The Exploration Drilling Program – Quality of the Sample

While there are numerous factors to be considered when looking at the type of drilling method for an exploration drilling program, ultimately it’s the quality of the samples that is the most important.

Geologists must have confidence in the accuracy of the sample and way that up against the time and cost involved. When that is done it’s easy to see why RC Drilling with its recent technical advances has become the preferred method for exploration drilling.

While diamond drilling will continue to be used were helicopter is the only means of getting a lightweight rig to the site, RC drilling continues to expand into geographic areas and to depths that were traditionally done by coring.

Time Factor – The Speed of Drilling Holes

In the exploration game time is money. Mining companies want their drilling programs done quickly and accurately. RC Drilling can be three times as productive as core drilling and a 250-300m hole can be drilled in a single 12hr shift depending on rock formations, the overall drilling conditions and the skill of the driller.

Aircore drilling in unconsolidated ground is a fast way to get accurate samples and is becoming more preferred than RAB as the means for initial exploration drilling.

With the air capacity of modern RC rigs drilling with hammer can be done below the water table to depths of 500m and still keep the sample dry, which is a key factor in handling and analysing the sample.

Show Me the Money – Accurate & Affordable Results

Geological exploration is a risky business. With investors looking for a return and mining companies needing to keep the market updated with their drilling results, there is always pressure to get drilling programs completed and results analysed.

RC drilling enables mining companies to get fast and accurate results enabling junior mining companies to raise further capital to continue drilling. In a lot of cases the initial RC holes will be used as a precollar for diamond drilling to greater depths.

In Pit Grade Control

RC drilling (In pit grade control) is used in open cut mines to define ore grades and also provide knowledge for mine planning and blasting. This information is critical to reduce waste rock (dilution) in concentrator feed as dilution can vary from 5-40%. RC grade control is the most cost effective and accurate way to define boundaries between waste rock and ore bodies.

RC Drilling is now even being utilised for underground mining operations to assist with grade control.

Multifunctional Survey Tools

Although drilling techniques and equipment have made tremendous advances it is still not possible to drill an exact straight hole. The exact path of the drill hole is essential for economical evaluation of mineralized rock formation, geological mapping, and geophysical downhole surveys.

Multifunctional Survey Tools are electronic instruments that measure the inclination and direction of a drill hole, along with magnetic and gravity field components. They are multifunctional tools with single and multi-shot capabilities.

When utilising high quality RC drilling equipment and consumables made out of 316 type stainless steel, factors like magnetism play less of an effect on down the hole surveys, giving better results for Geologists.

Spiral Stabiliser Subs

Spiral stabiliser subs improve the accuracy of deep RC holes & are a valuable addition to any RC drill string.

“While drilling 360m deep RC precollars we experienced problems with deviation of more than 5 degrees at the end of the hole. The Harlsan spiral stabilizer sub dramatically improved accuracy, enabling us to keep the holes within 1-2 degrees”
(Kennedy Drilling Australia).

The exact path of the drill hole is essential for economical evaluation of mineralized rock formation. Australian based RC manufacturers like Harlsan are producing some of the highest quality spiral stabiliser subs currently on the market.