# What's a spilled drop worth?



## 4metals (Oct 19, 2015)

I work with a lot of refiners that put karat gold and gold concentrates up in Aqua Regia directly. I often notice small acid spills, a drip here and a drip there lost while transferring or filtering and recently a client was wiping up a small spill and he threw the paper towels in the trash. I said to him "You know you're throwing away money" and he replied "Yeah, but how much can it be?" 

So I figured it out (any excuse for a new spreadsheet!)

Based on a few assumptions this is what I came up with;

First the assumptions.

Aqua Regia will digest about 7.5 ounces of metal. I make spreadsheets for acid usage based on the rate of 7.5 oz per liter of acid so the loaded acid, depending on the assay of what was digested, is loaded pretty consistently. 

There are 20 standard drops in a milliliter. 

Everything else is self explanatory.

View attachment acid value per wasted drop.xlsx


Pretty amazing that a drop, 1/20th of a milliliter is equal 25¢!

Save those papers!!!!!!!


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## glorycloud (Oct 19, 2015)

PM me your Paypal email address and I will send you a quarter 4metals. :lol:


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## Smack (Oct 19, 2015)

Right on brother, I keep everything, paper towels included.


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## Grelko (Oct 20, 2015)

4metals said:


> Pretty amazing that a drop, 1/20th of a milliliter is equal 25¢!
> 
> Save those papers!!!!!!!



I never thought it would be worth that much, but hey, 25 cents is 25 cents. If you spill 4 drops, that $1 could have bought another pack of papers "for the people using coffee filters", or a cup of coffee.


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## MarcoP (Oct 20, 2015)

Ah ah, spills! Hard not to make some. All acquaintance tests done were also to improve handling so to cause less spills, if values were spilled they were off course saved along filter papers.

C'mon, I've also learned to sweep the floor before I start depopulating and sweep again when I finish and put it in my sweeps bucket, amazing to see how many little buggers can fly around.

Thanks for the post and the spreadsheet 4metals.

Marco


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## Anonymous (Oct 20, 2015)

Brilliant, thanks 4metals. 

I have been wondering for ages how much a drop spilled from a heavily pregnant solution might be worth.


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## 4metals (Oct 20, 2015)

> I never thought it would be worth that much, but hey, 25 cents is 25 cents. If you spill 4 drops, that $1 could have bought another pack of papers "for the people using coffee filters", or a cup of coffee.



I don't know how to quantify this but I would assume that a refiner working in 5 gallon acid quantities easily spills 5 milliliters. That is only one teaspoon of liquid, but 100 drops. It's easy when working in small beakers to be careful and not even spill a drop but when you are working with larger quantities, not so easy.


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## Anonymous (Oct 20, 2015)

Which is why I think long and hard before super concentrating solutions - I'd like a LITTLE room for error 8)


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## 4metals (Oct 20, 2015)

> Which is why I think long and hard before super concentrating solutions



I believe in making solutions as concentrated as possible, for a few reasons. Number one is chemical usage and number two is the volume of waste generated. I find that in a manual handling situation, the more solution you have to handle the more you are likely to spill. 

I have built systems that allow the transfer of solutions mechanically by vacuum into sealed reservoirs and delivery of those solutions by fixed plumbing. These systems have less losses because there is less handling. Classically a refiner with 10 or 15 gallons of loaded aqua regia will transfer out of the vessel where the metal was digested with a scoop or small bucket and pour the solution into a buchner funnel. Each time that scoop is dipped into the pregnant acid a few milliliters cling to the outside of the scoop. Inevitably some drips off, if you have 30 scoops of a half gallon each to empty the digestion vessel the potential for losses grows. 

My favorite tool when walking around a refinery is my little dropper bottle of stannous chloride. I see a little green liquid on a countertop or on a paper towel in the garbage and I test it. Often I see that jet black positive test for gold, losses in the making. Nobody ever recovers 100% but careful refiners can come close. It's a question of where to look and how to properly handle the solutions.


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## Anonymous (Oct 20, 2015)

15 gallons of loaded Aqua Regia. Oh I can dream 8) 

I get the point though, it's all about minimising the handling, and moving, and the possibilities of spillages of any kind. I guess every time the liquid moves from one container to another, that opportunity for a loss occurs and as you say, they may seem minimal when taken in isolation but they stack up horrendously.

Jon


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## Harold_V (Oct 23, 2015)

I was never short sighted where spills were concerned, although I worked carefully, so spills were not routine. 
As long as I refined, I had my counters covered with layers of old newspaper, which got replaced on a fairly regular basis. The removed papers were incinerated, with the ash added to my store of waste material, to be processed by furnace at a future date. 

NOTHING is discarded if it comes in contact with precious metals. Not even rubber gloves. Not if you have any sense of what is right and what is wrong. 

Harold


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## Grelko (Feb 13, 2016)

4metals said:


> Aqua Regia will digest about 7.5 ounces of metal. I make spreadsheets for acid usage based on the rate of 7.5 oz per liter of acid so the loaded acid, depending on the assay of what was digested, is loaded pretty consistently.
> 
> There are 20 standard drops in a milliliter.
> 
> ...



Right now with gold at $1,237.90

1,237.90 x 7.5 = 9824.25
9824.25 divided by 20,000 drops/L = $0.4642125 per drop (100 drops/5mls = $46.42)


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## allenp (Feb 16, 2016)

We work with Platinum and each 44 gallon drum of tissues, polishing papers, spills and so on yields about 8 oz of Platinum


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