Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction 2017-03-23T09:50:58+00:00
  • To participate in the 911Metallurgist Forums, be sure to JOINLOGIN
  • Use Add New Topic to ask a New Question/Discussion about Hydrometallurgy.
  • OR Select a Topic that Interests you.
  • Use Add Reply = to Reply/Participate in a Topic/Discussion (most frequent).
    Using Add Reply allows you to Attach Images or PDF files and provide a more complete input.
  • Use Add Comment = to comment on someone else’s Reply in an already active Topic/Discussion.

Making Cyanide On-site (14 replies)

Maya Rothman
1 year ago
Maya Rothman 1 year ago

Mining Magazine of Jan/Feb 2015
features an interview with Synergen Met which is working on a modular
production unit which would operate on site to produce between 450 and 750 tpy
of cyanide. No more shipping or storage of pellets or concentrated liquids. No
more dilution on site. The production uses a small plasma torch to form the
cyanide: continuous production of small quantities of cyanide. Estimated cost $
1500 - 2500 / ton cyanide (the article does not specifies "cyanide"
as NaCN or HCN. It's not Ca(CN)2). Is on site production the next evolution for
the cyanide (gold and silver) leach processes?

Alan Carter
1 year ago
Alan Carter 1 year ago

Instead of a simple storage facility, handling a rather stable material, we will add a fairly complex chemical process that can produce a colorless gas/liquid (HCN). Alternatively do the two step process to produce NaCN (where does the Na come from, shipped on as salt, what do we do with the Cl?).

I normally like thinking outside the box, and heartily approve of people coming up with new ideas and concepts. But, I must be missing something here as I do not think that this would be approved by the local authorities in many areas. Unfortunately I do not see the advantage?

Bill Fraser
1 year ago
Bill Fraser 1 year ago

The big advantage for the mining industry to onsite production is that there should then be no cyanide impact outside the mine gates. This will help reduce the popular push to ban the use of cyanide completely.

Already we are under very tight restrictions regarding cyanide in tailings whether or not there is a discharge to the environment; leading to the increase in chemical destruction of cyanide in tailings. This trend will almost inevitably continue with tighter restriction on all facets of cyanide use. The transportation of cyanide is a major visible impact of gold mining on communities.

If there is a technically viable and low risk method to produce cyanide onsite from non-hazardous materials then not only is it desirable but it is likely that governments will eventually make it mandatory.

Victor Bergman
1 year ago
Victor Bergman 1 year ago

Yes, the industry has had some high profile losses of cyanide making its way to a mine.

I understand the process uses methane, nitrogen (from air) and sodium hydroxide to scrub HCN gas to make the NaCN. It comes with some onsite risks (HCN gas scrubbing and high temp plasma torch), but might find some applications in certain areas.

Bob Mathias
1 year ago
Bob Mathias 1 year ago

20 Years ago, in 1986, Crown Gold Recovery- now DRD gold at the Crown Mines plant signed an agreement with a patent holder previously by Omnia in SA to provide finance to him to trial run a miniature cyanide producing plant using a plasma electrode.
The entire project seemed absolutely exiting and I already saw hundreds of these small plants being installed on plants, much like oxygen plants after their introduction.
We stored plenty caustic, methane and propane gas which were the main constituents.
The plant targeted around 500 kilograms of cyanide a day but it never worked out, the plasma electrode part gave endless problems and the risk was eventually seen as to high-
it failed never to hear from it again-- good idea , no doubt, maybe we should have given it more time?
Cost wise it had all the advantages as the first amounts of liquid produced was around 32% CN - but it just did not have the order of magnitude required and too many holdups.

Helena Russell
1 year ago
Helena Russell 1 year ago

Rather than producing Sodium Cyanide, why not Potassium Cyanide? Sodium is the nasty one that has to be flushed out of the heaps and tailings ponds, after leaching has ended. There is no need to remove the potassium, as it can be taken up by plant life; as long as there are no chlorides with it.

Tony Verdeschi
1 year ago
Tony Verdeschi 1 year ago

KCA has the rights to the Shawinigan process for cyanide manufacture. I have a copy of the business plan from 1994. It requires a bed of coke, ammonia and a hydrocarbon source. The reported conversion efficiency was +90% into a gas stream containing as much as 25%v/v NaCN. But there were no takers to work with KCA on this. The flowsheet is very simple.

JohnnyD
1 year ago
JohnnyD 1 year ago

The technology we've developed at Synergen Met is actually fairly simple and very safe, meeting all requirements to operate on a gold mine in Australia that is signatory to the cyanide code. We are making a dilute stream of NaCN that is then pumped into the plant's existing NaCN holding tank. There is significant Government and mining company interest to remove cyanide trucks from transporting through communities so support from authorities is there.
Yes, plasma torch technologies have advanced significantly since the 1980s, so the cost savings now are very real.

David Kano
1 year ago
David Kano 1 year ago

On-site cyanide generation was looked at in the 1980s in Western Australia however no-one took it up. No doubt the technology has improved. Unless you are consuming serious quantities of cyanide or have a long life project, it is probably less 'complicated' to buy cyanide than to make cyanide.  That is, additional hazards as well as operational requirements being are transferred to the site.

However if there are significant cost savings, whatever significant means (50%?), as well as logistical challenges getting the cyanide to site (cf. PNG), operations should be interested.Show less

John Koenig
1 year ago
John Koenig 1 year ago

Is there any case studies or projected savings to gold mining operations? Safety will also improve in transport but it does add some complexity in remote locations? I suppose automation and safety systems on plant that is more of chemical processing nature than a typical gold process will be very important? Is there any additional risk or is it the same?

Alan Carter
1 year ago
Alan Carter 1 year ago

Look for articles by Kappes Cassiday, Inc back in the early '80s. They took a hard look at onsite generation of NaCN. So did I at OxyMin but liquid NaCN from vendors was just becoming available and it was cheaper than making our own, especially after capital costs, permitting costs, and safety issues. I would rather contend with a dumped load of liquid NaCN than I would a load of HCN.

Victor Bergman
1 year ago
Victor Bergman 1 year ago

Interesting to see the level of Negativity here now. Kind of clearly demonstrates why our mining industry is so retarded at coming forward. Local communities are becoming major decision makers in projects around the world, and at any point in time can cause major disruptions to operations due to scaremongering with regards cyanide transportation. Seen that very clearly in Argentina. That in itself is certainly one major selling point for on site production.

Bob Mathias
1 year ago
Bob Mathias 1 year ago

Any comments on the SART process?

Victor Bergman
1 year ago
Victor Bergman 1 year ago

What is your next move,are you guys planning to install that technology in cyanide consuming countries like Tanzania and South Africa? I guarantee that this project will attract most of cyanide consumers due to its low operating cost. I would like to be part of your team in this project and guarantee that; most of gold producing companies will acquire this technology.

Tony Verdeschi
1 year ago
Tony Verdeschi 1 year ago

Speaking about the use of cyanide for gold leaching, we came across an environmentally-friendly gold leaching reagent and our company is now marketing it widely. We are marketing it as EarthGold. It replaces sodium cyanide. It comes in a granular form and a number of samples have been sent to mining companies to test on their ore. It is applied exactly as sodium cyanide is applied. Certainly worth a look for companies wanting to remove the use of sodium cyanide to something that is environmentally friendly. It costs the same as sodium cyanide but is environmentally friendly. We do have some free samples available in Australia and South Africa if anyone wants to test it on their ore.


Please join and login to participate and leave a comment.