Rotary Riffle vs Puck Mill

[devan]

Hi everyone.
Please help settle a debate for me. When starting with a mid grade +40 mesh PGM sweep sample, is it more effective to rotary riffle, or puck mill the sample to -80 mesh for fire assay. I am working with sample sizes generally around 2 grams. Which method is best, in your opinion, for ensuring a homogenous sample?

Thanks.

 

[fireguy]

Hi everyone.
Please help settle a debate for me. When starting with a mid grade +40 mesh PGM sweep sample, is it more effective to rotary riffle, or puck mill the sample to -80 mesh for fire assay. I am working with sample sizes generally around 2 grams. Which method is best, in your opinion, for ensuring a homogenous sample?

Thanks.

Hi Devan:
What weight starting sample do you have? Are you talking about grinding the entire sample in the puck mill? How would you split the resulting sample?

I don't think there is quite enough information provided to make suggestions.

 

[devan]

I have about 1/4 lb of original sample. Is is better to rotary riffle the sample into needed sample sizes for analysis, or puck mill the entire sample to -80 (or even better, -100 mesh) then perhaps cone and quarter the sample, selecting a small amount of sub-sample from each of the four quarters to obtain the desired sample size for fire assay. I typically use between 1 and 3 gram samples. Trying to rotary riffle a sample that size is difficult with the model riffler we have (Gilson model SP 230). I believe that puck milling a -40 mesh sample to -80 or -100 mesh is far superior than trying to rotary riffle a -40 mesh sample, especially when only a few gram of sample are needed

 

[fireguy]

I have about 1/4 lb of original sample. Is is better to rotary riffle the sample into needed sample sizes for analysis, or puck mill the entire sample to -80 (or even better, -100 mesh) then perhaps cone and quarter the sample, selecting a small amount of sub-sample from each of the four quarters to obtain the desired sample size for fire assay. I typically use between 1 and 3 gram samples. Trying to rotary riffle a sample that size is difficult with the model riffler we have (Gilson model SP 230). I believe that puck milling a -40 mesh sample to -80 or -100 mesh is far superior than trying to rotary riffle a -40 mesh sample, especially when only a few gram of sample are needed

Hi Devan:
If you don't have any reason to save any of the original material, then pulverizing the entire sample will lead to a MUCH better sample. Ring and puck pulverizers homogenize while they grind. This might not be good enough for your blending needs, but is a start.

I would then dump the sample out of the pulverizer bowl onto a piece of rolling cloth:

Rubberized rolling cloth 36" x 36"


This is a common and effective way of blending ground material.

Let me know if you are not familiar with rolling cloth blending technique.

Mark