formula for ppm to troy oz.

[goldsilverpro]

Goran,
In 50 years, I can't specifically remember using the "long ton" in a calculation, although I probably have. I've always known it was 2240 pounds. I never knew how it was derived until I just now looked it up. It's one of those goofy British things involving 14 pound "stones". Here's the Wikipedia definition:

"A long ton is defined as exactly 2,240 pounds. The long ton arises from the traditional British measurement system: A long ton is 20 cwt, each of which is 8 stone (1 stone = 14 pounds). Thus a long ton is 20 × 8 × 14 lb = 2,240 lb,"

How a cwt, a hundredweight, comes out as 112 pounds is beyond me. Washington and Adams surely knew about "stones" but, thank God, stones have been completely eliminated from our (U.S.) memory over the last 200 years. When most people here say ton, they mean 2000 pounds. period.

The one unit I hate above all others is dm, decimeter. First of all, the meter, itself, is a BS unit. It is, "equal to one ten-millionth of the distance from the equator to the pole measured on a meridian:" Give me a break. Does anyone care about that other than the guy that proposed it? What was wrong with the yard? I spent 10 years as a PM plating guru and one of the most important relationships in plating was that of ASF, "amps per square foot", the amount of amperage you must apply per square foot of surface area on the part being plated in order to get decent plating. Unfortunately, the plating industry has gone metric and, instead of ASF, it is now amps/dm2. I could visualize ASF, but not this amps/dm2 idiocy. I can't wrap my brain around it. Of course, I am 77 and am an analog type of guy.

Snoman,
For 50 years, I've known that there are 231 in3 in a gallon. I use this factor more often than you would think.

 

[g_axelsson]

I just learned about the hundredweight (but my spellchecker knew more than me...) and the definition of a ton in imperial before I wrote my first post on this thread. That is how I just learned there is a long and a short ton.

When the meter was first devised it was at an age when every country had it's own standard or even more than one. Since it has it's roots in the French revolution they didn't have a king to use as the standard. I agree, the definition of the meter could be anything as long as everyone agrees on it. Today it is based on how far light travels in vacuum in 1/299 792 458 seconds, just because we can measure that with a very high degree of precision.
The metric system replaced a forest of different measurements systems back in the days.

Fun fact, the Swedish government tried to introduce a decimal system based on feet and inches, so for a while there were ten Swedish inches in a Swedish foot. The only trace left of that system is a Swedish mile ("mil" in Swedish) that is ten km. So instead of saying there is 56 km to my parents I'm saying there is 6 mil to drive. At least it's still decimal. A mil was slightly longer when it was first defined and it was based on a suitable distance between inns.
https://en.wikipedia.org/wiki/Swedish_units_of_measurement

Sweden went metric in 1889 but it took more than a hundred years until planks were sold in mm instead of inches ("tum" in Swedish). It takes several generations until a change like this goes through. Today there is only three countries that hasn't officially adapted the metric system, USA, Myanmar and Liberia.

But it's fine with me, you can go on and use imperial if you like. I only need the conversion factors from imperial to metric and then I do my calculations there.

Just to rub things in... the definition of the yard is based on the meter since 1959. :lol:

Göran

 

[Geo]

In the US, gold is weighed in the pennyweight and grains, not grams. Of course the refinery will give both units on the assay printout. If you want to talk about antiquated measurements, lets talk about furlongs, a rod, a hector, a peck, a bushel, a stone.

 

[4metals]

Real confusion enters the picture when you talk about tons. In the US a ton, also called a short ton or a US ton, is 2000 pounds. Where a metric ton is 2204 pounds or 1000 kg. When I talk about ppm as a measure of gold content I assume (and assumptions can be dangerous) that we are speaking about a metric ton because 1 ppm equals 1 gram per metric ton. The confusion comes from mixing ton types and thinking the PPM logic follows, it does follow but staying in metric makes it easy and clean.

And although I have lived with our system of weights and measures here in the US all my life, I much prefer science done metrically.

 

[snoman701]

I have my tape measures quantified in barley corns personally.

Units was the first month of high school chemistry class. Learning to move between them, learning them, learning the importance of them.

Science, always metric, as you said.

The weird part is machining, always english. But engineering, it depends on WHAT you are engineering. I still do all structural engineering calculations in english, while mechanical engineering is done in metric.

 

[geedigity]

Don't forget the difference between weight and mass. Here in the states we say pounds. Is it pounds force or pounds mass. Elsewhere it is either gram (mass) or newtons (force). If I use a balance, I am measuring pounds mass. If a digital scale or spring loaded one is used, I believe will not measure mass but measure weight or pounds force.

