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

Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction2017-04-04T06:57:36-04:00
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Started by Tarun Karakoti
What is the minimum size of ore in gold heap leach? Without problem of percolation!
Last replied to by Nurettin
  minimim size depends on screening quality and stacking homogeneity and partical shape. if you have a bad size distribution percolation will increase but leaching quality will decrease.  if you ...
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3140
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Started by Amar
Does anyone know the actual free cyanide concentration in GOLDIX 567 OR 570 and where do I find GOLDIX for sale?
Last replied to by David
Hi Mikhail, Best contact Florrea (Goldix): Yang ZhiyongPresidentMobile: + 86.136.0982.1616Tel: +86.24.3151.5191Fax: +86.24.3151.3277Email: yang.zhiyong@florrea.comSkype: yang.zhiyongMSN: yang_zhiyon...
11
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6491
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Started by
We use the Zadra strip/EW process to produce gold sludge, which is then sent to our furnace, after drying, to be refined. I was curious to know how one would determine the best flux recipe (constituents/amounts) for primary refining. Additionally, wh...
Last replied to by Marshal Meru
When gold slimes contain much lead ( up to 23%). They were treated in various ways, but the best results were obtained by dissolving in sulphuric acid and melting the residues in clay-lined pots (to p...
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1723
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Started by Sudhirkumar
Normally what is the optimum carbon concentration at the gold CIL process? I need some advice to maintain 7 CIL tanks.Currently we have 3 leach tanks in the front and then followed by 7 stages of CIL.
Last replied to by Philip Stewart
The amount of carbon in a tank and hence its concentration are important to ensure that the amount carbon and its residence time are sufficient to ensure that the solution concentration and the loadin...
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Started by Kumar Choudhry
Would you please help give information how is the correlation of density (%solid) to gold and silver recovery in gold Cyanidation (CIP) leach process. Is there any typical optimum value? And what is the explanation?
Last commented on by nurdyme
aiming at 50-55% solids, would the dissolution be high. on the part 55% percent part, i thought carbon would float and the residence time increases
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Started by Kumar Choudhry
I want to know if anyone has an idea or a resource book on how to conduct and interpret the results of preg-robbing test in both CIP and CIL. Also wants to know if the PRIs are good indicators of preg-robbers in ores associated with carbonaceous mate...
Last replied to by Charlie
Carbon is added at the initiation of the leach period to determine if preg-robbing constituents were present in the material. In the leach tests, if the gold extractions from the direct leach and the...
12
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Started by Sudhirkumar
We ran a milling in cyanide CIL plant for reprocessing a gold tailings dump for one and half years. We were achieving 60-70% dissolution in the mill then followed by adsorption in 6 CIL tanks.We are now looking at modifying the process and introducin...
Last commented on by Colette
You can use floc and coagulants with lamellas, and as with the use of any thickener ahead of a carbon process - the organics will adsorb onto your carbon, but usually nothing that a normal regen proce...
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Started by Zander Barcalow
I have been working with the entire intensive cyanide leach machine. Do we really need this equipment in the gold plant to treating the gravity concentrates?
Last replied to by Unterstarm
All the comments you have received are good, however please try the following and you may be surprised. Run five pounds through a splitter to get a good sample. Take a pound and re-grind to 250 mesh m...
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Started by
To all you clever Gold Metallurgists, which carbon does you prefer to use, Indian supply or Philippine supply (Coconut shell).Both countries sell Coconut shell carbon, getting a supplier that has tested their carbon to ATSM standard is the cruncher. ...
Last replied to by Obergruppenfuhrer
The source of the carbon is probably not as important as the quality control in the manufacturing process to produce a product with a decent balance of hardness, porosity and size distribution. In my ...
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Started by Sachin Prakash
We are having a problem of carbon floating in one of our CIL tanks. Does anyone know what causes that and how it can be rectified?
Last replied to by Tarun Karakoti
Considering all the contributions given, as rightly said, the problem is with that particular tank (Tk 04). First check and parameters like the current drawn by that agitator motor, agitator gearbox s...
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Started by Rahil Khan
I want the best technique to recycle the cyanide from tank#8 to tank#1. Which now we add 300ppm cyanide in tank#1 and we get 180ppm in tank#8 (tailing).
Last replied to by Sudhirkumar
I would suggest to you to follow what has said about splitting the cyanide addition on the 3 first CIL tanks. If the goal is not reached, I suggest to you to start looking at the thickening option to ...
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Started by Sudhirkumar
On the CIL processing of free milling oxide gold ore, how far I can drop the free cyanide concentration in the leach tank#1? In order to minimize the cyanide consumption without any impact on gold recovery! Currently our practice in the 1st leach tan...
