Gravity Separation & Concentration Methods

Gravity Separation & Concentration Methods2017-04-04T06:57:23-04:00
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Upgrading Slag Powder Containing Gold (4 replies and 1 comment)

1 year ago
balaji1967 1 year ago

Hi. we have plenty of low grade ore available here. I have low grade ore of black sand contains 4 to 5 ppm of Au by fire assay test with AAS finish, which i want to upgrade. Is trommel washing plant ok?. supplier says if the input is 100 tons of 5ppm then output will be 1 ton of 490 ppm. is that right? but testing facility is not available with him.or is there any other method where i can upgrade the ore from 5 ppm to 50 ppm?

1 year ago
TonyE 1 year ago
2 likes by balaji1967 and David

Consider attritioning the -1 mm particles in an attritioner in order to liberate the gold particles from the iron oxides/sulphides followed by a magnetic separation and a gravity concentration step such as a TBS.  

You need to do some fractional/magentic/gold testwork and analyses to guide you to the correct configuration.


1 year ago
SmartDog 1 year ago
2 likes by balaji1967 and David

The trommel plant might help in concentrating the gold containing black sands, IF the sands are contained in a regular body of material with a lot coarser material.  Trommel plants are basically classification circuits to remove large rocks and break up clay and mud.  It will only concentrate if a gravity separating device is included (jig, sluice, table, etc).

But if that is the case it might work.  To be safe you could obtain a small used unit process such as a highbanker, or mini trommel.

1 year ago
babygenius76 1 year ago
2 likes by balaji1967 and David

In your title, you call the material "slag powder," but I do not think the material has been put through some type of pyro (heat) treatment, correct? Be very careful because 4 to 5 ppm (i.e., 4 to 5 grams per tonne) for a "black sand" material (I assume alluvial material) is high grade.  Have you done a proper exploration on this deposit or did you grab some random samples and had them tested? I would advise that you do proper exploration first. 

After exploration, you may find that the average is closer to .25 grams per tonne. You will then need to do a proper metallurgical analysis with particle size distributions and lab/pilot scale testing to determine which gravity processes works best on your ore. It may not be the trommel. You will also need to look at the mining economics of the deposit.  Can you excavate and process sufficient volume given the costs? Using human labor for mining may seem cheap, but you will find that it becomes very expensive per gram of gold extracted.  You will end up losing money.

The worst thing you can do is to rely on your self-serving vendor. How does he know how much the trommel can upgrade on your ore? He does not. He just wants to sell you the equipment.  

1 year ago

Thanks for your reply and it is indeed very useful for me.

Now as you said it not pyro treated. It is basically a jewellery factory waste which goes to sewerage treatment and becomes solid residue from which people locally extract gold with their conventional process and the leftover is the material i am talking about. But it contains 4 ppm when we do fire assay. we will be getting sufficient quantity every month and that is not a problem.

My concern is it possible to upgrade this from 4 ppm to 40 ppm with machine. If so which will be a suitable method?

1 year ago
BATALEUR 1 year ago
2 likes by SmartDog and David

The starting point is to understand how the gold occurs in the black sands - is it liberated, associated with other metals or minerals, etc.  Do some basic mineralogy first.  Often gravity separation gives poor recoveries if the gold is not metallic and fully liberated; recovery of fine gold is also difficult.  A more likely route would be to cyanide the sands and adsorb the gold from solution onto activated carbon.  In all cases some testwork is needed before buying equipment.


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