Questions for Assay Bullion

[Nannai]

hi all

I am new to this forum and would very much appreciate assistance from you all.

Question 1
Is it a right way for cupelling prills alone and then later add silver to that same prills, cupel for inquatation and then parting?

Question 2
Which of these two loading cupellation techniques is correct?

i. Clip each alloy sample and place it directly into the red hot cupels inside the furnace.

ii.Preheat the cupels in the furnace. Unload the cupels then place the alloy sample into that preheated cupels and load it back inside the cupellation furnace.

thank you in advance for your responses.

 

[4metals]

You can produce dore beads (alloy cupelled without adding silver) and add the silver later but why add an additional step? I always add the silver first.

I don't see you mentioning lead. Wrap your sample in lead and place it in the hot cupel in the furnace. There are some cupels that can be preheated and removed from the furnace to charge them. All of the assayers that I know use a cupel that stays in the furnace after preheating. (and I know quite a few assayers)

 

[goldsilverpro]

You can produce dore beads (alloy cupelled without adding silver) and add the silver later but why add an additional step? I always add the silver first.

I also add the silver first unless I am interested in both gold and silver (usually, though, I only want the gold). In that case, I do 2 cupellations. Cupel the first without added silver and weigh the bead. Then, add silver to the bead and cupel a second time. After parting the 2nd bead, the weight of the resulting gold subtracted from the 1st bead weight gives the silver. Without proofs, though, the silver calculation will normally be 1% - 2% low.

In rare cases, the silver percentage will be at least 3 (I prefer 4 or 5) times the gold in the original sample. If you know this to be absolutely so, and, if you want both the gold and silver, you can cupel without added silver, weigh the bead, part, weigh the gold, and subtract the gold weight from the bead weight to get the silver.

In all cases, I assume that the only PMs are gold and silver. Also, I assume these are bullion samples wrapped in lead foil. If running a fusion (usually on electronics scrap) before the first cupelling, and I want both gold and silver, the same logic applies. If I only want the gold, I add silver to the fusion and only cupel once.

I don't see you mentioning lead. Wrap your sample in lead and place it in the hot cupel in the furnace. There are some cupels that can be preheated and removed from the furnace to charge them. All of the assayers that I know use a cupel that stays in the furnace after preheating. (and I know quite a few assayers)

As 4metals said, you have to wrap the sample in lead foil. For a .5 gram karat gold sample, I prefer 10-15 grams of lead foil - some use less. If you don't wrap in lead, you'll never remove all of the impurities away from the silver and gold, which is the whole purpose of cupelling. Like 4metals, I have also never seen anyone remove the hot cupels to add the lead buttons (from a fusion) or lead foil wraps. Unless your furnace is super hot, which is bad practice, I would think there would be a much greater chance of freezing the lead. Certain cupel materials hold the heat better than others, but I still wouldn't want to take the chance. Lead freezing is something you don't want to happen.

 

[Nannai]

Hi friends,
thankyou for time and effort for helping me. Now I understand what exactly to do.