Clean up!

[Geowizard]

ProspectingAK,

The type of equipment depends on the volume of concentrates and size of GOLD.

For a small scale high banker with a volume of one gallon of cons, it is a simple, low cost process to screen and pan the cons.

When you get busy with more volume to cleanup, it becomes a trade-off when cost is considered. You probably would not want to invest in a shaker table like an RP-4 unless you are running 5 gallons or more and expecting several ounces of GOLD. The intermediate cleanup of two to five gallons of concentrates can be ran through a Blue Bowl and finish by panning. GOLD spirals are sensitive to setup. Water flow, angle of the spiral, RPM and feed rate make for a complicated process to control. A Blue Bowl requires proper feeding and water flow. Every situation is different because of the size of GOLD you may encounter from one area to the next.

Proper classification is important and cannot be over-emphasized.

-Geowizard

[Geowizard]

Sizing the concentrates;

After having screened the concentrates, there are several fractions...

The 4 mesh plus was scanned for nuggets and the reject tossed.

The 4 mesh to 8 mesh remains in a bucket. This fraction is usually hand panned.

The 8 mesh to 16 mesh remains in a bucket. This fraction is usually hand panned.

The 16 mesh minus remains in a third bucket...

There are a wide variety of methods used for cleaning fine gold. It is usually more time consuming. Many times the solution is to use a wave table. Wave tables are expensive and require a foundation and power. A wave table is usually set up indoors - out of weather conditions that might affect the operation.

There are other methods to look at...

- Geowizard

[Geowizard]

Hand panning;

When hand panning concentrates, it's always a good idea to pan into a pan...

The second pan can be used to check for lost GOLD.

Note: If you use the same process to re-pan the lost GOLD - you will loose GOLD!

Here's why...

The lost GOLD is usually small GOLD that is too small to compete with larger sand or heavies.

The solution is to screen with smaller mesh screens. If you want to recover 20 mesh GOLD, use a 20 mesh screen.

If you want to recover 40 mesh GOLD, use a 40 mesh screen!

- Geowizard

[Jim_Alaska]

Do we really need two threads dealing with the same subject?

[Geowizard]

Jim,

You might ask Joe about that - he started the second thread...

I started this one last year. It appears to have more posts on the topic.

- Geowizard

[Geowizard]

Weight of GOLD;

Using gravity to separate GOLD is based on the weight of GOLD compared to other materials. Most prospectors already understand that. The part that is often not recognized is the weight of GOLD particles compared to other particles that may have the same weight because they are larger.

Using spherical shapes for reference, here's a link to compare sizes and relative weight;

http://www.alaska-gold.com/weight_of_spheres.pdf

Screening as mentioned keeps particle sizes in the same size range. That gives GOLD the weight advantage.

What about other heavies in the pan?

- Geowizard

[Geowizard]

GOLD has competition;

GOLD is in competition with other heavy metals. Gold weighs in at 19.32 grams per cubic centimeter.

The only way GOLD can win the battle to remain in the pan is to be of the same SIZE as the competition!

Prospectors can have additional screens to keep particles classified according to size. A typical cleanup might end with a 16 mesh screen. The problem is... If 40 mesh GOLD is in the pan, it will be lighter than 16 mesh cassiterite. Cassiterite is a common heavy metal found in cleanup concentrates in Alaska. The cassiterite will stay in the pan and the 40 mesh GOLD will be lost.

- Geowizard

[Geowizard]

Weight of Cassiterite;

Here's a link to a chart that compares the weight of cassiterite to GOLD in water;

http://www.alaska-gold.com/weight_of_cassiterite.pdf

WHY SCREENING WORKS:

After screening concentrates through a 16 mesh screen...there's a problem!

The problem: 16 mesh Cassiterite weighs more than 20 mesh GOLD. 20 mesh and smaller GOLD is LOST.

Solution: Use a 20 mesh screen. 20 mesh GOLD is 3X heavier than 20 mesh Cassiterite.

The next problem: 20 mesh cassiterite weighs more than 40 mesh GOLD. 40 mesh and smaller GOLD is LOST.

Solution: Use a 40 mesh screen. 40 mesh GOLD is 3X heavier than 40 mesh Cassiterite.

The next problem: 40 mesh cassiterite weighs more than 80 mesh GOLD. 80 mesh and smaller GOLD is LOST.

Solution: Use an 80 mesh screen. 80 mesh GOLD is 4X heavier than 80 mesh Cassiterite.

100 mesh GOLD is heavier than 80 mesh cassiterite.

Smaller GOLD requires more screens!

- Geowizard

[Geowizard]

Gravity concentration;

Gravity concentration in GOLD recovery is all about weight.

Fortunately, GOLD is the heavy weight champion!

GOLD, weighing in at 19.32 grams per cc has contenders in the contest to remain in the pan...

The other heavy weight contenders are:

Cassiterite at 7.15 grams per cc.

Hematite at 5.30 grams per cc.

Ilmenite at 4.79 grams per cc.

Magnetite at 5.15 grams per cc.

Arsenopyrite at 6.07 grams per cc.

Cinnabar at 8.1 grams per cc.

Uraninite at 8.72 grams per cc.

Chalcopyrite at 4.19 grams per cc.

That's the short list.

- Geowizard

[Geowizard]

Gravity is free!

Because we don't have pay for GRAVITY (yet)...

Gravity is a very popular way of recovering GOLD!

Another FREE resource is the realm of cyberspace where many very useful reports may be found.

important resources include the Mineral Industry Research Laboratory Reports.

The first report I can recommend is MIRL Report No. 76:

"A Study of Factors Suspected of Influencing the Settling Velocity of Fine GOLD Particles",

Here's a link: http://www.alaska-gold.com/mirl_n76.pdf

This report provides an important reference to the fundamental methods of GOLD recovery.

- Geowizard