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How to Improve Leach Plant Recovery (5 replies)
If the Copper content is from oxide minerals, use the SART Process to lower copper in solution then cyanide as usual.
You can read more about SART Process in this paper presented at World Gold 2011 in Montreal, October 3-4, 2011:
IMPROVING THE ECONOMICS OF GOLD-COPPER ORE PROJECTS USING SART TECHNOLOGY
What is copper content in ore?
What is copper content in solution?
Do you know what copper minerals are? They may or may not interfere with cyanidation. Mineralogy knowledge is needed first of all.
Copper in solution may not affect to some point as soon as you have low residence time and quick gold removal from the solution. Usually Cu has slower kinetics both leaching and adsorption than Au and Ag.
Where SART is used? I read just SGS booklets and articles on the lab tests. Where is it implemented in industrial environment?
The copper content is 0.8%, in solution at times will be 2.20. Initial detention of the solution is almost 12hrs.
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/thickening and additional water supply. What are the reserves and what fineness of the material you have? It may be the best economically to sell copper concentrate and get Au premium from it and leach flotation tailings. For this you will need some mineralogy done to find Cu mineralogy, liberation size and association to have an idea on concentrate that can be obtained.
The copper content is very high in solution. You may try dealing with by adsorption on zinc, electro winning, Cu solvent extraction or precipitation with sodium sulfide after Au sorption. Check the following existing technologies: MNR, AVR, SART (SGS), Cyanomet, AuGment, Vitrokele, Hannah (SGS), Cyanisorb, Cutech (Palmer/Clark process).
Many of them use CN recycling and Cu sulfide precipitation. During the processes pH drops to 4 or less, so they use enclosed reactors to keep and recycle volatile CN and turn it back into NaCN. So, it requires a lot of safety measures and very skilled personnel.
Electrowinning can be good for Cu concentration you have, but may be expensive and still will need capturing of CN from electric cell. It may have lowest capital costs.
Solvent extraction may be too expensive.
Based on your head grade and tail grade the gold recovery ranges 96.7-97.5%, and also the ore contains copper contents of about 0.8%, then if you maximize the gold recovery by altering the leaching parameters such as increase in residence time and cyanide concentration, you will increase the copper recovery as well because these parameters favor copper leaching
the options you have, you need to start with pretreatment stage such as flotation of copper to remove more copper followed by optimization of gold recovery (needs good financial status), beside that you can stay with same parameters then you need to reduce particles size of ore to increase surface area of particles which in turn gives easy accessibility of solution of gold in an ore, followed by acid wash to remove more copper before elution
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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