Last replied to by Sachin Prakash
First I must say you are one of the fortunate people to still be treating such forgiving ore. The cost of cyanide prompts for urgent and efficient ways to significantly bring down its consumption with...
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609
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Started by Maya Rothman
I would like to know if anyone has ideas on how to reduce settling of materials in leaching tanks. The plant is a gold production plant and the ore treated are oxide and fresh rock.
Last replied to by Sturmbann
There are two factors that you need to balance, the settling rate, which is a factor of pulp density and rheology, and the lift from the agitator.http://is.gd/raVkGnThis may help you understand. I sug...
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602
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Started by Rahil Khan
ILR pregnant solution is expected to contain much impurity than the CIL or CIP pregnant solution for electrowining. This may be due to the intensive leach conditions in the ILR than in the CIL or CIP.I want to know which process contributes to lesser...
Last replied to by Oberfuhrer
You will have fineness of bullion produced by intensive leach much higher than from CIL.
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Started by Sandeep Bisht
How do I improve recovery on a vat leach plant with a high Cu content and iron pyrite? Current pH 10 CN strength 0.07-0.1%. Detention time 18hrs. Head solution 1.5-2g/t tail 0.05. B/roll 3.1g/t, Hg 4.4g/t
Last replied to by Obergruppenfuhrer
What type of ore/material are you leaching?Copper concentration in the feed seems to be enough to have it separated with floatation first if the ore volume permits capital costs for grinding/flotation...
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Started by Raje Singh
Recently we had cost related issues with solid lead nitrate addition to our ore being treated. We reverted to the liquid lead nitrate and we have since observed significant drop in the DO levels in our tanks. A little test work showed that lead nitra...
Last replied to by Raje Singh
I think you said same points to escalate the subject at hand. Nevertheless, we have learnt a lot from this discussion. I will do all the recommended test works to know what really lead to the pH drop ...
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720
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Started by Gruppen
What is the best way to install a cyanide analyzer online for the leaching process? Someone has diagrams or similar?
Last replied to by Obersturmbann
There is a gas diffusion based system that is ideal for what you want to do. Reading is less than 3 minute cycle. It is designed for leaching circuit control.
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649
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Started by Subhash-Kumar-Roy
I want to know some of the ways fine carbons from CIL can be treated for the gold they contain to be stripped. Also do we have a double Decker carbon recovery screen?
Last replied to by Obersturmbann
Not having knowledge of your process it is difficult to assess the source of the fines. Agree with harry that the tonnage you refer to may be incorrect, suggest you check this. From our benchmarking t...
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Started by Raje Singh
Did anyone of you add air into the dump leach pads in order to improve the gold recovery?
Last replied to by Raje Singh
We have dump Leach, ore from the pit, and we are gold mine. I will start testing 100m2.
6
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Started by Sachin Prakash
The reaction of elemental sulphur and cyanide (S0+CN- = SCN-) does it occur? Theory says yes but I tried it in the lab using pure elemental sulphur and NaCN with no success
Last replied to by
I apologies for a very late response. I didn't see any notification that there were further responses to this conversation.Yes, I am aware that a number of researchers point to jarosites as a possible...
2
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681
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Started by Tarun Karakoti
For some time now, dissolved oxygen levels, cyanide concentration and pH at our ILR Plant keeps decreasing as leaching advances with a very high increase in temperature (around 89 degrees Celsius) and the evolution of a gas which i suspect to be ammo...
Last replied to by Unterstarm
I agree with the assessment he is making with the relative small amount of data that was available. The oxidation of the sulphides may even be beneficial to Frank's intensive cyanide leach circuit as...
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657
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Started by Helena Russell
Does anyone have a good explanation here: Occasionally, our pH above 12 tails solution free cyanide concentration using rhodanine titration method drops between 10 to sometimes 35 ppm from original pH 9 to 9.4 solutions? What metal elements could com...
Last replied to by Sandeep Bisht
Agreed! ICP scan will definitely provide a clear picture of metallic contents. Yes, I mean it is required to get AAS or ICP analysis of an ore. After having an idea about metallic percentage, it will ...
3
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671
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Started by Oberstorm
Does anyone has an experience doing leaching in the grinding circuit? How is the effect to the liner and grinding media consumption?
Last replied to by Amar
We are a hydro-met plant /copper-cobalt in DRC milling ore in raffinate (acidic solution from copper solvent extraction), approximately 10% of copper fed is leached in the milling circuit by mean of r...
