Laboratory Testing & General Mineral Processing Engineering

Laboratory Testing & General Mineral Processing Engineering 2017-03-23T09:50:31+00:00
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How to Recover Gold from Pyritic Ore (6 replies and 2 comments)

Standartenfurer
9 months ago
Standartenfurer 9 months ago

Hi. I'm interested in learning how to process the pyrite sulfide rich gold ores that are characteristic of the general area around Idaho Springs, Colorado. I'm a complete novice (currently I only run a sluicebox) and I understand that these are complex sulphide ores which are very challenging to process. I'm thinking a small leach operation might be best, but I don't know if I should also look at flotation and/or smelting. I understand that it could take years to learn, but I'm okay with that. Could you please give me a few pointers on where to begin? I realize that the first step is to find some rich ore that is in good supply and then design something particular to that. But in the meantime, where would you point me to begin learning the basics? Thank you. I just found your site and plan to be a regular.

Jorge Ganoza
9 months ago
Jorge Ganoza 9 months ago

It is important to collect samples from different zones (e.g. 4 to 6) to determine the gold and silver content, and also the presence of other elements (e.g. iron, copper, lead, zinc, arsenic, antimony, mercury, sulfur). If the results from the lab are interesting, it is important to get a mineralogical study to know the gangue minerals, gold bearing minerals, the presence of free gold, gold particle size, and degree of liberation.

The information is important to estimate the optimum recovery process and the potential recovery problems associated to the ore. If you want to evaluate one sample in particular you need at least 50 kg, but if the idea is to evaluate the metallurgical performance of several samples together, I think you should collect approximately 20 to 30 kg per sample.

For example, if the gold grade is 15 g/t (grams per tonne), you can evaluate gravity concentration, flotation, leaching, and a combination of two processes. If the gold grade is as low as 0.8 g/t, you should evaluate the heap leaching option. 

jpearcy
9 months ago
jpearcy 9 months ago

You can think of a roasting step prior to cyanide leaching. That is an option, although there are other ways as well.

Herman
8 months ago
Herman 8 months ago

I am in a similar situation but have my ore already with different assay reports as there are planets in the solar system. But they all agree there is lots of Zinc, gold, vanadium, some Yttrium and platinum and Rhodium.

I had a consultant chemist who got me going on a H2SO4 @60% leach but he has since disappeared and I am now trying to find out how to precipitate  the PGMs. Anybody who can help much appreciated. Thanks

Herman

kahonde
8 months ago

you can try gravity seperation technics to remove PGMs then you can leach using direct cyanidation to extract gold

kahonde
8 months ago
kahonde 8 months ago

the best way of leaching or treating  sulphide gold is through ammoniacal cyanidation or thiosulphate leaching.

 

max skinner
8 months ago
max skinner 8 months ago

One of the first things you need to find out is this, is the gold with the pyrite or in the pyrite, a big difference. If it is with the pyrite straight cyanidation or flotation can do the job. If the gold is in the pyrite it is a different ballgame. There is a process of nano grinding the pyrite ore, usually a concentrate, in an attritior with a solution of sodium thiosulfate. I have been experimenting with this and have been getting in the high 90's recovery. 

 

kahonde
8 months ago

What of using thiosulphate with particle ore sizes of 75um

Herman
8 months ago
Herman 8 months ago

The sulfuric acid leach formula I am using is patented but it is tested as 99 % leach of all PGMs and gold.Problem is that it doesnt include the precipitation formula.The formula I was using before I can say here was 1 part H2SO4 plus 4parts HCL plus 1  part ore if left alone will leach your ore down to just silicates.The end result was a white lump at the bottom of the container.If heated it would require less time of course to leach  but the extractions of the PGMs was individually with various salts. and PH adjustments in a particular order.The fellow I was working with before would autoclave the salts out from the precipitated powders.This would create crystals in the bottom of the autoclaves.I was around only half the time for the precipitation process so I was able to get the formulas for Platinum,paladium and rhodium but i missed the one on gold and silver and the other PGMs.The chemist said I wouldnt have to do the autoclaving with the new formula as it was much simpler but he has been gone for a long time now so I am stuck in the middle of all this half finished and Id like to get my money out of it.I was using the aqua regia folrmula before and dropping gold with SO2 gas which is real easy and safe compared to most stuff thats out there and the cost was good but the H2SO4 formulas is real cheap in comparison to many others including cyanide and thiosulphates.I had thought of ion exchange using resins but I am still learning that process and have a ways to go still.so.....anyone with anymore ideas or suggestions?or procedures?Thanks

Herman

 

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