Top Grades: Why Preliminary Grade Control Drilling Is Vital For A Profitable Mine

Posted on: 28 March 2017

Anybody who works in the mining industry knows how vital it is to fully assess a mine before drilling in earnest begins, and one of the most important aspects of preparing a mine for drilling is by conducting preliminary, grade control drilling. 

What is grade control drilling?

The aim of grade control drilling is to take samples of the ore contained within a prospective mine, which are thoroughly analysed by a mining geologist using various pieces of ore grading equipment. There are two main reasons to take samples in this way:

  • Ore grading: Grade control drilling is essential for discovering the grade and quality of the ore contained within a mine before full-scale drilling begins. Mining geologists can make estimates using certain varieties of ground-scanning technologies, but physical samples are required for accurately assessing the quality of a mine's ore.
  • Grade variability: The quality of the ore contained within a mine is almost never constant across the entirety of an ore vein, and taking surface samples only tells you the grade of the ores at or near surface level. The more comprehensive samples made available by grade control drilling allow geologists to assess how much the ore's grade fluctuates in different parts of the vein, a particularly useful quality when dealing with particularly deep or large ore veins.

Why is grade control drilling essential for creating a profitable mine?

Grade control drilling can be a pretty expensive task to undertake, especially when dealing with large samples taken from large-scale, open-cast mines. However, this is a price well worth paying, as grade control drilling helps improve your mine's profitability in a number of ways:

  • Increased productivity: Because grade control drilling takes deep, extensive ore samples, it vastly reduces the need for miners to stop drilling to allow geologists to reassess ore grades as they change. Miners can instead anticipate changes in ore grades, and preemptively modify their drilling and cutting techniques to suit the newly-encountered grade, significantly reducing drilling downtime.
  • Milling efficiency: For maximum efficiency, the grade of the ore fed into your ore milling equipment should be kept constant -- if a mill is faced with ore of a particularly high grade and quality, much of the valuable ore can be lost as waste and tailings, as the mill is designed to break down less valuable ores with lower metal contents. Grade control drilling informs miners of when and where they will reach particularly high-grade ores, allowing them to modify milling processes and mix the high-grade ore with ores of lower quality to maximise milling efficiency and profitability.
  • Economic viability: No ore vein goes on forever, and at some point the quality of the ore within a vein will degrade to the point where it is no longer profitable to mine. Grade control drilling informs miners and mine operators of this 'cut-off point' well in advance, preventing unnecessary exploratory drilling into unprofitable areas.

Contact a company like Rock On Ground for more information on grade control drilling and its applications.