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XRF to determine Sulphur (5 replies)

Marshal Dienes
10 months ago
Marshal Dienes 10 months ago

I am working on a V-Ti deposit that is hosted in a magnetite bearing gabbro and are planning open pit mining of the recently defined reserve. As mineralisation was visual I have abundant assays of the ore (several thousand) but very few (a few hundred) from the hanging wall waste material and I now need to assess the amount of Sulphur/sulphide in the waste rock, to (hopefully) demonstrate that there is little risk of the waste dump generating Acid Mine Drainage (AMD).

Has anyone used pXRF specifically to quantitatively measure Sulphur?

I have a 2014 Olympus Delta Pro which will give me S results on both SOIL and GEOCHEM Modes. Have also just purchased four Certified Sulphur Standards (500

ppm, 1800

ppm, 0.6%, and 1.2% S) from a commercial supplier. As I am expecting S values in the 100-1000ppm range and hope the Waste Rock Sulphur average is only a "few hundred ppm". Given the assays I have for S there are likely only very rare samples with >1% S.

I can validly demonstrate the ore has extremely low S, but not for the waste unless I get more analyses. I do have samples to test, and would prefer to use pXRF (at minimal cost) rather than send several hundred samples to the lab. I'm sure it works fine for plus 1% to 10% S. My issue is with S in the 100 to 10000

ppm range.

Does anyone have experience determining S using pXRF?

Which testing Mode is best?

What interference elements are there for the S spectra?

What detection limits would I likely get for S on each Mode?

I am looking to do around 1000 analyses (plus standards QAQC etc), hopefully with a 60 second read time (but can increase the time if needed to get the DL down, but for this many readings practically 2-3 minute times are as far as I can go).

Jean Rasczak
10 months ago
Jean Rasczak 10 months ago

I have used my Delta Pro to get S on flotation test samples.

I never did VS a standard. The data it gave me was OK to allow me to move on testing my stuff.

Dizzy Flores
10 months ago
Dizzy Flores 10 months ago

Have you collected and assayed any samples from the intended project? With the assays (using the lab you usually use) and sample material in hand it is easy to add a calibration to your Delta unit that will optimize performance on that particular matrix.

Marshal Dienes
10 months ago
Marshal Dienes 10 months ago

Yes i have. Nearly collected 1200 samples then will have around 100 to compare lab results on.

Marshal Meru
10 months ago
Marshal Meru 10 months ago

It would be wise to check the detection limits of your instrument with Olympus as depending on which detector and DPP you have in the instrument the detection limit can range from as low as 50ppm to up to a 1000 ppm. Soil mode is best for the detection of Sulphur. A longer read time will increase the accuracy of your result to a certain extent but will not change the detection limit. The main interference on Sulphur is the Lead M line but in your type of deposit that shouldn't be an issue.

Marshal Dienes
10 months ago
Marshal Dienes 10 months ago

Yes seeing DL for S in the 100-200 ppm range on SOIL Mode with 100 second read time, and most rock material 200-1000+ppm. Readings are quite low compared to S standards and calibration (post-) required. Will have lab data to compare to shortly.

Lead values are low. Average less than 100 and <1% above 200 ppm with max. less than 1000 ppm. Should not be a problem?!