Assaying, Microscopy, Mineralogy & XRF/XRD

Assaying, Microscopy, Mineralogy & XRF/XRD

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Pressed-Powder Compared to Glass-Fusion for XRF analysis (7 replies)

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OberstGruppen
8 years ago
OberstGruppen 8 years ago

I'm looking for some published information relating to differences between press-powder and glass fusion preparation for nickel laterite deposits. If you point me in the right direction particularly the likely shortcomings of pressed-powder in terms of analytic accuracy, grain size affects, interference between analytes and so on.

(unknown)
8 years ago
(unknown) 8 years ago

If you dig something up, I'd be interested in the results! A lot of this kind of stuff is never published as it is done for private companies. So, you might have some luck giving some of the lab managers you know a call. They can usually refer you to one of their internal experts who can help out. I've found this approach to work well in the past, and the labs are always happy to talk generics around specific methods.

O
OberstGruppen
8 years ago
OberstGruppen 8 years ago

Here is one I've found so far http://is.gd/nLPoni

(unknown)
8 years ago
(unknown) 8 years ago

If found a little info taken from page 16, "Chapter 11 - Sampling, Analysis and Quality Control" of the 2011 Field Geologist's Manual:

Pressed powder X-ray fluorescence is well suited to elements held in refractory minerals that pose difficulties for acid digest methods in particular. Consistent particle size distribution is essential to minimize errors due to mineralogical and particle size effects. Matrix matched controls are important when rapid matrix correction routines are used. It is not considered suitable for resource evaluation or lighter major elements although it is in limited use in robotic mine laboratories for grade control.

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OberstGruppen
8 years ago
OberstGruppen 8 years ago

This one pretty good on procedures http://is.gd/6bVC2G

(unknown)
8 years ago
(unknown) 8 years ago

In my experience the grinding as stated in a number of the references is critical. I would also add that the binding agent and skill of the operator in knowing the right "mix" and press equipment makes a huge difference. At the end of the day, so many difficulties were encountered that a change to ICP equipment was organized.

(unknown)
8 years ago
(unknown) 8 years ago

We manufacture CRMs for a number of nickel laterite operations and have always employed fusion XRF as the preferred certification method. In a production situation pressed pellet XRF can only work if you have a very good suite of matrix-matched CRMs characterized by fusion XRF that can be used in the calibration of the instrument. The limited round robin certification work we have done using pressed pellet XRF (for metals such W, Sn, etc.) has shown poor inter-laboratory consensus.

U
Unterstarm
8 years ago
Unterstarm 8 years ago

The grain size is critical. On a project we worked on (not Ni laterite) variable grain size produced by LM5 pulverizing produced an unpredictable low bias between 0-20percent. It was impossible to control in a commercial production environment and we changed over to fusion.

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