Gold Hog - Classifying
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Classification of Material
We could end up writing a whole book on this subject based on
all the conditions, equipment and settings each operator has. We will offer
some advice and maybe open up some “different thoughts” for you to chew on.
Before you begin.... keep this image in your mind.
These are "pickers" that would NOT go through a 1/8" screen.
HUGE???? Not really. The metal thing on the right is a ball point pen.
For most people, and the common rule, they classify to reduce large rocks
from building up in their sluice. Classifying also allows you to reduce the
water flow and pitch of your sluice bed. Smaller / lighter material requires
less “force” to push it down and out. Pretty simple right?
Most miners have riffles in their sluice. Larger rocks can
easily stop in front of, behind, or in-between these riffles. When this
happens, the ARMP action of the sluice is reduced to
ZERO in that area. Vortexes collapse, matting is covered, and no flow is
occurring. Not a good thing at all.
So, if we can classify down to very small material we can
reduce the water flow and the pitch and offer a better “sluice environment”
for catching gold, especially fine gold. Making more sense?
Now let’s explore a few thoughts…
The dream nugget theory…
Here is a simple “thought process” that might help many. Most dream about a
BIG nugget in their sluice. For the average miner it rarely, if ever occurs;
especially those working areas for placer gold. (Fine) So I want you to
imagine your “realistic dream nugget” for the area you are working. For many
a ¼” nugget is really big. Seriously… give this some thought and pick your
number… Now I want you to add 1/8” to that number. (Let’s be safe and save
you some sleep.) So, if your “once in a lifetime nugget” is 1/4”, you will
add 1/8” and screen to 3/8”. Get it? You picked the number, now we added
1/8”, just to be safe.
So screening, classifying or setting your grizzly / classification bars to
this level will actually produce more gold recovery. You can reduce your
water flow and pitch and have a better chance of catching all sizes of gold.
Washing large rocks…
Most miners know that large rocks have “material” stuck to them. Sometimes
this material may also contain gold. So, if at all possible we want an
“integrated” classification system on our equipment that will both classify
material down while also washing larger rocks prior to them being ejected.
Not an easy task for some equipment. However, if done properly this one
step can greatly increase recover rates.
Remember, we DO NOT want these large rocks rolling down our sluice bed.
Even the largest mining operations in operation today know that this is
critical. Huge equipment, moving tons and tons of material down massive
sluices and guess what? All the material is classified down to ½”.
Removing the “riffles”…
Classification is an important part of good recovery, however we think that
understanding WHY you classify is even more important. Experiment with your
equipment, do tests, and as always adjust to what works best for you.
What? Remove the riffles?
Don’t flip out just yet, read on.
Since riffles often cause may “hang up” issues it only makes sense to look
at removing them. If you can’t classify material, or don’t want to decrease
material run from classifying (often manual feeding) then it makes sense to
remove the obstacles that are causing the losses / blockages. Also, this
gives material run a different area in the sluice with more settling action.
This is one recommendation we often give to commercial operations. We
suggest that they convert at least a “portion” of their sluice bed into a
riffle-less design. We want an EASY FLOW / EASY ROLL section that has very
little restrictions, obstacles, or barriers that might slow down or hold
large rocks. It also offers a VERY SMOOTH water flow section with almost no
turbulence or material “throw up”. Remember the golden rule… GOLD FALLS
FAST. (1mm sphere drops approximately 48” per second through water.)
As an example, we often remove 1/3 of their riffled sluice bed and install
small ½” expanded metal over our Gold Hog UR mat.
This creates a section that allows ALL rocks to gently tumble down, yet
provides an extremely active fluid bed like bottom where gold simply CAN’T
escape. We often like to see this section up high in the sluice bed, and
once installed the operators are generally amazed that super fine gold is
now being caught and held in the upper portions of their sluice even on long
This takes a little “mental visualization” on your behalf. Picture it if
you can, a sluice bed that is 24” wide and 20 feet long. The entire sluice
is set up with riffles all the way down. Some call this the definition of
“Repeating the same action over and over expecting different results”.
Why would you do this? Our studies have shown you are much better off
exposing the SAME material to DIFFERENT “capture environments” during its
run down your sluice. (If you have the room.) Maybe it’s flat gold… maybe
it’s wire gold… maybe it’s super fine gold…maybe it’s a round nugget that
like to roll… who knows? Maybe you are creating too much turbulence all the
way down and not allowing for “quiet zones”? But for some reason it keeps
“traveling” and not settling or being captured.
Not only can this help commercial operations, but all prospectors as well.
Look at your equipment and visualize it. This often is great improvement to
a simple “stream sluice”. Since water flow is often gentle / limited,
having the entire sluice lined with nothing but ½” expanded and UR matting
allows material to move freely and still offer tremendous capture ability.