gold suspicious sample

[ahmadbayoumi]

Thanks a lot dear members for your advises .. I really appreciate your replies

I'm not a one of those that could pay money just for other person's word

1st of all, i agreed with this contact that I wont buy anything from him i.e no money will be paid for him at this moment or even later.

He will send me another kg for more inspecting and testing and if this found to be real gold again then he can send 100s of kgs in time intervals at his own cost then if I managed to get any gold out of these kgs then it will be a share between me and him like 1/3 meaning 1 third for me and 2 thirds for him out of the net cash after considering the cost of recovery.

So i'll not pay even a penny for him now or even later.

Regarding this threads shared by 4metal, they seem to be very informative and need considerable time to read .. Many thanks 4metals

Will read them thoroughly and then will get back to you in case of any query which for sure I'll have a lot.

Many thanks for all your help and time .. really this is a great forum that combines a great members

 

[ahmadbayoumi]

Thanks a lot 4metals for providing these 2 links as they are really very informative and contain a lot of hands-on experience not just theory:

I managed to get another almost 1.368kg of the same sand.I divided this sample into 4 portions:
1- 100g will send for fire assay
2- 68g will be used for making another test using AR
3- 200g will be used to test the leaching solution I’ll be using
4- 1kg will be used for leaching if the test is ok

Now, after reading the posts shared by Deano many times, I think using Chlorine Leaching will be the most suitable method for me.

However, I’m still having some question that need your help to answer before getting starting:

- Deano said:

“My preference is for pH 7, 200 grams per litre plain salt, calcium hypochlorite starting at 1 gram per litre”

But in another post he said:

“Try making up a leach solution with 20% salt and 5 grams per liter calcium hypochlorite at pH 7- 8 (equals pH 8-9 on a meter), sniff it carefully and see what level of chlorine there is in the air. Usually you have to try fairly hard to smell any chlorine.”

So should I start 2with 1g/L of calcium hypochlorite then keep adding 1g every while or should I prepare the whole leaching solution ahead using 200g Nacl/5g Ca(ClO)2/Litter of water?

- Deano said:
"Care must be taken that evaporation does not cause the salt level to rise to the level where salt starts to crystallise in the leach solution, apart from the operational problems this can cause there will be gold losses from co-precipitation."

So What will be the source of evaporation and how I can avoid it?

- Deano said:
A close check must be kept on carbon loadings, if loadings are allowed to get too high there will be loss of gold by attrition from the carbon.

What is carbon loadings as I really can’t understand this part?

- Deano said:
"Leaching is continued until there is no rise in the gold in solution levels, at this stage consult your clock for leach times."

What is meant by “no rise in the gold in solution levels”?

- Can I use the clorox bleach (5% Soduim hypochlorite) instead of calcium hypochlorite and use HCL to lower the ph around 8 ?

- Is it correct to use NaOH to rise the ph value and HCL to lower the ph value if needed to keep it around 7-8 ?

- Should I use a big thick plastic tank or a plastic bucket would be enough ?
Also should it be sealed or not ?

Sorry for these lots of questions but I really need to undertand not just use certain recipe.

 

[ahmadbayoumi]

Sorry, forgot to give the credit to Deano as his posts were very very useful and for sure he deserves a big thank you

 

[4metals]

You are biting off a big chunk here as you have no experience in the testing or the lab techniques involved. Let me try to answer your questions so you can bet a better grasp on what you do not know and set you on a path so you can either learn the necessary skills or not.

I would, as you are suggesting, send out the material for fire assay. I would also make a second AR test for your own quick identification process. I would do the AR before spending on the assay.

Why do you feel the leach you prefer is the best? Usually samples for leach testing are prepared using various leaches and conditions and run as jar tests simultaneously. This is a big undertaking for someone with none of the lab supplies to do this.

If the samples do produce gold, and the assay comes back showing the OPT (ounces per ton) contained you need to do much more homework. If you were to be looking at sand running 1 ounce per ton, that is relatively rich by the way, you will be looking for 0.0311 grams of gold in that 1 kilogram sample. That is not something you just drop out by conventional means and weigh on a scale. That is something that is measured by an instrument called an atomic absorption spetrophotometer.

