Business Innovation Centre of Tuscany (BIC Toscana) in Italy. The result was the design and construction of an innovative diamond belt gallery saw for the underground excavation of hard stone. A prototype was successfully tested at the Lugramar quarry in Portugal, where it was shown to reduce wastage by between 30 and 50%.

Portuguese pink marble is currently excavated in deep, open pit quarries. The process produces much wastage, particularly at depths below 60 metres where the quartz-flecked stone is subject to higher stress, causing fractures. In some cases, fractures can result in up to 85% of the marble being discarded. The waste and scrap materials left behind cause disfigurement of the local landscape, while the lubricants needed to operate traditional hydraulic-powered chain saw equipment used to excavate the material also contaminate the environment. Safety of workers operating the machinery is also an issue. Similar problems exist in the open pit quarrying of stone in Spain and Greece.

Leading Italian quarry equipment maker Benetti Macchine was commissioned to design and build equipment that could excavate hard and abrasive types of marble such as Portuguese pink marble (Mohs>3) more efficiently than the current technology. At the same time, a feasibility study was carried out on the development of a faster, more efficient block-cutting saw that could recover good quality material from waste blocks already excavated. Tests were also carried out to find ways of improving diamond tools used on all types of diamond belt machines currently in use.

Waste reduction
 

Benetti Macchine developed a specially designed gallery saw for use underground, incorporating diamond belt technology, capable of working on hard and abrasive types of marble with high fracture characteristics. With the new equipment, galleries for exploiting marble can be opened up directly from an existing open pit quarry, thus limiting the need to excavate deeper where the marble is likely to be more fractured. This means quarry operators can now excavate horizontally rather than just vertically.

"It is a new way of exploiting the materials," says Laura Bertolucci, co-ordinator of consulting services to SMEs at BIC Toscana. "One method of exploiting marble is open pit. But the underground method is very important where the material is heavily fractured. We can enter at a certain level and open a gallery at the right spot for the best vein. It is more efficient as you don't have to cut through fractured and waste marble to get to the right spot."

The underground method is also safer and more environmentally friendly. "Open pits create a bad impact, environmentally speaking, because you have a lot of material wasted - you create new mountains of waste material," explains Ms Bertolucci.

 
Better working environment
 

Aside from exploiting better quality material and producing up to 50% less wastage, the diamond belt technology also increases productivity by requiring less maintenance than the serrated chains currently used by gallery saws. The new equipment also runs on water (using aquaplaning technology) rather than lubricants such as oil and grease - thus reducing pollution.

As the diamond belt machines are completely automated, operators can control the excavation by remote control, which provides a safer and better working environment. The new technology also allows quarry operators to increase their skills and job qualifications and extends the opportunities for female employment.

 
Market potential
 

Project partners included leading quarries across southern Europe, such as Lugramar and Placido Josè Simoes in Portugal, Felekis Bross in Greece and Granitos Rosa Valencia in Spain. The Italian electronic device manufacturer CIEA collaborated with Benetti Macchine on the development of the electronic panel for the remote control of the new machine. Portuguese research institute CEVALOR , Italian research group ENEA and the ERICA Technological Laboratory also contributed their expertise.

This wide collaboration reflects the market potential of the new technology in southern Europe. "The potential is enormous in all countries which do not use underground exploitation methods for the excavation of hard stone - such as Portugal, Spain and Greece," says Ms Bertolucci. The Lugramar quarry had recently bought, via tender, the diamond belt gallery saw prototype for use in its operations.

But the potential does not end at European marble quarries: the diamond belt technology could be used in construction of urban metro tunnels or underground bunkers for nuclear power plants where an absolute lack of vibration during construction is vital.

 
Waste reduction
Better working environment
Market potential
   

Key data

Encouraging traditional sectors of industry to develop new technologies and processes is a priority of the Innovative products, processes and organisation key action The prime objective of this project was to develop new tools for the underground excavation of hard stone that would not only boost productivity by reducing waste but reduce pollution and improve worker safety.

Projects

Development of equipment for hard stone underground exploitation (BRST985466)

     

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