# Gravity Separation & Concentration Methods

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GhanaBob
5 years ago
GhanaBob 5 years ago

I frequently see Au grade of alluvial soil sample as both g/m3 and g/ton. I thought best practice is using g/m3 for alluvial. My questions: 1) why use g/ton? 2) how convert, say, .30g/m3 to g/ton? What is math? Thanks.

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Shanford
5 years ago
Shanford 5 years ago
2 likes by Paul Morrow and David

0.3g/m3 you divide by density (KG/M3) of ore. Then you convert KG into TONNE. It is not very possible to multiply direct by a certain factor because ore behave differently in terms of S.G...... g/m3 is rarely used because it does not involve the physical characteristics of ore.

GhanaBob
5 years ago

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elyas
5 years ago
elyas 5 years ago
1 like by Paul Morrow

g/ton is used in solid samples and g/m3 is used in slurry sample like to leached solution. both g/m3 & g/ton are ppm that use in different situation.

GhanaBob
5 years ago

right...g/ton is for hardrock measurements. and g/m3 is for volume measurement in alluvial.still dont know why ppm is brought into the conversation.... no weight imlicit in that.

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Pabloski
5 years ago
Pabloski 5 years ago
1 like by Paul Morrow

1) Is easy to measure how many tons you have instead of how many cubic meters. And as Shanford said, g/m3 does not invove phsyical characteristics of the ore, so be aware that volume can change, but not the weight.

2) g/ton = (g/m3) ÷ (ton/m3)

where (ton/m3) is the density of your ore converted to tonnes, cause usually is in kg/m3

GhanaBob
5 years ago

thanks Pabloski...so in your reply above, using 1.5 ton per m3 as density, the math works out to .2 g per ton ? To me, I see total disconnect in how we even consider density - and not volume - in measuring grade in alluvial. Its all about g/m3 in my thinking. thanks Mr. P

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Deano
5 years ago
Deano 5 years ago

When working large scale alluvial material the grade is always calculated as g/m3. The density of the bulk material can change rapidly depending on wash type and large rock %. The general density of alluvial material ranges from 1.5 to 2.5 tons/m3. Much more reliable to use volume measurement for reserves and processing.

GhanaBob
5 years ago

Deano, thanks for the response. What is confusing is when wash plant manufacturers state processing capacities in tons per hour, rather than m3. isnt alluvial all about volume? not density? B

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Deano
5 years ago
Deano 5 years ago

Yes when processing it is all about volume but when you are trying to sell a plant the numbers look much more impressive as tons/hour rather than m3/hour.

Think on it as a marketing ploy which has infected the easily impressed beginners in the industry.

GhanaBob
5 years ago

Bingo! Exactly. Thx