What I would do is wait for the results and if the gold is substantial (and 1 OPT is very substantial!) I would go the steps to verify the boundaries of the deposit so you can determine how much gold is in the deposit. If this is substantial, and verified by you as substantial by more sampling and more assay, then it pays to go the next step and recover the values.

So What will be the source of evaporation and how I can avoid it?

Deano works on rather large piles of ore, piles too big to put in a lab so it is outdoors. Outdoors in Australia with the hot sun and drought. Not unlike Egypt. You will need the ability to monitor the solutions and correct for volume fluctuations caused by evaporation. Large leach projects are projects for experienced people.

What is carbon loadings as I really can’t understand this part?

Since the gold is dissolved by the leach in small concentrations, you need a system of collection to remove the dilute gold from the leach to raise it up to a level where it can be collected and refined. There are many methods of doing this and Deano prefers to collect it on carbon. From there it is removed and processed by more conventional refining methods.

What is meant by “no rise in the gold in solution levels”?

When you get your preferred leach solution set up and begin pumping the leach, you need to analyze the solution as the leach will dissolve the gold and the level of gold in solution will rise. that has to be balanced with the rate you pump through the carbon which removes the gold from the liquid. This balancing is done with flow rates and analysis in a lab of the gold content in solution, and it is done by atomic absorption spectroscopy.

You sir seem to know about enough to get yourself in trouble with this material so I recommend caution. Apparently you are a good negotiator, your best path in this venture may be to do all of your preliminary testing and define the actual volume and value of the gold in this pile, and (with the help of a good legal contract) contact the recovery and lab work out. You can still profit nicely given the margins you defined earlier, and a working knowledge of what is happening will serve you well.

 

[ahmadbayoumi]

Many thanks for your reply 4 metals

After reading your reply, and despite the fact that I may be lacking some lab equipment but I became more enthusiastic to take the challenge.

So I really want to read and learn as it seems very interesting for me to know gold leaching.

I would, as you are suggesting, send out the material for fire assay. I would also make a second AR test for your own quick identification process. I would do the AR before spending on the assay.

That's what I already mentioned, I sent about 100g for fire assaying and will do another AR test on 68g for confirming gold in the sample. fire assaying will cost me nothing as it will be done by a friend of mine for free.

Why do you feel the leach you prefer is the best? Usually samples for leach testing are prepared using various leaches and conditions and run as jar tests simultaneously. This is a big undertaking for someone with none of the lab supplies to do this.

I think Chlorine leaching would be the best choice for me because the materials/equipment (NaClO, NaOH, Ca(ClO)2, HCL,Eh/Ph meters .. etc) used could be available in the market her in Egypt. Other leaching means/techniques might not be available in my area due various reasons.

If the samples do produce gold, and the assay comes back showing the OPT (ounces per ton) contained you need to do much more homework. If you were to be looking at sand running 1 ounce per ton, that is relatively rich by the way, you will be looking for 0.0311 grams of gold in that 1 kilogram sample. That is not something you just drop out by conventional means and weigh on a scale. That is something that is measured by an instrument called an atomic absorption spetrophotometer.

I think fire assay should give me the same results .. isn't it ?

What I would do is wait for the results and if the gold is substantial (and 1 OPT is very substantial!) I would go the steps to verify the boundaries of the deposit so you can determine how much gold is in the deposit. If this is substantial, and verified by you as substantial by more sampling and more assay, then it pays to go the next step and recover the values.

That's really what I'm looking for .. the next step .. and I need to learn

Since the gold is dissolved by the leach in small concentrations, you need a system of collection to remove the dilute gold from the leach to raise it up to a level where it can be collected and refined. There are many methods of doing this and Deano prefers to collect it on carbon. From there it is removed and processed by more conventional refining methods.

I need to know more about this so appreciate if you guide me to read any document or posts that give information about this topic.

