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Can fracking extract gold?


Daumic
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In few years hydraulic fracturing has revolutionized the world of energy by the production of shale gas and shale oil.

It is perhaps possible that fracking can reach another resource in the depth of the Earth: gold.

A new theory established by geochemists (1) describes a transport of gold by trisulphide ion in hydrothermal deposit. Trisulphide ion chelates gold and facilitates its transport towards the ground surface by water. But the stability of trisulphide ion depends of temperature and pressure. Trisulphide ion decays at a depth of some kilometres and leaves a first deposit of gold. According to this theory, a second transport by chloride and sulphide ions explains the gold deposits near the surface.

We can imagine a deep gold deposit under each hydrothermal gold deposit. The deep gold deposits are probably more massive than the upper deposits because the transport by trisulphide ion is more efficient than the transport by chloride and sulphide ions. These deep gold deposits are not accessible by classical process of mining.

These deep deposits are perhaps accessible by hydraulic fracturing. A depth of some kilometres is not a problem. The shale oil deposits of Permian Basin exploited in Texas by fracking have an equivalent depth of some kilometres. How can we extract gold? Perhaps by the following process:

-        two vertical wells to reach the deep layer of deposit,

-        horizontal drill between the vertical wells with a hydraulic fracturing,

-        circulation of water with gold chelatant in the fractured zone, for example pyridinethiol (2).

If this process works, gold extraction by fracking can be the beginning of a new chapter of fracking industry: the deep mining.

 

(1) Sulfur radical species form gold deposits on Earth (https://www.pnas.org/content/112/44/13484)

(2) Pyridinethiol‐Assisted Dissolution of Elemental Gold in Organic Solutions

 https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201810447

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Fracking involves pumping water ( with some biocide ) into underground cavities containing gas/oil.
And is already a dangerous process as it leads to seismic instability.

And you intend to pump chemicals which will essentially dissolve gold ore ???

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24 minutes ago, Daumic said:

The use of pyridinethiol is for chelating gold and not for dissolving ore.

That's a matter of perspective.
You intend to dissolve gold.

In fact it will dissolve a lot of metal oxides (zinc, iron etc)

So you will use huge amounts of a moderately toxic chemical, mainly to dissolve stuff you don't want.

 

Might still be an improvement on the use of mercury...

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On 9/1/2020 at 10:39 PM, John Cuthber said:

That's a matter of perspective.
You intend to dissolve gold.

In fact it will dissolve a lot of metal oxides (zinc, iron etc)

So you will use huge amounts of a moderately toxic chemical, mainly to dissolve stuff you don't want.

The great part of the ore is made of silicate that is not dissolved by pyridinethiol.

If pyridinethiol extracts other transition metals like zinc, it is not a bad thing, it can add a value to the extraction.

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On 8/26/2020 at 10:42 PM, Daumic said:

horizontal drill between the vertical wells with a hydraulic fracturing

I am not sure what you mean here.  I see two possibilities (Did you mean something else?) :

  • Drill a well which becomes horizontal at the zone of interest.  Drill a second (vertical) well to intersect the first at its end point. Employ fracing technology to facilitate penetration of the chemicals into the zone of interest.
  • Drill two vertical wells. Establish a connection between them by hydraulic fracturing.

The second method won't work economically. The first method is feasible in terms of well placement, but the fracturing pressures required would likely make this a non-starter. You have overlooked the significant strength difference between the comparatively weak sedimentary strata containing oil/gas and the much stronger metamorphic or igneous rocks that are gold bearing.

You have also ignored the greater cost of drilling wells in rock that is much harder and more abrasive than those encountered in oil/gas drilling. (Not to mention the greater challenge of achieving good directional results.)

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On 9/2/2020 at 11:35 PM, Area54 said:

I am not sure what you mean here.  I see two possibilities (Did you mean something else?) :

  • Drill a well which becomes horizontal at the zone of interest.  Drill a second (vertical) well to intersect the first at its end point. Employ fracing technology to facilitate penetration of the chemicals into the zone of interest.
  • Drill two vertical wells. Establish a connection between them by hydraulic fracturing.

