Modern Quarrying July-August 2016

QUARRYING SERVICES

once’, mines can reap the financial and operational rewards of thorough plan- ning and measurement. www.aelminingservices.com

type of explosives that each unique hole requires or if the hole needs slight drilling adjustments. A well planned and successfully exe- cuted blast has several benefits. It can deliver operation-specific fragmentation levels that result in improved productiv- ity and remove the need for secondary blasts. This is because the correct level of fragmentation reduces the levels of loading and hauling, and optimises plant operations by making processes such as crushing more efficient. A successful blast also improves safety because it reduces the amount of flyrock, while its environmental benefits include meeting airblast and ground vibration limits. While the information that surveying provides is crucial, it is what operations do with it that really counts. Through thor- ough measurement and analysis, opera- tions can take corrective action to reduce downtime and unnecessary secondary blasts. By ‘measuring twice and blasting

example, operations can check these factors as well as calculate drilling devi- ation from the design at fixed intervals. Boretrak comprises a control display unit (CDU) logger, a rack of rods, a probe and a gyroscope or gravity sensors. All of this equipment feeds into an interface which can represent the status of a drill- hole, removing all guesswork from blast planning. Other equipment which is crucial in checking drillholes is borehole calli- per logs, which comprise a tripod with a probe on a pulley which is lowered into the hole. The probe is equipped with arms that can open out on command to mea- sure the average diameter and average variance of the drillhole. In an ideal world, the hole should resemble a cylindrical tube – with smooth walls and an equal diameter through- out. In reality, however, there are often deviations. By measuring these devi- ations with the probe, blasting teams can determine the optimal amount and

Manare Mokoatlo, mining engineer, AEL Mining Services, presented the paper entitled The Importance of Blasthole Monitoring at the recent IQSA conference in Cape Town.

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MODERN QUARRYING July - August 2016