When you get your preferred leach solution set up and begin pumping the leach, you need to analyze the solution as the leach will dissolve the gold and the level of gold in solution will rise. that has to be balanced with the rate you pump through the carbon which removes the gold from the liquid. This balancing is done with flow rates and analysis in a lab of the gold content in solution, and it is done by atomic absorption spectroscopy.

As i wont be able to get atomic absorption spectroscopy, so is there any other handy tool/mechanism that I can use for doing the same ?

You sir seem to know about enough to get yourself in trouble with this material so I recommend caution. Apparently you are a good negotiator, your best path in this venture may be to do all of your preliminary testing and define the actual volume and value of the gold in this pile, and (with the help of a good legal contract) contact the recovery and lab work out. You can still profit nicely given the margins you defined earlier, and a working knowledge of what is happening will serve you well.

So does it means that dealing with black sand is not applicable for small/home refiners ?
But i have read here in this forum that there are some individuals have dealt with this kind of black sands while they are not in professional labs or so.

frankly, sending the sand for some professional labs may be one of the valid options but this would be may last resort in case I completely failed to do my homework.

Finally, I really need to learn and to do this kind of work with the simplest tools that could be used.

So, is there any work around that could help in this regards ..

PLS help, and guide me in this venture.

 

[Eu_citzen]

New here and enjoying the read.
I have a similar situation as you do; sand with gold in it, also quite a bit of silver.

My initial testing has been done on one kilo, which using a gold pan I panned it down to concentrates, and then had it assayed. I'd try that and see if it works for you.

 

[ahmadbayoumi]

New here and enjoying the read.
I have a similar situation as you do; sand with gold in it, also quite a bit of silver.

My initial testing has been done on one kilo, which using a gold pan I panned it down to concentrates, and then had it assayed. I'd try that and see if it works for you.

I'm thinking that, it may be better to use a water sluice as my 1st step to get concentrates so I may give it a try.

Now, I'm waiting to know about your trail.

 

[Eu_citzen]

New here and enjoying the read.
I have a similar situation as you do; sand with gold in it, also quite a bit of silver.

My initial testing has been done on one kilo, which using a gold pan I panned it down to concentrates, and then had it assayed. I'd try that and see if it works for you.

I'm thinking that, it may be better to use a water sluice as my 1st step to get concentrates so I may give it a try.

Now, I'm waiting to know about your trail.

I'd say it depends on the conditions. I have water readily available and as such use it; next step up is doing a larger sample as to verify the original results.
Then I'll be examining the actual amount of gold bearing material. (as in, is there enough sand to mine it and make a profit?)

 

[4metals]

Then I'll be examining the actual amount of gold bearing material. (as in, is there enough sand to mine it and make a profit?)

Smart! This is what has to be done in Egypt as well, it may be very high yield and in very limited quantities, which translates into "not profitable."

 

[4metals]

I think Chlorine leaching would be the best choice for me because the materials/equipment (NaClO, NaOH, Ca(ClO)2, HCL,Eh/Ph meters .. etc) used could be available in the market her in Egypt. Other leaching means/techniques might not be available in my area due various reasons.

The ore doesn't really care how difficult it is for you to obtain the leaching materials, the leach is selected based on the composition of the material and how it responds to the leach you use. For large scale leaching, using the most effective leach can make all the difference between profitability and bust. Determine the leach that works best first, then worry about where to get the supplies.

The process of leaching and analysis is not conducive to fire assay. It can be done by meticulously evaporating a known quantity of leach solution down to a solid salt and doing an assay fusion and cupelling the resulting lead from the fusion. The process is very time consuming and will make it difficult to control an active leach circuit. An atomic absorption is much quicker and allows control in real time. This is the kind of project that you can either do properly or risk losing everything. If you determine that there are hundreds of tons in the deposit and your recovery will produce hundreds of ounces, spending $7,000 to $10,000 on an instrument to do it efficiently isn't such a stretch. Which again gets back to the point of determining how much metal is available for recovery before you waste a huge amount of time and expense.

So does it means that dealing with black sand is not applicable for small/home refiners ?
But i have read here in this forum that there are some individuals have dealt with this kind of black sands while they are not in professional labs or so.

