Drills have different mining functions, from providing geologists with different samples of soil for analysis, to facilitating the extraction of precious minerals that would otherwise be difficult to reach.
How many methods of drilling are there?
As the mining industry advances and more excavating opportunities present themselves, the number of drilling methods increases. Whether it is for exploration, production, land-clearing or geotechnical purposes, there are drilling methods that serve every mining purpose.
Auger drilling is the simplest form of drilling. It involves the manual rotation of a helical screw into the ground, usually by two people although auger drills can also be mounted to small vehicles. Once the auger drill is deep enough, the earth is lifted up by the blade of the screw. This kind of drill specialises as an initial geochemical reconnaissance technique, which means it is used in softer soil to find the optimal place to mount a larger drill.
Rotary Air Blasting
Rotary air blasting is the most common shallow drilling method, in which a piston-driven hammer-like object drives the drill bit into the rock, fragmenting the hard surface into chips that are then lifted to the surface via compressed air. This method is ideal for drilling multiple holes in a short period of time, and less ideal for producing geological samples because the airblasting process can compromise the quality of the rock.
Aircore drilling involves a three-bladed drill bit with a hollow drill rod in order to penetrate loose soil and rock fragments. After the drilling is complete, compressed air is blasted through the drill rod in order to bring the cuttings to the surface. While this method is typically slower than rotary air blasting, it is more precise, meaning that the samples collected are less prone to contamination.
Reverse Circulation Drilling
Reverse circulation is a popular method for mining exploration that shares similarities with both rotary air blasting and aircore drilling. The same piston-driven hammer is used to drive the drill bit into the rock, however the larger rigs and machinery associated with reverse circulation drilling allow for the drill bit to be driven even further into the earth. Compressed air is then used to drive the fragmented earth to the surface. This method is ideal for geological exploration, as it produces contaminant-free samples and requires less handling, resulting in cost reduction and faster turnaround times.
Diamond Core Drilling
Diamond core drilling is the most expensive drilling method, as it involves using a drill bit that has been fortified with industrial diamonds attached to hollow drill rods to extract a continuous cylinder of rock from several kilometres below the earth. However, this method also produces the most accurate rock samples as the entire core of a mineral can be brought to the surface as opposed to mere fragments, making it ideal for procuring records on their strength, composition, porosity etc.
Blast Hole Drilling
Blast hole drilling is a method of drilling used to clear out large amounts of the earth and make the minerals below easier to access. It involves the drilling of holes into the earth. Explosive charges are then placed into each hole and detonated. After the explosion, the broken material is cleared and, if the drilling and blasting occurred underground, the tunnels created by the explosion are fortified to allow for safe human entry. Alternatively to explosives, gas pressure blasting pyrotechnics can also be used to displace the rock for excavation.
How much does a mining drill cost?
Typically, the price of operating a mining drill in Australia is approximately $1 per tonne of extracted material. As a result, the cost of a mining drill tends to scale into the tens of millions to the hundreds of millions due to the extravagant effort, resources and time that go into its operation, as well as the large amount of earth that gets displaced during its operation. However, there are many different measures that can be taken to significantly reduce mining costs. Pre-planning the drilling procedure so that it is executed as accurately as possible saves time and reduces the risk of costly interruptions, as does selecting the correct kind of drill for the job.
What types of drills are there?
As mining operations have become more sophisticated with the passage of time, new kinds of drill rigs have emerged to meet the demand of mining companies. Nowadays, various mining drills utilise different features to complete different kinds of mining tasks while being both manually operated and remotely automated. These rigs are available in various shapes and sizes, functioning in confined spaces as well as large quarries. As a result, there is a wide array of surface mining drill rigs available for many different kinds of operations.
Surface Top Hammer Drill Rigs
Top hammer drill rigs are equipped with powerful hydraulic drills as well as a hammer. The hammer strikes the drill rod, creating a percussive force that travels to the drill bit and displaces the rocks, leaving them susceptible to pressurized air or water. This kind of rig is renowned for its reliability in the toughest conditions, as well as its fuel economy and low operating costs. When partnered with the drill and blast method, this drill rig makes the excavation process efficient.
