# Best Process to use on Black Sands/Dredge Cons



## layo (Jun 4, 2013)

I am wanting to learn the processes involved to chemically recover PM's from black sand. My plan is to pulverize the sand to around 400 mesh. I am looking for opinions on the most practical chemical method to recover gold, platinum and silver. I am not looking for you all to give tutorials (by all means if you feel so inclined) but to point me towards your process of choice keeping cost and practicality in mind. If you have suggested reading please tell me what you would read.


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## Claudie (Jun 4, 2013)

Refining Precious Metals By C.M. Hoke 
There is a link in my signature line to a free, downloadable copy.


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## patnor1011 (Jun 4, 2013)

Black sands need to be assayed first. You must know about everything which is there.


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## Mark Dando (Jun 24, 2013)

I am a beginner at this so please excuse the ignorance. We have had our sand tested by XRF analysis and have found a whole host of mineral . I took some and concentrated it in a pan and separated the magnetite and got the following results The magnetic stuff contains 24 ppm of palladium and 9.5 ppm of Rhodium,The non magnetic stuff contains 3500 ppm of silver and 6ppm of gold also in are high values of indium and tellurium and tantalum. so what should be my next step in attempting to recover these minerals and is it worth while at these sort of values


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## Westerngs (Jun 25, 2013)

My first step would be to place the paper with the XRF assay results in the trash bin where it belongs. It is worthless.

My second step would be to take a representative sample and submit it to a reputable fire assay lab.


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## galenrog (Jun 26, 2013)

I have to agree. A proper fire assay is needed. While my experience is limited in qualitative and quantities testing, I do occasionally submit sands with no visible values to to assayed. This has saved me lots of labor as most samples indicated PM far below anything I am willing to attack with my one man show.

As to the XRF. These machines are good only for the purpose for which they were designed: testing solid metals. Even so,
The solid metal, which will be an alloy of some type in ordinary circumstances, may not be homogenous throughout, thus testing a little, or in some cases a lot, differently on different parts of the surface. Using XRF to test sands, slag, conglomerates, or any other non-homogenous sample is will always give improper and inaccurate readings.

There is also the matter of proper calibration, which many ignore, expecting miracle machine to simply give them the answer they desire. It is not that simple. A few decades ago, when I calibrated electronic test equipment for the military, I encountered countless situations of users wanting equipment to perform tasks that the equipment was not designed to do. More importantly, the volume of equipment that was received for repair that was used and abused well beyond when it should have come to a shop for repairs and calibration was astounding. 

Prior to a stroke, which I lovingly call a brain fart, I understood much of the process within the electronics of XRF machines. Now I let others do that. 

Also, somewhere on the forum is a more detailed and technical explanation of XRF and the reasons for inaccurate readings. I do not recall just where it is, but a search should turn up something.


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## g_axelsson (Jun 26, 2013)

I wrote a description of XRF a while ago... http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=12763#p186739
but there might be more descriptions out there.

Göran


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## galenrog (Jun 26, 2013)

That be the one! God bless those more organized upstairs than I.


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