Froth Flotation (Sulphide & Oxide)

Froth Flotation (Sulphide & Oxide)2017-04-04T06:57:31-04:00
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How to reduce pyrite content from gold concentrate (5 replies)

Sachin Prakash
3 years ago
Sachin Prakash 3 years ago

I have a problem with my gold concentrate. My ore contains a percentage of pyrite which suddenly found itself in my flotation concentrate. Do you know what laboratory tests, and collectors that I can use in the flotation to improve my product by a few points?


max skinner
3 years ago
max skinner 3 years ago
1 like by David

Just an idea I had a couple of years ago that worked. You have to make sure that your gold is with the pyrite and not in the pyrite. Here is what I did, I had a concentrate that assayed 8 ounces per ton with a lot of pyrite which contained no gold, I gave the concentrates a very mild roast which turned the surface of the pyrite to magnetite. I then did a magnetic separation and made a 800 ounce concentrate. There are reagents that will do a pretty good job of floating gold away from pyrite, contact Cytec and SNF Flomin.    

3 years ago
inOr 3 years ago
1 like by David

I second what Max Skinner asked about the content of your gold-pyrite mixture.  If the gold is not in the form of inclusions in the pyrite crystals, then gravity separation would be useful.  The remaining pyrite could be removed by roasting a finer grind of the high density fraction in air to convert pyrite to magnetite and the gas SO2, leaving the noble metal behind.  If you do it this way, you need to take precautions to vent the gas from the work area and remove or dilute it in the area surrounding your shops.  

On the other hand, if the gold is included within the pyrite crystals, then you could follow his suggestion about partially converting the pyrite grains to magnetite and separating magnetically.  Alternatively, you could try finely grinding the pyrite/gold material followed by roasting.  The iron oxides can be removed by gravity methods and/or magnetic separation.  

As usual, you need to experiment with your material to find the best method.  

Rahil Khan
3 years ago
Rahil Khan 3 years ago

As Max/inOr pointed out, you need to understand your gold deportment. With some deposits significant amounts of gold are hosted by the pyrite (or arsenopyrite) mineralization and depression may result in lost gold recovery.

You ask about collectors and pyrite floating?  The best type of collector is less collector

3 years ago
Unterstarm 3 years ago

If there is significant metallic gold association with silver, because silver has a reactive surface for collector bonding, collectors for silver indirectly also result in gold recovery. Consequently, gold flotation recovery requires a focus on floating the associated base metals (predominantly lead, copper) and often pyrite minerals. While lime is often used in base sulphide mineral flotation, because excess lime also tends to depress gold flotation, a balance must be maintained between good base metal metallurgy and gold recoveries. Natural pH is recommended for gold flotation. Alternatively using soda ash for pH adjustment can reduce gold depression. Where gold is associated with pyrite in base metal ores where iron sulphides are depressed and report to the tailings, a separate tailings pyrite flotation concentrate should be considered. Producing a pyrite concentrate with associated gold maximizes gold recovery. Reducing lime helps improve the gold recovery. 

JP Garnier
3 years ago
JP Garnier 3 years ago
1 like by David


Please precise what are the conditions of your current process and we may be able to further dig into solutions if indeed Au is not associated with pyrite and cannot be liberated by finer grinding or regrinding after your rougher stages.



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