Cyanide! You magnificent *******! I read your book!

FOLKS DO NOT USE CYANIDE. JUST DON'T.

Cyanide gives you no second chances if you make a mistake, only death.
 

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...I'm gonna have to read this again - maybe 3 or 4 times even!, before I fully grasp what all you're saying. Sorta makes ya wonder though, why you couldn't just build a huge hothouse, drop down many tons of ore, then raise the sorghum and let it extract out the metals. ...Guess it'd still be mixed with too many other metals and such, huh? Not to mention the time constraint.

SwS, I don't know what all you're up to over there, but by all means keep it up, my friend!! Maybe one day someone will figure out how to make a Star Trek-type transporter that they can set for gold, then just beam the gold particles right out of the earth without mining at all!! :laughing7:
 

Thank ya KCM. I'll explain here why you need to do this in two stages. Short version: arsenic kills like Lysol, 99.999% of what it touches dies.

Long version:

With the heavy arsenic and sulfide refractory ores, we need to process those two chemicals out to get to the gold that is held in the various types of pyrites: arsenopyrite, chalcopyrite, pyrrhotite, and regular pyrite.

Arsenic is the trickier of the two. Here's why. Arsenic is very reactive in a biological sense and it interferes with a lot of biochemical processes. Its really like a monkey with three arms made out of chainsaws.

Therefore we need to first isolate the arsenic and make it into one of the few insoluble forms that it can exist in.

That's our first step. We use the bacteria that can metabolize the sulfur as an energy source and thereby transform the arsenic into one of the stable forms.

Once that is done, we have nice oxidized arsenic-free gold ore concentrate. All we've done is speed up nature's process by a few thousand to a few million years.
 

Sorghum and Johnson grass?

Now I know my brain is in complete overload with forgetting about those. Too much wrenching this weekend I guess. I'd bet there would be more than a few ranchers who would pay dearly for that high grade of feed.

Standard alfalfa hay out here is going upwards of $11.00 for a 100 pound bale. From waste product you have to pay to get rid of to a revenue stream by simple processing.

You do know that we are making it hard for the EPA and their eco freak buddies to sleep at night, right? I hope they get ulcers from worrying and have to eat our sorghum to survive.

EDIT: I'll read through some of the stuff I have on hydroponics. I think if you size the system right, you'll get 99.9% bio-utilization of the available cyanide. If my math is right, the first system would utilize 99% of the available cyanide. If it is run through a second system, then that would utilize 99% of the available 1% of the remaining cyanide, thus resulting in a 99.99% utilization. I'm pretty what is left would be WAY below any natural background amount.
 

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FOLKS DO NOT USE CYANIDE. JUST DON'T.

Cyanide gives you no second chances if you make a mistake, only death.
 

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SS: Done quite a bit of hydroponic gardening over the years, and have a
few questions:

How many plants will it take to disperse/manage the amount of material they need to absorb?
How fast, and how large (tall) do the plants grow?
Outdoor hydroponic systems are difficult to maintain...are you thinking about growing indoor?
How long will it take a plant to uptake the material?

Then there's a dozen more questions about the needed lighting (metal halide or
HPS?), not to mention the electric bill that comes with operating the lights. You'll need
a fresh air intake as well as an exhaust to the outside. Once those chemicals are added
to the reservoir, the Ph of the res water is going to go nuts, so it will need to be adjusted
so the plants can properly intake the the nutrients.

Growing hydro is really not as simple as people make it out to be. IF ya know what you're
doing it can be a great way to grow (anything), but disaster can also strike in a hurry if
things are not carefully maintained.

I'm no chemist, but will do my best to chime in with beneficial info if it will be of help.
 

Why not purify the arsenic and sell it to the semiconductor companies? Thermal imagers use indium arsenide for the CCD chip, and blue/ultraviolet LED's use the same.

Multiple revenue streams from the same ore!
 

FOLKS DO NOT USE CYANIDE. JUST DON'T.

Cyanide gives you no second chances if you make a mistake, only death.
 

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FOLKS DO NOT USE CYANIDE. JUST DON'T.

Cyanide gives you no second chances if you make a mistake, only death.
 

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For metallic arsenic for sale, it'd need to be roasted without air. The gray form is what is needed. At least that's what I get from wiki.
 

FOLKS DO NOT USE CYANIDE. JUST DON'T.

Cyanide gives you no second chances if you make a mistake, only death.
 

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SaltwaterServr said:
Worldwide the preferred leaching chemical is cyanide at around 0.1 gram per liter of solution at fairly neutral pH and oxygenated too. That concentration will give you a fairly short residence time.
Click to expand...

