- To participate in the 911Metallurgist Forums, be sure to JOIN & LOGIN
- Use Add New Topic to ask a New Question/Discussion about Flotation.
- 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.
Improve gold recovery and depress Cu in flotation circuit (7 replies and 3 comments)
pH 8-9 adjusted by soda ash.
I would not try to depress this small amount of copper. You will depress gold doing it.
I would up my pH to 10 and go.
Gold floats like copper - 10 pH is optimum.
You may need a small cleaner cell for the rougher concentrate before leaching.
What are the assays of your rougher concentrate now?
"intensive leach prior to EW process" direct or carbon/strip in between?
The copper became problem since Cu content in EW cake about 25-35% and refinery regulation for Cu content max 5% in dore.
Current teratment are using sulfuric acid wash of EW cake prior to smelting.
Rougher concentrate assay about Au 50g/t, Ag 1500 g/t Cu 1200g/t.
Direct leaching and leach rate up to 95% gold.
The problem in leach due to many froth not breaks and cyanide consumption is too high. May be because of xhantate consume the cyanide.
Could you please help me what kind of chemical to break the froth prior to leaching.
Currently I have purchase some NaHS to trial in flotation.
After reading your information, I would like to make some comments,
If the sample or samples tested in the met lab are not representative, the metallurgical performance will be different in the industrial flotation circuit.
The gold and silver mineralogy should be similar, otherwise, the precious metals recovery will be different. The mineralogy has an impact on the degree of liberation of gold and silver bearing minerals.
If the flotation feed size in the testing program and the plant are not similar, the recovery of precious metals is affected.
Other parameter to evaluate is the retention in the lab and rougher flotation circuit. The flotation time in the lab is multiplied by a factor (e.g. 2.8, 3.0) to estimate the rougher flotation in an industrial flotation circuir. Try to evaluate it.
The copper content is low for flotation, but it could be a problem in the leaching circuit. It is importnat to know the copper mineralogy. For example, if there is malachite or crysocolla, they have a low recovery by flotation, but they can contaminate the concentrate in small quantities, which could consume NaCN. The presense of secondary sulphide copper mineras such as chalcocite or covellita is a problem because they can be reported easily in the concentrate and can be leached partially by NaCN. You should know your mineralogy to know the effect of NaCN.
First of all, thanks for pay attention for helping me.
Samples for lab test and flotation circuit are absolutely same because sampling point on flotation feed.
Flotation time in lab are 5 minutes and in the circuit about 30minutes.
Mineralogy shows "Major minerals identified by bulk XRD analysis is Quartz 72.8%. Dolomite 7.4%, and Orthoclase 7%.
Sulfide minerals identified is only Pyrite 0.5%. Other minerals, that are identified in the sample, are
Albite, Illite, and Kaolinite".
We have mineralogy data for froth concentrate in 2019 (different sample) shows 52% pyrite, 20% Quartz and 10% K Feldspar.
As with a cyanide process, copper can be a problem when looking for gold recovery. Almost any reagent that works well with gold, we also float copper to varying degrees. The opposite is often true also, any reagent that floats copper will also float gold and silver. The case is also true for depressants.
The answer is then generally to make this work for you by going for a high copper recovery, which will usually allow for a good gold and silver recovery. Then during the EW step set is up for best copper plating, whihc will often leave the gold and silver in the sludge. The sludge can then be leached for gold recovery.
Based on your new comments, the lab performed the tests using a sample from the flotation circuit. That's good. If the lab operator did not make any mistake, you can consider the result. I don't know if the test was repeated to confirm the first result. Sometimes, it is a good practice to repeat the test to evaluate the variability.
Apparently, there is a problem in the rougher flotation circuit, I think, you should review the addition of flotation reagents. I mean, addition points, dosificaction (ml/min), reagents feeder (clarkson, pump, solenoid valve, clamp). Also, the collector preparation system (equipment and strength)
Other point to evaluate is related to the flotation cells. Maybe, there is a mechanical problem in any of them. The Maintenance Department should provide information on the replacement of rotors and stators.
The metallurgical performance cell by cell can provide information on the recovery of precious metals cell by cell. You need to collect samples of feed, concentrator and tails. In this way, you can build a recovery curve cell by cell. It is important to collect samples 8 or 12 hours. Also, you can evaluate and confirm the retention time.
I will work to see recovery cell by cell, as you said maybe there are some problem with mechanical.
I am currently working on a small gold processing flotation. An old mine which was rest for many years and started again in 2020.
Mill feed grade:
150 TPD, Au 2g/t (rec 65%), Ag 100g/t (60%), Cu 70g/t (40%)
The rougher machine is from xhin hai type BF or JJF wich is equipped with self aerated with no cleaner, no scavenger. So concentrate from the rougher then send to intensive leach prior to EW process.
Pax: 70g/t, Aero: 60g/t, MIBC: 30g/t.
In the laboratory test by this dosage rate, gold recovery achieved 80-90%, Silver 70-80% and Cu 50-60%.
Gold recovery still very low and the copper is high.
Could anyone help me how to improve gold recovery and depress copper?
Thank you very much,