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The Value of Being Tool-Wise: How your choice of rock tools can make or break a contract

Friday, October 2nd, 2009

The cost of a modern drill rig for a large quarry or construction project can run into millions. First there is the capital cost; then the operating costs. If the rig achieves the production target in good time with low cost per unit output, then the value soars, a favorable ROI is achieved and everyone is happy. But when a million-dollar machine fails to deliver or masks further potential, personnel often try too hard to find solutions in the rig itself. The truth is that the route to higher productivity for any machine whose performance depends on cemented-carbide tipped tools is often found in the drilling-tool system.
Naturally, the choice of drill rig is extremely important, as are its operating settings in relation to the rock conditions. However, experience shows that paying closer attention to the tool system is almost always the solution to a productivity problem. In many instances, the results can be quite staggering.
In tunnels large and small
On a large and complex railway tunnel project in Norway – the entire length of which had to be pre-grouted – changing the drilling-tool system for one that could drill both ø48-mm blastholes and long ø54-mm grout holes gave multiple benefits. It boosted rig productivity by 20%, shortened the project time by about 100 days, improved safety, cut energy costs, reduced mucking, haulage and dumping costs and was kinder to the environment. In another large tunneling job, this time for a highway in South Korea, simply changing the drilling-tool system resulted in a sharp rise in productivity in difficult biotite-gneiss, as well as a 30% increase in rod life. This was achieved by eliminating rod breakage, raising the drilling speed, improving precision and reducing overbreak.
At the other end of the scale, in Iceland, an ingenious contractor used a quality ø279-mm pilot bit and a ø950-mm raise-boring head to bore directionally and back-ream a 255-meter micro-tunnel under a coastal golf course outside Reykjavik. He did so in record time without disrupting golfing activities, using seawater to flush out the cuttings of heavy-pebble laden lava. This tool-led solution, which was far superior to the expensive TBM solution proposed by competitors, generated even more value when the very same tools were later re-used on a second project elsewhere.
In quarries and highway projects
Throughout France and Germany, quarry managers are finding that a new ø60-mm tool system for drilling holes up to 152 mm in diameter with hydraulic tophammers at last offers a real alternative to air-hungry DTH hammers. Drilling straight, clean blastholes up to 25-meters deep nearly twice as fast as DTH hammers and using half the fuel, the new tool system also offers much greater flexibility in hole size in the ø90-152 mm range. Since it also uses lighter, more agile and more easily transportable drill rigs, it is highly suitable for drill-and-blast contractors.
On the DTH side, there are also new tool-led solutions that promise to bring down costs. For example, an advanced new grade of cemented-carbide has just been introduced for DTH bits. Tackling the widest range of rocks ever in an optimal manner, this new silver bullet only requires that the user chooses the best button-shape and bit-face design for the rock formation in question.
In terms of dimensional stone mining, where precision is mission-critical, the rock tools are even stronger determiners. In slate quarries in Spain, a new guide-bit fitted with cemented-carbide buttons instead of chisel-type inserts is meeting very high demands. Most crucially, it is maintaining hole-straightness in horizontal holes up to 25-meters long. Elsewhere, in much harder and more valuable stones, such as granite, the new button bit, drilling as straight as an arrow, needs far fewer re-grindings and offers much longer service-life than its predecessor.
Highway construction is another area where the choice of rock tools is often decisive. On a large motorway project in Croatia, which required huge volumes of rock to be excavated by drill-and-blast from a treacherous karst formation peppered with clay-filled joints, flushing-hole blockages were causing drill-strings to jam, and causing delays. However, thanks to swift customization of the drill-bits, the problem was quickly solved and production soared.
In municipal and small public works
Going down in size, a radically new 25-mm tool system for lightweight drill rigs is raising productivity and improving hole-straightness, quality and safety in urban drill-and-blast jobs throughout Scandinavia. Such examples of how the right choice of tool system adds value are countless and it thus worth remembering that, while your drill rig gets the most attention, it is the rock tools hiding down the hole that probably hold the key to better results and higher profits.
For further information visit: www.sandvik.com

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