I have a preference for the first method. As you noticed, this method permit to choose precisely the zone of interest.

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On 9/4/2020 at 9:11 PM, Daumic said:

I have a preference for the first method. As you noticed, this method permit to choose precisely the zone of interest.

Thank you for clarifying. Would you like to address my reservations, which I repeat below for your convenience:

The first method is feasible in terms of well placement, but the fracturing pressures required would likely make this a non-starter. You have overlooked the significant strength difference between the comparatively weak sedimentary strata containing oil/gas and the much stronger metamorphic or igneous rocks that are gold bearing.

You have also ignored the greater cost of drilling wells in rock that is much harder and more abrasive than those encountered in oil/gas drilling. (Not to mention the greater challenge of achieving good directional results.)

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On 9/7/2020 at 4:00 PM, Area54 said:

You have also ignored the greater cost of drilling wells in rock that is much harder and more abrasive than those encountered in oil/gas drilling. (Not to mention the greater challenge of achieving good directional results.)

If gold mining by fracking is possible, the gold value can amortize quickly the high cost of drilling and fracturing.

After the gold extraction, the drills and fractured zone remain for another use, like geothermal energy. T

Finally, the great value of gold can facilitate the development of geothermal energy.

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3 hours ago, Daumic said:

If gold mining by fracking is possible, the gold value can amortize quickly the high cost of drilling and fracturing.

After the gold extraction, the drills and fractured zone remain for another use, like geothermal energy. T

Finally, the great value of gold can facilitate the development of geothermal energy.

That reads more like unsupported optimism than a thoughtful and informed analysis.

For one thing, just because something is possible does not mean it will necessarily be economic. Until you put some meat on the bones of your idea and address the problems that exist for it then all you have is a highly speculative, vague notion. Thus, the answer to your question, can fracking extract gold, is probably, but not economically and not without major environmental concerns.

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On 9/2/2020 at 8:56 PM, Daumic said:

The great part of the ore is made of silicate that is not dissolved by pyridinethiol.

If pyridinethiol extracts other transition metals like zinc, it is not a bad thing, it can add a value to the extraction.

But zinc is already cheaper then the thiol, and you are bound to lose some of that expensive reagent.
Overall, this will probably lose money.

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On 9/12/2020 at 1:12 AM, Area54 said:

That reads more like unsupported optimism than a thoughtful and informed analysis.

For one thing, just because something is possible does not mean it will necessarily be economic. Until you put some meat on the bones of your idea and address the problems that exist for it then all you have is a highly speculative, vague notion. Thus, the answer to your question, can fracking extract gold, is probably, but not economically and not without major environmental concerns.

Unsupported optimism : this comment can be applied on high temperature geothermy. This sort of renewable energy is a promise never realised because its costs are too high. The extraction of gold or other high value metals in deep wells can help the financing of geothermy. Yes, it is speculative. Why not ? 

On 9/12/2020 at 8:08 PM, John Cuthber said:

But zinc is already cheaper then the thiol, and you are bound to lose some of that expensive reagent.
Overall, this will probably lose money.

In hydrothermal deposits, gold is more often associated with molybdenum or platinum than zinc.

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14 hours ago, Daumic said:

: this comment can be applied on high temperature geothermy.

Speaking of high temperatures; the sellers suggest storage of the thiol in the fridge. Nobody seems to have measured the boiling point.
These  facts suggest that it's not very stable at high temperatures.

How can you be sure that the material would survive the process?

 

14 hours ago, Daumic said:

In hydrothermal deposits, gold is more often associated with molybdenum or platinum than zinc.

It's slightly absurd to say that there will be more Pt and Mo than Zn and Fe.
The thiol doesn't choose the most valuable metal. It will largely react with the most common metals present.