Surface Down-The-Hole Drill Rigs
The purpose of a down-the-hole drill rig is to drill large-diameter holes downwards, consisting of a jackhammer screwed to the bottom of a drill string. Like other drill rigs, the DTH breaks up the rock so it can be flushed out using air or water. This particular rig specialises in high-capacity rock drilling in quarries, opencast mines and rock excavation projects.
Dimensional Stone Drill Rigs
The dimensional stone drill rig has a more esoteric function that its other drill rig counterparts, in that its purpose is to drill precise holes in the ground in order to excavate for natural rock such as granite, limestone, marble or sandstone, so that it can be extracted and fashioned into blocks for construction. This rig is designed to drill precise holes safely and efficiently.
Rotary Blasthole Drill Rigs
Rotary blasthole drill rigs drill into the earth in order to create holes that can then be filled with explosives that clear large sections of rock for subsequent mining operations. Rotary blasthole drill rigs are renowned for their precision and depth, boosting productivity by making the process of blast hole drilling easier and more cost-effective. In addition to the range of surface mining drill rigs, there is also a wide variety of underground drill rigs available that meet the stricter safety and logistical requirements that underground mining entails.
Development Drill Rigs
Development drill rigs are mining vehicles that drill holes into the surface of a coalbed that explosives can be inserted into and detonated. These vehicles are modular, meaning they can be disassembled, transported and reassembled with ease. They can also be used for small-scale mine development and large-scale tunneling.
Tunneling jumbos are versatile modular electro-hydraulic excavation machines that can be used for both fast face drilling and mechanised longhole drilling and bolting. Jumbos operate as stationary work stations that an operator safely conducts mining operations from, consisting of one, two or three drock drill carriages, ensuring high productivity and reliability. They are used specifically for underground drilling and blasting jobs, however they can also be used in tunneling if the hardness of the surrounding rocks prevents the use of tunneling machines.
Top Hammer Longhole Drill Rigs
Top hammer longhole drill rigs are ideal for mining operations where the highest priority is ore recovery and minimising the contamination of rock fragments. Like its surface mining counterpart, this drill contains a piston-powered hammer that impacts the drill in order to shatter the rock before using compressed air to disperse the debris.
Rock Support Drill Rigs
Rock support drill rigs are engineered to install rock bolts which stabilise the rock face by transferring the load from an unstable mine exterior to the confined (and therefore stronger) interior of the rock mass. These rigs ensure the safety of underground drilling and blasting by securing the rock mass and stopping it from caving in.
In-The-Hole Longhole Drill Rigs
In-The-Hole longhole drill rigs are mounted on tracked or articulated carriers in order to be transported into a mine where it uses extension rods to drill holes and extract ore with the aid of an ITH hammer similar to that of the top hammer drill rig. Additionally, the ITH longhole drill rig also flushes out debris with pressurised water. These rigs are designed with mobility and accuracy in mind.
Low Profile Drill Rigs
Low profile drill rigs are mining drills that are built at a low elevation so they can enter more confined spaces that regular drills cannot due to their size. They are ideal for development, rock support and production drilling in tabular ore bodies such as platinum and chrome mines. These drills come in single and double boom variants, meaning that their specialisation for spaces with low heights does not sacrifice their ability to reach higher spaces if the need be.
Narrow Vein Drill Rigs
Narrow vein drill rigs are similar to low profile drill rigs, in that they are designed to venture into and extract ore from confined spaces. However narrow vein drill rigs are designed less to accommodate height challenges and more for the general navigation of geologically complex mine spaces with widths less than 3-6m. Narrow vein deposits contain large amounts of gold, tin, copper, lead and zinc that narrow vein drill rigs allow us to access and utilise.
Secondary Breaking Drill Rigs
Secondary breaking drill rigs are compact support drills that increase drawpoint availability in narrow vein mines and back caving operations by breaking oversized boulders that are causing blockages. These drills eliminate the need for explosives, which in turn eliminates the need for time consuming ventilation and evacuation measures while promoting a safer mining environment. These small drill rigs are available in the form of jumbos, longhole rigs and drill-charge and drill-split breaking units.
Drills make up a significant part of all mining operations. However, there is a plethora of equipment needed in order to optimise any mining operation. Contact us so we can provide you with the best equipment advice, no matter what your next mining job entails.