| Modern
Irish Stone Production:
The fifteen-frame saws used to
process the limestone provide the Irish producers with both the cutting capacity to fulfil
any order and flexibility in the range of slab thicknesses available. Numerous circular
saws, wire saws and monoblades give a high capacity for the production of finished ashlar
and cladding. Mechanical processing capacity is complemented in all cases by the
experience and expertise of a workforce of skilled stonemasons and stonecutters. Eleven
polishing and dressing lines, operating to the high standards required by ISO 9000, ensure
the quality of finished Irish Blue Limestone cladding and ashlar.
The Irish Blue Limestone output from Irish quarries currently
amounts to 35,000 cubic metres per year.
The successful blending of traditional masonry skills and
the latest high technology cutting and processing equipment is the hallmark of the Irish
Blue Limestone producers. All the quarries are based on the massive crinoidal limestones.
The sequences are flat lying with few partings and this makes them very suitable for
mechanised extraction. Recovery of solid blocks about one metre thick is routine and the
sparse jointing enables the beds to be cut to the optimum width and breadth for
processing.
The
quality control in all the quarries begins at the production face. Even though there may
be a long history of extraction at any level within the quarry, the face is re-examined
prior to each phase of working to identify the optimum position for the diamond wire cuts
that extract the blocks. In order to place the wire in the correct location, two precisely
orientated boreholes are drilled to intersect at the back lower corner of the block.
The diamond segmented wire is fed through the holes and
joined before being attached to the drive mechanism. By carefully balancing wire tension,
wire speed and water flush, accurate cut faces can be created that simplify the quality
control during subsequent processing. Once the large block is freed from the face by the
wire cutting, it is toppled onto the quarry floor and split by traditional plug and
feather techniques. A major problem with diamond wire cutting is freeing the rear face of
the block. This has traditionally been released by drilling and splitting with plug and
feathers. The Irish Producers have revolutionised the process by using chain saws to make
the blind cut across the back of the block.
Consistent
spacing of the major stylolites; on which the blocks are normally split in all the
quarries; has enabled another Irish company to implement the use of a diamond-tipped
circular saw. The almost flat lying succession is ideal for the operation of this
equipment and careful alignment of the cuts give efficient production of regular
sawn-all-round blocks.
Refinements on the basic extraction techniques have been
accompanied by the introduction of mechanised drilling for cleaning and trimming the faces
and the use of large loading shovels to handle the blocks within the quarry.
Modernisation of the quarrying has been accompanied by a
programme of upgrading the processing capability within the industry. Overhead gantry
cranes and mechanised bogies enable more efficient feeding of the blocks into the frame
saws and the installation of increasingly powerful saws has further improved the accuracy
and quality of the finished panels. |