When our scale reports the amount of something to us, in grams for example, that may not actually be the truth. What type of scale are you using? When you think about it, your scale should report the result correctly i.e. Newtons not grams (unless the scale is a balance) or pounds force/pounds mass.

Sounds like a bunch of hogwash, but this will probably become important to me when I get into mining asteroids or other places with a different gravitational accelerations. At that time a gram in space will have to be a gram here on earth.

However, it is very unlikely I will get the opportunity to mine asteroids in my lifetime and therefore, I guess it doesn't really matter what type of scale you use to measure weight or mass.

 

[g_axelsson]

Don't forget the difference between weight and mass. Here in the states we say pounds. Is it pounds force or pounds mass. Elsewhere it is either gram (mass) or newtons (force). If I use a balance, I am measuring pounds mass. If a digital scale or spring loaded one is used, I believe will not measure mass but measure weight or pounds force.

When our scale reports the amount of something to us, in grams for example, that may not actually be the truth. What type of scale are you using? When you think about it, your scale should report the result correctly i.e. Newtons not grams (unless the scale is a balance) or pounds force/pounds mass.

Sounds like a bunch of hogwash, but this will probably become important to me when I get into mining asteroids or other places with a different gravitational accelerations. At that time a gram in space will have to be a gram here on earth.

However, it is very unlikely I will get the opportunity to mine asteroids in my lifetime and therefore, I guess it doesn't really matter what type of scale you use to measure weight or mass.

You are right in that a scale usually measures the force and just assume that the gravity is a constant. For most times that gives enough precision. When needing higher precision we use a calibration weight to adjust for any local variations. Equator or near the poles, high up in the mountains or down at sea level, living on top of a massive iron ore, all would affect a high precision scale.

A common scale that isn't affected by local gravitational variations is, as you say, a balance where you match the masses on two sides of a precision balance, but that won't work in zero gravity. Another way to measure mass is by using a spring and measure oscillations, that measures inertia that is directly proportional to mass. So when going for mining those meteorites, don't forget your springs and stopwatch.

Personally I prefer that a scale is calibrated in mass rather than force... It can be fooled by pressing down on it with a finger, but that's okay. If it was reporting force then it would still be true even if you push down on it but then you would have to know the local gravity constant and calculate the mass from force divided by g.

To bring this back to where we started... anyone else know why the formula given by macturney is wrong? Not just that the original question was wrong?

Btw, I highly suspect he was a drive by spammer that will come back in a week and edit his post to include a spam link. He spent 8 minutes on the forum and made a comment on an old thread. The reason I suspect him being a spammer also relates to the paragraph above.

Göran, physicist on retainer. :mrgreen:

 

[4metals]

The best guess I can get as to what he was posting about in with his factor was an assay ton, which he got wrong. In dealing with a metric ton an assayer uses a sample weighing 32.666 grams which makes every milligram in his sample equal to one ounce of gold in the ore. (edit, in a Metric Ton of the ore, to be clear!)

Or if using a US Ton, it's 29.1666. (Just to add to the confusion)

If he really meant 34.286 maybe he was part of that generation that studied the "new math"!!!!

 

[goldsilverpro]

Short ton: https://www.google.com/search?q=troy+ounces+in+a+short+ton&ie=utf-8&oe=utf-8

Metric ton: https://www.google.com/search?q=troy+ounces+in+a+metric+ton&ie=utf-8&oe=utf-8

Long ton: https://www.google.com/search?q=troy+ounces+in+a+long+ton&ie=utf-8&oe=utf-8

 

[4metals]

For 50 years, I've known that there are 231 in3 in a gallon. I use this factor more often than you would think.

Funny you should mention that factor Chris, I probably use it multiple times every week for some of the strangest things.

For example, I just built a new raised bed for planting in the greenhouse, the wife said she would bring 5 gallon pails from our topsoil pile to fill it. My first thought is she won't last long! So I did the trusty 96 x 30 x 24 = 69,120/231 = 299 gallons / 5 = 60 trips to the pile. That number changed her mind, I had to carry them all!

Maybe it's not such a handy factor, if I didn't use it I might have gotten 4 or 5 loads out of her before she quit. Oh well, it is handy sometimes.

 

[US minetrash]

Goran and 4metal had a good laugh (in their superior, knowing way) at macturney regarding his conversion factor, but mac is CORRECT.
And check out Goran's reply...WTH does 7 ppm of 3400 ounces mean?? 3400 oz (what unit?) at a grade of 7 ppm??? I can tell him that a 7 ppm ASSAY will not equate to a grade of .0238 oz/ton (troy).

