secondary drilling

secondary drilling

[′sek·ən‚der·ē ′dril·iŋ]
(mining engineering)
The process of drilling the so-called popholes for the purpose of breaking the larger masses of rock thrown down by the primary blast.
References in periodicals archive ?
LA Aluminum was able to cast-in steel nut inserts that eliminated the secondary drilling and tapping operation.
Outside of new and secondary drilling projects, EPL will spend about $61.2 million on intervention work at existing wells and on water flooding, a technique that injects hot water into a reservoir to reduce oil viscosity allowing it to flow more easily toward a production well.
Minor oil shows were observed in the Birkhead Formation, a secondary drilling target.
According to Haasbroek, even with the tighter pattern, many of the boulders remain intact and require secondary drilling. Also, because of persistent groundwater flows in the active mining areas, holes occasionally collapse and consequently, redrilling requirements can vary from around 9% during the dry season to as much as 40% during the rainy season.
And a secondary drilling operation is needed to open vacuum channels.
Until 1991 or 1992, Lincoln Brass turned out valves and fittings primarily on screw machines and a battery of other machines for secondary drilling, milling, threading, finishing, and so on.
Ozdemir explained that the circular-shaped opening created by TBMs is usually not suitable for mine operations, but this problem can be solved by backfilling behind the machine to create a flat floor, secondary drilling and blasting after excavation to create a more suitable cross-section, or by mounting a set of boom cutters on the sides of the TBM to create a horshoe-shaped entry.
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