Over the past few years, Long hole open stoping is being increasingly used in Underground mines – especially in metal mines. Long hole open stoping is a form of sub-level open stoping which involves excavating ore in a series of horizontal or sub-horizontal levels, known as “stopes.”
In long-hole open stoping, a series of vertical or inclined holes are drilled from the top of the stope to the bottom. These holes are typically drilled using a drilling Long Hole Drill Rig. Mines typically use the term Production Drilling to refer to all work performed on the stope. They use the term Development Drilling (using Jumbos) to create the access drifts for the long hole drill These holes are drilled in a pattern of rings, with multiple holes per ring. These rings are spaced at regular intervals across the stope. Once the holes are drilled, mines typically blast a subset of rings that is linked to the stop, and the broken ore is removed using an LHD (also called a scoop or bogger) loading trucks or conveyors or dumping into an ore-pass.
Long-hole open stoping is used in both hard rock and soft rock mining operations and is ideal for mining steeply dipping ore bodies, where it is more challenging to drill parallel drifts and cross cuts.
How Long Hole Open Stoping provides advantages over other mining methods
Long-hole open stoping is becoming more popular for a number of reasons:
Long-hole open stoping provides greater mining flexibility
Long-hole open stoping allows for greater flexibility in the mining process, as the drill holes can be adjusted as the mining progresses. This allows for more efficient extraction of the ore, and can help to minimize the amount of waste rock that needs to be removed.
Long-hole open stoping requires less development
Long-hole open stoping requires less development work than other underground mining methods, such as cut-and-fill or block caving. This can result in significant cost savings, and can make it more economical to mine smaller or lower-grade ore bodies.
Long hole open stoping gives you higher production rates
Long-hole open stoping can increase production rates compared to other underground mining methods, as more ore can be extracted in a shorter period of time. This can help to improve the overall efficiency and profitability of a mining operation.
Long hole open stoping is more environmentally friendly
Long-hole open stoping method generates less waste rock, which results in less environmental impact and may help to reduce the overall cost of waste rock disposal. Additionally, by requiring less development, it can help to minimize the overall environmental footprint of a mining operation.
Significant advancements in long hole open stoping technology
The advancements in technology for drilling and blasting, allowed for more accurate and efficient drilling of the holes, which made it possible to increase the rate of mining and reduce the mining cost. Companies such as Epiroc, Sandvik, GHH, Boart Longyear and others have developed amazing equipment that get you more meters, accurately. Over the past few years, the re-drill rates have decreased significantly with the new models.
Long hole open stoping is the best mining method for steeply dipping ore bodies
Long-hole open stoping is particularly well-suited for mining steeply dipping ore bodies, where other traditional methods such as room-and-pillar or cut-and-fill are technically and economically challenging.
Things to keep in mind
Long Hole open stoping also allows for greater flexibility, as the drill holes can be adjusted as the mining progresses, allowing for more efficient ore extraction. That said, it is important to note that Long-hole open stoping may not be the best method for all mining operations and careful analysis and comparison with other method should be done before deciding on the method.
Keep in mind that you need higher skilled and experienced Drillers and Blasters on your crews. It is typically more dangerous and noisy compared to other methods. Also, as the method involves drilling a large number of holes and blasting, it creates large amount of fly rock and dust. You should also take into account dilution that may be caused by increased dilution if the drill and blast was not designed and executed correctly.
Mines use GroundHog’s Short Interval Control and Fleet Management system to effectively plan all the development and production activities that need to be performed every shift. GroundHog has standard deployment templates for Long Hole Open Stoping mines, Cut-and-fill mines, room-and-pillar mines and for block-caving operations. Mines using GroundHog typically see a 30% increase in tons-to-surface within 9 months of implementing the system.
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