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745
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Started by
What is the best method to determine gold recovery improvements in a cyanide leach circuit?Depending on the head grade and through-put of a gold leach circuit, Just a 1% increase in gold recovery can mean millions of dollars of additional revenue per...
Last replied to by
Bottle rolls are an amenability test. Agitated leach is better for accurate work with standard agitation and O2 bubbling if required. Sample at 0.5, 1, 2, 4, 6, 8 and 24 hours with pH adjustment, CN t...
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753
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Started by Zander Barcalow
Is the use of Cyanide in gold production a real issue (w.r.t it's toxicity and environmental impact) to Local Authorities and gold producers?Is there enough concern out there to warrant a total shift towards a much friendlier reagent?
Last replied to by Marshal Meru
As a broad rule of thumb in initial costs estimates I used the cost of cyanide destruction (OPEX) as approximating the initial cost of the cyanide in the process. Again this will eventually be optimiz...
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2131
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Started by Rahil Khan
I am struggling to understand what is happening in my gold intensive cyanidation reactor. I am leaching for 14 hours and taking a profile by sampling every four hours. The curve flattens out after 6 hours and at the 8th hour, the gold concentration i...
Last replied to by Rahil Khan
It turns out that one of the major contributors was temperature which most likely killed the leachaid towards the end. We were leaching at 55 degrees and dropped to 50 degrees and saw a huge improveme...
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Started by Rahil Khan
I am using a drum filter after high pressure refractory gold leach. My problem: the final product, filter cake, always contains high gold content even when the spray water is opened what could be the cause of this?
Last replied to by Hauptsturm
Once before we had experts out to check every part of this process, we had filter drum header valve Teflon replaced and re-faced, filter drum pipes were replaced, we acid treated the filter cloths twi...
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Started by Zander Barcalow
Does anyone have an idea on whether or not it is useful and helpful to does NaCN via stage addition in cyanide leaching?
Last replied to by
Another good reason for staged addition of cyanide is that maintaining low concentrations of cyanide reduces dissolving copper minerals hence saving cyanide and yielding dore with less copper for less...
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920
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Started by Sandeep Bisht
Is it possible to avoid the adsorption of copper from cyanide solutions on the activated carbon in CIC operations?
Last replied to by
I think you are on to something here. It will however; be important not to look at the total copper in isolation. In other words it will be important to look at the actual cyanide soluble copper conte...
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Started by Raje Singh
What possible laboratory tests can be done to determine extent of calcium fouling on activated carbon?
Last replied to by
Is the fouling of the carbon by calcium a hypothesis as a plausible explanation for the current circuit performance or a demonstrated fact?A very simple comparison testing of the absorption (or remova...
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Started by Helena Russell
My problem is with regards to precipitation of Au and Ag at minimum concentration of CN. I need to lower the cyanide concentration to a limit in the Merrill Crowe processto 20 ppm of free cyanide and 50 of WAD, but I have problems with the precipita...
Last replied to by Gruppen
Try cutting back on Zn addition, Au and Ag come down by reduction to metal on the Zn surface and the rest as a result of hydroxide precipitation, try reducing Zn and keep copper in solution, also can ...
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Started by Tarun Karakoti
Wondering if it is possible to test for CN- only as opposed to free cyanide (HCN and CN-) in conventional CIL leaching, as a way to justify maintaining high pH in the circuit?My understanding is that at a pH of 9.3, 50% of the free cyanide is HCN, wh...
Last replied to by Tarun Karakoti
Thanks for all your input, really appreciate you taking your time to help out. Will need to digest all that has been said and look into it a little further, and if I come up with a reproducible conclu...
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Started by Zander Barcalow
How to recover silver from silver sulphide concentrates. Our method cannot melt the silver to reduction. What could be the reason?
Last replied to by Victor Bergman
Are you fully aware of the mineralogical host(s) for Silver? Knowledge of this should guide you in ascertaining both thermodynamic and rational evaluation of how Ag should behave. For example, if you ...
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Started by
I have some questions about diagnostic leaching.Should we compare the diagnostic leaching results with Gold deportment information from mineralogical analysis? These two results should be interpreted separately or they should agree with each other so...
Last replied to by Unterstarm
Just sharing of previous experience, often a GRG centrifugal concentration such as Knelson or Falcon should need to be run as the first part of Diagnostic leach to catch the free Gold content. Followi...
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598
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Started by Obergruppenfuhrer
What are the reasons why high cyanide concentration does have a decelerating effect in gold dissolution? Our process is batch type, maintaining pH of 10.5-11, leached for 24 hours. The ore contains: Gold, silver, high in quartz, high with pyrite, and...
Last replied to by Sturmbann
I think it's because of other secondary reactions that consume CN.

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