Assaying PGMs

[kjavanb123]

All,

I am curios as how the mixing different catalyst converters would change the final assaying for PGMs. Here as an example.

Cat 1: 1930ppm Pt, 0ppm Pd, and 400ppm Rh.
Cat 2: 0ppm Pt, 2029ppm Pd, and 96ppm Rh.
Cat 3: 1338ppm Pt, 0 ppm Pd, and 279ppm Rh.

Now if these 3 cats are being analyzed individually. what would be the PGM assay if the cat 1 and 2 are combined and homogenized then sampled and assayed? What about if all 3 get combined?

Regards,
Kevin

 

[rusty]

I have a similar question, if I milled 20 cats taking a tablespoon of material from each finished batch - then after milling 5 batches for a total of 100 cats would the combined tabelspoon samples be good enough to use for an assay to represent the total 100 cats previously milled. As the mill does a good job of homoginizing everything insdie.

 

[nickvc]

Kevin the combined powders will have exactly the same amount of PGMs in them as individually , the ppm will be less but in a bigger weight.

Rusty my only comment would be to take samples from all through the powders, top, bottom and sides from each batch, mix together and take a sample then from the mixed batch samples for assaying. There is a specific way to sample, quartering I believe they call it but for your purpose I guess it's as a guide to make sure you don't get totally screwed I assume so my method should suffice, well I use it and haven't had any comebacks about under assayed material I have sold.

 

[rusty]

Kevin the combined powders will have exactly the same amount of PGMs in them as individually , the ppm will be less but in a bigger weight.

Rusty my only comment would be to take samples from all through the powders, top, bottom and sides from each batch, mix together and take a sample then from the mixed batch samples for assaying. There is a specific way to sample, quartering I believe they call it but for your purpose I guess it's as a guide to make sure you don't get totally screwed I assume so my method should suffice, well I use it and haven't had any comebacks about under assayed material I have sold.

Well this is good news, no need to build a large tumbler to homoginize everything as one big load.

 

[Lobby]

Kevin,

You're confusing composition (% Pt, for example) with mass. You have the compositions of the three cats, but you didn't mention the weights of each of the cats.

You have to multiply the composition of each of the cats by each of the elements of interest, then sum the weights of the individual components.

 

[kjavanb123]

Kevin,

You're confusing composition (% Pt, for example) with mass. You have the compositions of the three cats, but you didn't mention the weights of each of the cats.

You have to multiply the composition of each of the cats by each of the elements of interest, then sum the weights of the individual components.

Hi Lobby,

Cat 1 weighs 1150 grams, Cat 2 weighs 800 grams, and Cat 3 weighs 800 grams. So if Cat 1 and Cat 2 are combined then the assay would be the same as Cat 1 and Cat 2??

I have the individual converters weighs and analysis, I like to know how can I estimate the PGM contents by mixing them together.

Regards,
Kevin

 

[samuel-a]

kjavanb123

It might help you to understand if you convert ppm to % then to absolute weight and then back to % or ppm.

1 ppm = 0.0001%

Here, your assay numbers are plotted in: ppm, percent and absolute weight.

Cat 1 - 1150g
pt - 1930 ppm = 0.193% = 2.2195g pt
Pd - 0 ppm
rh - 400 ppm = 0.04% = 0.46g Rh

cat 2 - 800g
pt - 0 ppm
Pd - 2029 ppm = 0.2029% = 1.6232g Pd
rh - 96 ppm = 0.0096% = 0.0768g Rh

cat 3 - 800g
pt - 1338 ppm = 0.1338% = 1.0704g Pt
Pd - 0 ppm
rh - 279 ppm = 0.0279% = 0.2232g Rh

-----------------------------------------------------

Combine all the cat's weight - 800g+800g+1150g = 2750g
Combine the total weight of each metal -
Pt - 2.2195g + 1.0704g = 3.2899g total Pt
Pd - 1.6232g total Pd
Rh - 0.46 + 0.0768g + 0.2232g = 0.76g total Rh