Mac was talking about getting an assay returned to him in ppm, or parts per million. This refers to a concentration without units.
And remember, over here it's troy ounces per avoirdupois ton

Mixing units is easy to do, but you're going to get confused if you do. A 7 ppm assay (here in the states) is not the same as 7 grams per tonne (I'm NOT talking about metric tons), but even so, it's a GOOD assay. And 7/34.286 IS about .2 oz/ton...high grade where I come from. Even a 7 gram per metric ton assay will NOT equate to about .028 opt.

Where does that 34.285 number come from? Let's try 480 grains of gold (a troy ounce) in a ton, meaning 2000 lbs, each of 16 oz, each ounce of 437.5 grains ( a troy oz is bigger than a av oz). 2000X16X437.5= 14 million grains. 480/14 million is .000034286, the concentration factor for 1 tr oz/ton. You can also see that you can multiply your ppm Au assay by .02916 to get the same #. 7 ppm X .02916= .204 oz/ton troy.

Over here we're used to drilling results in feet ( a lot of 5-foot intervals) and assays in oz/ton. It works.

 

[g_axelsson]

Goran and 4metal had a good laugh (in their superior, knowing way) at macturney regarding his conversion factor, but mac is CORRECT.
And check out Goran's reply...WTH does 7 ppm of 3400 ounces mean?? 3400 oz (what unit?) at a grade of 7 ppm??? I can tell him that a 7 ppm ASSAY will not equate to a grade of .0238 oz/ton (troy).

Mac was talking about getting an assay returned to him in ppm, or parts per million. This refers to a concentration without units.
And remember, over here it's troy ounces per avoirdupois ton

Mixing units is easy to do, but you're going to get confused if you do. A 7 ppm assay (here in the states) is not the same as 7 grams per tonne (I'm NOT talking about metric tons), but even so, it's a GOOD assay. And 7/34.286 IS about .2 oz/ton...high grade where I come from. Even a 7 gram per metric ton assay will NOT equate to about .028 opt.

Where does that 34.285 number come from? Let's try 480 grains of gold (a troy ounce) in a ton, meaning 2000 lbs, each of 16 oz, each ounce of 437.5 grains ( a troy oz is bigger than a av oz). 2000X16X437.5= 14 million grains. 480/14 million is .000034286, the concentration factor for 1 tr oz/ton. You can also see that you can multiply your ppm Au assay by .02916 to get the same #. 7 ppm X .02916= .204 oz/ton troy.

Over here we're used to drilling results in feet ( a lot of 5-foot intervals) and assays in oz/ton. It works.

The answer to your question is: enter the ppm number in your calculator and divide by 34.286 and that will be the weight in troy ounces.
MacT

Macturney never said per ton. That was my main point I tried to get through. And I wasn't alone.

PPM is a concentration value, not a mass value.

And the original question was about ore, but the next line he specified it by

ok sorry I guess maybe I didn't give enough information. for arguement sake lets say I have 1,000 lbs of material, and I have the ppm assay results how can I estimate the metal value of the material.

Given that question you can't just give a conversion factor without specify which weight it is related to. The correct answer with 1000 lbs is not 0.0342857139 but half, 0.01714285695

ppm simply means part per million and has no unit in itself. ppm is a scale factor of exactly 1/1000000.

I have no problem with calculate ppm to troy oz/ton... 1 ton (2000 lbs) = 7000*2000 grains = 14 million grains.
Then 7 ppm per ton is equal to 7/1000000*14000000 = 7*14 =98 grains per ton.

With 480 grains per troy ounce there are 14000000/480=29166.667 troy ounces per ton.
Then 7 ppm per ton is equal to 7/1000000*29166.667 =0.20417 troy ounces per ton.

Checking... 480*0.20417 = 98.0016 grains
1000000/29166.667 = 34.2857139 and the dimension is
million /(troy ounces/ton) = how many millionth of a ton (avoirdupois) there is in one troy ounce.

Ref :
https://en.wikipedia.org/wiki/Avoirdupois
https://en.wikipedia.org/wiki/Troy_weight

Finally...

And check out Goran's reply...WTH does 7 ppm of 3400 ounces mean?? 3400 oz (what unit?)

7 ppm of 3400 ounces is 0.0238 ounces (unit ounces, fl oz, toz, oz... pick one)
7 ppm of 3400 grams is 0.0238 grams
7 ppm of 3400 goats is 0.0238 goats
7ppm of 3400 is 0.0238, we don't need any units at all if we don't want it.
ppm doesn't affect what unit we uses, it is just a number and exactly 1/1000000.

If people learns to use math then they wouldn't have to memorize so many conversion factors.

Göran

 

[goldsilverpro]

If people learns to use math then they wouldn't have to memorize so many conversion factors.

I can do both but, since I understand all the math involved, the factors I memorize are much more meaningful and more permanently built into my head. I've saved a lot of time in my life by memorizing factors. To me, it's always been quite important to do so.