Hello again all.

Wherever I have got with the rod-mill / rod-milling and sieve-analysis quantifiying that comminution is good enough for now.
[I have another test-milled comminute where have the sub-150micron to
sieve to +75micron and -75micron, plus the very-very-fines I separated
by sedimentation (I stirred the comminute in a trug of water, left it
a settling time in the seconds range then ladled-out from the
near-surface the water there - which although barely-transluscent,
mostly opaque, pours straight through the 75micron sieve) to dry, then
weigh and plot the mass-fraction at size distribution graph].
The experiences along this path are the enough for now.

Rod-mill now - updated https://youtube.com/shorts/pEAhv19OkkQ?si=LoNvtbvVL2VKpuwX
"Rod-mill with new end-cover working well"
New end-cover presenting plane end-face (idler-wheel could prevent
axial motion) and good metal-to-metal contact (gasket should make fluid-sealed). Cover held in place with 6 studs and nuts.

I've already used "Stokes' Law" for the "sedimentation" trick.
Which gives by removing the very-very-fines
* expecially the fractured silica, which is hazardous, absent from the
dried everything else
* leaves gritty/"sandy" particles which sieve readily no "clogging"

If using sedimentation, elutriation, or "just" to classify comminute
if I form a circuit in processing minerals, it looks like I need to
use hydrocyclone(s).
Plastic ones are readily available in the small size range for
removing very-fines to the underflow (very few 10's of mm diameter and
very few hundreds of mm long).

Pumping?

My guess is
* centrifugal pump (would tolerate the fines)
* 3-phase motor, controlling speed with a VFD (Variable Frequency
Drive) [as already used on the rod-mill] to give target pressure
into the hydrocylone

What would you really do?

The first intent, by the way, is to recover the water for re-use
immediately.
Thus, a simplification in specifying the hydrocyclone is maximum
solids to the underflow, minumum solids to the overflow; thus no
target split on size, for what that's worth.

Thanks in advance.

Rich Smith

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"Jim Wilkins" <[email protected]> writes:

"Richard Smith" wrote in message news:[email protected]...

... then weigh and plot the mass-fraction ...

How do you weigh it?

I ask because accurate weighing is among the more involved and
error-prone operations in chemistry.

https://chem.libretexts.org/Ancillary_Materials/Demos_Techniques_and_Experiments/General_Lab_Techniques/Proper_Use_of_Balances

A general principle of measurement is try to be 10 times as accurate
as you require. With luck and practice the accumulating errors will
still leave you what you need, in your case the possible value of lost
gold versus the cost to recover it.

Kitchen scale from a "box store" - GBPounds6 - so about US$7or8.
1gram resolution on readout. Range 0 to 6kg.

I am currently test-grinding granite chippings, of no value &
builder's merchant cost. Finding out what happens. It's a "broadly"
exercise.
Most mass-fractions are in the hundreds and into 4-figures of
grams, so for now that's good enough.
So I am pleased with the results so far.
I got two large plastic kitchen bowls at the "box store", and quite a
number of stainless steels bowls of various sizes from a shop in an
ethnic area my friend passed through in London.
I am "just" pleased I have anything at the moment.

One result so far http://weldsmith.co.uk/tech/minerals/250709_sa_rm10gran/250709_sa_rm10gran.html "Particle Size Analysis on rod-mill "mis-grind" of 10mm granite chippings"

Another nearly done having updated mill.

Will look to improve weighing equipment if have jobs which matter.
Suggestion is resolve to 0.1g

Regards,

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...
Lacking those parts, perhaps a water bed fill/drain pump on a variable
speed drill with a latching trigger would do? https://www.amazon.com/Star-Water-Drill-Pump-024786/dp/B08MFS884W
...

You are right - "version a half" for a short recon. of the matter needs
to be something very simple using something existing.
Yes and can vary trigger pressure on the drill to change the speed and therefore pressure - qualitatively see whatever...

Thanks

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"Jim Wilkins" <[email protected]> writes:

"Richard Smith" wrote in message news:[email protected]...

"Jim Wilkins" <[email protected]> writes:

"Richard Smith" wrote in message news:[email protected]...

... then weigh and plot the mass-fraction ...

How do you weigh it?

I ask because accurate weighing is among the more involved and
error-prone operations in chemistry.

https://chem.libretexts.org/Ancillary_Materials/Demos_Techniques_and_Experiments/General_Lab_Techniques/Proper_Use_of_Balances

A general principle of measurement is try to be 10 times as accurate
as you require. With luck and practice the accumulating errors will
still leave you what you need, in your case the possible value of lost
gold versus the cost to recover it.

Kitchen scale from a "box store" - GBPounds6 - so about US$7or8.
1gram resolution on readout. Range 0 to 6kg.

I am currently test-grinding granite chippings, of no value &
builder's merchant cost. Finding out what happens. It's a "broadly" exercise.
Most mass-fractions are in the hundreds and into 4-figures of
grams, so for now that's good enough.
So I am pleased with the results so far.
I got two large plastic kitchen bowls at the "box store", and quite a
number of stainless steels bowls of various sizes from a shop in an
ethnic area my friend passed through in London.
I am "just" pleased I have anything at the moment.

One result so far http://weldsmith.co.uk/tech/minerals/250709_sa_rm10gran/250709_sa_rm10gran.html
"Particle Size Analysis on rod-mill "mis-grind" of 10mm granite chippings"

Another nearly done having updated mill.

