posted by Rod McCoremick, Blog author, Fordia Powered by Epiroc
June 4, 2018
As all good diamond drillers know, core recovery is what it is all about. Drillers and their supervisors are always looking for ways to get more core in the box quickly and at the lowest cost. The main goal of mineral exploration is to get a representative sample of mineral or ore deposits from the area being explored. Knowing all this, once you get the core, you need to handle it properly and make sure the geologists can get the information they need.
The geologists involved need to extract data and information in order to do their job, and they cannot do this if the core is not labelled, handled and presented properly. Diamond drillers can keep the geologists happy by following a few simple procedures.
Keep it clean
When the core barrel or inner tube is removed from the bore hole, make sure you do not dirty it with grease when handling.
Remove it properly
Remove the core carefully and make sure to remove the sample in sequence. Dip it in clean water to wash then pack it into the core box in sequence. Core should read like a book from left to right, top to bottom. Top of the hole is top left in the box and end of hole is bottom right.
Pack it properly
You should fit the pieces of core sample together and measure the length of the core run. This then gets recorded in your drilling report. If there is core left in the hole, this gets recorded and is a core loss. The next drill run should cancel this out with a gain of core. If there has been any washing away or core or cavities, this needs to be recorded as core losses as well.
Record it properly
Core boxes need to be sturdy and waterproof so the core samples are protected. Core boxes should be labelled with the name of the site, the bore hole number, core box number, depth at the top and bottom of the core, and the drilling contractor name. If any samples were removed, or if there have been any core losses or samples, indicate this by putting wooden blocks that fit between the slats. Usually, you should put a wooden block with the depth indicated on it after every run. Core recovery is measured in percentage - the amount of core in the box vs. the actual depth of the hole. Hole depth should be easy to determine – count the drill rods and the core barrels.
Keep it safe
When you transport by truck, make sure the samples are protected and strapped down in the truck to reduce the chance of damage.
No helper or driller team wants to have to do a core puzzle. If care is not taken in the handling, a core box could be dropped. It won’t be fun trying to file it into the box again!
For more information about core recovery read our blog, 5 Tips to Improve Core Recovery or Preventing Core Washout
So much goes into getting good core recovery, it is a hell of a waste if something happens to the core, it gets damaged, or the geologists cannot get the information they need from it. We want to help you get the best drilling performance possible and that includes making sure your core is handled and recorded properly. Contact us if you have any questions or need advice.