SaltwaterServr

In this first post you got the cyanide concentration (0.1 gram per liter of solution) wrong - which I see you later in the thread "somewhat" corrected

But what I really wanted to point out is what I underlined in the above quote --- you do NOT want to run your cyanide leach solution "at fairly neutral pH"

The pH NEEDS to be "at least" 10.5 - & 11 is recommended - & in "some" cases it "may" need to run as high as pH 13 --- the reason for the high pH (10.5 - 11) is that is the optimum pH level for the leach to do its work - AND - more importantly "do it safely" --- at a Ph below 10.5 you start to run a risk of exposure to the deadly cyanide gas --- pH 10.5 is the bottom pH level to prevent risk & still optimize the work of the leach - pH 11 is the "recommended" pH which still optimizes the leach work - but also "insures" no risk

Then when talking about growing sorghum to deal with your cyanide waste in an environmentally safe way (which by the way I find very interesting) you said the following

How's it work? Basically cyanide is HCN in solution. Hydrogen, carbon, and nitrogen. Any plant loves carbon and nitrogen. Sorghum and a few other species (I'm still researching wheat) can take the HCN and bust it apart to use the carbon and nitrogen.
Click to expand...

Cyanide is the chemical compound CN which is a carbon atom that is "triple bonded" to a nitrogen atom --- it is NOT an H (hydrogen) atom bonded to a C (carbon) atom bonded to a N (nitrogen) atom --- so HCN is NOT a reference to a chemical compound of hydrogen, carbon & nitrogen that stays in solution - at least not at the concentration of CN used for leaching AND at a pH below 10.5

HCN is the reference to the "deadly GAS" Hydrogen - Cyanide (H-CN) when proper concentration &/or pH is not maintained/controlled

HCN - being a "gas" does not stay in solution - it "gases off" - at which point it becomes deadly due to breathing it - which is why you want to maintain the high pH - in order to prevent the formation of the of the HCN gas

You later in the thread posted

Alright. Not so minor update. Looks like most cyanide circuits run at .25g/L to .5g/L for leaching
Click to expand...

The .5g/L is the correct cyanide concentration for optimum leaching run at the recommended (for safety concerns) pH of 11

If there is a lot of copper in the ore the leach can be made more selective to the gold by lowering the concentration of the cyanide - lowering the concentration of the cyanide (when a lot of copper is present) reduces consumption of the cyanide by the copper thereby making the lower concentration of cyanide more selective to the gold - and even though the cyanide concentration is lower - you still want to run at pH 11

The common cyanides used for leaching are potassium cyanide (KCN) sodium cyanide (NaCN) & some times calcium cyanide Ca(CN)2

The .5g/L concentration is achieved by dissolving 1 gram of any one of those cyanides in 1 liter water --- that level of cyanide will, without adding lime, give a protective alkalinity of about pH 10.5. - lime is added to increase the pH safety level to around 11. (NOTE - at pH 10.5 there is "some" HCN generated but the outgassing is slow/low enough that it gives you time to adjust your pH up to the safer 11 pH)

There is a smell of "bitter almonds" associated with HCN - the problem is that only about 50% of people can smell the bitter almond smell - its a genetic treat as to whether or not you can smell it - therefore when working with cyanide it should AWAYS be done with GOOD ventilation - if being done indoors you MUST have GOOD ventilation control systems in place

Acid of ANY kind added to a CN solution is the greatest danger of producing the "deadly HCN gas" --- NEVER work with acids & CN in the same work space &/or use the same equipment used with acid for also working with CN --- one mistake with acid & CN is likely to be the last mistake you will ever make & you likely will not live to tell about it

The point (reason) for posting this is that though CN leaching is a very effective way of leaching (some) ores - & for the most part also a safe way of leaching - "when done right" --- in fact - "when done right" - it is actually safer - & - more environmentally friendly then acid leaching --- the problem with CN leaching is the danger when not done right - one mistake can well be the last anything you do

Working with CN should ONLY be done after you have an absolute, full & complete understanding of working with it !!!! --- its not a "lets experiment" kind of thing - it doesn't give you any second chances when something goes wrong because of misinformation &/or incomplete information

Now then - concerning your idea of growing sorghum as an Eco friendly way to destroy the spent CN leach - I guess the question is - can you grow the sorghum in the high pH (high alkalinity) conditions that "need" to be maintained to prevent the CN from gassing off as HCN until the CN is actually destroyed ?

