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.

Gold recovery by electrowinning & reducing copper content (10 replies and 6 comments)

biteyaboy
6 months ago
biteyaboy 6 months ago

Currently we are processing our ore through knelson Concentrator to capture free gold, the remaining as tail we are keeping aside for froth flotation plant which is on commissioning stages. We’ve Acacia plant where our final concentrate treated as feed to that Acacia Plant. We are using Cyanide, Leach Aid and caustic to control the pH running for 18-24 hrs. Samples are taken within every 2 hrs for assay. Then at the end we get pregnant solution that will send to electrowinning, here its where challenge started.

Our main problem we’re facing copper is more coated in our mesh hence gold recovered is less. Is there any possibility to reduce copper content either in our concentrate or preg solution before sending to electrowinning ? or is there any alternative method that is used?

Thanks in advance.

Greg Henderson
6 months ago
Greg Henderson 6 months ago
3 likes by Arnmax, David and Bill Fraser

I am wondering why copper is reporting to the Knelson concentrate given that cyanide soluble copper minerals only have an SG of 5 or less compared with gold at 19.  Perhaps you are running the Knelson too aggressively with very short cycle times and low backwash water which is trapping copper minerals that should report to tails.  There may be native copper present if the orebody is encountering a supergene zone which may result in its collection in the concentrate.  You may have to introduce a tabling step ahead of the leach reactor to reject the copper minerals or native copper which should show as a distinct band that can be rejected. 

Removing copper from PLS prior to electrowinning is tricky without employing tactics such as ion exchange or acid washing your cathode deposition prior to gold smelting, so a closer look at why the copper is reporting to the gravity concentrator is recommended, starting with mineralogy. 

biteyaboy
6 months ago

knelson is flushing after every 30 minutes, what are you suggesting is the correct timing?

Wadzanayi
6 months ago

different ores require different flush cycles. Work on the flush cycles optimisation 30 min, 45min, 60min, 90min, 120min etc as compare the recovery vs concentrate grade curve. I agree with Greg Henderson that there might be a need to introduce a shaking table ( Gemini Table) to upgrade your KC concentrates. The cuts from the Gemini Table can be smelt as gravity gold.The tails from the Gemini Table can be re-milled to further liberate gold contained in the middlings. They shouldn't contain contain too much copper and you can then subject these to intensive cyanidation. This has worked for a mine that contains ROM grades of 2.8-3.1 Au g/t and 0.5-1 % Cu with 65% of feed content being gravity recoverable gold

Mikhail
6 months ago
Mikhail 6 months ago

It may be worth a try acid treatment

Marshal Meru
6 months ago
Marshal Meru 6 months ago
1 like by Arnmax

Hi, yes, as Greg says, you should test a tabling stage to upgrade the Knelson concentrate to reject the copper minerals or native copper. If it does not table and separate, if could be a deep association needing mineralogy to confirm + and exotic separation process.

biteyaboy
6 months ago

Tabling stage concentrate is giving the same problem. How can i perform exotic separation process?

Wadzanayi
6 months ago

Wats app me on +26374346761

Mikhail
6 months ago
Mikhail 6 months ago
1 like by Arnmax

I agree with the previous statement, you must first study the mineralogy and understand what is associated copper. If aggregates with gold, then served sulfuric acid leaching, it is possible to conduct tests on the sulfuric acid leaching.

biteyaboy
6 months ago

How can i do Sulfuric acid leaching? Tell me more about this then i will do some test

Mikhail
6 months ago

Try the easiest way to leach into agitation mode. For example: 100 grams of the concentrate + 200 ml of distilled water, the sulfuric acid concentration of 5 and 10 g / l, while 8 and 12 hours. Then analyzed for copper content. If you have problems getting a concentrate mass, you can reduce the mass the sample.

Jorge Quintanilla
6 months ago
Jorge Quintanilla 6 months ago

I think the better way is carbon adsorption of pregnant liquids before electrowinning , by simple activated carbon in column CIC.

So you can concentrate gold and copper into the activated carbon, then you can easily make two stages of desorption, first with cold cyanide solution for copper recovery, and then with other hot cyanide desorption for gold recovery, with this method you can extract more than 60 % of copper.

The remaining copper you can mantein in solution during electrowinning stage with low parameters of current and voltage in electrowinning cells. To obtain better results you must increase cyanide concentration and pH. I worked with 4000 ppm cyanide and 14 pH.

I advise try in laboratory at first.
Sorry for my poor english
regards

Jorge Quintanilla
6 months ago
Jorge Quintanilla 6 months ago

The sulfuric acid leaching is very complicate, in Bolivia we worked LPF, leaching, precipitation and flotation of copper. By the way, then I had opportunity to meet David Michaud.

The system is very complicated because for complete copper leaching you must consume lot quantity of acid, and then you must change pH to basic with high lime consumption . This system require rubber lining tanks and accessories. Is very dangerous. Even in low scale.

regards

papamet26
6 months ago
papamet26 6 months ago

well we are also facing that same problem, we are having copper plating on the mesh and I would like to know how best we can remove the copper from the mesh and also how best to avoid the copper in the upstream process because now our solid tails are reporting a higher Au content thus showing copper hindering the leaching process. NB: ours is a sulphide ore.

Mikhail
6 months ago
Mikhail 6 months ago

Sulfuric acid leaching is certainly not safe and expensive process, but it's the gold, all his expensive extraction technology.

But first of all necessary to determine the possibility of separating copper and gold by mechanical enrichment such as a table with pre-concentration regrinding.

Paul Morrow
6 months ago
Paul Morrow 6 months ago

biteyaboy,

what is your copper content:

  1. in the ore?
  2. in your Knelson concentrate?
Jorge Quintanilla
6 months ago
Jorge Quintanilla 6 months ago

Dear Papamet 26, could You describe your flowsheet please? 


Please join and login to participate and leave a comment.