native copper page 9 of jorc report, page-11

Buddy,

Most RC rigs have a cyclone sample collector that fills a 50kg sample bag as the rig drills one metre. The only hands on required is to remove the full bag and relace it with an empty one.

Over the years many people have tried different ways to get an accurate representitive sample from a 50kg plastic bag of sample.
Some of the popular methods were to push a 50mm plastic tube down into the sample bag from top to bottom. This was debated long and hard as not being accurate enough.

Most agree a mechanical splitter is the best option. Some use stand alone splitters and hand dump the 50kg bag onto the top of the splitter from where it falls through the splitter and quite accurately divides in a 1 to 10 ratio. One side feeds to a small 5kg sample bag and the remainder feeds into a clean plastic bag. Both the large and small bags are attached to the splitter and are removed once filled. The large bag is placed to one side and left for possible future use. The smaller bag is removed, tied off and sent to the lab.
On some rigs the splitter is mounted directly underneath the cyclone and does not require and hands on at all. The bags are moved in the same manner as the stand alone version.
In a perfect world the smaller bags of usually about 2.5 kilo go the lab unopened for assay and the onsite geo will use the large bag to collect some sample for washing and logging.
Once in the lab the entire 2.5 kg should be dumped into the primary crusher. This would be then split again to get a smaller sample for further crushin/pulverising before assay.
My point is that once you hand pick at a sample in the lab either to add back later or to classify you have compromised you accuracy.

Sampling and splitting on RC rigs by mechanical means has been designed to stop eyeball selection and eliminate bias.


There is a very high cost in getting a 2.5kg sample to the the lab. The numbers that come back need to consistantly accurate or as many people find out when you get down the face the grade going to mill does not match JORC announcements.

Driller