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Pyrite Flotation (6 replies)

Carmen Ibanz
10 months ago
Carmen Ibanz 10 months ago

Can you list the factors affects the floatability of pyrite from refractory low grade ore.

I used a Wemco lab flotation cell and aimed on analysing factors like collector dosages (PAX), Activator (Copper sulphate),MIBC , pH and others like pulp density and particle size (70 and 150 microns) .However how these factors affect the floatability of the pyrites from low grade refractory ore.

As i know this refractory ore generally locked in sulphides and not give economic recoveries with conventional cyanidation unless pre-treatment methods should be done. My option was to analyse how those mentioned factors and the others I don’t know affect the floatability and also i believe flotation method is cost effective and environmentally friendly but what other major reasons can support this selection of flotation method and not conventional cyanidation?

It is true that the ore is disseminated in pyrite, arsenopyrite , pyrrhotite.

Zander Barcalow
10 months ago
Zander Barcalow 10 months ago

Normally pyrite should float well under typical sulphide flotation regime. However, surface alteration such as tarnishing due to geo-chemical actions can be one of the inhibiting factors.

Dizzy Flores
10 months ago
Dizzy Flores 10 months ago

In your sense, does the refractory ore refer to the gold ore that gold is finely disseminated in pyrite and arsenopyrite? So, this is why you try to replace the cyanidation by flotation for gold recovery.

Ace Levy
10 months ago
Ace Levy 10 months ago

From your detailed post above I gather you are trying to optimize various conditions such as collector, activator etc. in a lab for best recovery of pyrite. Am I right? Can you please elaborate and be more specific on the nature of this refractory ore?

Jean Rasczak
10 months ago
Jean Rasczak 10 months ago

If I understand correctly you are working on a refractory gold ore with the gold being refractory because it is 'locked' in the pyrite. The normal options considered for this type of gold deposit are:

Make a sulphide concentrate by flotation then oxidize the sulphides by autoclaving, roasting or ultrafine grinding and atmospheric oxidation. In some cases the flotation tailings are cyanide leached to recover gold not floated to concentrate.

Oxidation of the total ore, either by roasting or autoclaving followed by cyanidation.

The choice is driven by the various step recoveries, their respective costs and the mineralogy of the ore.

Flotation is a cost effective and relatively easy way to concentrate gold locked in sulphides. Simple cyanidation will not leach gold locked in sulphides so flotation is an effective way to reduce the amount of material requiring more intensive treatment.

Carl Jenkins
10 months ago
Carl Jenkins 10 months ago

I gather that when you say the "ore" is disseminated in pyrite etc. you mean the gold is associated with these minerals and is refractory. Sometimes you can be lucky and just a finer grind on whole of ore may help to recover a large proportion of the gold if the particle size of the gold is sufficiently large. However as George has posted, the other options are as he has laid out.

The main problem I see is in you initial post where you say "low grade". The grade is the driver for any beneficiation and gold recovery process (followed by the amount of material). If it were possible to sell the concentrate if the gold grade of it was sufficient and the sulphide concentration is OK for further beneficiation then you may be able to investigate the sale of the concentrate to a third party. If not the costs of setting up a new facility for the oxidation of the concentrate is highly capital intensive and also has high operating costs. Again you may be lucky enough that you can float a concentrate and then do a finer regrind of the concentrate before leaching in the CIL circuit.

Grade is "God" in any process.

Sugar Watkins
10 months ago
Sugar Watkins 10 months ago

From my understanding, you would like to get a high pyrite flotation recovery because the gold is locked in the pyrite. And you are trying to analysing the effect of various factors on pyrite flotation.

I would suggest:

1.It will be good to find out the optimum particle size firstly. You mentioned 70um and 150 um. I guess it’s better to try several more sizes, because the gap is too large between 70um and 150um. The purpose of grinding is to achieve the sufficient liberation of pyrite without overgrinding. If you have access to some mineralogy tools, such as MLA and QEM-SCAN, it will be easy to look at the mineralogy and liberation after grinding, which could be very helpful for you to choose the suitable particle size.

2. pH is important for pyrite flotation. Normally, pyrite can float well at acid conditions without adding any activator. However, if you want to float the pyrite at alkaline conditions, you need to add Cu2+ as activator, because pyrite can be depressed at alkaline conditions.

3. The effectiveness of activator (e.g. copper sulphate) can be affected by the pulp chemistry, such as pH and Eh. Therefore, it is important to monitor the pulp chemistry when you testing.

4. Froth stability could also be important, and can be influenced by the collector dosage and also the addition of activator. It’s better to monitor the froth when you doing your test, and also calculate the water recovery for every test.

Since you are considering so many factors, it’s better to spend some time on the experimental design before you starting your test work. 

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