Now calculate the percentage of each metal's total from the total cats weight (and convert to ppm):
Pt - 3.2899g / 2750g = 0.00119% or 11.9 ppm
Pd - 1.6232g / 2750g = 0.00059% or 5.9 ppm
Rh - 0.76g / 2750g = 0.00027% or 2.7 ppm

I used this script to help in the calculation:
http://www.rapidtables.com/convert/number/PPM_to_Percent.htm


Just remember, this is very theoretical as it assumes the assays are spot on and sampling is done right and repeated in the same manner.
Hope this helps you.

 

[kjavanb123]

Hi Sam,

Thanks for your detailed explanation. I tried this calculation for 200 cat1 and 1000 cat 2, so what I did basically I did calculate the combined ppm for 1 cat1 and 5 cat 2 and multiply the result by 200 to get the ppm to 200 cat1 and 1000 cat2.

cat1: 1150g.
Pt: 1930ppm = 0.1930% x 1150g = 2.2195g
Pd: 0ppm = 0 g
Rh: 400ppm = 0.0400% x 1150g = 0.46g

cat2: 5 x 800g = 4000g
Pt: 0ppm = 0g
Pd: 2029ppm = 0.2029% x 4000g = 8.16g
Rh: 96ppm = 0.0096% x 4000g = 0.38g

Combining 1 cat1 and 5 cat 2 will have the following results
weight = 1150 g + 4000 g = 5150g
Pt: 2.2195g + 0g = 2.2195g / 5150g = 0.0004% / 0.0001% = 4ppm
Pd: 0 + 8.16g = 8.16g / 5150g = 0.0015% / 0.0001% = 15ppm
Rh: 0.46g + 0.38g = 0.84g / 5150g = 0.0001% / 0.0001% = 1ppm

Since we have 200 cat1 and 1000 cat 2, then I presume we need to multiply the above results by 200?
So combining 200 cat1 and 1000 cat2 will have the following assay
Pt: 800ppm
Pd:3000ppm
Rh: 200ppm

Is this correct??

Regards,
Kevin

 

[samuel-a]

Kev

Is this correct??

No, it does not.

But let my first apologize as i somewhat miss lead you in the percentage calculation and it might be the source of the confusion. Very stupid mistake on my part.

So this paragraph is wrong!

Now calculate the percentage of each metal's total from the total cats weight (and convert to ppm):
Pt - 3.2899g / 2750g = 0.00119% or 11.9 ppm
Pd - 1.6232g / 2750g = 0.00059% or 5.9 ppm
Rh - 0.76g / 2750g = 0.00027% or 2.7 ppm

When deviding a number by a bigger number, one must later multiply by 100 to represent the value in %. For example:
3.2899g / 2750g = 0.00119 x 100 = 0.119% = 1190 ppm
--------------------------------------------------------------

Now, let's move on

You must remember that ppm is a relativistic figure similar to percentage.
So you can't just sum them up as you would with absolute values.

The currect way to calculate this is:
Since your interest is just with cat 1 and 2, we will produce the the ppm and % of just them, similar to the ratio you you currently have 1:5 (thankfully, you made a simple one)

Cat 1 - 1150g
pt - 1930 ppm = 0.193% = 2.2195g pt
Pd - 0 ppm
rh - 400 ppm = 0.04% = 0.46g Rh

cat 2 - 800g x 5 = 4000g
pt - 0 ppm
Pd - 2029 ppm = 0.2029% = [stt]1.6232g Pd[/stt] 8.116g Pd
rh - 96 ppm = 0.0096% = [stt]0.0768g Rh[/stt] 0.384g Rh

As you can see, ppm and % does not change, only the absolute values (in this case, grams).

