Drill and blast has come a long way in recent years driven by an industry-wide need to improve safety and efficiency.
With enhanced software, advanced drill equipment, innovative explosives and superior detonation techniques we’re now able to achieve highly precise blasts, reducing dilution and delivering higher quality ore – and more safely.
Advanced blast fragmentation modelling software such as 2D Bench has impacted the way we plan blast patterns and parameters by allowing us to analyse and simulate the detonation of the proposed design.
2D Bench provides a cost effective solution for blast design, blast analysis and tie-in plans for shotfirers. When 2D Bench is combined with survey software such as Surpac it provides additional benefits such as 3D modelling and allows blast designs to be created using topographic information and pit designs.
This predictive software allows us to further enhance our blast outcomes by enabling changes to design parameters prior to implementation in the field.
Improved software reporting functions allow for accurate information to be passed on to the shotfirer.
Advanced drill equipment
One of the most dramatic changes in drill and blast has been drill equipment.
Recent advances to the state-of-the-art hydraulic drills used today include the use of CANbus control – systems which provide onboard monitoring and maintenance assessment. Modern drills have GPS hole location capabilities, rock recognition software, auto collaring and in some cases, auto drilling. Remote drills are also becoming more accepted in some applications.
Rock recognition software enables drill hole information and rock recognition information from the software in the drills to be fed into the blast design program. The type and amount of explosive for each hole comes from the design program and can be sent directly to the GPS enabled MPU (mobile processing unit). As the MPU positions over each hole it is automatically loaded as per the design.
Another equipment innovation developed in recent years and now utilised around Australia is the ANFO Hopper.
The ANFO Hopper, developed by Action Drill & Blast during a drill and blast project at Rio Tinto’s Western Turner Syncline project in WA, is a device that fits onto a front end loader or interchangeable tool carrier. It safely carries 1.8 tonnes of ANFO explosive onto sloping and uneven ground where blasting services previously required manual handling of bulk explosive products. It greatly reduces the risk of injury from repetitive manual handling and carrying load whilst walking on rough ground.
Further, direct delivery into the blast hole from the hopper enables more accurate record keeping of explosives consumed on a hole-by-hole basis. The use of the hopper also reduces the number of personnel required for contour blasting and provides a quicker turn around in the delivery of product to the blast holes.
Factors such as blast hole diameter and bench height, rock hardness, the presence of water, ground conditions, supply and storage cost, proximity to vibration sensitive receivers, fragmentation requirements for crushing, muck pile profile to suit excavation methods and equipment need to be considered when selecting the types of explosives to be used for mining operations.
The bulk explosives products available today allow us to better match the rock type to the explosives to achieve a much more controlled and productive blast. The main bulk explosives available are ANFO, Heavy ANFO and Emulsion.
Non-electric and electronic detonators are the main types of detonators available on the market today. Non-electric detonators have the advantage of being more cost effective and readily available from numerous suppliers and are widely recognised as being easier to use in the field. The main disadvantages of non-electric detonators is the timing precision or scatter that occurs, which is not desirable for vibration controlled blasting, and the limited range of detonator timing delays available on the market, which reduces design flexibility.
Electronic detonators have the advantage of high precision timing which is ideal for vibration controlled blasting and achieving improved fragmentation on a site specific basis. When modifications are required to blast designs, electronic detonators eliminate concerns relating to detonator scatter. Electronic systems with two way communication can identify detonator misfires prior to initiation.
However, electronic detonators are typically higher cost and have additional training requirements for shotfirers given the potential for incorrect data entry and the lack of visual check other than the display on the programming unit.
Safety will continue to drive innovation
Improving safety will always be a key driver of innovation in drill and blast. A commitment to continuous improvement in this area by in-house teams and contractors alike will ensure we remain focused on reducing risks in the workplace and maximising productivity.