Will look to improve weighing equipment if have jobs which matter.
Suggestion is resolve to 0.1g

Regards,
-----------------------------------
A good way to quickly judge accuracy is in parts per thousand, per ten thousand, etc, which immediately gives you the percentage of
uncertainty. The overall accuracy is no better than the least accurate measurement. Your scale resolves (not the same as accurate to) 1 part
in 6,000. If your samples are in kilograms it's a good match. A scale
should accept the typical weight of your sample plus its container,
ideally at half or more of full capacity for best resolution.

Ideally the company or government (Air Force) agreed to pay for the instruments I needed/wanted. These days I pay myself and make do with
what I find, which usually means commercially obsolete and out of calibration, or Asian import. I bought a mechanical scale that reads
to 0.01g from a gold etc dealer who had switched to digital. It reads
310g to within 0.01g, 1 part in 31,000. https://us.ohaus.com/en-us/dial-o-gramandcent-o-gram300series

At that level of resolution it's affected by air currents and breath,
though not as annoyingly as a more sensitive scale.

This is a good one for general use. The three weights extend the range. https://us.ohaus.com/en-us/triplebeam700series

Thanks for that expert guidance on accuracy and mess measurement.
It's the thinking process I see value in.
With this improvided activities there is a high risk of damage / loss of equipment, so am getting seemingly "good enough" quantitative
categorisations with low-cost things.

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"Jim Wilkins" <[email protected]> writes:

"Richard Smith" wrote in message news:[email protected]...

Pumping?

My guess is
* centrifugal pump (would tolerate the fines)
* 3-phase motor, controlling speed with a VFD (Variable Frequency
Drive) [as already used on the rod-mill] to give target pressure
into the hydrocylone

What would you really do?

Rich Smith

--------------------------

What -I- would really do is use the 120V 1 phase variable speed motor
I bought yesterday on half price closeout, and machine a shaft adapter
to the used filter pump from a neighbor's old pool. https://www.pennstateind.com/store/TCLVSKIT2.html?
It's the older 1/2HP model.

Lacking those parts, perhaps a water bed fill/drain pump on a variable
speed drill with a latching trigger would do? https://www.amazon.com/Star-Water-Drill-Pump-024786/dp/B08MFS884W

A valve on the discharge is the usual simple regulation, one on the
intake may cause cavitation and damage. https://datatool.pumps.org/pump-fundamentals/combined.html
"Closing a valve will add resistance to the system over the entire
range of flows ... Note the static head at zero flow will still be the
same."

I bought the motor to slow down my carbide grinder by driving the
green SiC wheel side shaft so I can grind steel lathe bits accurately
at low speed on the diamond plate wheel.

Yesterday I find a company less than a mile from where I live supplies hydrocyclones. Know them otherwise for mineral separation machinery -
were my largest customer for what I did in last welding job.

Day before had found in "the bible" of mineral processing (Wills
"Mineral Processing Technology") that have hydrocyclones down to 10mm
diameter for very fines. Actually held one yesterday.

My ventures enabled me to hold quite a conversation.

Running inlet pressure 3 to 4 Bar.

Regards,

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"Jim Wilkins" <[email protected]> writes:

https://www.sgs.com/es/-/media/sgscorp/documents/corporate/brochures/sgs-min-wa018-thiosulphate-leaching-alternative-to-cyanide-in-gold-processing-en-11.cdn.en.pdf

"The main chemical components of the leaching process (ammonium thiosulphate and ammonium sulphate) are common fertilizers..."

Thanks for this.
I am bemused by the gold extraction processes:
* mercury amalgamation
* cyanide leaching
* ...?

I have heard about both.
Apparently in historic gold mining areas in the USA it can be worth
re-working the tailing for the mercury.
I've seen videos of people using a retort with a condenser - which seems reliable and safe enough.

Cyanide is "funny" - in a way.
Seemingly can work very dilute and has the advantage of working when
alkaline. Meaning no other metal is "on the move".
One comment in a video I saw is that it is difficult to find a
replacement for cyanide which is LESS hazardous than cyanide...!!!

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"Jim Wilkins" <[email protected]> writes:

"Richard Smith" wrote in message news:[email protected]...

Pumping?

My guess is
* centrifugal pump (would tolerate the fines)
* 3-phase motor, controlling speed with a VFD (Variable Frequency
Drive) [as already used on the rod-mill] to give target pressure
into the hydrocylone

What would you really do?

Rich Smith

--------------------------

What -I- would really do is use the 120V 1 phase variable speed motor
I bought yesterday on half price closeout, and machine a shaft adapter
to the used filter pump from a neighbor's old pool. https://www.pennstateind.com/store/TCLVSKIT2.html?
It's the older 1/2HP model.

Lacking those parts, perhaps a water bed fill/drain pump on a variable
speed drill with a latching trigger would do? https://www.amazon.com/Star-Water-Drill-Pump-024786/dp/B08MFS884W

A valve on the discharge is the usual simple regulation, one on the
intake may cause cavitation and damage. https://datatool.pumps.org/pump-fundamentals/combined.html
"Closing a valve will add resistance to the system over the entire
range of flows ... Note the static head at zero flow will still be the
same."

I bought the motor to slow down my carbide grinder by driving the
green SiC wheel side shaft so I can grind steel lathe bits accurately
at low speed on the diamond plate wheel.

These are the 10mm hydrocyclones https://www.gravitycyclones.com/_files/ugd/e069c8_cef17ead15754d2395cede5022cbedd9.pdf
"Technical Specification Sheet GCH10F 10mm Fine Cut Cyclone"

Inlet pressure 3Bar to 3.5Bar
Flow-rate suggested to be about 0.2 m^3 hr^-1

0.2m^3/hr = (* 0.2 1e3)L hr^-1 = 200.0 L hr^-1 => 200L/hr
So that's about 3.3L per minute.

So changes any recommendation on pumps?

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