IM 2020 July/August 20 | Page 26

EXPLOSIVES AND BLASTING Safety benefits surfacing The success of WebGen in underground mining has led to an increased adoption of the technology in surface mining, according to Orica, with the company having completed successful surface blasts using the wireless system around the world. Its fully wireless capability presents an opportunity to overcome one of the industry’s most persistent limitations – a physical or wired connection to each primer in a blast, Mooney says. “Wired systems have a large physical presence and are susceptible to damage at every point Hexagon’s holistic approach to drill and blast incorporates solutions to improve yield, fragmentation and dilution. Incorporating technology ranging from blast design and high-precision drilling to post-blast analysis and optimisation, the approach empowers mines to take back the purchasing power on their bulk commodity explosives, according to the company. “A well-designed blast pattern and the effective execution of the blast plan using high-precision drills are an important part of an effective drill and blast operation,” the company said. Hexagon’s MinePlan portfolio features HxGN MinePlan Blast, a comprehensive software utility for drill and blast reconciliation. “Rather than risking high-wall stability problems, uneven blasting, poor fragmentation, unnecessarily high energy costs, and dangerous working conditions, MinePlan Blast incorporates charge and blast design templates that are based on sound engineering principles and methods proven in mines worldwide,” the company said. The MineOperate portfolio, meanwhile, features machine guidance for drills (as well as dozers and loading equipment), with the OP Pro HP solution ensuring drilling is performed to the right position and elevation. “It provides accuracy and instantaneous feedback, meaning improved loading times across the fleet, less mis-routed material, fewer hours of rework on ramps, roads, and benches, and fewer over- and under-drilled holes,” the company said. “It is proven to improve both the quality of material produced and fragmentation with precise drill hole placement and depth.” OP Pro HP integrates with Hexagon’s operational management hub, MineEnterprise, for a single source of reporting and support, the company says. Then there is fragmentation data to consider. Here, Blast Movement Technology (BMT) is an integral part of Hexagon’s drill and blast solutions, providing accurate ore location information for open-pit mines. BMT, via sensors and software, provides blast information used to recover a mine’s resources. It ensures that, post-blast, the mine retains a full vision of where its orebody moved to. Hexagon’s Split Engineering systems are used to automatically monitor different areas and processes along the operation, such as in shovels, excavators, loaders, haul trucks, crushers, conveyor belts, mill feed and screen decks, providing a unified approach to fragmentation management, Hexagon says. Monitoring trends in size at each point in the comminution circuit enables operational adjustments in real time, while alarms can be created for oversize events, reducing the downtime from inefficiencies caused by blockages and broken screen decks. HxGN MinePlan Blast is a comprehensive software utility for drill and blast reconciliation, Hexagon says along the connecting line,” he explained. “The potential for misfires due to downline damage has commonly led to the application of redundant initiation systems and can impede the loading of adjacent blast patterns due to flyrock damage.” Like other surface wireless systems, WebGen for surface, removes priming, loading, stemming and tie-in activities, in addition to reducing the time employees spend on the bench. With increased flexibility in pit planning and blasted inventory, mine operations enabled by WebGen can also prime and load larger single blasts as well as eliminate firing window variability, according to Mooney. The lack of wires can also eradicate potential hazards caused by weather events. “Due to the conductive characteristics of wires, lightning storms pose one of the primary challenges in surface mining around the world,” Mooney said. Typically, in the event of approaching lightning storms, a mining exclusion zone is placed around the loaded blast or, in some cases, the blast is cut short and immediately fired. This does not happen with WebGen blasts. “As WebGen does not require downlines and surface wires, lightning production costs and the risk of unplanned initiation of loaded blast holes can be eliminated, while production constraints from exclusion zones are completely removed.” At a depth of 3 m below the collar of a blast hole, WebGen units are protected from the hazards of lightning, according to Mooney. “The absence of lead wires in this scenario prevents current transfer,” he said. “Additionally, the magnetic field induced by lightning is not able to activate a WebGen unit to fire.” Mooney is confident some of these characteristics will lead to new, WebGen-enabled blasting techniques surfacing. “For example, with WebGen, it is now possible to allow traffic to safely flow over a loaded blast in surface operations, providing full flexibility in pit access and availability as well as significantly improving vertical advance and efficiency across the load and haul cycle,” Mooney said. “This can dramatically optimise sequencing in surface coal strip mining and drop cuts in surface metal mining.” Another example of “surface mining reimagined with WebGen” is multi-stratum blasting, Mooney says. “This method involves drilling and loading multiple benches in a single pass, providing stemming decks in between the loaded benches,” he said. “A single deck is fired and dug before firing the next deck, reducing cycle times and bench preparation costs, while increasing the overall rate of vertical advance, fleet utilisation and safety associated with operating around highwalls.” IM 24 International Mining | JULY/AUGUST 2020