That's all I have time for today - there is a lot more that needs to be discussed (if you are really interested in CN leaching) including method to recover your gold in a way to reuse the leach (rather then destroy it) &/or method to destroy it when spent

Kurt
 

If I remember right from FM 3-6 or 8 Military Chemistry and Compounds, HCN has a very low flashpoint, and in some cases it can be destroyed by the bursting charge in the chemical munition. That is why it's usually sprayed over the area and not delivered by artillery.

That may give us an important safety precaution. Keep an open flame over the cyanide leach container. If HCN is produced, it can burn off instead of spreading over the countryside! I'd think the products would be H2O, CO2, and N2. If your tank is flaming, add alkali.

Remember, this is from memory 20 years ago, so check it before use.
 

Capt Nemo said:
If I remember right from FM 3-6 or 8 Military Chemistry and Compounds, HCN has a very low flashpoint, and in some cases it can be destroyed by the bursting charge in the chemical munition. That is why it's usually sprayed over the area and not delivered by artillery.

That may give us an important safety precaution. Keep an open flame over the cyanide leach container. If HCN is produced, it can burn off instead of spreading over the countryside! I'd think the products would be H2O, CO2, and N2. If your tank is flaming, add alkali.

Remember, this is from memory 20 years ago, so check it before use.
Click to expand...

When leaching with CN the safest "safety precaution" is to run the leach at "no less" then pH 10.5 & PREFERED pH 11 --- AND - as well in a well ventilated work area --- I would not trust - in anyway - a flame over the leach vessel as a safety to destroy any HCN coming off the leach vessel - the flame would have to cover the "entire" vessel opening surface area (& then some) to "insure" any "reliable" destruction of HCN coming off the leach vessel

Bottom line - DO NOT produce the HCN in the first place - that is done by keeping the pH at no less then 10.5 & preferably at pH11

That was one of my main reasons for posting my OP --- it was to correct what SaltwaterServr posted when he said --- "Worldwide the preferred leaching chemical is cyanide at around 0.1 gram per liter of solution at fairly neutral pH"

At a neutral pH (pH7) you will definitely produce "dangerous" levels of HCN --- even at pH 10.5 "some" HCN will be produced - BUT - at pH 10.5 the evolution of the HCN is so low/slow that it does not (especially when done in combination with good ventilation) pose high risk of lethal exposure --- At pH 10.5 the evolution of the HCN is so low & slow it would take "prolonged" exposure &/or "poor" ventilation to ingest (breath) HCN of lethal concern --- in other words at pH 10.5 the HCN does not come roaring off the leach solution in lethal levels of concern under normal working conditions (good ventilation & short term exposure)

At pH 11 - the risk is "significantly" reduced - which is why pH 11 is the "recommend" pH for leaching

At the risk of a long post - but for clarification I will do my best to explain it

CN is a carbon atom that has a triple bond with a nitrogen atom & CN in & of its self is a nonvolatile cyanide salt

HCN is produced as a volatile gas when a hydrogen atom bonds (as a single bond) with the CN

Alkali conditions block the potential of H to bond with CN --- on the other hand acidic conditions facilitate the potential of H to bond with CN

The common CN salts used for leaching gold are KCN (potassium cyanide) NaCN (sodium cyanide) & Ca(CN)2 (calcium cyanide) --- K - Na & Ca are all alkali - thereby providing the alkali condition to "reduce" the potential of H to bond with the CN

I say "reduce" because the potential of H to bond with CN & produce HCN is not a question of just acidic - or - alkaline - but rather how alkaline (or acidic) --- in other words - the "more" alkaline the less the potential for H to bond with CN - or - the less alkaline the greater the potential for H to bond with CN --- so its not a matter of HCN being produced "only" if the pH goes below neutral (pH 7) - but rather - as pH is lowered - from the standard "safe" pH level of 10.5 to 11 - the potential of H bonding with CN increases the production of HCN from safe to less safe to unsafe levels of HCN --- the lower the pH goes - the more HCN is produced

That's why you want to maintain a work place for CN "completely" separated from a work place with acids --- an (accidental) addition of acid to a CN solution can/will produce a "rapid" evolution of HCN --- even if the acid addition does not change the over all pH - it is the moment of contact of the acid with the CN that will produce an unsafe rapid production of HCN

Now then - with all of that said - don't let CN leaching scare you - it is in fact a very safe method of leaching - in fact "safer" then leaching with acids - it is really just a matter of understanding the above & staying within the safe high pH working range

Keep in mind that at pH levels even "a bit" below the safe "working" range of 10.5 - 11 --- the HCN does not come roaring off - there is time to adjust the pH back up to the 10.5 - 11 range

This is al the time I have to post today - I will post more as time allows including why I say CN leaching is actually safer then acid leaching

Kurt
 

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