Laboratory Testing & General Mineral Processing Engineering

Laboratory Testing & General Mineral Processing Engineering 2017-03-23T09:50:31+00:00
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Proper crucible Size for 1 A.T. Assay (4 replies)

Dave
3 months ago
Dave 3 months ago

In Assaying for Everyone" 1910, p 27.

"The crucible commercially known as Battersea "B" or 20 gram size will be found convenient for use when 1 assay Ton of ore is taken; size "F" or 30 gram when 2 Assay Tons are used, together with the necessary amount of flux."
- J. Reginald Smith
Read more: http://andy321.proboards.com/thread/77052/assaying-gold-silver?page=1#ixzz4TDNtzIyu

That sounds small for a 20 gram crucible to hold 1A.T. of 29.166 grams pulp + 20 grams lead + reducing agent etc. Is the information correct?

David
3 months ago
David 3 months ago

lostsierra usually uses a 30 gram crucible. A 20 gram will work but it will be full. He has also used 40 gram size and use 5AT ton size to do 5AT assays.

Dave
3 months ago
Dave 3 months ago

Thanks, that is what I suspected - but I don't understand how they went about sizing crucibles. You don't want to fill them more than 3/4 of the way for an accurate assay.

"Assay Crucibles are available in sizes of 30, 40, 50, 55 and 65 grams.

A 30 gram crucible = 4 X 3 X 2 1/8" with a volume of 13.2 Cu.in.
A 40 gram crucible = 5 1/16 X 3 1/8 X 2 1/4" with a volume of 18.6 Cu.in.
A 50 gram crucible = 5 1/4 X 4 X 2.4" with a volume of 23 Cu.in."

What lightweight material did they use for one gram? It must have had a far greater volume than ores and lead.

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David
3 months ago
David 3 months ago

Capacities given are actual totals, not working capacities. The working capacity is variable and may be from 70% to 90% of those given. The total capacity in pounds of metal depends on the specific gravity and may be found approximately by multiplying the total liquid capacity in pints by the specific gravity of the metal.

I'll leave the rest to a fire assayer.

Dave
3 months ago
Dave 3 months ago

Thank you!

 

Dave

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