Stop Go Back! (to basics)
- 5 minutes read - 906 wordsHi Everyone,
A post has been doing the rounds from an exploration manager looking for a fieldy and geologist and was having trouble finding anyone. Considering the current environment this is likely to be an ongoing issue.
I would love for a technical solution to this problem so lets run though a small set of considerations around commercial of the shelf sensing on a exploration drill rig. Imagery
Ensure that the light output is stable in both intensity and colour balance, LEDs are a good choice here for practical reasons if you are willing to suffer higher maintenance costs and calibration issues quartz halogen bulbs are preferred. On the minuscule chance that you have some kind of fluorescent mineral then there are many more options that you can do in terms of lighting if you are willing. Focus with most small sensored systems such as phones, and most cheap cameras the depth of field is not normally an issue, however if you are using a system based on a larger sensor such as DSLRs then you need to be aware of this. Wash the chips, a pile of powder or a ball of mud with some bits in it is not very useful at all. You are almost limited to colour only based analysis in these cases, if you are wanting to do particle sizing or shape analysis you need the chips.
Hyperspectral
Water is going to be a problem, too much water on the sample will cause distortion of the spectra if you are drilling dry, things are likely to be OK until you get around the water table. You should consider doing a saturation test if you are wanting to go down this path. Instrument price can be prohibitive, multiband instruments are cheaper but might not provide much benefit over standard rgb cameras depending on band position and resolution. Particle size can have an effect on the spectrum depending on what you are interested in this might not be an issue.
XRF
Like hyperspectral water is an issue Unlike the hyperspectral and images you are going to need a licence and training which makes field deployment difficult. Great for commodities that have a strong response, Pb and Fe for example. Light elements not so great or not possible at all C and Li for example.
LIBS
Water again causes problems with the analysis However light elements are possible, Li for example Dependent on laser output you might have to apply for a licence
General Points
Anything with a small area of analysis XRF, LIBS, Hyperspectral, makes getting representative measurement time consuming can be a particular issue when the commodity that you are searching for is part of a single mineral and makes up a low proportion of the rock mass.
If you want drillers and offsiders to use the system it needs to be fast and simple, they are busy and would obviously prefer not to do it. Survivability if you are putting equipment in the field make sure that you are not going to break it and consider writing it’s operating temperature on the box. Most electronics are not happy above 45 degrees let alone 55+ degrees if you forgot that you left it in the ute in the sun.
Data transfer, if you are very keen on realtime analysis and you are out of 3G/4G connectivity satellite is a possibility which if you are limiting yourself to small size data transfers won’t be an issue. If you want to talk back to the rig this can be difficult.
Data management is critical you can do this in house or with a third party, if you are looking at 3rd party webservices make sure that you know how to get all your data from the cloud as they are likely to delete your data once the payment plan is ended.
Related to item 4 make sure that you have a sensible or at least consistent way of naming your files, if you would like to assess how well your images relate to mineralisation or some other parameter you need to be able to join the data and your other (metallurgical, assay, geophysics,etc) information together one to one.
File reading, make sure that you can read the output files that you are saving or have a way to convert them to something that you can deal with.
Handheld analytical instruments need their calibrations monitored some how. Remember to scan the calibration samples that the instrument comes with regularly.
If you are looking at analytical instruments double check that they are going to work in your environment certain elements can interfere with each other making measurement less accurate than specified on the box. If you are looking for something with very low concentrations you might have to be happy with proxy response of an element associated with the commodity you are chasing.
How many samples are you expecting to generate per day? For images you are only looking at ~1 second to capture an image, handheld instruments are going to take much longer approximately 1 minute to acquire a spectrum
With today’s tight labor market there are technological aids to help your exploration project. These devices still need to be manually operated and maintained. Also geologists and fieldies provide more value than just simply logging chips particularly in high uncertainty environments where decision need to be made with the drillers on the fly.
Thanks,
Ben.