Is your material black sands, is it magnetic? These are important details which cannot be omitted if you are serious.

It is also entirely possible that your material is amenable to concentration on a table. If you are skilled with a gold pan you should see if panning will allow you to concentrate some values, that is the first and simplest test to determine if a table is your answer.

 

[Eu_citzen]

Then I'll be examining the actual amount of gold bearing material. (as in, is there enough sand to mine it and make a profit?)

Smart! This is what has to be done in Egypt as well, it may be very high yield and in very limited quantities, which translates into "not profitable."

Indeed. In the meanwhile, I'll have to look into extracting the metals, to see what minerals I am dealing with.
ahmadbayoumi has it easier - going only after the gold.

 

[ahmadbayoumi]

ok .. fair enough dears

I'll start by panning as it's of course more easier.

But i have one query here .. what is the difference between the sluice and the table ?

And if i'm going to use the sluice, does it affect the efficiency ?

 

[4metals]

But i have one query here .. what is the difference between the sluice and the table ?

I am not a miner or a prospector and do not have a lot of table and sluice experience although I have operated both. It is my experience that a sluice is more targeted to the nuggets you can see, although some carpet sections do catch some of the flour gold which needs to be further panned down.

A table is like a sluice on steroids, it can be fine tuned and will produce finer separation than a sluice can produce and because of this it will have greater recovery, IF, and this is a big if, the material is amenable to processing on a table.

I would hope a few members with more experience sluicing and using a table would offer some opinions here.

 

[g_axelsson]

A table can be run continuous, you never have to stop to recover the gold, but you need higher concentration on what you put in. A sluice can be run at a higher speed but the gold is trapped in it so you have to stop now and then to get the gold out.

A gold mine close to me is running their ore through spiral concentrators and some other equipment, then the concentrated ore goes to a large table where most of the gold and a lead fraction is recovered. The tailings is then run through a flotation bath to capture other sulfides as copper and zinc and that also contains a bit of gold but quite a lot of silver apparently.

Göran

 

[4metals]

Goran,

I assume the material is crushed and screened to a constant size before the wheel and the table. Do you have an idea of the size it is classified to?

 

[ahmadbayoumi]

Many thanks for replies

However, every time a got an answer to one of my queries another question raises up searching for an answer as the others.

A table is like a sluice on steroids, it can be fine tuned and will produce finer separation than a sluice can produce and because of this it will have greater recovery, IF, and this is a big if, the material is amenable to processing on a table.

What is the characteristics of the this amenable material ?

I have been asked before what the material is so I'm posting here some pictures that has been taken for the sand sample I got.

As you can see, the gold could be seen with naked eyes. Also, I tried a magnet over the sand and a lot of the sand got trapped in the magnet meaning that the sand is magnetic and contains iron.

 

[g_axelsson]

Goran,

I assume the material is crushed and screened to a constant size before the wheel and the table. Do you have an idea of the size it is classified to?

Sorry, it was like fine sand I guess. It was a long time ago I visited the the wash plant, almost 20 years ago. The mine went bust (rather the owners with several mines) when the gold price fell around 1999, bought up by a group of local investors, made back the money in three months by running stored ore, sold again to a large mining company and on...
Last year they mined 48.000 ounces of gold. :wink:

The ore went into a jaw crusher, then fed into a ball mill and a rod mill in parallel, maybe sorted by size. The crushed ore then went through some gravity concentrators, what stuck in my mind was the room with spiral concentrators, the large table with a yellow band of gold flowing over it and the flotation plant.

The current owners have a detailed web page about the mine.
http://www.mandalayresources.com/properties/bjorkdal/
I live 170 km to the south.

Göran

 

[4metals]

I must admit that some things are easier to evaluate in person and since your eyes are about 5500 miles from mine (thank you Google) we have to put a lot of weight in your descriptions and your testing, and even then sometimes you never know until you try. This can be especially true with ore on a table.