Come to think of it, I can't see why pyrithione should dissolve gold.; it's not an oxidising agent.

You need to add an oxidant- in the paper they use peroxide.

But peroxides (and oxidants in general) destroy the thiol.

And the mix of metals and metal oxides (and sulphides etc) will also destroy peroxide (and any other oxidant).

Fundamentally, gold is pretty unreactive.

Almost anything else will react with any reagent more readily than gold does.

So, until you have washed all the metalliferous minerals out of the rocks and are left with clean silica, the gold won't dissolve.

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22 hours ago, Daumic said:

Unsupported optimism : this comment can be applied on high temperature geothermy.

Perhaps it can. Perhaps it cannot. That, however, is not relevant. I am applying it to your idea. Sidetracking into vague comparisons and loose analogies merely reflects the paucity of support for your proposal.

22 hours ago, Daumic said:

The extraction of gold or other high value metals in deep wells can help the financing of geothermy.

That is a claim for which you have provided zero support. Without that support it is of no more value than an assertion such as, "breeding unicorns should reduce global warming".

22 hours ago, Daumic said:

Yes, it is speculative. Why not ? 

Because this is a science forum and speculation is meant to accompanied by technical justification, through reasoned argument, or quality research material from reputable sources. Such support informs and provides a basis for interesting, robust discussion. It is also an implicit requirement of the rules. (Mods, please correct me if I have that point wrong.)

You just keep making the same assertion, while offering nothing substantive to support it. I would have thought, given your interest and belief in the concept, that you would have made an effort to assemble some data or argument to address at least one of the weaknesses I have noted about the project. Just repeating your beliefs doesn't work.

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  • 5 months later...

I don’t know how gold but oil and gas are extracted well with this method, it’s possible to change the approach and use other elements in hydraulic fracturing so that they do not dissolve gold, I think this would really be a breakthrough in gold and the metal industry where you can make high-quality metal by testing it with using spectrometers here is an example from a commercial website (in violation of rule 2.7) that analyzes the quality of metal showing the amount of chemical elements in it.

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  • 4 weeks later...
On 8/26/2020 at 11:42 PM, Daumic said:

In few years hydraulic fracturing has revolutionized the world of energy by the production of shale gas and shale oil.

It is perhaps possible that fracking can reach another resource in the depth of the Earth: gold.

 

Oil and gas reserves can only accumulate in strata that are at least somewhat permeable. These fluids are free are to migrate towards a low pressure zone within the formation (they are not enclosed in a solid crystalline matrix) and therefore the issue is not accessibility but whether or not the permeability is high enough to support an economic extraction rate. Hydraulic fracturing widens a proportion of pre-existing pores, and wedges them open with appropriately sized 'proppants' suspended in the fracking fluid. It's the geological equivalent of coronary bypass surgery.

On 8/26/2020 at 11:42 PM, Daumic said:

We can imagine a deep gold deposit under each hydrothermal gold deposit. The deep gold deposits are probably more massive than the upper deposits because the transport by trisulphide ion is more efficient than the transport by chloride and sulphide ions. These deep gold deposits are not accessible by classical process of mining.

These deep deposits are perhaps accessible by hydraulic fracturing. A depth of some kilometres is not a problem.

These 'hard rock deposits' have essentially zero permeabilty. The gold is enclosed in a welded crystalline matrix and therefore the issue in this case is accessibility. In order to get access to the gold particles for any form of liquid extraction process, the rock matrix has to be ground into fine particles otherwise significant contact between liquid and gold particles simply won't happen. Hydraulic fracturing cannot achieve this. Without the initial permeability, you cannot even get the fracking fluids into the formation in the first place other than possibly along pre-existing fault planes. Trying to widen these is probably not a great idea. 

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  • 4 weeks later...

The bigger problem is there's so much oil they don't care if they get all of it.

There's so little gold they want all of it. 

Usually a microgram per ton.

How will these hypothesizers chelate a ton of impermeable rock?

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