Now let's combine all the cats (1 of 1, 5 of 2) of it and see what will be the new % and ppm.
1150g + 4000g = 5150g

Pt - 2.2195g / 5150g = 0.00043 x 100 = 0.043% = 430 ppm
Pd - 8.116g / 5150g = 0.00157 x 100 = 0.157% = 1570 ppm
Rh - 0.844g / 5150g = 0.00016 x 100 = 0.016% = 160 ppm

Now, you can use these above relativistic values (ppm or %) to draw exact yield numbers for cat 1 and cat 2 mixed at 1:5 ratio (no matter the quantities, as long as it is 1:5 ratio of these specific cats).
200 cat 1 x 1150g = 230,000g
1000 cat 2 x 800g = 800,000g
800,000g + 230,000g = 1,030,000g

Pt - 0.043% of 1,030,000g = 442.9g
Pd - 0.157% of 1,030,000g = 1617.1g
Rh - 0.016% of 1,030,000g = 164.8 g

 

[goldsilverpro]

For something non-homogeneous like ground up cat material, I would definitely sample by the cone and quartering method. It's not perfect, but it's about the best way to do it without an expensive sample splitter. The link for the pdf no longer works so, but an internet search should bring up quite a bit.
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=84&t=5768&p=51582&hilit=cone+quartering#p51582

http://www.youtube.com/watch?v=RkBgp-A5nX4

http://www.chromatography-online.org/quant/Sample%20Collection,%20Transport%20and%20Storage/Reduction%20of%20the%20Sample%20to%20Analytical%20Size.html

http://toolboxes.flexiblelearning.net.au/demosites/series4/412/_TEST401/act1304ConiQuartSand.htm

 

[Barren Realms 007]

See if this helps.


View attachment Cone and Quartering.pdf

 

[kjavanb123]

Hi Sam,

Thanks so much for clearing out this calculation for me, now it makes sense, I had individual converters analysis and I was wondering how to calculate the estimate of mixing them all up. Thanks a lot.

As for shipping the mix ones, one simple method is to pack everything in separate bags or mark them, so just dump everything cat1 in bags marked cat1, and so with other cats in the mix, and notify the refiner about this.

Many thanks to you all,
Kevin

 

[samuel-a]

Kev

Happy to help. Once you get the point, it boils down to simple calculus.
You are very fortunate to have batches of same make and model. I don't know how deep are you involved in cats trading, but will come the time where mixed lots will depart your loading dock.
Given suffice quantities, you might really want to consider purchasing a hammer Mill and sampling training so you could assay large lots.
Many mill today offer automatic sampling option ,you would need to consult with the vendor regading your material.

 

[rusty]

So far I have approximately 600 lbs of milled cats this is the assay from that lot. Which ton are they using to determine the value using ppm. And how does my material look as for value per pound. Thanks

 

[skippy]

Value per kilo is a little easier to see. 531 ppm is the same as 0.531 parts per thousand. There are one thousand grams in a kilogram. Therefore a kilo of your material has 0.531 grams of palladium, 0.635g of platinum and 0.0836 grams of
rhodium. Was there a lot of aftermarket material in your batch?

 

[nickvc]

Rusty if my maths is right based on your assays I reckon your looking at around $19.75 at spot per pound, that's not working in Troy pounds or $43.45 a kilo.

 

[samuel-a]

Which ton are they using to determine the value using ppm.

Most likely metric ton (1000Kg).
But if you are unsure, it will be best to just ask them to clarify this for you. Better safe then sorry.

 

[rusty]

I have a substantial amount of PGM black powder - now washed free of excess zinc. This afternoon made a call to my favorite lab to ask how much material was required for an ICP assay.

Shocked when I was told 10 grams would be needed.

1. Would 10 grams of highly concentrated platinum group metals be excessive.
2. Would my sample be returned, 10 grams of blacks has substantial value.

Best Regards
rusty

 

[Lou]

You would be fine with 50 mg for ICP.

 

[goldsilverpro]

The standard cry from refiners and labs is, "Send bigger samples!" Not needed but it sure helps their bottom line.