Even if your ore is crushed to the size they recommend and it is the proper density, you can never be sure. If you are successful panning this material you have a better chance of success but there still things to consider. Since there is a new detail, magnetic sand, you may possibly have some black sands. I would weigh out a kilogram exactly and using a magnet, separate out the magnetic fraction. And write down the weight you removed. Then crush the rest of the sample and try it in a pan. Actually you could try this without crushing first to see if you are successful as long as the grains are relatively small and uniform in size. If it doesn't work without crushing I doubt it will get better but you have to try. Dry the sand, crush it, and re-pan the material. If you get a line of gold panning is an option. But, and there's always a but! But you have no idea how much of the value was lost panning so you need to collect all of the sand that was panned off, dry it and send it out for fire assay.

Running samples on a wave table may or may not work for you and all the theory in the world is useless until you try it and see. I can tell you a story from first hand experience.

Back in the 1980's I was incinerating and sampling jewelers sweeps and shipping them to a smelter in Europe. In addition to the refining fee's there was a $1.00 per pound fee on the incoming weight. We shipped thousands of pounds a month. The particular lot I am talking about was assayed to contain about 4% by weight gold. Or just over 18 grams per pound, much richer than the sands you are looking at. My thought was if I could eliminate a lot of the bulk on a wave table we could save a lot of money by shipping less pounds of a more concentrated material. A salesman from Action Mining told me his table was made for just that purpose. My material met his density criterion and his size criterion (ours was -60 mesh powder) and had enough gold for a good recovery. So he suggested I pack up 5 pounds and come out for a test on their newest best wave table.

So off I went to Action Mining with a 5 pound bag of assayed dirt. They confirmed the density and I reiterated the assay and they sieved a sample to determine size. Then they said it needs to be wetted by the water on the table and since it had been incinerated it needed a surfactant to help, otherwise it would float on the water. We wet the sample and mixed in a surfactant until it all sank quickly and it was put on the table with assurances by the smiling salesman that in a short while we would be looking at a line of gold on the table. When the brown water cleared, all that was there was the pretty blue color of their table, no gold, not even a hint, just a clean table.

The drain on the table ran out a pipe into a trench along the building that was just a swale the pipe dumped into so the water would soak into the ground by gravity. Seeing as my gold was obviously not on the table, we went outside to see the swale full of brown water. That was an expensive lesson as the sample had just shy of 3 ounces of gold in it which was now evenly distributed in a shallow 100 foot long trench. (Fortunately gold was in the $300 an ounce range then) I told them they might want to dig a few inches off the bottom of the trench and use one of their leaches to recover the gold that I was leaving behind. So I left with the words ringing in my ears from their staff that it should have worked. So you see, you never know until you try. I do remember my partner could not imagine that I left without all of the dirt from the trench holding our gold. I remember my professional advice was something like "Take a Valium and chill out!"

 

[Eu_citzen]

ok .. fair enough dears

I'll start by panning as it's of course more easier.

But i have one query here .. what is the difference between the sluice and the table ?

And if i'm going to use the sluice, does it affect the efficiency ?

I haven't operated a lot of tables, but have used plenty of sluices.
A table produces a much cleaner product, and the magnetics isn't a problem for most part. (unless there's lots!)
In fact, some run their sand through a sluice and finish it off using a table.

As said, a table doesn't have to be cleaned up like a sluice. But in my opinion a sluice is good for large amounts of low grade ore. Think of it as a first step of concentration.
If the ore is high grade, a table might be better.

If you can pan out the gold, I'd think a table or sluice will work.
As for efficiency, yes, there will be some loss. Both table and sluice will have to be set up right to work and recover most of the gold. A simple test is to pan the tailings of the sluice.

 

[ahmadbayoumi]

Yes, it was really an expensive lesson 4metals

Her in Egypt we say that "One can't learn for free" meaning that you have to pay something in return (money, time .. etc).

Thanks for your replies 4metals, Göran, and Eu_citzen

Now to summarize, both sluice and table might work and I should give it a try to confirm if it's really going to work or not.

Now my next step is to build my own sluice and table so any advise on the preferred design for both ?

For the sluice, I already did a small prototype earlier and it was working but it was a small scale one.

Now, I'd start building a larger one using something like a rain gutter.

However for the table I would start from scratch.