How Are Granite Blocks Extracted from Quarries?
Granite is extracted from quarries worldwide, where immense blocks are quarried to be processed and shaped into various customised products such as slabs, paving stones, and curbstones…
Quarries, where this natural stone is sourced, are located in various regions around the globe, each offering unique geological characteristics and colours. The diversity of granite quarries allows for a wide range of applications in construction and design projects.
Different techniques are used to extract granite blocks depending on the quarry size, site geology, and available technologies. Two of the most commonly used methods are extraction by explosive and diamond wire sawing.
Extraction by Explosives:
This technique involves breaking the rock using explosives. Holes are drilled into the rock, explosives are placed inside, and the rock is fractured. The granite blocks are then separated from the parent rock using specialised cutting machines.
However, this method is increasingly less common due to strict health and safety regulations and environmental concerns associated with explosives.
The process starts with drilling holes into the rock mass around the area to be extracted. Once the holes are prepared, a specific expanding explosive is used to detach the rock. This helps prevent unwanted cracks and preserves the stone’s quality.
Diamond Wire Sawing Extraction:
This modern and efficient technique is used to extract large, high-quality granite blocks. It uses a steel cable coated with synthetic diamonds, which is wrapped around the rock and rotated at high speed to cut the stone into sections. The process includes quarry preparation, drilling anchor holes, installing the wire, and cutting the rock.
This method has environmental advantages compared to traditional extraction methods, as it does not use explosives and generates less waste.
Extraction by Splitting and Squaring:
This technique is used in addition to extract raw stone. Special tools such as splitters and squaring machines ensure precision and control over the cutting direction. It is effective for extracting large or irregularly shaped granite blocks.
Depending on the quarry and stone specifics, other mechanical or manual extraction methods may be used to obtain natural stone:
Mechanical Rock Removal:
When the rock is friable or has weak layers, mechanical rock removal can be employed. This method uses mechanical equipment such as excavators, loaders, or diggers to dislodge and remove granite blocks from the quarry. It is often used in open-pit quarries where the rock is easily accessible.
Manual Splitting:
This traditional method is used to extract small granite blocks or for specific applications such as stone carving. Steel wedges are placed into pre-drilled splitting holes in the rock. The wedges are then hammered in to break the rock and produce granite blocks of the desired size.
After extracting granite from the quarry, several processing and shaping steps are required to produce finished products ready for use in construction and interior and exterior design.
These steps include sawing and cutting the granite to the desired dimensions and products, surface treatment based on the chosen finish (bush-hammered, flamed, sandblasted…), and processing with specialised machines and artisanal techniques. This allows for a wide range of granite products, such as slabs, paving stones, steps, curbs, and even basins or fountains.