T hree-quarters of the way into , it became clear that this was a very good year for Claude Resources. The Saskatoon-based gold miner had increased its year-to-date gold production by 63 per cent over , thanks in part to a successful implementation of the Alimak mining method at its Seabee gold mine in Saskatchewan. Raise climbing, widely known as the Alimak mining method after the company that introduced it, is a variation on longhole stoping developed for narrow-veined, tabular ore bodies. Successful users of the technique have found that it accelerates their path to production by centring development work within the ore body. In regular open stoping, overcuts and undercuts provide access to the ore along strike.
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A true innovation in underground mining, the Alimak Mining Method provides high safety standards while increasing productivity, adding greater flexibility and reducing overall mining costs. Manroc Developments Inc.
This type of mining is best suited for tabular narrow vein orebodies, with enough dip to allow for gravity-led ore flow. Experience has shown that raises from 75 to metres length are the most economical. Results are even more favourable when the ore boundaries can be interpolated between adjacent raises, allowing drill design to be adjusted as required.
Bottom Sill : These drifts are driven from the shaft or established mining areas to the new ore zone. The drifts are commonly sized to accommodate the large scooptrams used for production mucking. Drawpoints and Climber Nest: Drawpoints can be driven from either footwall or hangingwall, depending on how the ore zone is accessed. The climber nests are always in the hangingwall. The climbers require about 4. Top Sill Access : These drifts are also driven from the shaft or existing development but are not always required for the Alimak Mining Method when advanced blasting systems are implemented.
Raise Development : Raises must be large enough to accommodate a 2. Primary ground support is installed with each round taken. Hangingwall Support : Where required, the stope hangingwall is supported with deformed strand resin-grouted cable bolts at a regular pattern along the length of the raise.
This is quite effective as a means to minimize dilution, as the raise is centred in the stope and therefore the support is installed where it is needed most.
Drilling : Drill holes extend to just less than half way to the next raise and are oriented slightly down from horizontal. The down dip helps the toes break to the stope wall. The blasts are timed to slash down, with the footwall holes often the last to fire. It is safest to take a few rings per blast, so that miss-holes or other blasting problems are accessible for correction.
Mucking Swell : Normally, most of the ore remains in the stope while blasting, as it supports the walls during successive blasts. Some of the ore is mucked out in order to provide a void for the next blast. The broken ore often compacts slightly, resulting an effective swell of about one third its unbroken volume. Final Mucking : Once blasting is complete, the stope is mucked clean and often backfilled. Narrow vein orebodies tend to have lower tonnages, making them more sensitive to excess development costs.
There is significantly less waste development with raise mining than with regular open stoping for the following reasons:. Cablebolts are often installed along the hangingwall, in the centre of the stope where they are most effective. The stopes are mined in a shrinkage fashion, with added support gained from the broken ore remaining in place.
The geology is exposed down the entire dip length of the stope on both sides of the raise. The ore contacts can be both extrapolated from across the raise and interpolated between raises. Stopes can be as narrow as one meter, or even less in ideal circumstances. With better ground control, larger stopes can be taken. Fewer, larger stopes can be taken quicker because there are fewer cycles, i. With less development, faster ore access, better ground control, and faster overall mining, it is easy to see how raise mining will cost less than regular open stoping.
Over the years, we have been perfecting a method which enables us to blast a stope in its entirety. For a mass blast, the raise is typically no longer than meters long and thin enough that the swell fits in the same volume as the raise and undercut combined, as this is used as the void.
Manroc has been very successful at mining orebodies with widths as narrow as 1 metre, while maintaining a very desirable dilution, which is in most cases much better than the dilution obtained by conventionally drilled stopes. Less development, specifically less waste development, offers substantial cost savings.
The stope being blasted all at once means it will take less time to get the ore on the ground. Additionally, there will be only the one blast clearance as opposed to several throughout the blasting of the stope.
Moving forward, there have been significant advancements in wireless blasting technologies that allow for multiple blasts within a single, fully-loaded stope.
This technology eliminates the limitations for lower-access only stopes, yielding even more costs savings. Our full team of experienced Raise Miners, Supervisors and Managers, ensure your project is carried out meticulously, while meeting all budget and time constraints.
Contact Us. Alimak Production Mining. The Alimak Mining Method Orebody Requirements This type of mining is best suited for tabular narrow vein orebodies, with enough dip to allow for gravity-led ore flow.
Raise Climber Mining Method Details The raise climber mining method will generally be comprised of the following steps:. Lateral Development Bottom Sill : These drifts are driven from the shaft or established mining areas to the new ore zone. Raise Excavation Raise Development : Raises must be large enough to accommodate a 2. Production Drilling : Drill holes extend to just less than half way to the next raise and are oriented slightly down from horizontal. Advantages to Alimak Raise Mining Less Development Narrow vein orebodies tend to have lower tonnages, making them more sensitive to excess development costs.
A ramp is not required and, in many cases, neither is the upper sill, muck pass or ventilation raise of a regular stoping system. The change in geometry and improvement in ground support allows stope heights in the order of 75 to metres, eliminating many sub-levels and their associated development. The sub-horizontal production drill hole direction allows the use of the undercut as a slot and because of the increased stope height, there will be significantly fewer of these than there would be slots required for regular open stoping in the same area.
Less Dilution Cablebolts are often installed along the hangingwall, in the centre of the stope where they are most effective. More Selectivity The geology is exposed down the entire dip length of the stope on both sides of the raise. Faster Overall Extraction With better ground control, larger stopes can be taken.
Lower costs With less development, faster ore access, better ground control, and faster overall mining, it is easy to see how raise mining will cost less than regular open stoping.
Mass Blasting Over the years, we have been perfecting a method which enables us to blast a stope in its entirety. Our Commitment Manroc Developments Inc.
Alimak Production Mining