Quality excavation with instrumented and automated drilling equipment

Abstract

The quality concept is now much more widely understood than it used to be a decade ago. Then it was limited more to the production and technical finishing of a certain machine or piece of equipment. Today quality management comprises all the chain from recognizing the user’s needs, designing, manufacturing and delivering the equipment up to task planning and end use. Excavation which is done with an awareness of quality and safety is also economic and effective.

Drill holes which are correctly positioned, have the correct alignment and proper length are the basis of good-quality blasting operations. Here the benefits of instrumentation and automation have been proved during recent years. Profitability analyses of controlled contour tunnel excavation and surface blasting as well as underground stoping have proved that the profits gained by precise drilling are very significant. The instrumentation of drilling equipment is accordingly giving a good return on investment. In practice it has been shown that in a road tunnel drilled by a computerized drilling jumbo, the saving in concrete lining was 0.26 million USD for each km of tunnel. In addition, the pull-out was increased by 10%. In an open pit mine, with 6 Mt/y output, an increase of drilling accuracy was found to improve the economy by 0.35 million USD annually, due alone to reduced drilling and blasting costs.

In rock excavation using the drill and blast method the quality concept means optimized blasting, minimum damage of the surrounding rock, maintaining the required contour tolerances and correct positioning of the tunnels, ramps and other underground caverns. From the ore excavation point of view it means low dilution and minimum ore losses. In bench blasting the marks of quality are, for example, correct fragmentation and control of level, casting and toes.

The fast development of information technology and availability of electronic components for difficult conditions have made the instrumentation of drilling equipment a standard tool for today’s miners and contractors. Drilling instrumentation comprises a full series of equipment starting from gravity based angle indicators and ending at modern computer controlled units. In addition to angle measuring, modern instruments perform many other tasks, such as giving the hole direction, measuring the hole depth, recording penetration rates, collecting operation data and drilling parameters as well as collecting production rates. The computer-controlled drilling jumbos perform pre-programmed drilling patterns. Today’s automated long hole drilling units drill holes up to programmed depths, taking care of both coupling and uncoupling of the rod string and control of the drilling itself.

Quality awareness is increasing the use of instrumentation and automation. The level of instrumentation and automation is chosen in accordance with the operator’s needs in order to optimize the return on investment in each particular case. Future enlargement possibilities will include rock identification based on the drilling parameters. Drilling of total fans independently will be the next step in long hole instrumentation and automation. Advanced positioning and navigation systems are in active use in both underground and surface applications. The drilling equipment will be increasingly integrated into the mine planning and control systems with the overall goal of a more optimized excavation and total mining process.